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

Makefile

@@ -28,7 +28,7 @@ RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 CFLAGS += -I$(SYSEXITS)
 
 .PHONY: all
-all: dj false fop hru intcmp mm npc rpn scrut sleep str strcmp swab true
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
 
 build:
 	# keep build/include until bindgen(1) has stdin support
@@ -102,11 +102,15 @@ 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
@@ -118,13 +122,6 @@ scrut: build/bin/scrut
 build/bin/scrut: src/scrut.c build
 	$(CC) $(CFLAGS) -o $@ src/scrut.c
 
-.PHONY: sleep
-sleep: build/bin/sleep
-build/bin/sleep: src/sleep.rs build rustlibs
-	$(RUSTC) $(RUSTFLAGS) \
-		--extern sysexits=build/o/libsysexits.rlib \
-		-o $@ src/sleep.rs
-
 .PHONY: str
 str: build/bin/str
 build/bin/str: src/str.c build

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)

docs/sleep.1

@@ -1,53 +0,0 @@
-.\" 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 SLEEP 1
-
-.SH NAME
-
-sleep \(en wait a moment
-
-.SH SYNOPSIS
-
-sleep
-.RB [ seconds ]
-
-.SH DESCRIPTION
-
-Sleep waits the given amount of seconds before exiting.
-
-.SH DIAGNOSTICS
-
-Sleep exits successfully when the time specified has elapsed, or unsuccessfully
-if the time fails to elapse or if invoked incorrectly. In the latter scenario
-sleep will also print a usage synopsis.
-
-.SH BUGS
-
-User may still be tired after invoking sleep.
-
-.SH EXAMPLES
-
-The following invocation sleeps for five seconds.
-
-.RS
-.R sleep 5
-.RE
-
-The following sh(1p) command line sleeps for five minutes, or for sixty
-seconds, five times, using rpn(1) and xargs(1p).
-
-.RS
-.R $ rpn 60 5 '*' | xargs sleep
-.RE
-
-.SH COPYRIGHT
-
-Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
-<https://gnu.org/licenses/gpl.html>.
-
-.SH SEE ALSO
-
-sleep(3)

src/mm.c

@@ -106,15 +106,6 @@ oserr(char *s, char *r){
 	} \
 	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} */
@@ -187,15 +178,12 @@ int main(int argc, char *argv[]){
 				k = 1;
 				break;
 			default:
-				retval = usage(argv[0]);
+				fprintf(stderr, "Usage: %s (-aenu) (-i [input])..."
+					" (-o [output])...\n", argv[0]);
+				retval = EX_USAGE;
 				terminate;
 			}
 
-	if(optind != argc){
-		retval = usage(argv[0]);
-		terminate;
-	}
-
 	files[0].s += files[0].s == 0;
 	files[1].s += files[1].s == 0;
 	

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/scrut.c

@@ -1,6 +1,5 @@
 /*
- * Copyright (c) 2023–2024 DTB <trinity@trinity.moe>
+ * Copyright (c) 2023 DTB <trinity@trinity.moe>
- * 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
@@ -18,15 +17,13 @@
  */
 
 #include <stdio.h> /* fprintf(3), stderr, NULL */
-#include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
+#include <stdlib.h> /* EXIT_FAILURE */
 #include <string.h> /* memset(3), strchr(3) */
-#ifndef EX_USAGE
-#	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)];
@@ -60,7 +57,7 @@ int main(int argc, char *argv[]){
 
 	argv += optind;
 	do{	if(access(*argv, F_OK) != 0 || lstat(*argv, &buf) == -1)
-			return EXIT_FAILURE; /* doesn't exist or isn't stattable */
+			return 1; /* doesn't exist or isn't stattable */
 
 		for(i = 0; ops[i] != '\0'; ++i)
 			if(ops[i] == 'e')
@@ -100,8 +97,8 @@ usage:				fprintf(stderr, "Usage: %s (-%s) [file...]\n",
 						&& !S_ISLNK(buf.st_mode))
 					|| (ops[i] == 'S'
 						&& !S_ISSOCK(buf.st_mode)))
-				return EXIT_FAILURE;
+				return 1;
 	}while(*++argv != NULL);
 
-	return EXIT_SUCCESS;
+	return 0;
 }

src/sleep.rs

@@ -1,47 +0,0 @@
-/*
- * 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,
-	process::ExitCode,
-	thread::sleep,
-	time::Duration
-};
-
-extern crate sysexits;
-use sysexits::EX_USAGE;
-
-fn usage(s: &str) -> ExitCode {
-	eprintln!("Usage: {} [seconds]", s);
-	ExitCode::from(EX_USAGE as u8)
-}
-
-fn main() -> ExitCode {
-	let argv = args().collect::<Vec<String>>();
-
-	if argv.len() == 2 {
-		if let Ok(s) = argv[1].parse::<u64>() {
-			sleep(Duration::from_secs(s));
-			ExitCode::SUCCESS
-		} else {
-			usage(&argv[0])
-		}
-	} else {
-		usage(&argv[0])
-	}
-}