retval(1) sans documentation

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 simexec scrut str strcmp swab true
+all: dj false fop hru intcmp mm npc retval rpn scrut str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -122,6 +122,11 @@ npc: build/bin/npc
 build/bin/npc: src/npc.c build
 	$(CC) $(CFLAGAS) -o $@ src/npc.c
 
+.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
@@ -132,11 +137,6 @@ scrut: build/bin/scrut
 build/bin/scrut: src/scrut.c build
 	$(CC) $(CFLAGS) -o $@ src/scrut.c
 
-.PHONY: simexec
-simexec: build/bin/simexec
-build/bin/simexec: src/simexec.c build
-	$(CC) $(CFLAGS) -o $@ src/simexec.c
-
 .PHONY: str
 str: build/bin/str
 build/bin/str: src/str.c build

docs/simexec.1

@@ -1,79 +0,0 @@
-.\" 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 SIMEXEC 1 2024-07-23 "Harakit-overgrown X.X.X"
-.SH NAME
-simexec \(en execute a program with argv
-.\"
-.SH SYNOPSIS
-
-simexec
-.B binary argv...
-.SH DESCRIPTION
-Execute a binary with a certain argv.
-.SH CAVEATS
-
-Non-binary programs cannot be executed on their own. The PATH environment
-variable is not used and a valid pathname (relative or absolute) must be
-specified.
-
-.BR simexec (1)
-requires caution.
-.B argv
-are not just the operands for the binary but in fact the direct
-.B argv
-it will receive in runtime;
-the first argv entry is the program\(cqs name, and omitting this, though valid
-use of
-.BR simexec (1),
-can break false assumptions made by programmers.
-for example, the
-.BR true (1)
-implementation in the GNU coreutils project suffers a segmentation fault it is
-given no argv[0].
-
-While POSIX.1-2017 doesn't mandate there being an argv[0] per se, a Strictly
-Conforming POSIX Application must pass an argv[0]. It has also been said that
-those who do not pass an argv[0] are mean and nasty and smell of elderberries.
-
-.BR simexec (1)
-directly uses the
-.BR execv (3p)
-library function. It cannot execute shell scripts intelligently (via shebang).
-It is inadviseable to use
-.BR simexec (1)
-to simply execute a program when other methods would suffice.
-.\"
-.SH DIAGNOSTICS
-
-.BR simexec (1)
-exits with the returned value of
-.BR execv (3p),
-which will be 255 if an error occurs in execution, such as the binary not being
-found.
-This is indistinguishable from the executed binary exiting with the same
-status.
-
-Simexec will print a error message and return the proper
-.BR sysexits.h (3)
-value if invoked in an invalid manner.
-.\"
-.SH AUTHOR
-
-Written by DTB
-.MT trinity@trinity.moe
-.ME .
-.\"
-.SH COPYRIGHT
-.\"
-Copyright \(co 2022–2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
-<https://gnu.org/licenses/gpl.html>.
-.\"
-.SH SEE ALSO
-.BR execv (3p)
-
-The C89 standard's draft, section 2.1.2.2: "Hosted environment".
-
-POSIX.1-2017 System Interfaces: execv. Particularly under the RATIONALE section header.

src/retval.rs

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022–2024 DTB <trinity@trinity.moe>
+ * 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
@@ -16,19 +16,24 @@
  * along with this program. If not, see https://www.gnu.org/licenses/.
  */
 
-#include <stdio.h> /* fprintf(3), NULL */
-#include <unistd.h> /* execv(3), */
-#include <sysexits.h> /* EX_USAGE */
+use std::{ env::args, process::ExitCode };
 
-char *program_name = "simexec";
+extern crate sysexits;
+use sysexits::EX_USAGE;
 
-int main(int argc, char *argv[]){
-	if (argc < 2) {
-		fprintf(stderr, "Usage: %s binary argv...\n",
-			argv[0] == NULL ? program_name : argv[0]
-		);
-		return EX_USAGE;
-	}
-
-	execv(argv[1], &argv[2]);
+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])
+	}
 }