peek(1): warn on pledge(2) or unveil(2) errors

I could trace strcmp(1) as far back as
<293436c5ad/src/streq.c>
in my repo.

Makefile

@@ -32,7 +32,7 @@ RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 CFLAGS += -I$(SYSEXITS)
 
 .PHONY: all
-all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
+all: docs dj false fop hru intcmp mm npc peek rpn scrut str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -109,8 +109,8 @@ build/bin/hru: src/hru.rs build rustlibs
 
 .PHONY: intcmp
 intcmp: build/bin/intcmp
-build/bin/intcmp: src/intcmp.c build
-	$(CC) $(CFLAGS) -o $@ src/intcmp.c
+build/bin/intcmp: src/intcmp.rs build rustlibs
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/intcmp.rs
 
 .PHONY: mm
 mm: build/bin/mm
@@ -120,7 +120,12 @@ build/bin/mm: src/mm.rs build rustlibs
 .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

docs/peek.1

@@ -0,0 +1,111 @@
+.\" Copyright (c) 2023-2024 DTB <trinity@trinity.moe>
+.\" 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 PEEK 1 2024-08-14 "Harakit X.X.X"
+.SH NAME
+peek \(en read from the standard input, furtively
+.\"
+.SH SYNOPSIS
+
+peek
+.RB ( -i )
+.\"
+.SH DESCRIPTION
+
+Read input from the standard input with terminal echo disabled.
+.\"
+.SH OPTIONS
+
+.IP \fB-i\fP
+Allows input to come from sources other than terminals (pipes).
+.\"
+.SH DIAGNOSTICS
+
+In the event of an error, a debug message will be printed and the program will
+exit with the appropriate
+.BR sysexits.h (3)
+error code.
+
+In order to ensure the user\(cqs terminal is still usable after premature
+termination, the program attempts to handle the SIGINT signal; if it cannot,
+an error message is printed and execution continues. If the program 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\(cqs
+.BR pinentry (1)
+utility.
+
+Accepting input without showing what is being typed is useful when keying in
+secrets in public settings or in places where surveillance cameras are
+installed.
+.\"
+.SH CAVEATS
+
+This program does nothing to prevent others from seeing the key presses input to
+a keyboard. It also does not protect against the sound of typing being analyzed
+to determine what was input without needing to see screen or keyboard.
+
+Accepting secrets in shell scripts is probably not advisable.
+
+On systems that support it, the
+.BR ioctl (2)
+command TIOCSTI can be used to insert characters into the standard input. This
+doesn't allow snooping but can be used for general mischief.
+.\"
+.SH EXAMPLES
+
+This is an
+.BR sh (1p)
+command line that hashes a given password. It uses
+.BR head (1p)
+to only accept one line of input,
+.BR xargs (1p)
+and
+.BR printf (1p)
+to strip the trailing newline,
+.BR htpasswd (1) 
+from Apache\(cqs utilities to hash the input with the bcrypt algorithm, and
+.BR cut (1p)
+to print only the resulting hash:
+
+.RS
+$ peek | head -n 1 | xargs printf '%s' | htpasswd -nBi _ | cut -d : -f 2
+.RE
+
+This is an
+.BR sh (1p)
+command line that allows a user to write blindly into a text file but displaying
+only written lines. Some writers have the habit of prematurely revising their 
+work and use tools with functionality similar to this to prevent it. 
+It uses
+.BR mm (1)
+to pipe the output of the program to both the standard error and the regular
+file writing.txt:
+
+.RS
+$ echo Input ^D to quit. && peek | mm -eo - >writing.txt
+.RE
+.\"
+.SH AUTHOR
+
+Written by DTB
+.MT trinity@trinity.moe
+.ME .
+.\"
+.SH COPYRIGHT
+
+Copyright \(co 2023-2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
+<https://gnu.org/licenses/gpl.html>.
+.\"
+.SH SEE ALSO
+.BR ioctl (2),
+.BR ioctl_tty (2),
+.BR read (1p),
+.BR sh (1p),
+.BR stty (1p)

docs/strcmp.1

@@ -4,7 +4,7 @@
 .\" 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 2024-06-17 "Harakit X.X.X"
+.TH STRCMP 1 2024-07-15 "Harakit X.X.X"
 .SH NAME
 strcmp \(en compare strings
 .\"
@@ -20,15 +20,15 @@ Check whether string arguments are the same.
 .SH DIAGNOSTICS
 
 The program will exit successfully if the strings are identical. Otherwise, it
-will exit with an error code of 1 if a string passed has a lesser byte value
-than one of the prior strings:
+will exit with an error code less than 128 if a string passed has a lesser byte
+value than one of the prior strings:
 
 .RS
 strcmp b a
 .RE
 
-or with an error code of 255 if it has a greater byte value than one of the
-prior strings:
+or with an error code greater than 128 if it has a greater byte value than one
+of the prior strings:
 
 .RS
 strcmp a b

src/intcmp.c

@@ -1,82 +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 <errno.h> /* errno */
-#include <stdio.h> /* fprintf(3), stderr */
-#include <stdlib.h> /* strtol(3), size_t, EXIT_FAILURE */
-#include <unistd.h> /* getopt(3), optind */
-#include <sysexits.h>
-
-/* 0b00? */		/*                     Equal | -e  | 0b001 | 1 */
-#define EQUAL	0x01	/*                   Greater | -g  | 0b010 | 2 */
-/* 0b0?0 */		/*          Greater or Equal | -ge | 0b011 | 3 */
-#define GREATER	0x02	/*                      Less | -l  | 0b100 | 4 */
-/* 0b?00 */		/*             Less or Equal | -le | 0b101 | 5 */
-#define LESS	0x04	/* Inequal (Greater or Less) | -gl | 0b110 | 6 */
-
-static char *program_name = "intcmp";
-
-int main(int argc, char *argv[]){
-	int c;
-	size_t i;
-	unsigned char mode;
-	int r; /* reference integer */
-
-	mode = 0;
-
-	if(argc < 3)
-		goto usage;
-
-	while((c = getopt(argc, argv, "egl")) != -1)
-		switch(c){
-		case 'e': mode |= EQUAL;   break;
-		case 'g': mode |= GREATER; break;
-		case 'l': mode |= LESS;	   break;
-		default:  goto usage;
-		}
-
-	if(optind + 2 /* ref cmp */ > argc){
-usage:		fprintf(stderr,
-			"Usage: %s [-egl] integer integer...\n",
-			argv[0] == NULL ? program_name : argv[0]);
-		return EX_USAGE;
-	}
-
-	i = optind;
-
-	do{	r = c;
-		c = strtol(argv[i], &argv[i], 10);
-		if(*argv[i] != '\0' || errno != 0){
-			fprintf(stderr, "%s: argument #%d: Invalid integer\n",
-				argv[0], (int)i);
-			return EX_USAGE;
-		}
-
-		if(i == optind)
-			continue;
-
-		/* rule enforcement; if a mode isn't permitted and the numbers
-		 * correspond to it, return 1 */
-		if(		(!(mode & EQUAL) && r == c)
-				|| (!(mode & GREATER) && r > c)
-				|| (!(mode & LESS) && r < c))
-			return 1;
-	}while(++i < argc);
-	
-	return 0;
-}

src/intcmp.rs

@@ -0,0 +1,79 @@
+/*
+ * 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/.
+ */
+
+use std::{
+	env::args,
+	process::ExitCode
+};
+
+extern crate getopt;
+use getopt::GetOpt;
+
+extern crate sysexits;
+use sysexits::EX_USAGE;
+
+fn usage(s: &str) -> ExitCode {
+	eprintln!("Usage: {} [-egl] integer integer...", s);
+	ExitCode::from(EX_USAGE as u8)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+	let mut e = false; /* args can be == */
+	let mut g = false; /* args can be > */
+	let mut l = false; /* args can be < */
+	let mut optind = 0;
+
+	if argv.len() < 3 { return usage(&argv[0]); }
+
+	while let Some(opt) = argv.getopt("egl") {
+		match opt.opt() {
+			Ok("e") => e = true,
+			Ok("g") => g = true,
+			Ok("l") => l = true,
+			_ => { return usage(&argv[0]); },
+		}
+		optind = opt.ind();
+	}
+
+	if argv.len() - optind < 2 /* see usage */ { return usage(&argv[0]); }
+
+	let mut prev: Option<usize> = None; /* no previous operand */
+	let mut currn: usize;
+
+	for arg in argv.iter().skip(optind) { /* iterate operands */
+		match arg.parse::<usize>() { /* parse current operand */
+			Ok(n) => currn = n,
+			_ => {
+				eprintln!("{}: {}: Invalid integer", &argv[0], arg);
+				return ExitCode::from(EX_USAGE as u8);
+			}
+		}
+
+		if let Some(prevn) = prev { /* if there was a previous opr., test */
+			if (!e && prevn == currn)
+					|| (!g && prevn > currn)
+					|| (!l && prevn < currn)
+				{ return ExitCode::FAILURE; }
+		}
+
+		prev = Some(currn); /* there is a previous operand */
+	}
+
+	ExitCode::SUCCESS
+}

src/peek.c

@@ -0,0 +1,137 @@
+/*
+ * 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 */
+#include <sysexits.h> /* EX_IOERR, EX_OK, EX_USAGE */
+#include <termios.h> /* tcgetattr(3), tcsetattr(3), struct termios, ECHO */
+#include <unistd.h> /* getopt(3), isatty(3), pledge(2), unveil(2),
+                     * STDIN_FILENO */
+
+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;
+
+	/* Failure isn't reported because this is the termination routine anyway;
+	 * errors will be obvious. */
+	if (tcgetattr(STDIN_FILENO, &t) == 0) {
+		t.c_lflag |= ECHO;
+		(void)tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
+	}
+
+	if (sig != 0) { exit(EXIT_FAILURE); } /* Terminated by signal. */
+
+	return;
+}
+
+static int
+ioerr(char *argv0) {
+	perror(argv0);
+	restore_echo(0);
+	return EX_IOERR;
+}
+
+static int
+usage(char *argv0) {
+	(void)fprintf(stderr, "Usage: %s [-i]\n", argv0);
+
+	return EX_USAGE;
+}
+
+int main(int argc, char *argv[]){
+#ifdef __OpenBSD__
+	if (pledge("stdio tty unveil", "") != 0 || unveil(NULL, NULL) != 0) {
+		/* This isn't fatal; these return values could be cast to void just as
+		 * easily. */
+		(void)perror(argv[0] == NULL ? argv[0] : program_name);
+	}
+#endif
+
+	if (argc > 0) { /* option parsing */
+		char allow_nonterminals;
+		int c;
+
+		program_name = argv[0];
+
+		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) {
+			(void)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(program_name); }
+#else
+		if (signal(SIGINT, restore_echo) == SIG_ERR) { perror(program_name); }
+#endif
+	}
+
+	/* Banish terminal echo; this terminates when it fails, because it's the
+	 * whole point of the program. */
+	{
+		struct termios t;
+
+		if (tcgetattr(STDIN_FILENO, &t) != 0) { return ioerr(program_name); }
+		t.c_lflag ^= ECHO;
+		if (tcsetattr(STDIN_FILENO, TCSAFLUSH, &t) != 0) {
+			return ioerr(program_name);
+		}
+	}
+
+	{ /* Input loop */
+		int c;
+
+		while ((c = fgetc(stdin)) != EOF) {
+			if (fputc(c, stdout) == EOF) { return ioerr(program_name); }
+		}
+	}
+
+	restore_echo(0);
+
+	return EX_OK;
+}

src/strcmp.c

@@ -1,24 +1,43 @@
-#include <stdio.h> /* fprintf(3), stderr */
-#include <stdlib.h> /* EXIT_FAILURE */
-#include <sysexits.h>
+/*
+ * Copyright (c) 2022–2024 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/.
+ */
 
-static char *program_name = "strcmp";
+#include <stdio.h> /* fprintf(3), stderr */
+#include <stdlib.h> /* size_t */
+#include <sysexits.h> /* EX_USAGE */
+
+char *program_name = "strcmp";
 
 int main(int argc, char *argv[]){
-	int i;
-
-	if(argc < 3){
+	if (argc < 3) {
 		fprintf(stderr, "Usage: %s string string...\n",
-			argv[0] == NULL ? program_name : argv[0]);
+			argv[0] == NULL ? program_name : argv[0]
+		);
 		return EX_USAGE;
 	}
 
-	for(; *argv[1] != '\0'; ++argv[1])
-		for(i = 2; i < argc; ++i)
-			if(*argv[i-1] > *argv[i])
-				return 1;
-			else if(*argv[i-1] < *argv[i]++)
-				return -1; /* actually 255 */
+	/* This compares the Nth character of arg[2] onward with argv[1]'s Nth
+	 * character, rather than comparing each arg with argv[1] sequentially. */
+	for (; *argv[1] != '\0'; ++argv[1]) { /* iterate chars in argv[1] */
+		for (size_t i = 2; i < argc; ++argv[i], ++i) { /* iterate &argv[2] */
+			/* this never overruns because of nul termination */
+			if (*argv[i-1] != *argv[i]) { return *argv[i-1] - *argv[i]; }
+		}
+	}
 
 	return 0;
 }