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use std::{
ffi::{OsStr, OsString},
fs::File,
io,
path::{Path, PathBuf},
process::Command,
};
use globset::{Glob, GlobSet, GlobSetBuilder};
use crate::process::{CommandError, CommandReader, CommandReaderBuilder};
/// A builder for a matcher that determines which files get decompressed.
#[derive(Clone, Debug)]
pub struct DecompressionMatcherBuilder {
/// The commands for each matching glob.
commands: Vec<DecompressionCommand>,
/// Whether to include the default matching rules.
defaults: bool,
}
/// A representation of a single command for decompressing data
/// out-of-process.
#[derive(Clone, Debug)]
struct DecompressionCommand {
/// The glob that matches this command.
glob: String,
/// The command or binary name.
bin: PathBuf,
/// The arguments to invoke with the command.
args: Vec<OsString>,
}
impl Default for DecompressionMatcherBuilder {
fn default() -> DecompressionMatcherBuilder {
DecompressionMatcherBuilder::new()
}
}
impl DecompressionMatcherBuilder {
/// Create a new builder for configuring a decompression matcher.
pub fn new() -> DecompressionMatcherBuilder {
DecompressionMatcherBuilder { commands: vec![], defaults: true }
}
/// Build a matcher for determining how to decompress files.
///
/// If there was a problem compiling the matcher, then an error is
/// returned.
pub fn build(&self) -> Result<DecompressionMatcher, CommandError> {
let defaults = if !self.defaults {
vec![]
} else {
default_decompression_commands()
};
let mut glob_builder = GlobSetBuilder::new();
let mut commands = vec![];
for decomp_cmd in defaults.iter().chain(&self.commands) {
let glob = Glob::new(&decomp_cmd.glob).map_err(|err| {
CommandError::io(io::Error::new(io::ErrorKind::Other, err))
})?;
glob_builder.add(glob);
commands.push(decomp_cmd.clone());
}
let globs = glob_builder.build().map_err(|err| {
CommandError::io(io::Error::new(io::ErrorKind::Other, err))
})?;
Ok(DecompressionMatcher { globs, commands })
}
/// When enabled, the default matching rules will be compiled into this
/// matcher before any other associations. When disabled, only the
/// rules explicitly given to this builder will be used.
///
/// This is enabled by default.
pub fn defaults(&mut self, yes: bool) -> &mut DecompressionMatcherBuilder {
self.defaults = yes;
self
}
/// Associates a glob with a command to decompress files matching the glob.
///
/// If multiple globs match the same file, then the most recently added
/// glob takes precedence.
///
/// The syntax for the glob is documented in the
/// [`globset` crate](https://docs.rs/globset/#syntax).
///
/// The `program` given is resolved with respect to `PATH` and turned
/// into an absolute path internally before being executed by the current
/// platform. Notably, on Windows, this avoids a security problem where
/// passing a relative path to `CreateProcess` will automatically search
/// the current directory for a matching program. If the program could
/// not be resolved, then it is silently ignored and the association is
/// dropped. For this reason, callers should prefer `try_associate`.
pub fn associate<P, I, A>(
&mut self,
glob: &str,
program: P,
args: I,
) -> &mut DecompressionMatcherBuilder
where
P: AsRef<OsStr>,
I: IntoIterator<Item = A>,
A: AsRef<OsStr>,
{
let _ = self.try_associate(glob, program, args);
self
}
/// Associates a glob with a command to decompress files matching the glob.
///
/// If multiple globs match the same file, then the most recently added
/// glob takes precedence.
///
/// The syntax for the glob is documented in the
/// [`globset` crate](https://docs.rs/globset/#syntax).
///
/// The `program` given is resolved with respect to `PATH` and turned
/// into an absolute path internally before being executed by the current
/// platform. Notably, on Windows, this avoids a security problem where
/// passing a relative path to `CreateProcess` will automatically search
/// the current directory for a matching program. If the program could not
/// be resolved, then an error is returned.
pub fn try_associate<P, I, A>(
&mut self,
glob: &str,
program: P,
args: I,
) -> Result<&mut DecompressionMatcherBuilder, CommandError>
where
P: AsRef<OsStr>,
I: IntoIterator<Item = A>,
A: AsRef<OsStr>,
{
let glob = glob.to_string();
let bin = try_resolve_binary(Path::new(program.as_ref()))?;
let args =
args.into_iter().map(|a| a.as_ref().to_os_string()).collect();
self.commands.push(DecompressionCommand { glob, bin, args });
Ok(self)
}
}
/// A matcher for determining how to decompress files.
#[derive(Clone, Debug)]
pub struct DecompressionMatcher {
/// The set of globs to match. Each glob has a corresponding entry in
/// `commands`. When a glob matches, the corresponding command should be
/// used to perform out-of-process decompression.
globs: GlobSet,
/// The commands for each matching glob.
commands: Vec<DecompressionCommand>,
}
impl Default for DecompressionMatcher {
fn default() -> DecompressionMatcher {
DecompressionMatcher::new()
}
}
impl DecompressionMatcher {
/// Create a new matcher with default rules.
///
/// To add more matching rules, build a matcher with
/// [`DecompressionMatcherBuilder`].
pub fn new() -> DecompressionMatcher {
DecompressionMatcherBuilder::new()
.build()
.expect("built-in matching rules should always compile")
}
/// Return a pre-built command based on the given file path that can
/// decompress its contents. If no such decompressor is known, then this
/// returns `None`.
///
/// If there are multiple possible commands matching the given path, then
/// the command added last takes precedence.
pub fn command<P: AsRef<Path>>(&self, path: P) -> Option<Command> {
for i in self.globs.matches(path).into_iter().rev() {
let decomp_cmd = &self.commands[i];
let mut cmd = Command::new(&decomp_cmd.bin);
cmd.args(&decomp_cmd.args);
return Some(cmd);
}
None
}
/// Returns true if and only if the given file path has at least one
/// matching command to perform decompression on.
pub fn has_command<P: AsRef<Path>>(&self, path: P) -> bool {
self.globs.is_match(path)
}
}
/// Configures and builds a streaming reader for decompressing data.
#[derive(Clone, Debug, Default)]
pub struct DecompressionReaderBuilder {
matcher: DecompressionMatcher,
command_builder: CommandReaderBuilder,
}
impl DecompressionReaderBuilder {
/// Create a new builder with the default configuration.
pub fn new() -> DecompressionReaderBuilder {
DecompressionReaderBuilder::default()
}
/// Build a new streaming reader for decompressing data.
///
/// If decompression is done out-of-process and if there was a problem
/// spawning the process, then its error is logged at the debug level and a
/// passthru reader is returned that does no decompression. This behavior
/// typically occurs when the given file path matches a decompression
/// command, but is executing in an environment where the decompression
/// command is not available.
///
/// If the given file path could not be matched with a decompression
/// strategy, then a passthru reader is returned that does no
/// decompression.
pub fn build<P: AsRef<Path>>(
&self,
path: P,
) -> Result<DecompressionReader, CommandError> {
let path = path.as_ref();
let Some(mut cmd) = self.matcher.command(path) else {
return DecompressionReader::new_passthru(path);
};
cmd.arg(path);
match self.command_builder.build(&mut cmd) {
Ok(cmd_reader) => Ok(DecompressionReader { rdr: Ok(cmd_reader) }),
Err(err) => {
log::debug!(
"{}: error spawning command '{:?}': {} \
(falling back to uncompressed reader)",
path.display(),
cmd,
err,
);
DecompressionReader::new_passthru(path)
}
}
}
/// Set the matcher to use to look up the decompression command for each
/// file path.
///
/// A set of sensible rules is enabled by default. Setting this will
/// completely replace the current rules.
pub fn matcher(
&mut self,
matcher: DecompressionMatcher,
) -> &mut DecompressionReaderBuilder {
self.matcher = matcher;
self
}
/// Get the underlying matcher currently used by this builder.
pub fn get_matcher(&self) -> &DecompressionMatcher {
&self.matcher
}
/// When enabled, the reader will asynchronously read the contents of the
/// command's stderr output. When disabled, stderr is only read after the
/// stdout stream has been exhausted (or if the process quits with an error
/// code).
///
/// Note that when enabled, this may require launching an additional
/// thread in order to read stderr. This is done so that the process being
/// executed is never blocked from writing to stdout or stderr. If this is
/// disabled, then it is possible for the process to fill up the stderr
/// buffer and deadlock.
///
/// This is enabled by default.
pub fn async_stderr(
&mut self,
yes: bool,
) -> &mut DecompressionReaderBuilder {
self.command_builder.async_stderr(yes);
self
}
}
/// A streaming reader for decompressing the contents of a file.
///
/// The purpose of this reader is to provide a seamless way to decompress the
/// contents of file using existing tools in the current environment. This is
/// meant to be an alternative to using decompression libraries in favor of the
/// simplicity and portability of using external commands such as `gzip` and
/// `xz`. This does impose the overhead of spawning a process, so other means
/// for performing decompression should be sought if this overhead isn't
/// acceptable.
///
/// A decompression reader comes with a default set of matching rules that are
/// meant to associate file paths with the corresponding command to use to
/// decompress them. For example, a glob like `*.gz` matches gzip compressed
/// files with the command `gzip -d -c`. If a file path does not match any
/// existing rules, or if it matches a rule whose command does not exist in the
/// current environment, then the decompression reader passes through the
/// contents of the underlying file without doing any decompression.
///
/// The default matching rules are probably good enough for most cases, and if
/// they require revision, pull requests are welcome. In cases where they must
/// be changed or extended, they can be customized through the use of
/// [`DecompressionMatcherBuilder`] and [`DecompressionReaderBuilder`].
///
/// By default, this reader will asynchronously read the processes' stderr.
/// This prevents subtle deadlocking bugs for noisy processes that write a lot
/// to stderr. Currently, the entire contents of stderr is read on to the heap.
///
/// # Example
///
/// This example shows how to read the decompressed contents of a file without
/// needing to explicitly choose the decompression command to run.
///
/// Note that if you need to decompress multiple files, it is better to use
/// `DecompressionReaderBuilder`, which will amortize the cost of compiling the
/// matcher.
///
/// ```no_run
/// use std::{io::Read, process::Command};
///
/// use grep_cli::DecompressionReader;
///
/// let mut rdr = DecompressionReader::new("/usr/share/man/man1/ls.1.gz")?;
/// let mut contents = vec![];
/// rdr.read_to_end(&mut contents)?;
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[derive(Debug)]
pub struct DecompressionReader {
rdr: Result<CommandReader, File>,
}
impl DecompressionReader {
/// Build a new streaming reader for decompressing data.
///
/// If decompression is done out-of-process and if there was a problem
/// spawning the process, then its error is returned.
///
/// If the given file path could not be matched with a decompression
/// strategy, then a passthru reader is returned that does no
/// decompression.
///
/// This uses the default matching rules for determining how to decompress
/// the given file. To change those matching rules, use
/// [`DecompressionReaderBuilder`] and [`DecompressionMatcherBuilder`].
///
/// When creating readers for many paths. it is better to use the builder
/// since it will amortize the cost of constructing the matcher.
pub fn new<P: AsRef<Path>>(
path: P,
) -> Result<DecompressionReader, CommandError> {
DecompressionReaderBuilder::new().build(path)
}
/// Creates a new "passthru" decompression reader that reads from the file
/// corresponding to the given path without doing decompression and without
/// executing another process.
fn new_passthru(path: &Path) -> Result<DecompressionReader, CommandError> {
let file = File::open(path)?;
Ok(DecompressionReader { rdr: Err(file) })
}
/// Closes this reader, freeing any resources used by its underlying child
/// process, if one was used. If the child process exits with a nonzero
/// exit code, the returned Err value will include its stderr.
///
/// `close` is idempotent, meaning it can be safely called multiple times.
/// The first call closes the CommandReader and any subsequent calls do
/// nothing.
///
/// This method should be called after partially reading a file to prevent
/// resource leakage. However there is no need to call `close` explicitly
/// if your code always calls `read` to EOF, as `read` takes care of
/// calling `close` in this case.
///
/// `close` is also called in `drop` as a last line of defense against
/// resource leakage. Any error from the child process is then printed as a
/// warning to stderr. This can be avoided by explicitly calling `close`
/// before the CommandReader is dropped.
pub fn close(&mut self) -> io::Result<()> {
match self.rdr {
Ok(ref mut rdr) => rdr.close(),
Err(_) => Ok(()),
}
}
}
impl io::Read for DecompressionReader {
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
match self.rdr {
Ok(ref mut rdr) => rdr.read(buf),
Err(ref mut rdr) => rdr.read(buf),
}
}
}
/// Resolves a path to a program to a path by searching for the program in
/// `PATH`.
///
/// If the program could not be resolved, then an error is returned.
///
/// The purpose of doing this instead of passing the path to the program
/// directly to Command::new is that Command::new will hand relative paths
/// to CreateProcess on Windows, which will implicitly search the current
/// working directory for the executable. This could be undesirable for
/// security reasons. e.g., running ripgrep with the -z/--search-zip flag on an
/// untrusted directory tree could result in arbitrary programs executing on
/// Windows.
///
/// Note that this could still return a relative path if PATH contains a
/// relative path. We permit this since it is assumed that the user has set
/// this explicitly, and thus, desires this behavior.
///
/// On non-Windows, this is a no-op.
pub fn resolve_binary<P: AsRef<Path>>(
prog: P,
) -> Result<PathBuf, CommandError> {
if !cfg!(windows) {
return Ok(prog.as_ref().to_path_buf());
}
try_resolve_binary(prog)
}
/// Resolves a path to a program to a path by searching for the program in
/// `PATH`.
///
/// If the program could not be resolved, then an error is returned.
///
/// The purpose of doing this instead of passing the path to the program
/// directly to Command::new is that Command::new will hand relative paths
/// to CreateProcess on Windows, which will implicitly search the current
/// working directory for the executable. This could be undesirable for
/// security reasons. e.g., running ripgrep with the -z/--search-zip flag on an
/// untrusted directory tree could result in arbitrary programs executing on
/// Windows.
///
/// Note that this could still return a relative path if PATH contains a
/// relative path. We permit this since it is assumed that the user has set
/// this explicitly, and thus, desires this behavior.
///
/// If `check_exists` is false or the path is already an absolute path this
/// will return immediately.
fn try_resolve_binary<P: AsRef<Path>>(
prog: P,
) -> Result<PathBuf, CommandError> {
use std::env;
fn is_exe(path: &Path) -> bool {
let Ok(md) = path.metadata() else { return false };
!md.is_dir()
}
let prog = prog.as_ref();
if prog.is_absolute() {
return Ok(prog.to_path_buf());
}
let Some(syspaths) = env::var_os("PATH") else {
let msg = "system PATH environment variable not found";
return Err(CommandError::io(io::Error::new(
io::ErrorKind::Other,
msg,
)));
};
for syspath in env::split_paths(&syspaths) {
if syspath.as_os_str().is_empty() {
continue;
}
let abs_prog = syspath.join(prog);
if is_exe(&abs_prog) {
return Ok(abs_prog.to_path_buf());
}
if abs_prog.extension().is_none() {
for extension in ["com", "exe"] {
let abs_prog = abs_prog.with_extension(extension);
if is_exe(&abs_prog) {
return Ok(abs_prog.to_path_buf());
}
}
}
}
let msg = format!("{}: could not find executable in PATH", prog.display());
return Err(CommandError::io(io::Error::new(io::ErrorKind::Other, msg)));
}
fn default_decompression_commands() -> Vec<DecompressionCommand> {
const ARGS_GZIP: &[&str] = &["gzip", "-d", "-c"];
const ARGS_BZIP: &[&str] = &["bzip2", "-d", "-c"];
const ARGS_XZ: &[&str] = &["xz", "-d", "-c"];
const ARGS_LZ4: &[&str] = &["lz4", "-d", "-c"];
const ARGS_LZMA: &[&str] = &["xz", "--format=lzma", "-d", "-c"];
const ARGS_BROTLI: &[&str] = &["brotli", "-d", "-c"];
const ARGS_ZSTD: &[&str] = &["zstd", "-q", "-d", "-c"];
const ARGS_UNCOMPRESS: &[&str] = &["uncompress", "-c"];
fn add(glob: &str, args: &[&str], cmds: &mut Vec<DecompressionCommand>) {
let bin = match resolve_binary(Path::new(args[0])) {
Ok(bin) => bin,
Err(err) => {
log::debug!("{}", err);
return;
}
};
cmds.push(DecompressionCommand {
glob: glob.to_string(),
bin,
args: args
.iter()
.skip(1)
.map(|s| OsStr::new(s).to_os_string())
.collect(),
});
}
let mut cmds = vec![];
add("*.gz", ARGS_GZIP, &mut cmds);
add("*.tgz", ARGS_GZIP, &mut cmds);
add("*.bz2", ARGS_BZIP, &mut cmds);
add("*.tbz2", ARGS_BZIP, &mut cmds);
add("*.xz", ARGS_XZ, &mut cmds);
add("*.txz", ARGS_XZ, &mut cmds);
add("*.lz4", ARGS_LZ4, &mut cmds);
add("*.lzma", ARGS_LZMA, &mut cmds);
add("*.br", ARGS_BROTLI, &mut cmds);
add("*.zst", ARGS_ZSTD, &mut cmds);
add("*.zstd", ARGS_ZSTD, &mut cmds);
add("*.Z", ARGS_UNCOMPRESS, &mut cmds);
cmds
}