coreutils/src/tac/tac.rs

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#![crate_name = "uu_tac"]
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/*
* This file is part of the uutils coreutils package.
*
* (c) Arcterus <arcterus@mail.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
extern crate getopts;
extern crate libc;
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#[macro_use]
extern crate uucore;
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use std::fs::File;
use std::io::{BufReader, Read, stdin, stdout, Stdout, Write};
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static NAME: &'static str = "tac";
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static VERSION: &'static str = env!("CARGO_PKG_VERSION");
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pub fn uumain(args: Vec<String>) -> i32 {
let mut opts = getopts::Options::new();
opts.optflag("b", "before", "attach the separator before instead of after");
opts.optflag("r", "regex", "interpret the sequence as a regular expression (NOT IMPLEMENTED)");
opts.optopt("s", "separator", "use STRING as the separator instead of newline", "STRING");
opts.optflag("h", "help", "display this help and exit");
opts.optflag("V", "version", "output version information and exit");
let matches = match opts.parse(&args[1..]) {
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Ok(m) => m,
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Err(f) => crash!(1, "{}", f)
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};
if matches.opt_present("help") {
let msg = format!("{0} {1}
Usage:
{0} [OPTION]... [FILE]...
Write each file to standard output, last line first.", NAME, VERSION);
print!("{}", opts.usage(&msg));
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} else if matches.opt_present("version") {
println!("{} {}", NAME, VERSION);
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} else {
let before = matches.opt_present("b");
let regex = matches.opt_present("r");
let separator = match matches.opt_str("s") {
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Some(m) => {
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if m.is_empty() {
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crash!(1, "separator cannot be empty")
} else {
m
}
}
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None => "\n".to_owned()
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};
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let files = if matches.free.is_empty() {
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vec!("-".to_owned())
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} else {
matches.free
};
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tac(files, before, regex, &separator[..]);
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}
0
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}
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fn tac(filenames: Vec<String>, before: bool, _: bool, separator: &str) {
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let mut out = stdout();
let sbytes = separator.as_bytes();
let slen = sbytes.len();
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for filename in &filenames {
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let mut file = BufReader::new(
if filename == "-" {
Box::new(stdin()) as Box<Read>
} else {
match File::open(filename) {
Ok(f) => Box::new(f) as Box<Read>,
Err(e) => {
show_warning!("failed to open '{}' for reading: {}", filename, e);
continue;
},
}
});
let mut data = Vec::new();
match file.read_to_end(&mut data) {
Err(e) => {
show_warning!("failed to read '{}': {}", filename, e);
continue;
},
Ok(_) => (),
};
// find offsets in string of all separators
let mut offsets = Vec::new();
let mut i = 0;
loop {
if i + slen > data.len() {
break;
}
if &data[i..i+slen] == sbytes {
offsets.push(i);
i += slen;
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} else {
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i += 1;
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}
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}
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drop(i);
// if there isn't a separator at the end of the file, fake it
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if offsets.is_empty() || *offsets.last().unwrap() < data.len() - slen {
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offsets.push(data.len());
}
let mut prev = *offsets.last().unwrap();
let mut start = true;
for off in offsets.iter().rev().skip(1) {
// correctly handle case of no final separator in file
if start && prev == data.len() {
show_line(&mut out, &[], &data[*off+slen..prev], before);
start = false;
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} else {
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show_line(&mut out, sbytes, &data[*off+slen..prev], before);
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}
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prev = *off;
}
show_line(&mut out, sbytes, &data[0..prev], before);
}
}
fn show_line(out: &mut Stdout, sep: &[u8], dat: &[u8], before: bool) {
if before {
out.write_all(sep).unwrap_or_else(|e| crash!(1, "failed to write to stdout: {}", e));
}
out.write_all(dat).unwrap_or_else(|e| crash!(1, "failed to write to stdout: {}", e));
if !before {
out.write_all(sep).unwrap_or_else(|e| crash!(1, "failed to write to stdout: {}", e));
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}
}