simexec(1): import from trinity/src

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 pschdir rpn scrut str strcmp swab true
+all: dj false fop hru intcmp mm npc rpn scrut str strcmp swab true
 
 # keep build/include until bindgen(1) has stdin support
 # https://github.com/rust-lang/rust-bindgen/issues/2703
@@ -122,11 +122,6 @@ 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: rpn
 rpn: build/bin/rpn
 build/bin/rpn: src/rpn.rs build rustlibs

docs/simexec.1

@@ -0,0 +1,49 @@
+.TH SIMEXEC 1
+
+.SH NAME
+
+simexec \(en execute a program with the given argv
+
+.SH SYNOPSIS
+
+simexec
+.RB [ pathname ]
+.RB [ argv... ]
+
+.SH DESCRIPTION
+
+Simexec executes a given program with the given argv.
+
+.SH PITFALLS
+
+Non-binary programs cannot be executed. The PATH environment variable is not used and a valid pathname (relative or absolute) must be specified.
+.PP
+Simexec relies on the user to take proper precautions.
+argv is not just the operands for the program but in fact directly the argv it will receive in runtime;
+the first argv entry is the program's name, and forgoing this, though acceptable by simexec, can break customary assumptions.
+for example, the true(1) implementation in the GNU coreutils suffers a segmentation fault if there is no argv[0].
+.PP
+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.
+.PP
+Simexec directly uses the execv library function. It cannot execute shell scripts intelligently (via shebang).
+It is inadviseable to use simexec as an alternative to simply calling a program, and in fact probably inadviseable to use simexec at all.
+
+.SH DIAGNOSTICS
+
+Simexec returns the value of execv(3), which will be -1 (or 0xFF; 255) if an error occurs.
+This is not distinguishable from the executed program returning the same exit status.
+.PP
+Simexec will print a error message and return the proper sysexits(3) value if used in an invalid manner.
+
+.SH COPYRIGHT
+
+Public domain.
+
+.SH SEE ALSO
+
+exec(3)
+.PP
+The C89 standard's draft, section 2.1.2.2: "Hosted environment".
+.PP
+POSIX.1-2017 System Interfaces: execv. Particularly under the RATIONALE section header.

src/pschdir.rs

@@ -1,61 +0,0 @@
-/*
- * 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/simexec.c

@@ -0,0 +1,35 @@
+/*
+ * 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 <stdio.h> /* fprintf(3), NULL */
+#include <unistd.h> /* execv(3), */
+#include <sysexits.h> /* EX_USAGE */
+
+char *program_name = "simexec";
+
+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]);
+}