peek(1): remove unused variables, clean up some typos

Makefile

@@ -9,13 +9,23 @@
 # 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?
 
-PREFIX=/usr/local
+DESTDIR ?= dist
+PREFIX ?= /usr/local
 
-CC=cc
-RUSTC=rustc
+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
@@ -27,36 +37,40 @@ build:
 
 .PHONY: clean
 clean:
-	rm -rf build/ dist/
+	rm -rf build dist
 
 dist: all
-	mkdir -p dist/bin dist/share/man/man1
-	cp build/bin/* dist/bin/
-	cp docs/*.1 dist/share/man/man1/
+	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
-	mkdir -p $(PREFIX)
-	cp -r dist/* $(PREFIX)/
+	cp -r $(DESTDIR)/* /
 
 .PHONY: test
 test: build
 	tests/posix-compat.sh
 	$(RUSTC) --test src/getopt-rs/lib.rs -o build/test/getopt
 
-build/o/libsysexits.rlib: build
+.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 - include/sysexits.h \
+	printf '#define EXIT_FAILURE 1\n' | cat - $(SYSEXITS)sysexits.h \
 		> build/include/sysexits.h 
 	bindgen --default-macro-constant-type signed --use-core --formatter=none \
-		"$$(printf '#include <sysexits.h>\n' \
-			| cpp -M -idirafter "build/include" - \
-			| sed 's/ /\n/g' | grep sysexits.h)" \
-		| $(RUSTC) $(RUSTFLAGS) --crate-type lib -o build/o/libsysexits.rlib -
-
-build/o/libgetopt.rlib: src/getopt-rs/lib.rs
-	$(RUSTC) $(RUSTFLAGS) --crate-type=lib --crate-name=getopt \
-		-o build/o/libgetopt.rlib src/getopt-rs/lib.rs
+		build/include/sysexits.h | $(RUSTC) $(RUSTFLAGS) --crate-type lib -o $@ -
 
 .PHONY: dj
 dj: build/bin/dj
@@ -70,17 +84,13 @@ build/bin/false: src/false.c build
 
 .PHONY: fop
 fop: build/bin/fop
-build/bin/fop: src/fop.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/fop.rs
+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 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
+build/bin/hru: src/hru.rs build rustlibs 
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/hru.rs
 
 .PHONY: intcmp
 intcmp: build/bin/intcmp
@@ -92,18 +102,20 @@ 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
+	$(CC) $(CFLAGS) -o $@ src/npc.c
+
+.PHONY: peek
+peek: build/bin/peek
+build/bin/peek: src/peek.c build
+	$(CC) $(CFLAGS) -o $@ src/peek.c
 
 .PHONY: rpn
 rpn: build/bin/rpn
-build/bin/rpn: src/rpn.rs build build/o/libsysexits.rlib
-	$(RUSTC) $(RUSTFLAGS) \
-		--extern sysexits=build/o/libsysexits.rlib \
-		-o $@ src/rpn.rs
+build/bin/rpn: src/rpn.rs build rustlibs
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/rpn.rs
 
 .PHONY: scrut
 scrut: build/bin/scrut

docs/peek.1

@@ -0,0 +1,90 @@
+.\" Copyright (c) 2023-2024 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 PEEK 1
+
+.SH NAME
+
+peek \(en read from the standard input, furtively
+
+.SH SYNOPSIS
+
+peek
+.RB ( -i )
+
+.SH DESCRIPTION
+
+Peek reads input from the standard input with terminal echo disabled.
+
+.SH OPTIONS
+
+.B -i
+.RS
+Allows input to come from sources other than terminals (i.e. a pipe).
+.RE
+
+.SH DIAGNOSTICS
+
+Peek prints an error message and exits with the appropriate status from
+sysexits.h(3) if it encounters an unrecoverable error.
+
+Peek tries to handle the signal SIGINT (^C) to ensure the user's terminal is
+still usable after premature termination; if the signal can't be handled, it
+prints an error message and continues. If peek is interrupted, it exits
+unsuccessfully, without an error message.
+
+.SH RATIONALE
+
+This tool was originally written to accept passwords in shell scripts, as an
+extremely simple alternative to the GNU Privacy Guard project's pinentry(1).
+Accepting input without showing what is being typed is useful when keying in
+secrets in public settings or places with installed surveillance cameras.
+
+.SH BUGS
+
+This does nothing to prevent others seeing the keyboard being used to input
+secrets or mask the sound of typing. Audio or video recordings of typing can be
+used to determine what was input without needing to see the characters appear
+on the screen.
+
+Accepting secrets in shell scripts is probably not adviseable.
+
+On systems that support it, the ioctl(2) command TIOCSTI can be used to insert
+characters into the standard input going to peek. This doesn't allow snooping
+but can be used for general mischief.
+
+.SH EXAMPLES
+
+This is an sh(1p) command line that hashes a given password. It uses head(1p)
+to only accept one line of input, xargs(1p) and printf(1p) to strip the
+trailing newline, htpasswd(1) from Apache's utilities to hash the input with
+the bcrypt algorithm, and cut(1p) to print only the resulting hash:
+
+.RS
+.R $ peek | head -n 1 | xargs printf '%s' | htpasswd -nBi _ | cut -d : -f 2
+.RE
+
+This is an sh(1p) command line that lets a user blindly write into a text file,
+only able to see written lines. Some writers have the habit of prematurely
+revising their work and use tools like this to prevent it. It uses mm(1) to
+pipe the output of peek to both the standard error and the regular file
+writing.txt.
+
+.RS
+.R $ echo Input ^D to quit. && peek | mm -eo - >writing.txt
+.RE
+
+.SH AUTHOR
+
+Written by DTB <trinity@trinity.moe>.
+
+.SH COPYRIGHT
+
+Copyright (c) 2023-2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/gpl.html>.
+
+.SH SEE ALSO
+
+ioctl(2), ioctl_tty(2), read(1), sh(1)

src/fop.rs

@@ -22,10 +22,12 @@ use std::{
 	process::{ Command, exit, Stdio },
 };
 
-extern crate sysexits;
 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() {
@@ -55,7 +57,7 @@ fn main() {
 	});
 
 	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|e| {
-		eprintln!("{}: {}: {}.", argv[0], argv[1], e);
+		eprintln!("{}: {}: {}", argv[0], argv[1], e);
 		exit(EX_DATAERR);
 	});
 
@@ -75,13 +77,13 @@ fn main() {
 		.stdout(Stdio::piped())
 		.spawn()
 		.unwrap_or_else( |e| {
-			eprintln!("{}: {}: {}.", argv[0], argv[command_arg], 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.",
+			"{}: {}: No such index in input",
 			argv[0],
 			index.to_string(),
 		);
@@ -94,7 +96,7 @@ fn main() {
 	}
 
 	let output = spawned.wait_with_output().unwrap_or_else(|e| {
-		eprintln!("{}: {}: {}.", argv[0], argv[command_arg], e);
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e.strerror());
 		exit(EX_IOERR);
 	});
 
@@ -103,7 +105,7 @@ fn main() {
 	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);
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e);
 		exit(EX_IOERR);
 	});
 
@@ -111,8 +113,8 @@ fn main() {
 
 	stdout().write_all(
 		fields.join(&d.to_string()).as_bytes()
-	).unwrap_or_else(|e|{
-		eprintln!("{}: {}.", argv[0], e);
+	).unwrap_or_else(|e| {
+		eprintln!("{}: {}", argv[0], e.strerror());
 		exit(EX_IOERR);
 	});
 }

src/hru.rs

@@ -23,8 +23,10 @@ use std::{
 	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] = [
@@ -49,7 +51,7 @@ fn convert(input: u128) -> Result<(f64, (u32, &'static str)), String> {
 		let c = match 10_u128.checked_pow(n) {
 			Some(c) => c,
 			None => {
-				return Err(format!("10^{}: Integer overflow.", n.to_string()));
+				return Err(format!("10^{}: Integer overflow", n.to_string()));
 			},
 		};
 
@@ -79,7 +81,7 @@ fn main() -> ExitCode {
 				f
 			},
 			Err(err) => {
-				eprintln!("{}: {}.", argv[0], err);
+				eprintln!("{}: {}", argv[0], err);
 				return ExitCode::from(EX_DATAERR as u8);
 			},
 		};
@@ -87,7 +89,7 @@ fn main() -> ExitCode {
 		let (number, prefix) = match convert(n) {
 			Ok(x) => x,
 			Err(err) => {
-				eprintln!("{}: {}.", argv[0], err);
+				eprintln!("{}: {}", argv[0], err);
 				return ExitCode::from(EX_SOFTWARE as u8);
 			},
 		};
@@ -98,7 +100,7 @@ fn main() -> ExitCode {
 
 		stdout().write_all(format!("{} {}\n", out, si_prefix).as_bytes())
 			.unwrap_or_else(|e| {
-				eprintln!("{}: {}.", argv[0], e);
+				eprintln!("{}: {}", argv[0], e.strerror());
 				exit(EX_IOERR);
 			});
 	}

src/peek.c

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2023–2024 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 <signal.h> /* sigaction(2), signal(2), struct sigaction, SIGINT */
+#include <stdio.h> /* fprintf(3), fgetc(3), perror(3), fputc(3), stderr, stdin,
+                    * stdout, EOF, NULL */
+#include <stdlib.h> /* exit(3), EXIT_FAILURE */
+#if !defined EX_IOERR || !defined EX_OK || !defined EX_USAGE
+#	include <sysexits.h>
+#endif
+#include <termios.h> /* tcgetattr(3), tcsetattr(3), struct termios, ECHO */
+#include <unistd.h> /* getopt(3), isatty(3), STDIN_FILENO */
+
+static char *program_name = "peek";
+
+/* Restores terminal echo; otherwise when a user ^Cs the terminal would
+ * continue to not display typed text. If sig isn't zero, this will terminate
+ * the program. */
+static void restore_echo(int sig){
+	static struct termios t;
+
+	tcgetattr(STDIN_FILENO, &t);
+	t.c_lflag |= ECHO;
+	tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
+
+	/* If, for whatever ungodly reason, exit(3) returns, the user will notice
+	 * their typed characters on the screen. */
+	if(sig != 0)
+		exit(EXIT_FAILURE);
+
+	return;
+}
+
+static int ioerr(char *s){ perror(s); restore_echo(0); return EX_IOERR; }
+static int usage(char *s){
+	fprintf(stderr, "Usage: %s (-1enot) (-p [program [arguments...]])\n", s);
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+
+	if(argc < 1)
+		return usage(program_name);
+
+	{ /* option parsing */
+		char allow_nonterminals;
+		int c;
+
+		allow_nonterminals = 0;
+		while((c = getopt(argc, argv, "i")) != -1)
+			switch(c){
+			case 'i':	allow_nonterminals = 1; break;
+			default:	return usage(argv[0]);
+			}
+
+		if(argc > optind)
+			return usage(argv[0]);
+
+		if(!allow_nonterminals && isatty(STDIN_FILENO) != 1){
+			fprintf(stderr, "%s: Must be run in a terminal"
+			    " (option -i skips this check)\n", argv[0]);
+			return EX_USAGE;
+		}
+	}
+
+	{ /* install signal handler */
+		/* There isn't a difference in functionality between the signal(2) and
+		 * sigaction(2) methods. sigaction(2) is vastly preferred for
+		 * portability but some configurations can only use signal(2). */
+		/* Errors aren't terminating because the worst that happens is some
+		 * terminal phooeyness if things go awry. */
+#if defined _POSIX_C_SOURCE
+		struct sigaction act = { 0 };
+
+		act.sa_handler = restore_echo;
+		if(sigaction(SIGINT, &act, NULL) != 0)
+			perror(argv[0]);
+#else
+		if(signal(SIGINT, restore_echo) == SIG_ERR)
+			perror(argv[0]);
+#endif
+	}
+	
+	{ /* banish terminal echo */
+		struct termios t;
+
+		tcgetattr(STDIN_FILENO, &t);
+		t.c_lflag ^= ECHO;
+		tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
+	}
+
+	{ /* actual input loop */
+		int c;
+
+		while((c = fgetc(stdin)) != EOF)
+			if(fputc(c, stdout) == EOF)
+				return ioerr(argv[0]);
+	}
+
+	restore_echo(0);
+
+	return EX_OK;
+}

src/rpn.rs

@@ -172,7 +172,7 @@ fn eval(
 					};
 				} else {
 					return Err(EvaluationError {
-						message: format!("{}: Unexpected operation.", op),
+						message: format!("{}: Unexpected operation", op),
 						code: EX_DATAERR,
 					})
 				}

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/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);
+	});
+}