forked from bonsai/harakit
Merge branch 'swab' (closes #22)
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commit
05b5a4480c
9
Makefile
9
Makefile
@ -17,7 +17,7 @@ CC=cc
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RUSTC=rustc
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.PHONY: all
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all: dj false fop hru intcmp rpn scrut str strcmp true
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all: dj false fop hru intcmp rpn scrut str strcmp swab true
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build:
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# keep build/include until bindgen(1) has stdin support
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@ -108,6 +108,13 @@ strcmp: build/bin/strcmp
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build/bin/strcmp: src/strcmp.c build
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$(CC) $(CFLAGS) -o $@ src/strcmp.c
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.PHONY: swab
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swab: build/bin/swab
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build/bin/swab: src/swab.rs build build/o/libsysexits.rlib
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$(RUSTC) $(RUSTFLAGS) --extern getopt=build/o/libgetopt.rlib \
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--extern sysexits=build/o/libsysexits.rlib \
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-o $@ src/swab.rs
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.PHONY: true
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true: build/bin/true
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build/bin/true: src/true.c build
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71
docs/swab.1
Normal file
71
docs/swab.1
Normal file
@ -0,0 +1,71 @@
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.\" Copyright (c) 2024 DTB <trinity@trinity.moe>
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.\"
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.\" This work is licensed under CC BY-SA 4.0. To see a copy of this license,
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.\" visit <http://creativecommons.org/licenses/by-sa/4.0/>.
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.TH swab 1
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.SH NAME
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swab \(en swap bytes
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.SH SYNOPSIS
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swab
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.RB ( -f )
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.RB ( -w
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.R [
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.B word size
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.R ])
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.SH USAGE
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Swab swaps the latter and former halves of a block of bytes.
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.SH EXAMPLES
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The following sh(1p) line:
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.R printf 'hello world!\n' | swab
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Produces the following output:
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.R ehll oowlr!d
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.SH OPTIONS
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The
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.B -f
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option ignores system call interruptions.
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.PP
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The
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.B -w
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option configures the word size; that is, the size in bytes of the block size
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on which to operate. By default the word size is 2. The word size must be
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cleanly divisible by 2, otherwise the block of bytes being processed can't be
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halved.
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.SH DIAGNOSTICS
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If an error is encountered in input, output, or invocation, a diagnostic
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message will be written to standard error and swab will exit with the
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appropriate status from sysexits.h(3).
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.SH RATIONALE
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Swab was modeled after the
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.R conv=swab
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functionality specified in the POSIX dd utility but additionally allows the
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word size to be configured.
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.PP
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Swab is useful for fixing the endianness of binary files produced on other
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machines.
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.SH COPYRIGHT
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Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
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<https://gnu.org/licenses/agpl.html>.
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.SH SEE ALSO
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dd(1p)
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90
src/swab.rs
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90
src/swab.rs
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@ -0,0 +1,90 @@
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/*
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* Copyright (c) 2024 DTB <trinity@trinity.moe>
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU Affero General Public License as published by the Free
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* Software Foundation, either version 3 of the License, or (at your option) any
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* later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see https://www.gnu.org/licenses/.
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*/
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use std::{
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env::args,
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io::{ stdin, stdout, Error, ErrorKind, Read, Write },
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process::ExitCode,
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vec::Vec
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};
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extern crate getopt;
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use getopt::{ Opt, Parser };
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extern crate sysexits;
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use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
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fn oserr(s: &str, e: Error) -> ExitCode {
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eprintln!("{}: {}", s, e);
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ExitCode::from(EX_OSERR as u8)
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}
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fn usage(s: &str) -> ExitCode {
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eprintln!("Usage: {} (-f) (-w [wordsize])", s);
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ExitCode::from(EX_USAGE as u8)
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}
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fn main() -> ExitCode {
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let argv = args().collect::<Vec<String>>();
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let mut buf: Vec<u8> = Vec::new();
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let mut input = stdin();
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let mut output = stdout().lock();
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let mut opts = Parser::new(&argv, "fw:");
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let mut force = false;
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let mut wordsize: usize = 2;
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loop {
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match opts.next() {
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None => break,
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Some(opt) =>
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match opt {
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Ok(Opt('f', None)) => force = true,
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Ok(Opt('w', Some(arg))) => {
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match arg.parse::<usize>() {
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Ok(w) if w % 2 == 0 => { wordsize = w; () },
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_ => { return usage(&argv[0]); },
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}
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},
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_ => { return usage(&argv[0]); }
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}
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}
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}
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buf.resize(wordsize, 0);
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loop {
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match input.read(&mut buf) {
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Ok(0) => break ExitCode::from(EX_OK as u8),
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Ok(v) if v == wordsize => {
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let (left, right) = buf.split_at(v/2);
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if let Err(e) = output.write(&right)
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.and_then(|_| output.write(&left)) {
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break oserr(&argv[0], e)
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}
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},
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Ok(v) => {
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if let Err(e) = output.write(&buf[..v]) {
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break oserr(&argv[0], e)
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}
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},
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Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
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Err(e) => break oserr(&argv[0], e)
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}
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}
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}
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