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use std::collections::HashMap;
use std::ffi::OsStr;
use std::fmt;
use std::io::{self, Read};
use std::path::Path;
use std::process::{self, Stdio};
use globset::{Glob, GlobSet, GlobSetBuilder};
/// A decompression command, contains the command to be spawned as well as any
/// necessary CLI args.
#[derive(Clone, Copy, Debug)]
struct DecompressionCommand {
cmd: &'static str,
args: &'static [&'static str],
}
impl DecompressionCommand {
/// Create a new decompress command
fn new(
cmd: &'static str,
args: &'static [&'static str],
) -> DecompressionCommand {
DecompressionCommand {
cmd, args
}
}
}
impl fmt::Display for DecompressionCommand {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{} {}", self.cmd, self.args.join(" "))
}
}
lazy_static! {
static ref DECOMPRESSION_COMMANDS: HashMap<
&'static str,
DecompressionCommand,
> = {
let mut m = HashMap::new();
const ARGS: &[&str] = &["-d", "-c"];
m.insert("gz", DecompressionCommand::new("gzip", ARGS));
m.insert("bz2", DecompressionCommand::new("bzip2", ARGS));
m.insert("xz", DecompressionCommand::new("xz", ARGS));
m.insert("lz4", DecompressionCommand::new("lz4", ARGS));
const LZMA_ARGS: &[&str] = &["--format=lzma", "-d", "-c"];
m.insert("lzma", DecompressionCommand::new("xz", LZMA_ARGS));
m
};
static ref SUPPORTED_COMPRESSION_FORMATS: GlobSet = {
let mut builder = GlobSetBuilder::new();
builder.add(Glob::new("*.gz").unwrap());
builder.add(Glob::new("*.bz2").unwrap());
builder.add(Glob::new("*.xz").unwrap());
builder.add(Glob::new("*.lz4").unwrap());
builder.add(Glob::new("*.lzma").unwrap());
builder.build().unwrap()
};
static ref TAR_ARCHIVE_FORMATS: GlobSet = {
let mut builder = GlobSetBuilder::new();
builder.add(Glob::new("*.tar.gz").unwrap());
builder.add(Glob::new("*.tar.xz").unwrap());
builder.add(Glob::new("*.tar.bz2").unwrap());
builder.add(Glob::new("*.tar.lz4").unwrap());
builder.add(Glob::new("*.tgz").unwrap());
builder.add(Glob::new("*.txz").unwrap());
builder.add(Glob::new("*.tbz2").unwrap());
builder.build().unwrap()
};
}
/// DecompressionReader provides an `io::Read` implementation for a limited
/// set of compression formats.
#[derive(Debug)]
pub struct DecompressionReader {
cmd: DecompressionCommand,
child: process::Child,
done: bool,
}
impl DecompressionReader {
/// Returns a handle to the stdout of the spawned decompression process for
/// `path`, which can be directly searched in the worker. When the returned
/// value is exhausted, the underlying process is reaped. If the underlying
/// process fails, then its stderr is read and converted into a normal
/// io::Error.
///
/// If there is any error in spawning the decompression command, then
/// return `None`, after outputting any necessary debug or error messages.
pub fn from_path(path: &Path) -> Option<DecompressionReader> {
let extension = match path.extension().and_then(OsStr::to_str) {
Some(extension) => extension,
None => {
debug!(
"{}: failed to get compresson extension", path.display());
return None;
}
};
let decompression_cmd = match DECOMPRESSION_COMMANDS.get(extension) {
Some(cmd) => cmd,
None => {
debug!(
"{}: failed to get decompression command", path.display());
return None;
}
};
let cmd = process::Command::new(decompression_cmd.cmd)
.args(decompression_cmd.args)
.arg(path)
.stdout(Stdio::piped())
.stderr(Stdio::piped())
.spawn();
let child = match cmd {
Ok(process) => process,
Err(_) => {
debug!(
"{}: decompression command '{}' not found",
path.display(), decompression_cmd.cmd);
return None;
}
};
Some(DecompressionReader::new(*decompression_cmd, child))
}
fn new(
cmd: DecompressionCommand,
child: process::Child,
) -> DecompressionReader {
DecompressionReader {
cmd: cmd,
child: child,
done: false,
}
}
fn read_error(&mut self) -> io::Result<io::Error> {
let mut errbytes = vec![];
self.child.stderr.as_mut().unwrap().read_to_end(&mut errbytes)?;
let errstr = String::from_utf8_lossy(&errbytes);
let errstr = errstr.trim();
Ok(if errstr.is_empty() {
let msg = format!("decompression command failed: '{}'", self.cmd);
io::Error::new(io::ErrorKind::Other, msg)
} else {
let msg = format!(
"decompression command '{}' failed: {}", self.cmd, errstr);
io::Error::new(io::ErrorKind::Other, msg)
})
}
}
impl io::Read for DecompressionReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
if self.done {
return Ok(0);
}
let nread = self.child.stdout.as_mut().unwrap().read(buf)?;
if nread == 0 {
self.done = true;
// Reap the child now that we're done reading.
// If the command failed, report stderr as an error.
if !self.child.wait()?.success() {
return Err(self.read_error()?);
}
}
Ok(nread)
}
}
/// Returns true if the given path contains a supported compression format or
/// is a TAR archive.
pub fn is_compressed(path: &Path) -> bool {
is_supported_compression_format(path) || is_tar_archive(path)
}
/// Returns true if the given path matches any one of the supported compression
/// formats
fn is_supported_compression_format(path: &Path) -> bool {
SUPPORTED_COMPRESSION_FORMATS.is_match(path)
}
/// Returns true if the given path matches any of the known TAR file formats.
fn is_tar_archive(path: &Path) -> bool {
TAR_ARCHIVE_FORMATS.is_match(path)
}
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