mm(1): error out when given positional arguments

Reviewed-on: bonsai/coreutils#28

.editorconfig

@@ -0,0 +1,14 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = tab
+indent_size = 4
+insert_final_newline = true
+
+[*akefile]
+indent_size = 2
+
+[*.sh]
+indent_size = 2

.gitignore

@@ -1 +1,2 @@
 build/
+dist/

CONTRIBUTING

@@ -90,26 +90,44 @@ notice:
  *     USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-When writing code, make sure lines never exceed 80 characters in width when
+Make sure lines never exceed 80 columns in width when using four-character
-using two-character-wide tabs.
+indentation steps. This helps contributors with smaller screens, those using
+side-by-side editor windows or panes, and those who have no text wrapping in
+their editor or terminal.
 
-For usage text and help messages, please do not implement a -h option. Just
+For usage text and help messages, do not implement a -h option. Instead, print
-print usage information when any erroneous option is specified. Follow the
+usage information when any erroneous option is specified. Follow the NetBSD
-NetBSD style guide for usage text output format [1].
+style guide for the usage text’s output format [1].
 
-If committing a new source file for a utility, format the commit message like
+[1] <http://cvsweb.netbsd.org/bsdweb.cgi/~checkout~/src/share/misc/style>
-this:
 
-$ git commit -m 'tool(1): <information>'
+If committing a new source file, format the commit message following these
+guidelines:
+
+$ git commit -m 'tool(1): add feature x'
 
 If committing a new library or header file:
 
-$ git commit -m 'library(1): <information>'
+$ git commit -m 'library(3): fix overflow'
+$ git commit -m 'header.h(3): add header.h(3)'
+
+If committing a new manual page:
+
+$ git commit -m 'tool.1: add author details'
 
 If modifying some other file or directory:
 
-$ git commit -m 'README: clarification'
+$ git commit -m 'README: clarify'
-$ git commit -m 'tests: posix: fixed bug #47'
+$ git commit -m 'tests/posix: fix bug #47'
-$ git commit -m 'docs: tool(1): added author information'
 
-etc.
+For multiple of these:
+
+$ git commit -m 'Makefile, tool(1): add tool(1)'
+$ git commit -m 'tool(1): add tool(1); library(3), library.3: add library(3)'
+$ git commit -m 'tool(1): fix #42 & add feature x'
+
+Commit messages should be written in the present tense.
+
+--
+This work © 2023–2024 by Emma Tebibyte is licensed under CC BY-SA 4.0. To view a
+copy of this license, visit <http://creativecommons.org/licenses/by-sa/4.0/>

GNUmakefile

@@ -1,73 +0,0 @@
-# Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
-# Copyright (c) 2023 DTB <trinity@trinity.moe>
-# SPDX-License-Identifier: FSFAP
-#
-# Copying and distribution of this file, with or without modification, are
-# permitted in any medium without royalty provided the copyright notice and this
-# notice are preserved.  This file is offered as-is, without any warranty.
-
-# If we want to use POSIX make we can’t use ifeq
-# .POSIX:
-# .PRAGMA: posix_202x
-.PHONY: clean
-.PHONY: install
-.PHONY: test
-
-PREFIX=/usr/local
-CC=cc
-CFLAGS=-O3 -Lbuild
-
-ifeq ($(CC), gcc)
-	CFLAGS=-O3 -s -Wl,-z,noseparate-code,-z,nosectionheader -flto -Lbuild
-endif
-
-ifeq ($(CC), clang)
-	CFLAGS=-O3 -Wall -Lbuild
-endif
-
-ifeq ($(CC), tcc)
-	CFLAGS=-O3 -s -Wl -flto -Lbuild
-endif
-
-build: build_dir false intcmp scrut str strcmp true
-
-build_dir:
-	mkdir -p build
-
-clean:
-	rm -rf build/
-
-install: build
-	mkdir -p $(PREFIX)/bin $(PREFIX)/lib $(PREFIX)/man/man1 $(PREFIX)/man/man3
-	cp -f build/*.o $(PREFIX)/lib/
-	cp -f build/*.so $(PREFIX)/lib/
-	cp -f build/* $(PREFIX)/bin/
-	cp -f docs/*.1 $(PREFIX)/man/man1/
-	cp -f docs/*.3 $(PREFIX)/man/man3/
-
-test: build
-	tests/cc-compat.sh
-	tests/posix-compat.sh
-
-false: src/false.c build_dir
-	$(CC) $(CFLAGS) -o build/false src/false.c
-
-intcmp: src/intcmp.c build_dir
-	$(CC) $(CFLAGS) -o build/intcmp src/intcmp.c
-
-scrut: src/scrut.c libfileis build_dir
-	$(CC) $(CFLAGS) -lfileis -o build/scrut src/scrut.c
-
-str: src/str.c build_dir
-	$(CC) $(CFLAGS) -o build/str src/str.c
-
-strcmp: src/strcmp.c build_dir
-	$(CC) $(CFLAGS) -o build/strcmp src/strcmp.c
-
-true: src/true.c build_dir
-	$(CC) $(CFLAGS) -o build/true src/true.c
-
-libfileis: src/libfileis.c src/libfileis.h build_dir
-	$(CC) $(CFLAGS) -c -fPIC -o build/libfileis.o src/libfileis.c
-	$(CC) -shared -o build/libfileis.so build/libfileis.o
-

Makefile

@@ -0,0 +1,141 @@
+# Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+# Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
+# Copyright (c) 2023 Sasha Koshka <sashakoshka@tebibyte.media>
+# Copyright (c) 2024 Aaditya Aryal <aryalaadi123@gmail.com>
+# SPDX-License-Identifier: FSFAP
+#
+# Copying and distribution of this file, with or without modification, are
+# permitted in any medium without royalty provided the copyright notice and this
+# notice are preserved.  This file is offered as-is, without any warranty.
+
+.POSIX:
+
+# if using BSD make(1), remove these pragmas because they break it
+.PRAGMA: posix_202x # future POSIX standard support à la pdpmake(1)
+.PRAGMA: command_comment # breaks without this?
+
+DESTDIR ?= dist
+PREFIX ?= /usr/local
+
+SYSEXITS != printf '\043include <sysexits.h>\n' | cpp -M - | sed 's/ /\n/g' \
+	| sed -n 's/sysexits\.h//p' || printf 'include\n'
+
+CC ?= cc
+RUSTC ?= rustc
+RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
+	--extern sysexits=build/o/libsysexits.rlib \
+	--extern strerror=build/o/libstrerror.rlib
+CFLAGS += -I$(SYSEXITS)
+
+.PHONY: all
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
+
+build:
+	# keep build/include until bindgen(1) has stdin support
+	# https://github.com/rust-lang/rust-bindgen/issues/2703
+	mkdir -p build/bin build/include build/lib build/o build/test
+
+.PHONY: clean
+clean:
+	rm -rf build dist
+
+dist: all
+	mkdir -p $(DESTDIR)/$(PREFIX)/bin $(DESTDIR)/$(PREFIX)/share/man/man1
+	cp build/bin/* $(DESTDIR)/$(PREFIX)/bin
+	cp docs/*.1 $(DESTDIR)/$(PREFIX)/share/man/man1
+
+.PHONY: install
+install: dist
+	cp -r $(DESTDIR)/* /
+
+.PHONY: test
+test: build
+	tests/posix-compat.sh
+	$(RUSTC) --test src/getopt-rs/lib.rs -o build/test/getopt
+
+.PHONY: rustlibs
+rustlibs: build/o/libsysexits.rlib build/o/libgetopt.rlib \
+	build/o/libstrerror.rlib
+
+build/o/libgetopt.rlib: build src/getopt-rs/lib.rs
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=getopt \
+		-o $@ src/getopt-rs/lib.rs
+
+build/o/libstrerror.rlib: build src/strerror.rs
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib -o $@ \
+		src/strerror.rs
+
+build/o/libsysexits.rlib: build $(SYSEXITS)sysexits.h
+	# bandage solution until bindgen(1) gets stdin support
+	printf '#define EXIT_FAILURE 1\n' | cat - $(SYSEXITS)sysexits.h \
+		> build/include/sysexits.h 
+	bindgen --default-macro-constant-type signed --use-core --formatter=none \
+		build/include/sysexits.h | $(RUSTC) $(RUSTFLAGS) --crate-type lib -o $@ -
+
+.PHONY: dj
+dj: build/bin/dj
+build/bin/dj: src/dj.c build
+	$(CC) $(CFLAGS) -o $@ src/dj.c
+
+.PHONY: false
+false: build/bin/false
+build/bin/false: src/false.c build
+	$(CC) $(CFLAGS) -o $@ src/false.c
+
+.PHONY: fop
+fop: build/bin/fop
+build/bin/fop: src/fop.rs build rustlibs
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/fop.rs
+
+.PHONY: hru
+hru: build/bin/hru
+build/bin/hru: src/hru.rs build rustlibs 
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/hru.rs
+
+.PHONY: intcmp
+intcmp: build/bin/intcmp
+build/bin/intcmp: src/intcmp.c build
+	$(CC) $(CFLAGS) -o $@ src/intcmp.c
+
+.PHONY: mm
+mm: build/bin/mm
+build/bin/mm: src/mm.c build
+	$(CC) $(CFLAGS) -o $@ src/mm.c
+
+
+.PHONY: npc
+npc: build/bin/npc
+build/bin/npc: src/npc.c build
+	$(CC) $(CFLAGAS) -o $@ src/npc.c
+
+.PHONY: rpn
+rpn: build/bin/rpn
+build/bin/rpn: src/rpn.rs build rustlibs
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/rpn.rs
+
+.PHONY: scrut
+scrut: build/bin/scrut
+build/bin/scrut: src/scrut.c build
+	$(CC) $(CFLAGS) -o $@ src/scrut.c
+
+.PHONY: str
+str: build/bin/str
+build/bin/str: src/str.c build
+	$(CC) $(CFLAGS) -o $@ src/str.c
+
+.PHONY: strcmp
+strcmp: build/bin/strcmp
+build/bin/strcmp: src/strcmp.c build
+	$(CC) $(CFLAGS) -o $@ src/strcmp.c
+
+.PHONY: swab
+swab: build/bin/swab
+build/bin/swab: src/swab.rs build build/o/libsysexits.rlib
+	$(RUSTC) $(RUSTFLAGS) --extern getopt=build/o/libgetopt.rlib \
+		--extern sysexits=build/o/libsysexits.rlib \
+		-o $@ src/swab.rs
+
+.PHONY: true
+true: build/bin/true
+build/bin/true: src/true.c build
+	$(CC) $(CFLAGS) -o $@ src/true.c

README

@@ -17,6 +17,31 @@ purposes beyond its scope.
 
 See docs/ for more on the specific utilities currently implemented.
 
+Building
+
+The coreutils require a POSIX-compliant environment to compile, including a C
+compiler and preprocessor (cc(1) and cpp(1) by default) with the -idirafter
+flag, a Rust compiler (rustc(1) by default), bindgen(1), and a POSIX-compliant
+make(1) utility.
+
+To build and install:
+
+$ make
+$ make PREFIX="/your/preferred/location" install
+
+To build with a different compiler than the default:
+
+$ make CC=clang
+$ make RUSTC=gccrs
+
+To test the utilities:
+
+$ make test
+
+To remove all untracked files:
+
+$ make clean
+
 Read More
 
 An Introduction to the Unix Shell
@@ -30,3 +55,10 @@ Master Foo Discourses on the Unix-Nature
 
 Shell Programming!
 <https://tldp.org/LDP/abs/html/why-shell.html>
+
+--
+Copyright © 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+Copyright © 2024 DTB <trinity@trinity.moe>
+
+This work is licensed under CC BY-SA 4.0. To view a copy of this license, visit
+<http://creativecommons.org/licenses/by-sa/4.0/>.

docs/dj.1

@@ -0,0 +1,160 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH dj 1
+
+.SH NAME
+
+dj \(en disk jockey
+
+.SH SYNOPSIS
+
+dj
+.RB ( -AdHnq )
+.RB ( -a
+.RB [ byte ])
+.RB ( -c
+.RB [ count ])
+
+.RB ( -i
+.R [
+.B input file
+.R ])
+.RB ( -b
+.R [
+.B input block size
+.R ])
+.RB ( -s
+.R [
+.B input offset
+.R ])
+
+.RB ( -o
+.R [
+.B output file
+.R ])
+.RB ( -B
+.R [
+.B output block size
+.R ])
+.RB ( -S
+.R [
+.B output offset
+.R ])
+
+.SH USAGE
+
+The
+.B -i
+option takes a path as an argument to open and use in place of standard input.
+The
+.B -o
+option does the same in place of standard output. Dj does not truncate output
+files and instead writes over the bytes in the existing file.
+.PP
+The
+.B -b
+option takes a numeric argument as the size in bytes of the input buffer and
+the
+.B -B
+option does the same for the output buffer, the default for both being 1024
+bytes, or one kibibyte (KiB).
+.PP
+The
+.B -s
+option takes a numeric argument as the number of bytes to skip into the input
+before starting to read, and the
+.B -S
+option skips a number of bytes through the output before starting to write from
+the input. If the input is a stream the bytes are read and discarded. If the
+output is a stream, nul characters are printed.
+.PP
+The
+.B -a
+option takes one argument of one byte in length and pads the input buffer with
+that byte in the event that a read doesn't fill the input buffer, and the
+.B -A
+option takes no arguments and pads with nuls.
+The
+.B -c
+option specifies an amount of reads to make, and if 0 (the default) dj will
+continue reading until a partial or empty read.
+.PP
+On a partial or empty read, dj prints a diagnostic message (unless the
+.B -q
+option is specified) and exits (unless the
+.B -n
+option is specified, in which case only two consecutive empty reads will cause
+dj to exit).
+At exit, usage statistics are printed unless the option
+.B -q
+is specified a second time. The
+.B -H
+option will make these diagnostics human-readable.
+
+.SH DIAGNOSTICS
+
+The
+.B -d
+option prints all information, user-specified or otherwise, before program
+execution.
+.PP
+When dj exits, by default statistics are printed for input and output to
+standard error in the following format:
+.PP
+.R {records read} {ASCII unit separator} {partial records read}
+.R {ASCII record separator} {records written} {ASCII unit separator}
+.R {partial records written} {ASCII group separator} {bytes read}
+.R {ASCII record separator} {bytes written} {ASCII file separator}
+.PP
+If the
+.B -H
+option is specified dj instead uses this following format:
+.PP
+.R {records read} '+' {partial records read} '>' {records written}
+.R '+' {partial records written} ';' {bytes read} '>' {bytes written}
+.R {ASCII line feed}
+.PP
+The
+.B -q
+option suppresses error messages which print when a read or write is partial or
+empty and when used twice suppresses diagnostic output entirely.
+.PP
+In non-recoverable errors that don't pertain to dj's read-write cycle, a
+diagnostic message is printed and dj exits with the appropriate sysexits(3)
+status.
+
+.SH BUGS
+
+If
+.B -n
+is specified along with a specified count, actual byte output may be lower than
+expected (the product of the count multiplied by the input block size). If the
+.B -a
+or
+.B -A
+options are used this could make data written nonsensical.
+.PP
+Many lowercase options have capitalized variants and vice-versa which can be
+confusing. Capitalized options tend to affect output or are more intense
+versions of lowercase options.
+
+.SH RATIONALE
+
+Dj was modeled after the dd utility specified in POSIX but adds additional
+features: typical option formatting, allowing seeks to be specified in bytes
+rather than in blocks, allowing arbitrary bytes as padding, and printing in a
+format that's easy to parse for machines. It also neglects character
+conversion, which may be dd's original intent but is irrelevant to its modern
+use.
+
+.SH COPYRIGHT
+
+Copyright (C) 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+dd(1)

docs/false.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 2022 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2022, 2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
@@ -32,4 +32,4 @@ This work is marked with CC0 1.0. To see a copy of this license, visit
 
 .SH SEE ALSO
 
-true(1)
+true(1p)

docs/hru.1

@@ -0,0 +1,57 @@
+.\" Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH rpn 1
+
+.SH NAME
+
+hru \(en human readable units
+
+.SH SYNOPSIS
+
+hru
+
+.SH DESCRIPTION
+
+Hru reads byte counts in the form of whole numbers from the standard input and
+writes to the standard output the same number converted one of the units of data
+defined by the International System of Units.
+
+The program will convert the byte count to the highest unit possible where the
+value is greater than one.
+
+.SH DIAGNOSTICS
+
+If encountering non-integer characters in the standard input, hru will exit with
+the appropriate error code as defined by sysexits.h(3) and print an error
+message.
+
+.SH RATIONALE
+
+The GNU project’s ls(1) implementation contains a human-readable option (-h)
+that, when specified, makes the tool print size information in a format more
+immediately readable. This functionality is useful not only in the context of
+ls(1) so the decision was made to split it into a new tool. The original
+functionality in GNU’s ls(1) can be emulated with fop(1) combined with this
+program.
+
+.SH STANDARDS
+
+Hru follows the standard unit prefixes as specified by the Bureau International
+des Poids et Mesures (BIPM) in the ninth edition of The International System of
+Units (SI).
+
+.SH AUTHOR
+
+Written by Emma Tebibyte <emma@tebibyte.media>.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 Emma Tebibyte. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+GNU ls(1), The International System of Units (SI) 9th Edition

docs/intcmp.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 2023 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
@@ -75,4 +75,4 @@ Copyright © 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
 
 .SH SEE ALSO
 
-strcmp(1), scrut(1), str(1), test(1)
+strcmp(1), scrut(1), str(1), test(1p)

docs/mm.1

@@ -0,0 +1,76 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH mm 1
+
+.SH NAME
+
+mm \(en middleman
+
+.SH SYNOPSIS
+
+mm
+.RB ( -aenu )
+.RB ( -i
+.RB [ input ])
+.RB ( -o
+.RB [ output ])
+
+.SH DESCRIPTION
+
+Mm catenates input files and writes them to the start of each output file.
+
+.SH OPTIONS
+
+Mm, upon receiving the
+.B -a
+option, will open subsequent outputs for appending rather than updating.
+.PP
+The
+.B -i
+option opens a path as an input. Without any inputs specified mm will use
+standard input. Standard input itself can be specified by giving the path '-'.
+.PP
+The
+.B -o
+option opens a path as an output. Without any outputs specified mm will use
+standard output. Standard output itself can be specified by giving the
+path '-'. Standard error itself can be specified with the
+.B -e
+option.
+.PP
+The
+.B -u
+option ensures neither input or output will be buffered.
+.PP
+The
+.B -n
+option tells mm to ignore SIGINT signals.
+
+.SH DIAGNOSTICS
+
+If an output can no longer be written mm prints a diagnostic message, ceases
+writing to that particular output, and if there are more outputs specified,
+continues, eventually exiting unsuccessfully.
+.PP
+On error mm prints a diagnostic message and exits with the appropriate
+sysexits.h(3) status.
+
+.SH BUGS
+
+Mm does not truncate existing files, which may lead to unexpected results.
+
+.SH RATIONALE
+
+Mm was modeled after the cat and tee utilities specified in POSIX.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+cat(1p), dd(1), dj(1), tee(1p)

docs/npc.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 2023 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
@@ -62,7 +62,7 @@ Copyright © 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
 
 .SH SEE ALSO
 
-cat(1), cat-v(1)
+cat(1p), cat-v(1)
 
 .I UNIX Style, or cat -v Considered Harmful
 by Rob Pike

docs/rpn.1

@@ -0,0 +1,70 @@
+.\" Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH rpn 1
+
+.SH NAME
+
+rpn \(en reverse polish notation evaluation
+
+.SH SYNOPSIS
+
+rpn
+.RB [numbers...]\ [operators...]
+
+.SH DESCRIPTION
+
+Rpn evaluates reverse polish notation expressions either read from the standard
+input or parsed from provided arguments. See the STANDARD INPUT section.
+
+Upon evaluation, rpn will print the resulting number on the stack to the
+standard output. Any further specified numbers will be placed at the end of the
+stack.
+
+For information on for reverse polish notation syntax, see rpn(7).
+
+.SH STANDARD INPUT
+
+If arguments are passed to rpn, it interprets them as an expression to be
+evaluated. Otherwise, it reads whitespace-delimited numbers and operations from
+the standard input.
+
+.SH DIAGNOSTICS
+
+If encountering a syntax error, rpn will exit with the appropriate error code
+as defined by sysexits.h(3) and print an error message.
+
+.SH CAVEATS
+
+Due to precision constraints and the way floats are represented in accordance
+with the IEEE Standard for Floating Point Arithmetic (IEEE 754), floating-point
+arithmetic has rounding errors. This is somewhat curbed by using the
+machine epsilon as provided by the Rust standard library to which to round
+numbers. Because of this, variation is expected in the number of decimal places 
+rpn can handle based on the platform and hardware of any given machine.
+
+.SH RATIONALE
+
+An infix notation calculation utility, bc(1p), is included in the POSIX
+standard, but does not accept expressions as arguments; in scripts, any
+predefined, non-interactive input must be piped into the program. A dc(1)
+pre-dates the standardized bc(1p), the latter originally being a preprocessor
+for the former, and was included in UNIX v2 onward. While it implements reverse
+polish notation, it still suffers from being unable to accept an expression as
+an argument.
+
+.SH AUTHOR
+
+Written by Emma Tebibyte <emma@tebibyte.media>.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 Emma Tebibyte. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+bc(1p), dc(1), rpn(7), IEEE 754

docs/scrut.1

@@ -0,0 +1,93 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH scrut 1
+
+.SH NAME
+
+scrut \(en scrutinize file properties
+
+.SH SYNOPSIS
+
+scrut
+.RB ( -bcdefgkprsuwxLS )
+.RB [ file... ]
+
+.SH DESCRIPTION
+
+Scrut determines if given files comply with the opted requirements.
+
+.SH OPTIONS
+
+.B -b
+requires the given files to exist and be block special files.
+.PP
+.B -c
+requires the given files to exist and be character special files.
+.PP
+.B -d
+requires the given files to exist and be directories.
+.PP
+.B -e
+requires the given files to exist, and is redundant to any other option.
+.PP
+.B -e
+requires the given files to exist and be regular files.
+.PP
+.B -g
+requires the given files to exist and have their set group ID flags set.
+.PP
+.B -k
+requires the given files to exist and have their sticky bit set.
+.PP
+.B -p
+requires the given files to exist and be named pipes.
+.PP
+.B -r
+requires the given files to exist and be readable.
+.PP
+.B -u
+requires the given files to exist and have their set user ID flags set.
+.PP
+.B -w
+requires the given files to exist and be writable.
+.PP
+.B -x
+requires the given files to exist and be executable.
+.PP
+.B -L
+requires the given files to exist and be symbolic links.
+.PP
+.B -S
+requires the given files to exist and be sockets.
+
+.SH EXIT STATUS
+
+Scrut prints a debug message and exits unsuccessfully with the appropriate
+sysexits.h(3) error code if invoked incorrectly. Scrut exits successfully if
+the given files comply with their requirements and unsuccessfully otherwise.
+
+.SH STANDARDS
+
+Scrut is nearly compatible with POSIX's test utility though it is narrower in
+scope. Notably, the
+.B -h
+option is now invalid and therefore shows usage information instead of being an
+alias to the modern
+.B -L
+option.
+
+.SH AUTHOR
+
+Written by DTB <trinity@trinity.moe>.
+
+.SH COPYRIGHT
+
+Copyright © 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+access(3p), lstat(3p), test(1p)

docs/str.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 2023 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
@@ -55,4 +55,4 @@ Copyright © 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
 
 .SH SEE ALSO
 
-ctype(3), strcmp(1), ascii(7)
+ctype(3p), strcmp(1), ascii(7)

docs/strcmp.1

@@ -1,10 +1,9 @@
-.\" Copyright (c) 2023 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
 .\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
 
-
 .TH STRCMP 1
 
 .SH NAME
@@ -60,4 +59,4 @@ Copyright © 2023 DTB. License AGPLv3+: GNU AGPL version 3 or later
 
 .SH SEE ALSO
 
-strcmp(3), intcmp(1), scrut(1), test(1)
+strcmp(3), intcmp(1), scrut(1), test(1p)

docs/swab.1

@@ -0,0 +1,71 @@
+.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
+.\"
+.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
+.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
+
+.TH swab 1
+
+.SH NAME
+
+swab \(en swap bytes
+
+.SH SYNOPSIS
+
+swab
+.RB ( -f )
+.RB ( -w
+.R [
+.B word size
+.R ])
+
+.SH USAGE
+
+Swab swaps the latter and former halves of a block of bytes.
+
+.SH EXAMPLES
+
+The following sh(1p) line:
+
+.R printf 'hello world!\n' | swab
+
+Produces the following output:
+
+.R ehll oowlr!d
+
+.SH OPTIONS
+
+The
+.B -f
+option ignores system call interruptions.
+.PP
+The
+.B -w
+option configures the word size; that is, the size in bytes of the block size
+on which to operate. By default the word size is 2. The word size must be
+cleanly divisible by 2, otherwise the block of bytes being processed can't be
+halved.
+
+.SH DIAGNOSTICS
+
+If an error is encountered in input, output, or invocation, a diagnostic
+message will be written to standard error and swab will exit with the
+appropriate status from sysexits.h(3).
+
+.SH RATIONALE
+
+Swab was modeled after the
+.R conv=swab
+functionality specified in the POSIX dd utility but additionally allows the
+word size to be configured.
+.PP
+Swab is useful for fixing the endianness of binary files produced on other
+machines.
+
+.SH COPYRIGHT
+
+Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/agpl.html>.
+
+.SH SEE ALSO
+
+dd(1p)

docs/true.1

@@ -1,4 +1,4 @@
-.\" Copyright (c) 2022 DTB <trinity@trinity.moe>
+.\" Copyright (c) 2022, 2024 DTB <trinity@trinity.moe>
 .\" Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
 .\"
 .\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
@@ -32,4 +32,4 @@ This work is marked with CC0 1.0. To see a copy of this license, visit
 
 .SH SEE ALSO
 
-false(1)
+false(1p)

include/sysexits.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2023 DTB <trinity@trinity.moe>
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: CC0
+ *
+ * This work is marked with CC0 1.0. To view a copy of this license, visit
+ * <http://creativecommons.org/publicdomain/zero/1.0>.
+ */
+
+#ifndef _SYSEXITS_H
+#define _SYSEXITS_H 2
+
+#ifndef EXIT_FAILURE
+#include <stdlib.h>
+#endif
+
+#define EX_OK EXIT_SUCCESS
+
+#define EX__BASE EXIT_FAILURE /* base value for error messages */
+#define EX_USAGE EXIT_FAILURE /* command line usage error */
+#define EX_DATAERR EXIT_FAILURE /* data format error */
+#define EX_NOINPUT EXIT_FAILURE /* cannot open input */
+#define EX_NOUSER EXIT_FAILURE /* addressee unknown */
+#define EX_NOHOST EXIT_FAILURE /* host name unknown */
+#define EX_UNAVAILABLE EXIT_FAILURE /* service unavailable */
+#define EX_SOFTWARE EXIT_FAILURE /* internal software error */
+#define EX_OSERR EXIT_FAILURE /* system error (e.g., can't fork) */
+#define EX_OSFILE EXIT_FAILURE /* critical OS file missing */
+#define EX_CANTCREAT EXIT_FAILURE /* can't create (user) output file */
+#define EX_IOERR EXIT_FAILURE /* input/output error */
+#define EX_TEMPFAIL EXIT_FAILURE /* temp failure; user is invited to retry */
+#define EX_PROTOCOL EXIT_FAILURE /* remote error in protocol */
+#define EX_NOPERM EXIT_FAILURE /* permission denied */
+#define EX_CONFIG EXIT_FAILURE /* configuration error */
+
+#define EX__MAX EXIT_FAILURE /* maximum listed value */
+
+#endif

src/dj.c

@@ -0,0 +1,452 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+#include <ctype.h> /* isupper(3), tolower(3) */
+#include <errno.h> /* errno */
+#include <fcntl.h> /* open(2) */
+#include <stdio.h> /* fprintf(3), stderr */
+#include <stdlib.h> /* free(3), malloc(3), strtol(3), size_t */
+#include <string.h> /* memcpy(3), memmove(3), memset(3) */
+#include <sysexits.h> /* EX_OK, EX_USAGE */
+#include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
+                     * optarg, optind, STDIN_FILENO, STDOUT_FILENO */
+extern int errno;
+
+/* dj uses two structures that respectively correspond to the reading and
+ * writing ends of its jockeyed "pipe". User-configurable members are noted
+ * with their relevant options. */
+struct Io{
+	int bs;			/* buffer size (-bB) */
+	size_t bufuse;	/* buffer usage */
+	char *buf;		/* buffer */
+	int bytes;		/* bytes processed */
+	int fd;			/* file descriptor */
+	int fl;			/* file opening flags */
+	char *fn;		/* file name (may be stdin_name or stdout_name) (-io) */
+	int prec;		/* partial records processed */
+	int rec;		/* records processed */
+	long seek;		/* bytes to seek/skip (will be 0 after skippage) (-sS) */
+} ep[2]; /* "engineered pipe"; also "extended play", for the deejay */
+
+/* Additionally, the following global variables are used to store user options.
+ */
+
+/* (-a)  */ static int align; /* Only the lower 8b are used but align is
+                               * negative if no alignment is being done. */
+
+/* (-c)  */ static int count; /* 0 if dj(1) runs until no more reads are
+                               * possible. */
+
+/* ASCII field separator delimited statistics */
+            static char *fmt_asv   = "%d\037%d\036%d\037%d\035%d\036%d\034";
+/* human-readable statistics */
+            static char *fmt_human = "%d+%d > %d+%d; %d > %d\n";
+/* pointer to chosen formatting */
+/* (-H)  */ static char *fmt_output; /* fmt_asv (default) or fmt_human (-H) */
+
+/* (-dq) */ static char debug;       /*
+ *  -d  increments             dj -qq | 0 - no diagnostic output whatsoever
+ *   -q decrements             dj -q  | 1 - typical output without
+ *                                    |     notifications on partial reads or
+ *                                    |     writes
+ *                             dj     | 2 - typical output (default)
+ *                             dj -d  | 3 - verbose status messages */
+
+/* (-n)  */ static char noerror;     /* 0 - exits on partial reads or writes
+                                      *     (default)
+                                      * 1 - retries on partial reads/writes
+                                      *     (-n) */
+
+/* Non-configurable defaults. */
+#define bs_default 1024 /* GNU dd(1) default; twice POSIX but a neat 2^10 */
+static char *program_name = "<no argv[0]>";
+static char *stdin_name = "<stdin>";
+static char *stdout_name = "<stdout>";
+static int read_flags = O_RDONLY; /* These flags are consistent with Busybox */
+static int write_flags = O_WRONLY | O_CREAT; /* dd(1). */
+
+/* Macro to set defaults for user-configurable options. */
+#define setdefaults do{ \
+	align = -1; \
+	count = 0; \
+	debug = 2; \
+	fmt_output = fmt_asv; \
+	noerror = 0; \
+	ep[0].fl = read_flags; \
+	Io_setdefaults(&ep[0]); \
+	ep[1].fl = write_flags; \
+	Io_setdefaults(&ep[1]); }while(0)
+
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+
+/* Macro to check if fd is a std* file, e.g. stdin. */
+#define fdisstd(fd) \
+		((fd) == STDIN_FILENO \
+		|| (fd) == STDOUT_FILENO \
+		|| (fd) == STDERR_FILENO)
+
+/* Macro to call the cleanup functions that operate on struct io on the
+ * particular io[2] used in main. Error conditions are not checked because this
+ * is only used when the program is about to terminate (hence its name). */
+#define terminate(io) do{ \
+	Io_buffree(&(io)[0]); \
+	Io_buffree(&(io)[1]); \
+	Io_fdclose(&(io)[0]); \
+	Io_fdclose(&(io)[1]); }while(0)
+
+/* Allocates *io's buffer. Returns NULL if unsuccessful. */
+static void *
+Io_bufalloc(struct Io *io){
+
+	return (io->buf = malloc(io->bs * (sizeof *io->buf)));
+}
+
+/* Frees *io's buffer. Returns io. */
+static struct Io *
+Io_buffree(struct Io *io){
+
+	free(io->buf);
+
+	return io;
+}
+
+/* Fills the unused portion of io's buffer with padding, updating io->bufuse.
+ * Returns io. */
+static struct Io *
+Io_bufrpad(struct Io *io, int padding){
+	
+	memset(io->buf + io->bufuse, padding, io->bs - io->bufuse);
+	io->bufuse = io->bs;
+
+	return io;
+}
+
+/* Copies from the buffer in src as much as possible to the free space in the
+ * dest buffer, removing the copied units from src and permuting the remaining
+ * units in the src buffer to the start of the buffer, modifying both the src
+ * and dest bufuse and returning dest. */
+static struct Io*
+Io_bufxapp(struct Io *dest, struct Io *src){
+	int n;
+
+	n = MIN(src->bufuse, dest->bs - dest->bufuse);
+	memcpy(dest->buf + dest->bufuse, src->buf, n);
+	dest->bufuse += n;
+	memmove(src->buf, src->buf + n, src->bs - n);
+	src->bufuse -= n;
+
+	return dest;
+}
+
+/* Copies from the buffer in src to the buffer in dest no more than n units,
+ * removing the copied units from src and permuting the remaining units in the
+ * src buffer to the start of the buffer, modifying both the src and dest
+ * bufuse and returning dest. */
+static struct Io*
+Io_bufxfer(struct Io *dest, struct Io *src, int n){
+
+	memcpy(dest->buf, src->buf, (dest->bufuse = n));
+	memmove(src->buf, src->buf + n, (src->bufuse -= n));
+
+	return dest;
+}
+
+/* Closes io->fn and returns -1 on error, otherwise io->fd. */
+static int
+Io_fdclose(struct Io *io){
+
+	return fdisstd(io->fd)
+		? 0
+		: close(io->fd);
+}
+
+/* Opens io->fn and saves the file descriptor into io->fd. Returns io->fd,
+ * which will be -1 if an error occured. */
+static int
+Io_fdopen(struct Io *io, char *fn){
+	int fd;
+	
+	if((fd = open(fn, io->fl,
+					/* these are the flags used by touch(1p) */
+					S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH))
+				!= -1
+			&& Io_fdclose(io) == 0){
+		io->fd = fd;
+		io->fn = fn;
+	}
+
+	return fd;
+}
+
+/* Seeks io->seek bytes through *io's file descriptor, (counter-intuitively)
+ * returning -1 if successful and a sysexits.h exit code if an unrecoverable
+ * error occurred. io->buf will be cleared of useful bytes and io->seek will
+ * be set to zero to indicate the seek occurred. */
+static int
+Io_fdseek(struct Io *io){
+	int (*op)(int, void *, size_t);
+	
+	if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
+		return -1;
+
+	/* repeated code to get the condition out of the loop */
+	if(io->fl == write_flags){
+		memset(io->buf, '\0', io->bs);
+		/* We're going to cheat and use bufuse as the retval for write(2),
+		 * which is fine because it'll be zeroed as this function returns
+		 * anyway. */
+		do{
+			if((io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = write(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else if(io->fl == read_flags){
+		do{
+			if((io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek)))
+					== 0)
+				/* second chance */
+				io->bufuse = read(io->fd, io->buf, MIN(io->bs, io->seek));
+		}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	}else
+		return EX_SOFTWARE;
+
+	io->bufuse = 0;
+
+	return -1;
+}
+
+/* Reads io->bs bytes from *io's file descriptor into io->buf, storing the
+ * number of read bytes in io->bufuse and updating io->bytes. If io->bufuse is
+ * 0, errno will probably be set. Returns io. */
+static struct Io *
+Io_read(struct Io *io){
+
+	io->bytes += (io->bufuse = read(io->fd, io->buf, io->bs));
+
+	return io;
+}
+
+/* Sets the variables in a struct *io to the defaults. Identifies the read/
+ * write ends of the "pipe" by checking io->fl. Returns io. */
+static struct Io *
+Io_setdefaults(struct Io *io){
+
+	io->bs = bs_default;
+	io->buf = NULL;
+	io->bytes = 0;
+	io->fd = (io->fl == read_flags) ? STDIN_FILENO : STDOUT_FILENO;
+	io->fn = (io->fl == read_flags) ? stdin_name   : stdout_name;
+	io->prec = 0;
+	io->rec = 0;
+	io->seek = 0;
+
+	return io;
+}
+
+/* Writes io->bufuse units from io->buf to io->fd, permuting any unwritten
+ * bytes to the start of io->buf and updating io->bufuse. If io->bufuse doesn't
+ * change, errno will probably be set. Returns io. */
+static struct Io *
+Io_write(struct Io *io){
+	int t;
+
+	if((t = write(io->fd, io->buf, io->bufuse)) > 0)
+		memmove(io->buf, io->buf + t, (io->bufuse -= t));
+	io->bytes += t;
+
+	return io;
+}
+
+/* Prints an error message suitable for the event of an operating system error,
+ * with the error itself to be described in the string s. */
+static int
+oserr(char *s){
+
+	fprintf(stderr, "%s: %s: %s\n", program_name, s, strerror(errno));
+
+	return EX_OSERR;
+}
+
+/* Prints statistics regarding the use of dj, particularly partially and
+ * completely read and written records, accessing debug, ep, and fmt_output. */
+static void
+output(void){
+
+	if(debug >= 1)
+		fprintf(stderr, fmt_output,
+			ep[0].rec, ep[0].prec, ep[1].rec, ep[1].prec,
+			ep[0].bytes, ep[1].bytes);
+
+	return;
+}
+
+/* Parses the string s to an integer, returning either the integer or in the
+ * case of an error a negative integer. This is used for argument parsing
+ * (e.g. -B [int]) in dj and no negative integer would be valid anyway. */
+static long
+parse(char *s){
+	long r;
+
+	errno = 0;
+	r = strtol(s, &s, 0);
+	return (*s == '\0' /* no chars left unparsed */ && errno == 0)
+		? r
+		: -1;
+}
+
+static int
+usage(void){
+
+	fprintf(stderr, "Usage: %s (-AdfHqQ) (-a [byte]) (-c [count])\n"
+		"\t(-i [input file]) (-b [input block size]) (-s [input offset])\n"
+		"\t(-o [output file]) (-B [output block size]) (-S [output offset])\n",
+		program_name);
+
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+	int c;
+	int i;
+
+	setdefaults;
+
+	if(argc > 0){
+		program_name = argv[0];
+		while((c = getopt(argc, argv, "a:Ab:B:c:di:hHnqs:S:o:")) != -1)
+			switch(c){
+			case 'i': case 'o':
+				i = (c == 'o');
+				if(optarg[0] == '-' && optarg[1] == '\0'){ /* optarg == "-" */
+					ep[i].fd = (i == 0) ? STDIN_FILENO : STDOUT_FILENO;
+					ep[i].fn = (i == 0) ? stdin_name   : stdout_name;
+					break;
+				}else if(Io_fdopen(&ep[i], optarg) != -1)
+					break;
+				terminate(ep);
+				return oserr(optarg);
+			case 'A': align = '\0'; break;
+			case 'd': ++debug; break;
+			case 'n': noerror = 1; break;
+			case 'H': fmt_output = fmt_human; break;
+			case 'q': --debug; break;
+			case 'a':
+				if(optarg[0] != '\0' && optarg[1] == '\0'){
+					align = optarg[0];
+					break;
+				}
+				/* FALLTHROUGH */
+			case 'c': case 'b': case 's': case 'B': case 'S':
+				if(c == 'c' && (count = parse(optarg)) >= 0)
+					break;
+				i = isupper(c);
+				c = tolower(c);
+				if((c == 'b' && (ep[i].bs = parse(optarg)) > 0)
+						|| (c == 's' && (ep[i].seek = parse(optarg)) >= 0))
+					break;
+				/* FALLTHROUGH */
+			default:
+				terminate(ep);
+				return usage();
+			}
+	}
+
+	if(debug >= 3)
+		fprintf(stderr,
+			"argv0=%s\n"
+			"in=%s\tibs=%d\tskip=%ld\talign=%hhx\tcount=%d\n"
+			"out=%s\tobs=%d\tseek=%ld\tdebug=%2d\tnoerror=%d\n",
+			program_name,
+			ep[0].fn, ep[0].bs, ep[0].seek, align, count,
+			ep[1].fn, ep[1].bs, ep[1].seek, debug, noerror);
+
+	if(argc > optind){
+		terminate(ep);
+		return usage();
+	}
+
+	for(i = 0; i <= 1; ++i){
+		if(Io_bufalloc(&ep[i]) == NULL){
+			fprintf(stderr, "%s: Failed to allocate %d bytes\n",
+				program_name, ep[i].bs);
+			terminate(ep);
+			return EX_OSERR;
+		}else if(ep[i].seek > 0)
+			switch(Io_fdseek(&ep[i])){
+			case EX_OK:
+				output();
+				terminate(ep);
+				return EX_OK;
+			}
+	}
+
+	do{	/* read */
+		Io_read(&ep[0]);
+		if(!noerror && ep[0].bufuse == 0)
+			Io_read(&ep[0]); /* second chance */
+		if(ep[0].bufuse == 0) /* that's all she wrote */
+			break;
+		else if(ep[0].bufuse < ep[0].bs){
+			++ep[0].prec;
+			if(debug >= 2){
+				fprintf(stderr, "%s: Partial read:\n\t", program_name);
+				output();
+			}
+			if(!noerror)
+				count = 1;
+			if(align >= 0)
+				Io_bufrpad(&ep[0], align);
+		}else
+			++ep[0].rec;
+
+		/* write */
+		do{	if(ep[1].bs > ep[0].bs){ /* io[1].bs > io[0].bs */
+				Io_bufxapp(&ep[1], &ep[0]);
+				if(ep[0].bs + ep[1].bufuse <= ep[1].bs && count != 1)
+					continue; /* we could write more */
+			}else
+				Io_bufxfer(&ep[1], &ep[0], MIN(ep[0].bufuse, ep[1].bs));
+
+			c = ep[1].bufuse;
+			Io_write(&ep[1]);
+			if(!noerror && ep[1].bufuse == c)
+				Io_write(&ep[1]); /* second chance */
+			if(c == ep[1].bufuse){ /* no more love */
+				count = 1;
+				break;
+			}else if(c > ep[1].bufuse && ep[1].bufuse > 0){
+				ep[1].prec += 1;
+				if(debug >= 2){
+					fprintf(stderr, "%s: Partial write:\n\t", program_name);
+					output();
+				}
+				if(!noerror)
+					count = 1;
+			}else if(ep[1].bufuse == 0 && c < ep[1].bs)
+				++ep[1].prec;
+			else
+				++ep[1].rec;
+		}while(ep[0].bufuse > 0);
+	}while(count == 0 || --count > 0);
+
+	output();
+	terminate(ep);
+
+	return EX_OK;
+}

src/fop.rs

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	env::args,
+	io::{ Read, stdin, stdout, Write },
+	process::{ Command, exit, Stdio },
+};
+
+extern crate getopt;
+extern crate strerror;
+extern crate sysexits;
+
+use getopt::{ Opt, Parser };
+use strerror::StrError;
+use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
+
+fn main() {
+	let argv = args().collect::<Vec<String>>();
+	let mut d = '␞';
+	let mut arg_parser = Parser::new(&argv, "d:");
+
+	while let Some(opt) = arg_parser.next() {
+		match opt {
+			Ok(Opt('d', Some(arg))) => {
+				let arg_char = arg.chars().collect::<Vec<char>>();
+				if arg_char.len() > 1 {
+					eprintln!("{}: {}: Not a character.", argv[0], arg);
+					exit(EX_USAGE);
+				} else { d = arg_char[0]; }
+			},
+			_ => {},
+		};
+	}
+
+	let index_arg = arg_parser.index();
+	let command_arg = arg_parser.index() + 1;
+
+	argv.get(command_arg).unwrap_or_else(|| {
+		eprintln!("Usage: {} [-d delimiter] index command [args...]", argv[0]);
+		exit(EX_USAGE);
+	});
+
+	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[1], e);
+		exit(EX_DATAERR);
+	});
+
+	let mut buf = String::new();
+	let _ = stdin().read_to_string(&mut buf);
+	let mut fields = buf.split(d).collect::<Vec<&str>>();
+
+	let opts = argv
+		.iter()
+		.clone()
+		.skip(command_arg + 1)
+		.collect::<Vec<&String>>();
+
+	let mut spawned = Command::new(argv.get(command_arg).unwrap())
+		.args(opts)
+		.stdin(Stdio::piped())
+		.stdout(Stdio::piped())
+		.spawn()
+		.unwrap_or_else( |e| {
+			eprintln!("{}: {}: {}", argv[0], argv[command_arg], e.strerror());
+			exit(EX_UNAVAILABLE);
+		});
+
+	let field = fields.get(index).unwrap_or_else(|| {
+		eprintln!(
+			"{}: {}: No such index in input",
+			argv[0],
+			index.to_string(),
+		);
+		exit(EX_DATAERR);
+	});
+
+	if let Some(mut child_stdin) = spawned.stdin.take() {
+		let _ = child_stdin.write_all(field.as_bytes());
+		drop(child_stdin);
+	}
+
+	let output = spawned.wait_with_output().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e.strerror());
+		exit(EX_IOERR);
+	});
+
+	let mut replace = output.stdout.clone();
+
+	if replace.pop() != Some(b'\n') { replace = output.stdout; }
+
+	let new_field = String::from_utf8(replace).unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e);
+		exit(EX_IOERR);
+	});
+
+	fields[index] = &new_field;
+
+	stdout().write_all(
+		fields.join(&d.to_string()).as_bytes()
+	).unwrap_or_else(|e| {
+		eprintln!("{}: {}", argv[0], e.strerror());
+		exit(EX_IOERR);
+	});
+}

src/getopt-rs/error.rs

@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+use std::{ error, fmt };
+
+use crate::ErrorKind::{ self, * };
+
+/// A basic error type for [`Parser`](struct.Parser.html)
+#[derive(Debug, Eq, PartialEq)]
+pub struct Error {
+    culprit: char,
+    kind: ErrorKind,
+}
+
+impl Error {
+    /// Creates a new error using a known kind and the character that caused the
+	/// issue.
+    pub fn new(kind: ErrorKind, culprit: char) -> Self {
+        Self { culprit, kind }
+    }
+
+    /// Returns the [`ErrorKind`](enum.ErrorKind.html) for this error.
+    pub fn kind(self) -> ErrorKind {
+        self.kind
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.kind {
+            MissingArgument => write!(
+				f, 
+				"option requires an argument -- {:?}",
+				self.culprit,
+			),
+            UnknownOption => write!(f, "unknown option -- {:?}", self.culprit),
+        }
+    }
+}
+
+impl error::Error for Error {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        None
+    }
+}

src/getopt-rs/errorkind.rs

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/// What kinds of errors [`Parser`](struct.Parser.html) can return.
+#[derive(Debug, Eq, PartialEq)]
+pub enum ErrorKind {
+    /// An argument was not found for an option that was expecting one.
+    MissingArgument,
+    /// An unknown option character was encountered.
+    UnknownOption,
+}

src/getopt-rs/lib.rs

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+//! # getopt
+//!
+//! `getopt` provides a minimal, (essentially) POSIX-compliant option parser.
+
+pub use crate::{
+	error::Error,
+	errorkind::ErrorKind,
+	opt::Opt,
+	parser::Parser,
+	result::Result
+};
+
+mod error;
+mod errorkind;
+mod opt;
+mod parser;
+mod result;
+#[cfg(test)]
+mod tests;

src/getopt-rs/opt.rs

@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+use std::fmt;
+
+/// A single option.
+///
+/// For `Opt(x, y)`:
+///   - `x` is the character representing the option.
+///   - `y` is `Some` string, or `None` if no argument was expected.
+///
+/// # Example
+///
+/// ```
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// use getopt::Opt;
+///
+/// // args = ["program", "-abc", "foo"];
+/// # let args: Vec<String> = vec!["program", "-abc", "foo"]
+/// #     .into_iter()
+/// #     .map(String::from)
+/// #     .collect();
+/// let optstring = "ab:c";
+/// let mut opts = getopt::Parser::new(&args, optstring);
+///
+/// assert_eq!(Opt('a', None), opts.next().transpose()?.unwrap());
+/// assert_eq!(Opt('b', Some("c".to_string())), opts.next().transpose()?.unwrap());
+/// assert_eq!(None, opts.next().transpose()?);
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct Opt(pub char, pub Option<String>);
+
+impl fmt::Display for Opt {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Opt({:?}, {:?})", self.0, self.1)
+    }
+}

src/getopt-rs/parser.rs

@@ -0,0 +1,382 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+use std::collections::HashMap;
+
+use crate::{ error::Error, errorkind::ErrorKind, opt::Opt, result::Result };
+
+/// The core of the `getopt` crate.
+///
+/// `Parser` is implemented as an iterator over the options present in the given
+/// argument vector.
+///
+/// The method [`next`](#method.next) does the heavy lifting.
+///
+/// # Examples
+///
+/// ## Simplified usage:
+/// ```
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// use getopt::Opt;
+///
+/// // args = ["program", "-abc", "foo"];
+/// # let args: Vec<String> = vec!["program", "-abc", "foo"]
+/// #     .into_iter()
+/// #     .map(String::from)
+/// #     .collect();
+/// let mut opts = getopt::Parser::new(&args, "ab:c");
+///
+/// assert_eq!(Some(Opt('a', None)), opts.next().transpose()?);
+/// assert_eq!(1, opts.index());
+/// assert_eq!(Some(Opt('b', Some("c".to_string()))), opts.next().transpose()?);
+/// assert_eq!(2, opts.index());
+/// assert_eq!(None, opts.next());
+/// assert_eq!(2, opts.index());
+/// assert_eq!("foo", args[opts.index()]);
+/// # Ok(())
+/// # }
+/// ```
+///
+/// ## A more idiomatic example:
+/// ```
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// use getopt::Opt;
+///
+/// // args = ["program", "-abc", "-d", "foo", "-e", "bar"];
+/// # let mut args: Vec<String> = vec!["program", "-abc", "-d", "foo", "-e", "bar"]
+/// #     .into_iter()
+/// #     .map(String::from)
+/// #     .collect();
+/// let mut opts = getopt::Parser::new(&args, "ab:cd:e");
+///
+/// let mut a_flag = false;
+/// let mut b_flag = String::new();
+/// let mut c_flag = false;
+/// let mut d_flag = String::new();
+/// let mut e_flag = false;
+///
+/// loop {
+///     match opts.next().transpose()? {
+///         None => break,
+///         Some(opt) => match opt {
+///             Opt('a', None) => a_flag = true,
+///             Opt('b', Some(arg)) => b_flag = arg.clone(),
+///             Opt('c', None) => c_flag = true,
+///             Opt('d', Some(arg)) => d_flag = arg.clone(),
+///             Opt('e', None) => e_flag = true,
+///             _ => unreachable!(),
+///         },
+///     }
+/// }
+///
+/// let new_args = args.split_off(opts.index());
+///
+/// assert_eq!(true, a_flag);
+/// assert_eq!("c", b_flag);
+/// assert_eq!(false, c_flag);
+/// assert_eq!("foo", d_flag);
+/// assert_eq!(true, e_flag);
+///
+/// assert_eq!(1, new_args.len());
+/// assert_eq!("bar", new_args.first().unwrap());
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Debug, Eq, PartialEq)]
+pub struct Parser {
+    opts: HashMap<char, bool>,
+    args: Vec<Vec<char>>,
+    index: usize,
+    point: usize,
+}
+
+impl Parser {
+    /// Create a new `Parser`, which will process the arguments in `args`
+	/// according to the options specified in `optstring`.
+    ///
+    /// For compatibility with
+	/// [`std::env::args`](https://doc.rust-lang.org/std/env/fn.args.html),
+    /// valid options are expected to begin at the second element of `args`, and
+	/// `index` is
+    /// initialised to `1`.
+    /// If `args` is structured differently, be sure to call
+	/// [`set_index`](#method.set_index) before the first invocation of
+	/// [`next`](#method.next).
+    ///
+    /// `optstring` is a string of recognised option characters; if a character
+	/// is followed by a colon (`:`), that option takes an argument.
+    ///
+    /// # Note:
+    /// Transforming the OS-specific argument strings into a vector of `String`s
+	/// is the sole responsibility of the calling program, as it involves some
+	/// level of potential information loss (which this crate does not presume
+	/// to handle unilaterally) and error handling (which would complicate the
+	/// interface).
+    pub fn new(args: &[String], optstring: &str) -> Self {
+        let optstring: Vec<char> = optstring.chars().collect();
+        let mut opts = HashMap::new();
+        let mut i = 0;
+        let len = optstring.len();
+
+        while i < len {
+            let j = i + 1;
+
+            if j < len && optstring[j] == ':' {
+                opts.insert(optstring[i], true);
+                i += 1;
+            } else {
+                opts.insert(optstring[i], false);
+            }
+            i += 1;
+        }
+
+        Self {
+            opts,
+            // "explode" the args into a vector of character vectors, to allow
+			// indexing
+            args: args.iter().map(|e| e.chars().collect()).collect(),
+            index: 1,
+            point: 0,
+        }
+    }
+
+    /// Return the current `index` of the parser.
+    ///
+    /// `args[index]` will always point to the the next element of `args`; when
+	/// the parser is
+    /// finished with an element, it will increment `index`.
+    ///
+    /// After the last option has been parsed (and [`next`](#method.next) is
+	/// returning `None`),
+    /// `index` will point to the first non-option argument.
+    pub fn index(&self) -> usize {
+        self.index
+    }
+
+    // `point` must be reset to 0 whenever `index` is changed
+
+    /// Modify the current `index` of the parser.
+    pub fn set_index(&mut self, value: usize) {
+        self.index = value;
+        self.point = 0;
+    }
+
+    /// Increment the current `index` of the parser.
+    ///
+    /// This use case is common enough to warrant its own optimised method.
+    pub fn incr_index(&mut self) {
+        self.index += 1;
+        self.point = 0;
+    }
+}
+
+impl Iterator for Parser {
+    type Item = Result<Opt>;
+
+    /// Returns the next option, if any.
+    ///
+    /// Returns an [`Error`](struct.Error.html) if an unexpected option is
+	/// encountered or if an
+    /// expected argument is not found.
+    ///
+    /// Parsing stops at the first non-hyphenated argument; or at the first
+	/// argument matching "-";
+    /// or after the first argument matching "--".
+    ///
+    /// When no more options are available, `next` returns `None`.
+    ///
+    /// # Examples
+    ///
+    /// ## "-"
+    /// ```
+    /// use getopt::Parser;
+    ///
+    /// // args = ["program", "-", "-a"];
+    /// # let args: Vec<String> = vec!["program", "-", "-a"]
+    /// #     .into_iter()
+    /// #     .map(String::from)
+    /// #     .collect();
+    /// let mut opts = Parser::new(&args, "a");
+    ///
+    /// assert_eq!(None, opts.next());
+    /// assert_eq!("-", args[opts.index()]);
+    /// ```
+    ///
+    /// ## "--"
+    /// ```
+    /// use getopt::Parser;
+    ///
+    /// // args = ["program", "--", "-a"];
+    /// # let args: Vec<String> = vec!["program", "--", "-a"]
+    /// #     .into_iter()
+    /// #     .map(String::from)
+    /// #     .collect();
+    /// let mut opts = Parser::new(&args, "a");
+    ///
+    /// assert_eq!(None, opts.next());
+    /// assert_eq!("-a", args[opts.index()]);
+    /// ```
+    ///
+    /// ## Unexpected option:
+    /// ```
+    /// use getopt::Parser;
+    ///
+    /// // args = ["program", "-b"];
+    /// # let args: Vec<String> = vec!["program", "-b"]
+    /// #     .into_iter()
+    /// #     .map(String::from)
+    /// #     .collect();
+    /// let mut opts = Parser::new(&args, "a");
+    ///
+    /// assert_eq!(
+    ///     "unknown option -- 'b'".to_string(),
+    ///     opts.next().unwrap().unwrap_err().to_string()
+    /// );
+    /// ```
+    ///
+    /// ## Missing argument:
+    /// ```
+    /// use getopt::Parser;
+    ///
+    /// // args = ["program", "-a"];
+    /// # let args: Vec<String> = vec!["program", "-a"]
+    /// #     .into_iter()
+    /// #     .map(String::from)
+    /// #     .collect();
+    /// let mut opts = Parser::new(&args, "a:");
+    ///
+    /// assert_eq!(
+    ///     "option requires an argument -- 'a'".to_string(),
+    ///     opts.next().unwrap().unwrap_err().to_string()
+    /// );
+    /// ```
+    fn next(&mut self) -> Option<Result<Opt>> {
+        if self.point == 0 {
+            /*
+             * Rationale excerpts below taken verbatim from "The Open Group Base
+			 * Specifications Issue 7, 2018 edition", IEEE Std 1003.1-2017
+			 * (Revision of IEEE Std 1003.1-2008).
+             * Copyright © 2001-2018 IEEE and The Open Group.
+             */
+
+            /*
+             * If, when getopt() is called:
+             *      argv[optind]    is a null pointer
+             *      *argv[optind]   is not the character '-'
+             *      argv[optind]    points to the string "-"
+             * getopt() shall return -1 without changing optind.
+             */
+            if self.index >= self.args.len()
+                || self.args[self.index].is_empty()
+                || self.args[self.index][0] != '-'
+                || self.args[self.index].len() == 1
+            {
+                return None;
+            }
+
+            /*
+             * If:
+             *      argv[optind]    points to the string "--"
+             * getopt() shall return -1 after incrementing index.
+             */
+            if self.args[self.index][1] == '-' && self.args[self.index].len() == 2 {
+                self.incr_index();
+                return None;
+            }
+
+            // move past the starting '-'
+            self.point += 1;
+        }
+
+        let opt = self.args[self.index][self.point];
+        self.point += 1;
+
+        match self.opts.get(&opt) {
+            None => {
+                if self.point >= self.args[self.index].len() {
+                    self.incr_index();
+                }
+                Some(Err(Error::new(ErrorKind::UnknownOption, opt)))
+            }
+            Some(false) => {
+                if self.point >= self.args[self.index].len() {
+                    self.incr_index();
+                }
+
+                Some(Ok(Opt(opt, None)))
+            }
+            Some(true) => {
+                let arg: String = if self.point >= self.args[self.index].len() {
+                    self.incr_index();
+                    if self.index >= self.args.len() {
+                        return Some(Err(Error::new(
+									ErrorKind::MissingArgument,
+									opt,
+								)));
+                    }
+                    self.args[self.index].iter().collect()
+                } else {
+                    self.args[self.index]
+                        .clone()
+                        .split_off(self.point)
+                        .iter()
+                        .collect()
+                };
+
+                self.incr_index();
+
+                Some(Ok(Opt(opt, Some(arg))))
+            }
+        }
+    }
+}

src/getopt-rs/result.rs

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+use std::result;
+
+use crate::error::Error;
+
+/// A specialized `Result` type for use with [`Parser`](struct.Parser.html)
+pub type Result<T> = result::Result<T, Error>;

src/getopt-rs/tests.rs

@@ -0,0 +1,228 @@
+/*
+ * Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *     The Clear BSD License
+ *
+ *     Copyright © 2017-2023 David Wildasin
+ *     All rights reserved.
+ *
+ *     Redistribution and use in source and binary forms, with or without
+ *     modification, are permitted (subject to the limitations in the disclaimer
+ *     below) provided that the following conditions are met:
+ *
+ *          * Redistributions of source code must retain the above copyright
+ *          notice, this list of conditions, and the following disclaimer.
+ *
+ *          * Redistributions in binary form must reproduce the above copyright
+ *          notice, this list of conditions, and the following disclaimer in the
+ *          documentation and/or other materials provided with the distribution.
+ *
+ *          * Neither the name of the copyright holder nor the names of its
+ *          contributors may be used to endorse or promote products derived from
+ *          this software without specific prior written permission.
+ *
+ *     NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED
+ *     BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
+ *     BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ *     FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *     HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ *     TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ *     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+use crate::{Opt, Parser};
+
+macro_rules! basic_test {
+    ($name:ident, $expect:expr, $next:expr, [$($arg:expr),+], $optstr:expr) => (
+        #[test]
+        fn $name() -> Result<(), String> {
+            let expect: Option<Opt> = $expect;
+            let args: Vec<String> = vec![$($arg),+]
+				.into_iter()
+				.map(String::from)
+				.collect();
+            let next: Option<String> = $next;
+            let mut opts = Parser::new(&args, $optstr);
+
+            match opts.next().transpose() {
+                Err(error) => {
+                    return Err(format!("next() returned {:?}", error))
+                },
+                Ok(actual) => if actual != expect {
+                    return Err(
+						format!("expected {:?}; got {:?}", expect, actual)
+					)
+                },
+            };
+
+            match next {
+                None => if opts.index() < args.len() {
+                    return Err(format!(
+							"expected end of args; got {:?}", args[opts.index()]
+					))
+                },
+                Some(n) => if args[opts.index()] != n {
+                    return Err(format!(
+							"next arg: expected {:?}; got {:?}",
+							n,
+							args[opts.index()]
+					))
+                },
+            };
+
+            Ok(())
+        }
+    )
+}
+
+#[rustfmt::skip] basic_test!(
+	blank_arg, None, Some(String::new()), ["x", ""], "a"
+);
+#[rustfmt::skip] basic_test!(
+	double_dash, None, Some("-a".to_string()), ["x", "--", "-a", "foo"], "a"
+);
+#[rustfmt::skip] basic_test!(no_opts_1, None, None, ["x"], "a");
+#[rustfmt::skip] basic_test!(
+	no_opts_2, None, Some("foo".to_string()), ["x", "foo"], "a"
+);
+#[rustfmt::skip] basic_test!(
+	no_opts_3, None, Some("foo".to_string()), ["x", "foo", "-a"], "a"
+);
+#[rustfmt::skip] basic_test!(
+	single_dash, None, Some("-".to_string()), ["x", "-", "-a", "foo"], "a"
+);
+#[rustfmt::skip] basic_test!(
+	single_opt,
+	Some(Opt('a', None)),
+	Some("foo".to_string()),
+	["x", "-a", "foo"],
+	"a"
+);
+#[rustfmt::skip] basic_test!(
+	single_optarg,
+	Some(Opt('a', Some("foo".to_string()))),
+	None,
+	["x", "-a", "foo"],
+	"a:"
+);
+
+macro_rules! error_test {
+    ($name:ident, $expect:expr, [$($arg:expr),+], $optstr:expr) => (
+        #[test]
+        fn $name() -> Result<(), String> {
+            let expect: String = $expect.to_string();
+            let args: Vec<String> = vec![$($arg),+]
+				.into_iter()
+				.map(String::from)
+				.collect();
+            let mut opts = Parser::new(&args, $optstr);
+
+            match opts.next() {
+                None => {
+                    return Err(format!(
+							"unexpected successful response: end of options"
+					))
+                },
+                Some(Err(actual)) => {
+                    let actual = actual.to_string();
+
+                    if actual != expect {
+                        return Err(
+							format!("expected {:?}; got {:?}", expect, actual)
+						);
+                    }
+                },
+                Some(Ok(opt)) => {
+                    return Err(
+						format!("unexpected successful response: {:?}", opt)
+					)
+                },
+            };
+
+            Ok(())
+        }
+    )
+}
+
+#[rustfmt::skip] error_test!(
+	bad_opt,
+	"unknown option -- 'b'",
+	["x", "-b"],
+	"a"
+);
+
+#[rustfmt::skip] error_test!(
+	missing_optarg,
+	"option requires an argument -- 'a'",
+	["x", "-a"],
+	"a:"
+);
+
+#[test]
+fn multiple() -> Result<(), String> {
+    let args: Vec<String> = vec!["x", "-abc", "-d", "foo", "-e", "bar"]
+        .into_iter()
+        .map(String::from)
+        .collect();
+    let optstring = "ab:d:e".to_string();
+    let mut opts = Parser::new(&args, &optstring);
+
+    macro_rules! check_result {
+        ($expect:expr) => {
+            let expect: Option<Opt> = $expect;
+            match opts.next().transpose() {
+                Err(error) => {
+					return Err(format!("next() returned {:?}", error));
+				},
+                Ok(actual) => {
+                    if actual != expect {
+                        return Err(
+							format!("expected {:?}; got {:?}", expect, actual)
+						);
+                    }
+                }
+            };
+        };
+    }
+
+    check_result!(Some(Opt('a', None)));
+    check_result!(Some(Opt('b', Some("c".to_string()))));
+    check_result!(Some(Opt('d', Some("foo".to_string()))));
+    check_result!(Some(Opt('e', None)));
+    check_result!(None);
+
+    Ok(())
+}
+
+#[test]
+fn continue_after_error() {
+    let args: Vec<String> = vec!["x", "-z", "-abc"]
+        .into_iter()
+        .map(String::from)
+        .collect();
+    let optstring = "ab:d:e".to_string();
+    for _opt in Parser::new(&args, &optstring) {
+        // do nothing, should not panic
+    }
+}

src/hru.rs

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	cmp::Ordering,
+	env::args,
+	io::{ stdin, stdout, Write },
+	process::{ ExitCode, exit },
+};
+
+extern crate strerror;
+extern crate sysexits;
+
+use strerror::StrError;
+use sysexits::{ EX_DATAERR, EX_IOERR, EX_SOFTWARE };
+
+const LIST: [(u32, &str); 10] = [
+	(3, "k"),
+	(6, "M"),
+	(9, "G"),
+	(12, "T"),
+	(15, "P"),
+	(18, "E"),
+	(21, "Z"),
+	(24, "Y"),
+	(27, "R"),
+	(30, "Q")
+];
+
+fn convert(input: u128) -> Result<(f64, (u32, &'static str)), String> {
+
+	let mut out = (input as f64, (0_u32, ""));
+	if input < 1000 { return Ok(out); }
+
+	for (n, p) in LIST {
+		let c = match 10_u128.checked_pow(n) {
+			Some(c) => c,
+			None => {
+				return Err(format!("10^{}: Integer overflow", n.to_string()));
+			},
+		};
+
+		match c.cmp(&input) {
+			Ordering::Less => {
+				out = (input as f64 / c as f64, (n, p));
+			},
+			Ordering::Equal => {
+				return Ok((input as f64 / c as f64, (n, p)));
+			},
+			Ordering::Greater => {},
+		};
+	}
+
+	Ok(out)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut buf = String::new();
+	while let Ok(_) = stdin().read_line(&mut buf) {
+		if buf.is_empty() { return ExitCode::SUCCESS; }
+
+		let n: u128 = match buf.trim().parse() {
+			Ok(f) => {
+				buf.clear();
+				f
+			},
+			Err(err) => {
+				eprintln!("{}: {}", argv[0], err);
+				return ExitCode::from(EX_DATAERR as u8);
+			},
+		};
+
+		let (number, prefix) = match convert(n) {
+			Ok(x) => x,
+			Err(err) => {
+				eprintln!("{}: {}", argv[0], err);
+				return ExitCode::from(EX_SOFTWARE as u8);
+			},
+		};
+
+		let si_prefix = format!("{}B", prefix.1);
+
+		let out = ((number * 10.0).round() / 10.0).to_string();
+
+		stdout().write_all(format!("{} {}\n", out, si_prefix).as_bytes())
+			.unwrap_or_else(|e| {
+				eprintln!("{}: {}", argv[0], e.strerror());
+				exit(EX_IOERR);
+			});
+	}
+
+	ExitCode::SUCCESS
+}

src/intcmp.c

@@ -18,11 +18,9 @@
 
 #include <errno.h> /* errno */
 #include <stdio.h> /* fprintf(3), stderr */
-#include <stdlib.h> /* strtol(3), size_t */
+#include <stdlib.h> /* strtol(3), size_t, EXIT_FAILURE */
-#ifndef EX_USAGE
-#	include <sysexits.h> /* EX_USAGE */
-#endif
 #include <unistd.h> /* getopt(3), optind */
+#include <sysexits.h>
 
 /* 0b00? */		/*                     Equal | -e  | 0b001 | 1 */
 #define EQUAL	0x01	/*                   Greater | -g  | 0b010 | 2 */

src/libfileis.c

@@ -1,63 +0,0 @@
-/*
- * Copyright (c) 2023 DTB <trinity@trinity.moe>
- * SPDX-License-Identifier: AGPL-3.0-or-later
- *
- * This program is free software: you can redistribute it and/or modify it under
- * the terms of the GNU Affero General Public License as published by the Free
- * Software Foundation, either version 3 of the License, or (at your option) any
- * later version.
- * 
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
- * details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see https://www.gnu.org/licenses/.
- */
-
-#include "libfileis.h"
-
-#include <unistd.h> /* access(3), F_OK, R_OK, W_OK, X_OK */
-
-int f_executable(char *path){	return access(path, X_OK) == 0; } /* test -x */
-int f_exists(char *path){	return access(path, F_OK) == 0; } /* test -e */
-int f_readable(char *path){	return access(path, R_OK) == 0; } /* test -r */
-int f_writeable(char *path){	return access(path, W_OK) == 0; } /* test -w */
-
-#include <sys/stat.h> /* lstat(3), struct stat, S_ISBLK, S_ISCHR, S_ISDIR,
-                       * S_ISFIFO, S_ISGID, S_ISREG, S_ISLNK, S_ISSOCK,
-                       * S_ISUID, S_ISVTX */
-
-static struct stat buf;
-
-int f_blockspecial(char *path){ /* test -b */
-	return lstat(path, &buf) != -1 && S_ISBLK(buf.st_mode);
-}
-int f_charspecial(char *path){ /* test -c */
-	return lstat(path, &buf) != -1 && S_ISCHR(buf.st_mode);
-}
-int f_directory(char *path){ /* test -d */
-	return lstat(path, &buf) != -1 && S_ISDIR(buf.st_mode);
-}
-int f_fifospecial(char *path){ /* test -p */
-	return lstat(path, &buf) != -1 && S_ISFIFO(buf.st_mode);
-}
-int f_gid(char *path){ /* test -g */
-	return lstat(path, &buf) != -1 && (buf.st_mode & S_ISGID);
-}
-int f_regular(char *path){ /* test -f */
-	return lstat(path, &buf) != -1 && S_ISREG(buf.st_mode);
-}
-int f_socket(char *path){ /* test -S */
-	return lstat(path, &buf) != -1 && S_ISSOCK(buf.st_mode);
-}
-int f_sticky(char *path){ /* test -k */
-	return lstat(path, &buf) != -1 && (buf.st_mode & S_ISVTX);
-}
-int f_symlink(char *path){ /* test -h; test -L */
-	return lstat(path, &buf) != -1 && S_ISLNK(buf.st_mode);
-}
-int f_uid(char *path){ /* test -u */
-	return lstat(path, &buf) != -1 && (buf.st_mode & S_ISUID);
-}

src/libfileis.h

@@ -1,62 +0,0 @@
-/*
- * Copyright (c) 2023 DTB <trinity@trinity.moe>
- * SPDX-License-Identifier: AGPL-3.0-or-later
- *
- * This program is free software: you can redistribute it and/or modify it under
- * the terms of the GNU Affero General Public License as published by the Free
- * Software Foundation, either version 3 of the License, or (at your option) any
- * later version.
- * 
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
- * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
- * details.
- *
- * You should have received a copy of the GNU Affero General Public License
- * along with this program. If not, see https://www.gnu.org/licenses/.
- */
-
-/* libfileis functions return true if the condition is true and false if the
- * condition is false. Returned values are 0 or 1 only. */
-
-/* True if file exists and is a block special file. */
-	int f_blockspecial(char *path);
-
-/* True if file exists and is a character special file. */
-	int f_charspecial(char *path);
-
-/* True if file exists and is a directory. */
-	int f_directory(char *path);
-
-/* True if file exists and is executable. */
-	int f_executable(char *path);
-
-/* True if file exists (regardless of type). */
-	int f_exists(char *path);
-
-/* True if file exists and is a named pipe (FIFO). */
-	int f_fifospecial(char *path);
-
-/* True if file exists and its set group ID flag is set. */
-	int f_gid(char *path);
-
-/* True if file exists and is readable. */
-	int f_readable(char *path);
-
-/* True if file exists and is a regular file. */
-	int f_regular(char *path);
-
-/* True if file exists and is a socket. */
-	int f_socket(char *path);
-
-/* True if file exists and its sticky bit is set. */
-	int f_sticky(char *path);
-
-/* True if file exists and is a symbolic link. */
-	int f_symlink(char *path);
-
-/* True if file exists and its set user ID flag is set. */
-	int f_uid(char *path);
-
-/* True if file exists and is writeable. */
-	int f_writeable(char *path);

src/mm.c

@@ -0,0 +1,236 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+#include <errno.h> /* errno */
+#include <signal.h> /* signal(2), SIG_ERR, SIG_IGN, SIGINT */
+#include <stdio.h> /* fclose(3), fopen(3), fprintf(3), getc(3), putc(3),
+                    * setvbuf(3), size_t, _IONBF, NULL */
+#include <stdlib.h> /* free(3), realloc(3) */
+#include <string.h> /* strcmp(3), strerror(3) */
+#include <unistd.h> /* getopt(3) */
+#if !defined EX_IOERR || !defined EX_OK || !defined EX_OSERR \
+		|| !defined EX_USAGE
+#	include <sysexits.h>
+#endif
+extern int errno;
+
+/* This structure is how open files are tracked. */
+struct Files{
+	size_t a;	/* allocation */
+	size_t s;	/* used size */
+	char *mode;	/* file opening mode */
+	char **names;	/* file names */
+	FILE **files;	/* file pointers */
+};
+
+/* How much to grow the allocation when it's saturated. */
+#ifndef ALLOC_INCREMENT
+#	define ALLOC_INCREMENT 1
+#endif
+
+/* How much to grow the allocation at program start. */
+#ifndef ALLOC_INITIAL
+#	define ALLOC_INITIAL 10
+#endif
+
+/* pre-allocated strings */
+static char *program_name = "<no argv[0]>";
+static char *stdin_name = "<stdin>";
+static char *stdout_name = "<stdout>";
+static char *stderr_name = "<stderr>";
+static char *(fmode[]) = { (char []){"rb"}, (char []){"rb+"} };
+static char *wharsh = "wb";
+
+/* Adds the open FILE pointer for the file at the path s to the files struct,
+ * returning the FILE if successful and NULL if not, allocating more memory in
+ * the files buffers as needed. */
+static FILE *
+Files_append(struct Files *files, FILE *file, char *name){
+
+	if(file == NULL || (files->s == files->a
+			&& ((files->files = realloc(files->files,
+					(files->a += (files->a == 0)
+						? ALLOC_INITIAL
+						: ALLOC_INCREMENT)
+					* sizeof *(files->files))) == NULL
+				|| (files->names = realloc(files->names,
+					files->a * sizeof *(files->names))) == NULL)))
+		return NULL;
+
+	files->names[files->s] = name;
+	return files->files[files->s++] = file;
+}
+
+/* Opens the file at the path p and puts it in the files struct, returning NULL
+ * if either the opening or the placement of the open FILE pointer fail. */
+#define Files_open(files, p) \
+	Files_append((files), fopen((p), (files)->mode), (p))
+
+/* Prints a diagnostic message based on errno and returns an exit status
+ * appropriate for an OS error. */
+static int
+oserr(char *s, char *r){
+
+	fprintf(stderr, "%s: %s: %s\n", s, r, strerror(errno));
+
+	return EX_OSERR;
+}
+
+/* Hijacks i and j from main and destructs the files[2] struct used by main by
+ * closing its files and freeing its files and names arrays, returning retval
+ * from main. */
+#define terminate \
+	for(i = 0; i < 2; ++i){ \
+		for(j = 0; j < files[i].s; ++j) \
+			if(files[i].files[j] != stdin \
+					&& files[i].files[j] != stdout \
+					&& files[i].files[j] != stderr) \
+				fclose(files[i].files[j]); \
+		free(files[i].files); \
+		free(files[i].names); \
+	} \
+	return retval
+
+/* Prints a usage text, in which s is the program being run (i.e. argv[0]), and
+ * returns an exit status appropriate for a usage error. */
+int usage(char *s){
+
+	fprintf(stderr, "Usage: %s (-aenu) (-i [input])... (-o [output])...\n", s);
+
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+	int c;
+	struct Files files[2]; /* {read, write} */
+	size_t i;
+	size_t j;
+	size_t k; /* loop index but also unbuffer status */
+	int retval;
+
+	/* Initializes the files structs with their default values, standard
+	 * input and standard output. If an input or an output is specified
+	 * these initial values will be overwritten, so to, say, use mm(1)
+	 * equivalently to tee(1p), -o - will need to be specified before
+	 * additional files to ensure standard output is still written. */
+	for(i = 0; i < 2; ++i){
+		files[i].a = 0;
+		files[i].s = 0;
+		files[i].mode = fmode[i];
+		files[i].files = NULL;
+		files[i].names = NULL;
+		Files_append(&files[i], i == 0 ? stdin : stdout,
+			i == 0 ? stdin_name : stdout_name);
+		files[i].s = 0;
+	}
+
+	k = 0;
+
+	if(argc > 0)
+		program_name = argv[0];
+
+	if(argc > 1)
+		while((c = getopt(argc, argv, "aehi:no:u")) != -1)
+			switch(c){
+			case 'a': /* "rb+" -> "ab" */
+				files[1].mode[0] = 'a';
+				files[1].mode[2] = '\0';
+				break;
+			case 'e':
+				if(Files_append(&files[1], stderr, stderr_name) != NULL)
+					break;
+				retval = oserr(argv[0], "-e");
+				terminate;
+			case 'i':
+				if((strcmp(optarg, "-") == 0 && Files_append(&files[0],
+							stdin, stdin_name) != NULL)
+						|| Files_open(&files[0], optarg) != NULL)
+					break;
+				retval = oserr(argv[0], optarg);
+				terminate;
+			case 'o':
+				if((strcmp(optarg, "-") == 0 && Files_append(&files[1],
+							stdout, stdout_name) != NULL)
+						|| Files_open(&files[1], optarg) != NULL)
+					break;
+				/* does not exist, so try to create it */
+				if(errno == ENOENT){
+					files[1].mode = wharsh;
+					if(Files_open(&files[1], optarg) != NULL){
+						files[1].mode = fmode[1];
+						break;
+					}
+				}
+				retval = oserr(argv[0], optarg);
+				terminate;
+			case 'n':
+				if(signal(SIGINT, SIG_IGN) != SIG_ERR)
+					break;
+				retval = oserr(argv[0], "-n");
+				terminate;
+			case 'u':
+				k = 1;
+				break;
+			default:
+				retval = usage(argv[0]);
+				terminate;
+			}
+
+	if(optind != argc){
+		retval = usage(argv[0]);
+		terminate;
+	}
+
+	files[0].s += files[0].s == 0;
+	files[1].s += files[1].s == 0;
+	
+	/* Unbuffer files. */
+	if(k){
+		for(i = 0;
+			i < files[0].s;
+			setvbuf(files[0].files[i++], NULL, _IONBF, 0));
+		for(i = 0;
+			i < files[1].s;
+			setvbuf(files[1].files[i++], NULL, _IONBF, 0));
+	}
+
+	retval = EX_OK;
+
+	/* Actual program loop. */
+	for(i = 0; i < files[0].s; ++i) /* iterate ins */
+		while((c = getc(files[0].files[i])) != EOF) /* iterate chars */
+			for(j = 0; j < files[1].s; ++j) /* iterate outs */
+				if(putc(c, files[1].files[j]) == EOF){
+					/* notebook's full */
+					retval = EX_IOERR;
+					fprintf(stderr, "%s: %s: %s\n",
+						program_name, files[1].names[j], strerror(errno));
+					if(fclose(files[1].files[j]) == EOF)
+						fprintf(stderr, "%s: %s: %s\n",
+							program_name, files[1].names[j], strerror(errno));
+					/* massage out the tense muscle */
+					for(k = j--; k < files[1].s - 1; ++k){
+						files[1].files[k] = files[1].files[k+1];
+						files[1].names[k] = files[1].names[k+1];
+					}
+					if(--files[1].s == 0)
+						terminate;
+				}
+
+	terminate;
+}

src/npc.c

@@ -18,10 +18,9 @@
 
 #include <stdio.h> /* fprintf(3), fputs(3), getc(3), putc(3), stdin, stdout,
                     * EOF */
+#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
 #include <unistd.h> /* getopt(3) */
-#if !defined EX_USAGE || !defined EX_OK
+#include <sysexits.h>
-#	include <sysexits.h>
-#endif
 
 int main(int argc, char *argv[]){
 	int c;

src/rpn.rs

@@ -0,0 +1,248 @@
+/*
+ * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and permission
+ * notice:
+ *
+ *     MIT License
+ * 
+ *     Copyright (c) 2022 Lilly Cham
+ * 
+ *     Permission is hereby granted, free of charge, to any person obtaining a
+ *     copy of this software and associated documentation files 
+ *     (the "Software"), to deal in the Software without restriction, including
+ *     without limitation the rights
+ *     to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ *     sell copies of the Software, and to permit persons to whom the Software
+ *     is furnished to do so, subject to the following conditions:
+ *
+ *     The above copyright notice and this permission notice shall be included
+ *     in all copies or substantial portions of the Software.
+ * 
+ *     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ *     OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+ *     NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ *     DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ *     OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ *     USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+use std::{
+	collections::VecDeque,
+	env::args,
+	fmt::{ self, Display, Formatter },
+	io::stdin,
+	process::ExitCode,
+};
+
+use CalcType::*;
+
+extern crate sysexits;
+
+use sysexits::EX_DATAERR;
+
+#[derive(Clone, PartialEq, PartialOrd, Debug)]
+// enum CalcType is a type containing operations used in the calculator
+enum CalcType {
+	Add,
+	Subtract,
+	Multiply,
+	Divide,
+	Power,
+	Floor,
+	Modulo,
+	Val(f64),
+	Invalid(String),
+}
+
+impl From<&str> for CalcType {
+	fn from(value: &str) -> Self {
+		match value {
+			"+" => Add,
+			"-" | "−" => Subtract,
+			"*" | "×" => Multiply,
+			"/" | "÷" => Divide,
+			"^" | "**" => Power,
+			"//" => Floor,
+			"%" => Modulo,
+			_ => {
+				match value.parse::<f64>() {
+					Ok(x) => Val(x),
+					Err(_) => Invalid(value.to_owned()),
+				}
+			},
+		}
+	}
+}
+
+impl Display for CalcType {
+	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+		let y: String;
+		write!(f, "{}", match self {
+			Add => "addition",
+			Subtract => "subtraction",
+			Multiply => "multiplication",
+			Divide => "division",
+			Power => "exponentiation",
+			Floor => "floor division",
+			Modulo => "modulus",
+			Val(x) => {
+				y = x.to_string(); &y
+			},
+			Invalid(i) => {
+				y = i.to_string(); &y
+			},
+		})
+	}
+}
+
+#[derive(Debug, Clone)]
+struct EvaluationError {
+	message: String,
+	code: i32,
+}
+
+// I’m no math nerd but I want the highest possible approximation of 0.9
+// repeating and it seems this can give it to me
+const PRECISION_MOD: f64 = 0.9 + f64::EPSILON * 100.0;
+
+fn eval(
+	input: &str,
+	initial_stack: VecDeque<f64>,
+) -> Result<(VecDeque<f64>, bool), EvaluationError> {
+	let mut stack = initial_stack;
+	let mut oper = false;
+
+	if input.is_empty() {
+		stack.clear();
+		return Ok((stack, oper));
+	}
+
+	// Split the input into tokens.
+	let mut toks: VecDeque<CalcType> = input
+		.split_whitespace()
+		.rev()
+		.map(|t| CalcType::from(t))
+		.collect();
+	let mut ops: VecDeque<CalcType> = VecDeque::new();
+
+	while let Some(n) = toks.pop_back() {
+		match n {
+			Val(v) => stack.push_back(v),
+			Invalid(i) => {
+				return Err(EvaluationError {
+					message: format!("{}: Invalid token", i),
+					code: EX_DATAERR,
+				})
+			},
+			op => {
+				ops.push_back(op.clone());
+				oper = true;
+
+				let vals = (
+					stack.pop_back(),
+					stack.pop_back(),
+				);
+
+				if let (Some(x), Some(y)) = vals {
+					match op {
+						Add => stack.push_back(y + x),
+						Subtract => stack.push_back(y - x),
+						Multiply => stack.push_back(y * x),
+						Divide => stack.push_back(y / x),
+						Power => stack.push_back(y.powf(x)),
+						Floor => stack.push_back((y / x).floor()),
+						Modulo => stack.push_back(y % x),
+						_ => {},
+					};
+				} else {
+					return Err(EvaluationError {
+						message: format!("{}: Unexpected operation", op),
+						code: EX_DATAERR,
+					})
+				}
+			},
+		};
+	}
+
+	Ok((stack, oper))
+}
+
+// Round a float to the given precision level
+fn round_precise(value: &f64, precision: usize) -> f64 {
+	let multiplier = 10_f64.powi(precision as i32);
+	(value * multiplier).round() / multiplier
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut stack = VecDeque::new();
+	let mut buf = String::new();
+	// Set floating-point precision for correcting rounding errors based on
+	// machine epsilon
+	let precision = (-f64::EPSILON.log10() * PRECISION_MOD).ceil() as usize;
+	
+	if argv.get(1).is_none() {
+		while let Ok(_) = stdin().read_line(&mut buf) {
+			match eval(&buf.trim(), stack) {
+				Ok(s) => {
+					buf.clear();
+					stack = s.0.clone();
+
+					let val = match stack.iter().last() {
+						Some(v) => v,
+						None => break,
+					};
+
+					if s.1 == false { continue; }
+
+					println!("{}", round_precise(val, precision).to_string());
+				},
+				Err(err) => {
+					eprintln!("{}: {}", argv[0], err.message);
+					return ExitCode::from(err.code as u8);
+				},
+			};
+		}
+	} else {
+		let input = argv
+			.iter()
+			.skip(1)
+			.map(|x| x.to_owned())
+			.collect::<Vec<String>>()
+			.join(" ");
+
+		match eval(&input, stack) {
+			Ok(s) => {
+				stack = s.0.clone();
+
+				let val = match stack.iter().last() {
+					Some(v) => v,
+					None => return ExitCode::from(0),
+				};
+
+				println!("{}", round_precise(val, precision).to_string())
+			},
+			Err(err) => {
+				eprintln!("{}: {}", argv[0], err.message);
+				return ExitCode::from(err.code as u8);
+			},
+		};
+	}
+	ExitCode::from(0)
+}

src/scrut.c

@@ -17,14 +17,13 @@
  */
 
 #include <stdio.h> /* fprintf(3), stderr, NULL */
-#include <string.h> /* strchr(3) */
+#include <stdlib.h> /* EXIT_FAILURE */
-#ifndef EX_USAGE
+#include <string.h> /* memset(3), strchr(3) */
-#	include <sysexits.h>
-#endif
 #include <unistd.h> /* access(3), getopt(3), F_OK, R_OK, W_OK, X_OK */
 #include <sys/stat.h> /* lstat(3), stat struct, S_ISBLK, S_ISCHR, S_ISDIR,
                        * S_ISFIFO, S_ISGID, S_ISREG, S_ISLNK, S_ISSOCK,
                        * S_ISUID, S_ISVTX */
+#include <sysexits.h>
 
 static char args[] = "bcdefghkprsuwxLS";
 static char ops[(sizeof args) / (sizeof *args)];
@@ -34,17 +33,24 @@ int main(int argc, char *argv[]){
 	struct stat buf;
 	int c;
 	size_t i;
+	char *p;
 
 	if(argc < 2)
 		goto usage;
 
-	i = 0;
+	memset(ops, '\0', sizeof ops);
 	while((c = getopt(argc, argv, args)) != -1)
-		if(strchr(args, c) == NULL)
+		if((p = strchr(args, c)) == NULL)
 			goto usage;
 		else
-			ops[i++] = c;
+			ops[p - args] = c;
-	ops[i] = '\0';
+	/* straighten out ops */
+	for(i = 0, p = ops; i < (sizeof ops) / (sizeof *ops); ++i)
+		if(ops[i] != '\0'){
+			*p = ops[i];
+			if(&ops[i] != p++)
+				ops[i] = '\0';
+		}
 
 	if(optind == argc)
 		goto usage;

src/str.c

@@ -20,10 +20,9 @@
 #include <ctype.h>
 #include <stddef.h> /* NULL */
 #include <stdio.h> /* fprintf(3) */
+#include <stdlib.h> /* EXIT_FAILURE */
 #include <string.h> /* strcmp(3) */
-#if !defined EX_USAGE
+#include <sysexits.h>
-#	include <sysexits.h>
-#endif
 
 static char *program_name = "str";
 

src/strcmp.c

@@ -1,7 +1,6 @@
 #include <stdio.h> /* fprintf(3), stderr */
-#ifndef EX_USAGE
+#include <stdlib.h> /* EXIT_FAILURE */
-#	include <sysexits.h> /* EX_USAGE */
+#include <sysexits.h>
-#endif
 
 static char *program_name = "strcmp";
 

src/strerror.rs

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
+ * SPDX-License-Identifier: FSFAP
+ *
+ * Copying and distribution of this file, with or without modification, are
+ * permitted in any medium without royalty provided the copyright notice and
+ * this notice are preserved.  This file is offered as-is, without any warranty.
+ */
+
+use std::ffi::{ c_int, c_char, CStr };
+
+pub trait StrError { fn strerror(&self) -> String; }
+
+impl StrError for std::io::Error {
+	/* wrapper function for use in Rust */
+	fn strerror(&self) -> String {
+		/* Get the raw OS error. If it’s None, what the hell is going on‽ */
+		let errno = self.raw_os_error().unwrap_or(0) as c_int;
+
+		/* Get a CStr from the error message so that it’s referenced and then
+		 * convert it to an owned value. If the string is not valid UTF-8,
+		 * return that error instead. */
+		match unsafe { CStr::from_ptr(strerror(errno)) }.to_str() {
+			Ok(s) => s.to_owned(), // yay!! :D
+			Err(e) => e.to_string(), // awww :(
+		}
+	}
+}
+
+/* binding to strerror(3p) */
+extern "C" { fn strerror(errnum: c_int) -> *mut c_char; }

src/swab.rs

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Affero General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ * 
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+use std::{
+	env::args,
+	io::{ stdin, stdout, Error, ErrorKind, Read, Write },
+	process::ExitCode,
+	vec::Vec
+};
+
+extern crate getopt;
+use getopt::{ Opt, Parser };
+
+extern crate sysexits;
+use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
+
+fn oserr(s: &str, e: Error) -> ExitCode {
+	eprintln!("{}: {}", s, e);
+	ExitCode::from(EX_OSERR as u8)
+}
+
+fn usage(s: &str) -> ExitCode {
+	eprintln!("Usage: {} (-f) (-w [wordsize])", s);
+	ExitCode::from(EX_USAGE as u8)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut buf: Vec<u8> = Vec::new();
+	let mut input = stdin();
+	let mut output = stdout().lock();
+
+	let mut opts = Parser::new(&argv, "fw:");
+	let mut force = false;
+	let mut wordsize: usize = 2;
+
+	loop {
+		match opts.next() {
+			None => break,
+			Some(opt) =>
+				match opt {
+					Ok(Opt('f', None)) => force = true,
+					Ok(Opt('w', Some(arg))) => {
+						match arg.parse::<usize>() {
+							Ok(w) if w % 2 == 0 => { wordsize = w; () },
+							_ => { return usage(&argv[0]); },
+						}
+					},
+					_ => { return usage(&argv[0]); }
+				}
+		}
+	}
+
+	buf.resize(wordsize, 0);
+
+	loop {
+		match input.read(&mut buf) {
+			Ok(0) => break ExitCode::from(EX_OK as u8),
+			Ok(v) if v == wordsize => {
+				let (left, right) = buf.split_at(v/2);
+				if let Err(e) = output.write(&right)
+						.and_then(|_| output.write(&left)) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Ok(v) => {
+				if let Err(e) = output.write(&buf[..v]) {
+					break oserr(&argv[0], e)
+				}
+			},
+			Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
+			Err(e) => break oserr(&argv[0], e)
+		}
+	}
+}

src/test.rs

@@ -0,0 +1,10 @@
+extern crate strerror;
+
+use strerror::raw_message;
+
+fn main() {
+	stdout.write_all(b"meow\n").unwrap_or_else(|e| {
+		eprintln!("{}", raw_message(e));
+		std::process::exit(1);
+	});
+}

tests/cc-compat.sh

@@ -1,39 +0,0 @@
-#!/bin/sh
-
-# Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
-# SPDX-License-Identifier: FSFAP
-#
-# Copying and distribution of this file, with or without modification, are
-# permitted in any medium without royalty provided the copyright notice and this
-# notice are preserved.  This file is offered as-is, without any warranty.
-
-set -e
-
-if ! ls GNUmakefile >/dev/null 2>&1
-then
-	printf '%s: Run this script in the root of the project.\n' "$0" 1>&2 
-	exit 64 # sysexits.h(3) EX_USAGE
-fi
-
-make clean
-
-for CC in cc \
-	clang \
-	gcc \
-	tcc \
-	'zig cc'
-do
-	export CC
-
-	command -v "$(printf '%s\n' "$CC" | cut -d ' ' -f1)" >/dev/null 2>&1 \
-		|| continue
-
-	printf '%s: %s: Testing build.\n' "$0" "$CC"
-
-	make CC="$CC" && printf '%s: Build successful.\n' "$0"
-
-	ls -lA build/
-
-	make clean
-	printf '\n'
-done

tests/posix-compat.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-# Copyright (c) 2023 Emma Tebibyte <emma@tebibyte.media>
+# Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
 # SPDX-License-Identifier: FSFAP
 #
 # Copying and distribution of this file, with or without modification, are
@@ -9,7 +9,7 @@
 
 set -e
 
-if ! ls GNUmakefile >/dev/null 2>&1
+if ! ls Makefile >/dev/null 2>&1
 then
 	printf '%s: Run this script in the root of the project.\n' "$0" 1>&2 
 	exit 1