tests: bonsai/peek.mk

Makefile

@@ -19,7 +19,7 @@ PREFIX ?= /usr/local
 # for conditionally compiling OS features
 OS != uname
 OS_INCLUDE != test -e include/$(OS).mk && printf 'include/$(OS).mk\n' \
-	|| include/None.mk
+	|| printf '/dev/null\n'
 
 # normalized prefix
 PREFIX_N != dirname $(PREFIX)/.
@@ -42,7 +42,7 @@ BIN = build/bin
 default: all test
 
 .PHONY: all
-all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
+all: 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
@@ -137,6 +137,11 @@ npc: build/bin/npc
 build/bin/npc: src/npc.c build
 	$(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 rustlibs

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)

src/dj.c

@@ -170,12 +170,6 @@ usage(char *argv0) {
 }
 
 int main(int argc, char *argv[]) {
-#ifdef __OpenBSD__
-	if (pledge("cpath rpath stdio unveil wpath", NULL) == -1) {
-		return oserr(NULL", errno);
-	}
-#endif
-
    	int align;    /* low 8b used, negative if no alignment is being done */
 	int count;    /* -1 if dj(1) runs until no more reads are possible */
 	char *fmt;    /* set to fmt_asv (default) or fmt_human (-H) */
@@ -183,6 +177,12 @@ int main(int argc, char *argv[]) {
 	bool retry;   /* false if exits on partial reads or writes */
 	struct Io io[2 /* { in, out } */];
 
+#ifdef __OpenBSD__
+	if (pledge("cpath rpath stdio unveil wpath", NULL) == -1) {
+		return oserr(NULL, errno);
+	}
+#endif
+
 	/* Set defaults. */
 	align = -1;
 	count = -1;
@@ -217,13 +217,9 @@ int main(int argc, char *argv[]) {
 						break;
 					} else {
 						int fd;
+
 #ifdef __OpenBSD__
-						char *perms = "wc";
-
-						/* modify perms in-place to read-only */
-						if (i == 0) { perms = "r"; }
-
-						if (unveil(optarg, perms) == -1) {
+						if (unveil(optarg, i == 0 ? "r" : "wc") == -1) {
 							return oserr(NULL, errno);
 						}
 #endif
@@ -267,6 +263,7 @@ int main(int argc, char *argv[]) {
 			}
 		}
 	}
+
 #ifdef __OpenBSD__
 	if (unveil(NULL, NULL) == -1) { return oserr(NULL, errno); }
 #endif

src/false.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
  * SPDX-License-Identifier: CC0
  *
  * This work is marked with CC0 1.0. To view a copy of this license, visit
@@ -10,9 +11,9 @@
 #	include <unistd.h> /* pledge(2) */
 #endif
 
-int main() {
+int main(void) {
 #ifdef __OpenBSD__
 	pledge(NULL, NULL);
 #endif
-return 1;
+	return 1;
 }

src/fop.rs

@@ -39,7 +39,7 @@ fn main() {
 	let mut d = '\u{1E}'.to_string(); /* ASCII record separator */
 	let mut optind = 1;
 
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio proc exec");
 		if let Err(e) = pledge(Some(promises), None) {
 			eprintln!("{}: {}", argv[0], e.strerror());

src/hru.rs

@@ -86,7 +86,7 @@ fn main() -> ExitCode {
 		return ExitCode::from(EX_USAGE as u8);
 	}
 
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
 			eprintln!("{}: {}", argv[0], e.strerror());

src/intcmp.rs

@@ -34,7 +34,6 @@ use sysexits::EX_USAGE;
 #[cfg(target_os="openbsd")] use openbsd::{ Promises, pledge };
 #[cfg(target_os="openbsd")] use strerror::StrError;
 
-
 fn usage(s: &str) -> ExitCode {
 	eprintln!("Usage: {} [-egl] integer integer...", s);
 	ExitCode::from(EX_USAGE as u8)
@@ -43,7 +42,7 @@ fn usage(s: &str) -> ExitCode {
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
 
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
 			eprintln!("{}: {}", argv[0], e.strerror());

src/libopenbsd.rs

@@ -17,7 +17,7 @@
  */
 
 use std::{
-	ffi::CString,
+	ffi::{ CString, c_char },
 	io::Error,
 	ptr::null,
 };
@@ -33,13 +33,13 @@ mod openbsd {
 	}
 }
 
-pub struct Promises(*const i8);
+pub struct Promises(*const c_char);
 
 impl Promises {
 	pub fn new(promises: &str) -> Self {
 		let p = CString::new(promises).unwrap();
 
-		Promises(p.into_raw() as *const i8)
+		Promises(p.into_raw() as *const c_char)
 	}
 }
 
@@ -81,10 +81,10 @@ pub fn unveil(
 	permissions: Option<UnveilPerms>,
 ) -> Result<(), Error> {
 	let path_c = path.map(CString::new).map(Result::unwrap);
-	let arg1 = path_c.map(|p| p.into_raw() as *const i8).unwrap_or(null());
+	let arg1 = path_c.map(|p| p.into_raw() as *const c_char).unwrap_or(null());
 
 	let arg2 = permissions
-		.map(|p| p.0.into_raw() as *const i8)
+		.map(|p| p.0.into_raw() as *const c_char)
 		.unwrap_or(null());
 
 	unsafe {

src/mm.rs

@@ -51,8 +51,8 @@ fn main() -> ExitCode {
 	let argv = args().collect::<Vec<_>>();
 	let usage = format!("Usage: {} [-aetu] [-i input] [-o output]", argv[0]);
 
-	if cfg!(target_os="openbsd") {
-		let promises = Promises::new("rpath stdio unveil");
+	#[cfg(target_os="openbsd")] {
+		let promises = Promises::new("cpath rpath stdio unveil wpath");
 		if let Err(e) = pledge(Some(promises), None) {
 			eprintln!("{}: {}", argv[0], e.strerror());
 			return ExitCode::from(EX_OSERR as u8);
@@ -76,29 +76,11 @@ fn main() -> ExitCode {
 			Ok("t") => t = false,
 			Ok("i") => { /* add inputs */
 				let input = opt.arg().unwrap();
-
-				if cfg!(target_os="openbsd") {
-					let perms = UnveilPerms::new(vec!['r']);
-					if let Err(e) = unveil(Some(&input), Some(perms)) {
-						eprintln!("{}: {}", argv[0], e.strerror());
-						return ExitCode::from(EX_OSERR as u8);
-					}
-				}
-
 				ins.push(input);
 				mode = Some(In); /* latest argument == -i */
 			},
 			Ok("o") => { /* add output */
 				let output = opt.arg().unwrap();
-
-				if cfg!(target_os="openbsd") {
-					let perms = UnveilPerms::new(vec!['w', 'c']);
-					if let Err(e) = unveil(Some(&output), Some(perms)) {
-						eprintln!("{}: {}", argv[0], e.strerror());
-						return ExitCode::from(EX_OSERR as u8);
-					}
-				}
-
 				outs.push(output);
 				mode = Some(Out); /* latest argument == -o */
 			},
@@ -124,7 +106,25 @@ fn main() -> ExitCode {
 		}
 	}
 
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
+		for input in &ins {
+			let perms = UnveilPerms::new(vec!['r']);
+
+			if let Err(e) = unveil(Some(&input), Some(perms)) {
+				eprintln!("{}: {}", argv[0], e.strerror());
+				return ExitCode::from(EX_OSERR as u8);
+			}
+		}
+
+		for output in &outs {
+			let perms = UnveilPerms::new(vec!['c', 'w']);
+
+			if let Err(e) = unveil(Some(&output), Some(perms)) {
+				eprintln!("{}: {}", argv[0], e.strerror());
+				return ExitCode::from(EX_OSERR as u8);
+			}
+		}
+
 		if let Err(e) = unveil(None, None) {
 			eprintln!("{}: {}", argv[0], e.strerror());
 			return ExitCode::from(EX_OSERR as u8);

src/npc.c

@@ -39,22 +39,20 @@ usage(char *argv0) {
 }
 
 int main(int argc, char *argv[]) {
-#ifdef __OpenBSD__
-	program_name = argv[0] == NULL ? program_name : argv[0];
-
-	if (pledge("stdio", NULL) == -1) {
-		perror(program_name);
-		return EX_OSERR;
-	}
-#endif
 	int c;
 	char showend = 0; /* print a dollar sign before each newline */
 	char showtab = 0; /* prints tab characters in caret notation */
 
-	if (argc > 0) {
-#ifndef __OpenBSD__
-		program_name = argv[0];
+#ifdef __OpenBSD__
+	if (pledge("stdio", NULL) == -1) {
+		perror(argv[0] == NULL ? program_name : argv[0]);
+		return EX_OSERR;
+	}
 #endif
+
+	if (argc > 0) {
+		program_name = argv[0];
+
 		while ((c = getopt(argc, argv, "et")) != -1) {
 			switch (c){
 				case 'e': showend = 1; break;

src/peek.c

@@ -0,0 +1,147 @@
+/*
+ * 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 <stdbool.h> /* bool */
+#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[]){
+	bool is_term; /* Is stdin a terminal? */
+	bool must_be_term = 1; /* Must it be? */
+
+#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
+
+	is_term = isatty(STDIN_FILENO);
+
+	if (argc > 0) { /* option parsing */
+		int c;
+
+		program_name = argv[0];
+
+		while ((c = getopt(argc, argv, "i")) != -1) {
+			switch (c) {
+				case 'i':	must_be_term = 0; break;
+				default:	return usage(argv[0]);
+			}
+		}
+
+		if (argc > optind) { return usage(argv[0]); }
+	}
+
+	if (!is_term && must_be_term) {
+		(void)fprintf(
+		    stderr,
+		    "%s: Must be run in a terminal (specify -i to skip this check)\n",
+		    argv[0]
+		);
+		return EX_USAGE;
+	}
+
+	if (is_term) {
+		{ /* 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 older systems only have 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); }
+		}
+	}
+
+	if (is_term) { restore_echo(0); }
+
+	return EX_OK;
+}

src/rpn.rs

@@ -198,7 +198,7 @@ fn round_precise(value: &f64, precision: usize) -> f64 {
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
 
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
 			eprintln!("{}: {}", argv[0], e.strerror());

src/scrut.c

@@ -17,6 +17,7 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
+#include <assert.h> /* assert(3) */
 #include <stdio.h> /* fprintf(3), stderr, NULL */
 #include <stdlib.h> /* EXIT_FAILURE, EXIT_SUCCESS */
 #include <string.h> /* memset(3), strchr(3) */
@@ -29,6 +30,7 @@
 
 char *program_name = "scrut";
 #define OPTS "bcdefgkprsuwxLS"
+/* this is an array so main:sel's size can be known at compile time */
 static char opts[] = OPTS;
 
 static int
@@ -58,7 +60,10 @@ int main(int argc, char *argv[]) {
 		memset(sel, '\0', sizeof sel);
 		for (int c; (c = getopt(argc, argv, opts)) != -1;) {
 			if ((p = strchr(opts, c)) == NULL) { return usage(argv[0]); }
-			else { sel[p - opts] = c; }
+			else {
+				assert(p - opts < sizeof sel / sizeof *sel); /* bounds check */
+				sel[p - opts] = c;
+			}
 		}
 
 		/* straighten out selections; permute out nulls */
@@ -73,7 +78,7 @@ int main(int argc, char *argv[]) {
 
 	if (optind == argc) { return usage(argv[0]); }
 
-	for (argv += optind ; *argv != NULL; ++argv) {
+	for (argv += optind ; *argv != NULL; argv = &argv[1]) {
 		struct stat buf;
 
 #ifdef __OpenBSD__

src/strcmp.c

@@ -26,18 +26,22 @@
 char *program_name = "strcmp";
 
 int main(int argc, char *argv[]) {
-	program_name = argv[0] == NULL ? program_name : argv[0];
-	int i;
+	unsigned int i;
 
 #ifdef __OpenBSD__
 	if (pledge("stdio", NULL) == -1) {
-		perror(program_name);
+		perror(argv[0] == NULL ? program_name : argv[0]);
+
 		return EX_OSERR;
 	}
 #endif
 
 	if (argc < 3) {
-		(void)fprintf(stderr, "Usage: %s string string...\n", program_name);
+		(void)fprintf(
+			stderr,
+			"Usage: %s string string...\n",
+			argv[0] == NULL ? program_name : argv[0]
+		);
 
 		return EX_USAGE;
 	}

src/swab.rs

@@ -54,7 +54,7 @@ fn usage(s: &str) -> ExitCode {
 fn main() -> ExitCode {
 	let argv = args().collect::<Vec<String>>();
 	
-	if cfg!(target_os="openbsd") {
+	#[cfg(target_os="openbsd")] {
 		let promises = Promises::new("stdio");
 		if let Err(e) = pledge(Some(promises), None) {
 			return oserr(&argv[0], e);

src/true.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2023–2024 Emma Tebibyte <emma@tebibyte.media>
+ * Copyright (c) 2024 DTB <trinity@trinity.moe>
  * SPDX-License-Identifier: CC0
  *
  * This work is marked with CC0 1.0. To view a copy of this license, visit
@@ -10,7 +11,7 @@
 #	include <unistd.h> /* pledge(2) */
 #endif
 
-int main() {
+int main(void) {
 #ifdef __OpenBSD__
 	pledge(NULL, NULL);
 #endif

tests/bonsai/dj.mk

@@ -19,7 +19,7 @@ dj_tests: dj_help dj_full dj_null # dj_skip_stdin
 dj_full: $(BIN)/dj /dev/full
 	case "$$(uname)" in \
 	Linux) \
-		$(BIN)/dj -Hi /dev/zero -o /dev/full 2>&1 \
+		! $(BIN)/dj -Hi /dev/zero -o /dev/full 2>&1 \
 			| tee /dev/stderr \
 			| xargs -I out test '1+0 > 0+0; 1024 > 0' = out \
 		;; \

tests/bonsai/mm.mk

@@ -1,4 +1,4 @@
-# Copyright (c) 2024 E$(NAME)a Tebibyte <e$(NAME)a@tebibyte.media>
+# Copyright (c) 2024 Emma Tebibyte <emma@tebibyte.media>
 # SPDX-License-Identifier: FSFAP
 #
 # Copying and distribution of this file, with or without modification, are
@@ -6,7 +6,7 @@
 # notice are preserved.  This file is offered as-is, without any warranty.
 
 .PHONY: mm_tests
-mm_tests: mm_args mm_help mm_stderr
+mm_tests: mm_args mm_help mm_stderr mm_remaining
 
 .PHONY: mm_none
 mm_none: $(BIN)/mm
@@ -25,3 +25,10 @@ mm_help: $(BIN)/mm
 # check if stderr is empty upon specifying -e
 mm_stderr: $(BIN)/mm
 	test "$$(printf 'test\n' | $(BIN)/mm -e 2>&1 >/dev/null )" = "test"
+
+.PHONY: mm_remaining
+# check to make sure remaining arguments are used
+mm_remaining: $(BIN)/mm
+	test "$$($(BIN)/mm -i README COPYING)" = "$$(cat README COPYING)"
+	$(BIN)/mm -i README -o /tmp/mm_test0 /tmp/mm_test1
+	diff /tmp/mm_test0 /tmp/mm_test1

tests/bonsai/npc.mk

@@ -32,11 +32,29 @@ npc_ascii: npc_ascii_controls npc_ascii_symbols npc_ascii_uppers # \
 .PHONY: npc_ascii_controls
 # (control characters)
 npc_ascii_controls:
+	# The following test prints the bytes 0x00 (inclusive) through 0x20
+	# (exclusive) and pipes them through npc(1). npc(1) should then replace all
+	# non-printing, non-space (in the isspace(3p) sense) characters with their
+	# graphical carat-char counterparts (see the npc(1) man page). The head(1p)
+	# invocation then strips off everything past the first line (or past the
+	# first newline byte, 0x0A) and xargs(1p) is used to test(1p) the output
+	# against the known good answer.
+
+	# Immediately before that newline, 0x09 is printed - in ASCII, the
+	# horizontal tab. If xargs' -I option is used, tr(1p) should used to delete
+	# that tab. If the tab is left as part of input, OpenBSD's xargs(1)
+	# implementation has been observed to strip it along with the other
+	# trailing whitespace (the newline), but Busybox's and GNU's xargs(1)
+	# implementations have been observed to leave the tab in. All three
+	# implementations strip off the trailing tab if `-I` is not used. The POSIX
+	# specification for `-I` is ambiguous as to which behavior is correct.
+	# This comment is the result of much bewilderment and debugging.
+
 	# ASCII 0x00 to 0x0a (before the newline, due to xargs(1p) issues)
 	awk 'BEGIN{ for (i = 0; i < 32; ++i) printf("%c", i); }' \
 		| $(BIN)/npc \
 		| head -n 1 \
-		| xargs -I out test "^@^A^B^C^D^E^F^G^H" = out
+		| xargs test "^@^A^B^C^D^E^F^G^H" =
 
 	# ASCII 0x0a (otherwise the head|tail sequence won't work) to 0x1f
 	awk 'BEGIN{ for (i = 0; i < 32; ++i) printf("%c", i); print }' \

tests/bonsai/peek.mk

@@ -0,0 +1,24 @@
+# Copyright (c) 2024 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.
+
+# Testing peek is hard as it requires visual confirmation that text isn't being
+# echoed. These tests don't go that far but are a start, and have already
+# caught a bug in -i behavior.
+
+.PHONY: peek_tests
+peek_tests: peek_help peek_stdio
+
+.PHONY: peek_help
+peek_help: $(BIN)/peek
+	! $(BIN)/peek -h
+
+.PHONY: peek_stdio
+# Test peek -i
+peek_stdio: $(BIN)/peek
+	printf 'Test.\n' \
+		| $(BIN)/peek -i \
+		| xargs test 'Test.' =

tests/bonsai/rpn.mk

@@ -30,7 +30,7 @@ rpn_mul: $(BIN)/rpn
 .PHONY: rpn_div
 rpn_div: $(BIN)/rpn
 	test "$$($(BIN)/rpn 12 5 /)" = 2.4
-	test "$$($(BIN)/rpn 3 0 /)" -eq inf
+	test "$$($(BIN)/rpn 3 0 /)" = inf
 
 .PHONY: rpn_mod
 rpn_mod: $(BIN)/rpn