considering a different project directory struture

inspired by freebsd source tree

bin/fop/fop.rs

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2023–2024 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
+ * 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::{ Read, stdin, stdout, Write },
+	process::{ Command, exit, Stdio },
+};
+
+extern crate getopt;
+extern crate strerror;
+extern crate sysexits;
+
+use getopt::{ Opt, Parser };
+use strerror::StrError;
+use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
+
+fn main() {
+	let argv = args().collect::<Vec<String>>();
+	let mut d = '␞';
+	let mut arg_parser = Parser::new(&argv, "d:");
+
+	while let Some(opt) = arg_parser.next() {
+		match opt {
+			Ok(Opt('d', Some(arg))) => {
+				let arg_char = arg.chars().collect::<Vec<char>>();
+				if arg_char.len() > 1 {
+					eprintln!("{}: {}: Not a character.", argv[0], arg);
+					exit(EX_USAGE);
+				} else { d = arg_char[0]; }
+			},
+			_ => {},
+		};
+	}
+
+	let index_arg = arg_parser.index();
+	let command_arg = arg_parser.index() + 1;
+
+	argv.get(command_arg).unwrap_or_else(|| {
+		eprintln!("Usage: {} [-d delimiter] index command [args...]", argv[0]);
+		exit(EX_USAGE);
+	});
+
+	let index = argv[index_arg].parse::<usize>().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[1], e);
+		exit(EX_DATAERR);
+	});
+
+	let mut buf = String::new();
+	let _ = stdin().read_to_string(&mut buf);
+	let mut fields = buf.split(d).collect::<Vec<&str>>();
+
+	let opts = argv
+		.iter()
+		.clone()
+		.skip(command_arg + 1)
+		.collect::<Vec<&String>>();
+
+	let mut spawned = Command::new(argv.get(command_arg).unwrap())
+		.args(opts)
+		.stdin(Stdio::piped())
+		.stdout(Stdio::piped())
+		.spawn()
+		.unwrap_or_else( |e| {
+			eprintln!("{}: {}: {}", argv[0], argv[command_arg], e.strerror());
+			exit(EX_UNAVAILABLE);
+		});
+
+	let field = fields.get(index).unwrap_or_else(|| {
+		eprintln!(
+			"{}: {}: No such index in input",
+			argv[0],
+			index.to_string(),
+		);
+		exit(EX_DATAERR);
+	});
+
+	if let Some(mut child_stdin) = spawned.stdin.take() {
+		let _ = child_stdin.write_all(field.as_bytes());
+		drop(child_stdin);
+	}
+
+	let output = spawned.wait_with_output().unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e.strerror());
+		exit(EX_IOERR);
+	});
+
+	let mut replace = output.stdout.clone();
+
+	if replace.pop() != Some(b'\n') { replace = output.stdout; }
+
+	let new_field = String::from_utf8(replace).unwrap_or_else(|e| {
+		eprintln!("{}: {}: {}", argv[0], argv[command_arg], e);
+		exit(EX_IOERR);
+	});
+
+	fields[index] = &new_field;
+
+	stdout().write_all(
+		fields.join(&d.to_string()).as_bytes()
+	).unwrap_or_else(|e| {
+		eprintln!("{}: {}", argv[0], e.strerror());
+		exit(EX_IOERR);
+	});
+}