zn(1): proof of concept

Makefile

@@ -31,8 +31,8 @@ RUSTLIBS = --extern getopt=build/o/libgetopt.rlib \
 	--extern strerror=build/o/libstrerror.rlib
 CFLAGS += -I$(SYSEXITS)
 
-.PHONY: all
-all: dj false fop hru intcmp mm npc rpn simexec scrut str strcmp swab true
+all: argued dj false fop hru intcmp mm npc pschdir retval rpn scrut simexec \
+	str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -87,6 +87,11 @@ build/o/libsysexits.rlib: build/include/sysexits.h
 build/include/sysexits.h: build $(SYSEXITS)sysexits.h
 	printf '\043define EXIT_FAILURE 1\n' | cat - $(SYSEXITS)sysexits.h > $@
 
+.PHONY: argued
+argued: build/bin/argued
+build/bin/argued: src/argued.rs build
+	$(RUSTC) $(RUSTFLAGS) -o $@ src/argued.rs
+
 .PHONY: dj
 dj: build/bin/dj
 build/bin/dj: src/dj.c build
@@ -122,6 +127,16 @@ npc: build/bin/npc
 build/bin/npc: src/npc.c build
 	$(CC) $(CFLAGAS) -o $@ src/npc.c
 
+.PHONY: pschdir
+pschdir: build/bin/pschdir
+build/bin/pschdir: src/pschdir.rs build
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/pschdir.rs
+
+.PHONY: retval
+retval: build/bin/retval
+build/bin/retval: src/retval.rs build rustlibs
+	$(RUSTC) $(RUSTFLAGS) $(RUSTLIBS) -o $@ src/retval.rs
+
 .PHONY: rpn
 rpn: build/bin/rpn
 build/bin/rpn: src/rpn.rs build rustlibs
@@ -156,3 +171,8 @@ build/bin/swab: src/swab.rs build rustlibs
 true: build/bin/true
 build/bin/true: src/true.c build
 	$(CC) $(CFLAGS) -o $@ src/true.c
+
+.PHONY: zn
+zn: build/bin/zn
+build/bin/zn: src/zn.c build
+	$(CC) $(CFLAGS) -o $@ src/zn.c

docs/argued.1

@@ -0,0 +1,28 @@
+.\" Copyright (c) 2022–2024 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 ARGUED 1 2024-07-23 "Harakit-overgrown X.X.X"
+.SH NAME
+argued \(en check for arguments
+.\"
+.SH DESCRIPTION
+
+.BR argued (1)
+exits successfully if any arguments are provided, and unsuccessfully
+otherwise.
+.\"
+.SH AUTHOR
+
+Written by DTB
+.MT trinity@trinity.moe
+.ME .
+.\"
+.SH COPYRIGHT
+
+This work is marked with CC0 1.0. To see a copy of this license, visit
+<http://creativecommons.org/publicdomain/zero/1.0>.
+.\"
+.SH SEE ALSO
+.BR test (1)

src/argued.rs

@@ -0,0 +1,28 @@
+/*
+ * 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/.
+ */
+
+ use std::{ env::args, process::ExitCode };
+
+ fn main() -> ExitCode {
+ 	let argv = args().collect::<Vec<String>>();
+
+ 	match argv.len() {
+ 		0 | 1 => ExitCode::FAILURE,
+ 		_ =>     ExitCode::SUCCESS
+ 	}
+ }

src/pschdir.rs

@@ -0,0 +1,61 @@
+/*
+ * 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, io::Error, process::{ Command, ExitCode } };
+
+extern crate strerror;
+use strerror::StrError;
+
+extern crate sysexits;
+use sysexits::{ EX_UNAVAILABLE, EX_USAGE };
+
+fn error(p: &str, n: &str, e: Error) -> ExitCode {
+	eprintln!("{}: {}: {}", p, n, e.strerror());
+	ExitCode::from(EX_UNAVAILABLE as u8)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+
+	if argv.len() < 3 {
+		eprintln!("Usage: {} directory command [argument]", argv[0]);
+		return ExitCode::from(EX_USAGE as u8);
+	}
+
+	let cmdargs = argv.iter().clone().skip(3).collect::<Vec<&String>>();
+
+	match Command::new(argv[2].clone())
+			.current_dir(argv[1].clone())
+			.args(cmdargs)
+			.spawn() {
+		Ok(mut child) => match child.wait() {
+			Ok(status) => {
+				match status.code() {
+					Some(code) => ExitCode::from(code as u8),
+					None => {
+						eprintln!("{}: {}: process terminated by signal",
+							argv[0], argv[2]);
+						ExitCode::FAILURE
+					}
+				}
+			},
+			Err(e) => error(&argv[0], &argv[2], e)
+		},
+		Err(e) => error(&argv[0], &argv[2], e)
+	}
+}

src/retval.rs

@@ -0,0 +1,39 @@
+/*
+ * 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 };
+
+extern crate sysexits;
+use sysexits::EX_USAGE;
+
+fn usage(s: &str) -> ExitCode {
+	eprintln!("Usage: {} status", s);
+	ExitCode::from(EX_USAGE)
+}
+
+fn main() -> ExitCode {
+	let argv = args().collect::<Vec<String>>();
+
+	match argv.len() {
+		2 => match argv[1].parse::<u8>() {
+				Ok(e) => ExitCode::from(e),
+				_ => usage(&argv[0])
+			},
+		_ => usage(&argv[0])
+	}
+}

src/zn.c

@@ -0,0 +1,61 @@
+/*
+ * 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 <limits.h> /* _POSIX_MAX_CANON */
+#include <stdio.h> /* fgets(3) */
+#include <string.h> /* strtok(3) */
+#include <sysexits.h> /* EX_OSERR */
+#include <unistd.h> /* fork(2) */
+#include <sys/wait.h> /* wait(2), WIFEXITED, WEXITSTATUS */
+
+static char *sep = " \t\v\n";
+
+static char **
+get_args(char *s) {
+	size_t c = 0;
+	static char *v[10];
+
+	if ((v[c] = strtok(s, sep)) == NULL) { return NULL; }
+
+	while (++c < sizeof v / sizeof *v) {
+		if ((v[c] = strtok(NULL, sep)) == NULL) { return v; }
+	}
+
+	return v;
+}
+
+static char *
+get_line(FILE *stream) {
+	static char buffer[_POSIX_MAX_CANON];
+
+	return fgets(buffer, sizeof *buffer * MAX_CANON, stream);
+}
+
+int main(int argc, char *argv[]) {
+	char **a;
+	char *s;
+
+	while ((s = get_line(stdin)) != NULL) {
+		a = get_args(s);
+		switch (fork()) {
+			case -1: perror(argv[0]); return EX_OSERR;
+			case  0: execvp(a[0], a);
+			default: (void)wait(NULL);
+		}
+	}
+}