1
0
forked from bonsai/harakit

Merge branch 'swab' (closes #22)

This commit is contained in:
Emma Tebibyte 2024-03-18 20:53:08 -06:00
commit 05b5a4480c
Signed by untrusted user: emma
GPG Key ID: 06FA419A1698C270
3 changed files with 169 additions and 1 deletions

View File

@ -17,7 +17,7 @@ CC=cc
RUSTC=rustc
.PHONY: all
all: dj false fop hru intcmp rpn scrut str strcmp true
all: dj false fop hru intcmp rpn scrut str strcmp swab true
build:
# keep build/include until bindgen(1) has stdin support
@ -108,6 +108,13 @@ strcmp: build/bin/strcmp
build/bin/strcmp: src/strcmp.c build
$(CC) $(CFLAGS) -o $@ src/strcmp.c
.PHONY: swab
swab: build/bin/swab
build/bin/swab: src/swab.rs build build/o/libsysexits.rlib
$(RUSTC) $(RUSTFLAGS) --extern getopt=build/o/libgetopt.rlib \
--extern sysexits=build/o/libsysexits.rlib \
-o $@ src/swab.rs
.PHONY: true
true: build/bin/true
build/bin/true: src/true.c build

71
docs/swab.1 Normal file
View File

@ -0,0 +1,71 @@
.\" Copyright (c) 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 swab 1
.SH NAME
swab \(en swap bytes
.SH SYNOPSIS
swab
.RB ( -f )
.RB ( -w
.R [
.B word size
.R ])
.SH USAGE
Swab swaps the latter and former halves of a block of bytes.
.SH EXAMPLES
The following sh(1p) line:
.R printf 'hello world!\n' | swab
Produces the following output:
.R ehll oowlr!d
.SH OPTIONS
The
.B -f
option ignores system call interruptions.
.PP
The
.B -w
option configures the word size; that is, the size in bytes of the block size
on which to operate. By default the word size is 2. The word size must be
cleanly divisible by 2, otherwise the block of bytes being processed can't be
halved.
.SH DIAGNOSTICS
If an error is encountered in input, output, or invocation, a diagnostic
message will be written to standard error and swab will exit with the
appropriate status from sysexits.h(3).
.SH RATIONALE
Swab was modeled after the
.R conv=swab
functionality specified in the POSIX dd utility but additionally allows the
word size to be configured.
.PP
Swab is useful for fixing the endianness of binary files produced on other
machines.
.SH COPYRIGHT
Copyright (c) 2024 DTB. License AGPLv3+: GNU AGPL version 3 or later
<https://gnu.org/licenses/agpl.html>.
.SH SEE ALSO
dd(1p)

90
src/swab.rs Normal file
View File

@ -0,0 +1,90 @@
/*
* 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,
io::{ stdin, stdout, Error, ErrorKind, Read, Write },
process::ExitCode,
vec::Vec
};
extern crate getopt;
use getopt::{ Opt, Parser };
extern crate sysexits;
use sysexits::{ EX_OK, EX_OSERR, EX_USAGE };
fn oserr(s: &str, e: Error) -> ExitCode {
eprintln!("{}: {}", s, e);
ExitCode::from(EX_OSERR as u8)
}
fn usage(s: &str) -> ExitCode {
eprintln!("Usage: {} (-f) (-w [wordsize])", s);
ExitCode::from(EX_USAGE as u8)
}
fn main() -> ExitCode {
let argv = args().collect::<Vec<String>>();
let mut buf: Vec<u8> = Vec::new();
let mut input = stdin();
let mut output = stdout().lock();
let mut opts = Parser::new(&argv, "fw:");
let mut force = false;
let mut wordsize: usize = 2;
loop {
match opts.next() {
None => break,
Some(opt) =>
match opt {
Ok(Opt('f', None)) => force = true,
Ok(Opt('w', Some(arg))) => {
match arg.parse::<usize>() {
Ok(w) if w % 2 == 0 => { wordsize = w; () },
_ => { return usage(&argv[0]); },
}
},
_ => { return usage(&argv[0]); }
}
}
}
buf.resize(wordsize, 0);
loop {
match input.read(&mut buf) {
Ok(0) => break ExitCode::from(EX_OK as u8),
Ok(v) if v == wordsize => {
let (left, right) = buf.split_at(v/2);
if let Err(e) = output.write(&right)
.and_then(|_| output.write(&left)) {
break oserr(&argv[0], e)
}
},
Ok(v) => {
if let Err(e) = output.write(&buf[..v]) {
break oserr(&argv[0], e)
}
},
Err(e) if e.kind() == ErrorKind::Interrupted && force => continue,
Err(e) => break oserr(&argv[0], e)
}
}
}