Merge branch 'dj-fix' (closes #66)

.editorconfig

@@ -12,6 +12,3 @@ indent_size = 2
 
 [*.sh]
 indent_size = 2
-
-[configure]
-indent_size = 2

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
-using four-character-wide indentation steps.
+Make sure lines never exceed 80 columns in width when using four-character
+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
-print usage information when any erroneous option is specified. Follow the
-NetBSD style guide for usage text output format [1].
+For usage text and help messages, do not implement a -h option. Instead, print
+usage information when any erroneous option is specified. Follow the NetBSD
+style guide for the usage text’s output format [1].
 
-If committing a new source file for a utility, format the commit message like
-this:
+[1] <http://cvsweb.netbsd.org/bsdweb.cgi/~checkout~/src/share/misc/style>
 
-$ 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 'tests: posix: fixed bug #47'
-$ git commit -m 'docs: tool(1): added author information'
+$ git commit -m 'README: clarify'
+$ git commit -m 'tests/posix: fix bug #47'
 
-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/>

Makefile

@@ -17,7 +17,7 @@ CC=cc
 RUSTC=rustc
 
 .PHONY: all
-all: dj false fop intcmp rpn scrut str strcmp true
+all: dj false fop hru intcmp mm rpn scrut str strcmp swab true
 
 build:
 	# keep build/include until bindgen(1) has stdin support
@@ -54,7 +54,7 @@ build/o/libsysexits.rlib: build
 		| $(RUSTC) $(RUSTFLAGS) --crate-type lib -o build/o/libsysexits.rlib -
 
 build/o/libgetopt.rlib: src/getopt-rs/lib.rs
-	$(RUSTC) $(RUSTCFLAGS) --crate-type=lib --crate-name=getopt \
+	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=getopt \
 		-o build/o/libgetopt.rlib src/getopt-rs/lib.rs
 
 .PHONY: dj
@@ -74,11 +74,23 @@ build/bin/fop: src/fop.rs build build/o/libgetopt.rlib build/o/libsysexits.rlib
 		--extern sysexits=build/o/libsysexits.rlib \
 		-o $@ src/fop.rs
 
+.PHONY: hru
+hru: build/bin/hru
+build/bin/hru: src/hru.rs build build/o/libgetopt.rlib build/o/libsysexits.rlib
+	$(RUSTC) $(RUSTFLAGS) --extern getopt=build/o/libgetopt.rlib \
+		--extern sysexits=build/o/libsysexits.rlib \
+		-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: rpn
 rpn: build/bin/rpn
 build/bin/rpn: src/rpn.rs build build/o/libsysexits.rlib
@@ -101,6 +113,13 @@ 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

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/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/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/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)

src/dj.c

@@ -203,28 +203,28 @@ Io_fdseek(struct Io *io){
 	
 	if(!fdisstd(io->fd) && lseek(io->fd, io->seek, SEEK_SET) != -1)
 		return -1;
-	else if(io->fl == write_flags){
-		memset(io->buf, '\0', io->bs);
-		/* This is a dirty trick; rather than testing conditions and operating
-		 * likewise, because the parameters to read or write are going to be
-		 * the same either way, just use a function pointer to keep track of
-		 * the intended operation. */
-		op = (int (*)(int, void *, size_t))&write;
-		/* Function pointer casts are risky; this works because the difference
-		 * is in the second parameter and only that write(2) makes the buffer
-		 * const whereas read(2) does not. To avoid even the slightest
-		 * undefined behavior comment out the cast, just be ready for a
-		 * -Wincompatible-function-pointer-types if your compiler notices it.
-		 */
-	}else
-		op = &read;
 
-	/* 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 = (*op)(io->fd, io->buf, MIN(io->bs, io->seek))) == 0)
-			/* second chance */
-			io->bufuse = (*op)(io->fd, io->buf, MIN(io->bs, io->seek));
-	}while((io->seek -= io->bufuse) > 0 && io->bufuse != 0);
+	/* 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;
 

src/fop.rs

@@ -18,7 +18,7 @@
 
 use std::{
 	env::args,
-	io::{ Read, stdin, Write },
+	io::{ Read, stdin, stdout, Write },
 	process::{ Command, exit, Stdio },
 };
 
@@ -26,7 +26,7 @@ extern crate sysexits;
 extern crate getopt;
 
 use getopt::{ Opt, Parser };
-use sysexits::{ EX_DATAERR, EX_USAGE };
+use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
 
 fn main() {
 	let argv = args().collect::<Vec<String>>();
@@ -54,43 +54,65 @@ fn main() {
 		exit(EX_USAGE);
 	});
 
-	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|_| {
-		eprintln!("{}: {}: Not an integer.", argv[0], argv[1]);
+	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();
-	stdin().read_to_string(&mut buf).unwrap();
+	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 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();
+		.unwrap_or_else( |e| {
+			eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
+			exit(EX_UNAVAILABLE);
+		});
 
 	let field = fields.get(index).unwrap_or_else(|| {
 		eprintln!(
 			"{}: {}: No such index in input.",
 			argv[0],
-			index.to_string()
+			index.to_string(),
 		);
 		exit(EX_DATAERR);
 	});
 
 	if let Some(mut child_stdin) = spawned.stdin.take() {
-		child_stdin.write_all(field.as_bytes()).unwrap();
+		let _ = child_stdin.write_all(field.as_bytes());
 		drop(child_stdin);
 	}
 
-	let output = spawned.wait_with_output().unwrap();
+	let output = spawned.wait_with_output().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
+		exit(EX_IOERR);
+	});
 
-	let new_field = String::from_utf8(output.stdout).unwrap();
+	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;
 
-	print!("{}", fields.join(&d.to_string()));
+	stdout().write_all(
+		fields.join(&d.to_string()).as_bytes()
+	).unwrap_or_else(|e|{
+		eprintln!("{}: {}.", argv[0], e);
+		exit(EX_IOERR);
+	});
 }

src/hru.rs

@@ -0,0 +1,107 @@
+/*
+ * 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 sysexits;
+
+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);
+				exit(EX_IOERR);
+			});
+	}
+
+	ExitCode::SUCCESS
+}

src/mm.c

@@ -0,0 +1,224 @@
+/*
+ * 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
+
+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:
+				fprintf(stderr, "Usage: %s (-aenu) (-i [input])..."
+					" (-o [output])...\n", argv[0]);
+				retval = EX_USAGE;
+				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/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)
+		}
+	}
+}