329 lines
12 KiB
Rust
329 lines
12 KiB
Rust
//! `MatchPattern` defines a match pattern used to match filenames encountered
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//! during encoding or decoding of a `pxar` archive.
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//! `fnmatch` is used internally to match filenames against the patterns.
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//! Shell wildcard pattern can be used to match multiple filenames, see manpage
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//! `glob(7)`.
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//! `**` is treated special, as it matches multiple directories in a path.
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use std::ffi::{CStr, CString};
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use std::fs::File;
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use std::io::Read;
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use std::os::unix::io::{FromRawFd, RawFd};
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use failure::{bail, Error};
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use libc::{c_char, c_int};
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use nix::errno::Errno;
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use nix::fcntl;
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use nix::fcntl::{AtFlags, OFlag};
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use nix::sys::stat;
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use nix::sys::stat::{FileStat, Mode};
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use nix::NixPath;
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pub const FNM_NOMATCH: c_int = 1;
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extern "C" {
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fn fnmatch(pattern: *const c_char, string: *const c_char, flags: c_int) -> c_int;
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}
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#[derive(Debug, PartialEq, Clone, Copy)]
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pub enum MatchType {
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None,
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Positive,
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Negative,
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PartialPositive,
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PartialNegative,
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}
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/// `MatchPattern` provides functionality for filename glob pattern matching
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/// based on glibc's `fnmatch`.
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/// Positive matches return `MatchType::PartialPositive` or `MatchType::Positive`.
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/// Patterns starting with `!` are interpreted as negation, meaning they will
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/// return `MatchType::PartialNegative` or `MatchType::Negative`.
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/// No matches result in `MatchType::None`.
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/// # Examples:
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/// ```
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/// # use std::ffi::CString;
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/// # use self::proxmox_backup::pxar::{MatchPattern, MatchType};
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/// # fn main() -> Result<(), failure::Error> {
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/// let filename = CString::new("some.conf")?;
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/// let is_dir = false;
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///
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/// /// Positive match of any file ending in `.conf` in any subdirectory
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/// let positive = MatchPattern::from_line(b"**/*.conf")?.unwrap();
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/// let m_positive = positive.matches_filename(&filename, is_dir)?;
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/// assert!(m_positive == MatchType::Positive);
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///
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/// /// Negative match of filenames starting with `s`
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/// let negative = MatchPattern::from_line(b"![s]*")?.unwrap();
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/// let m_negative = negative.matches_filename(&filename, is_dir)?;
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/// assert!(m_negative == MatchType::Negative);
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/// # Ok(())
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/// # }
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/// ```
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#[derive(Clone)]
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pub struct MatchPattern {
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pattern: CString,
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match_positive: bool,
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match_dir_only: bool,
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split_pattern: (CString, CString),
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}
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impl MatchPattern {
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/// Read a list of `MatchPattern` from file.
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/// The file is read line by line (lines terminated by newline character),
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/// each line may only contain one pattern.
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/// Leading `/` are ignored and lines starting with `#` are interpreted as
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/// comments and not included in the resulting list.
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/// Patterns ending in `/` will match only directories.
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///
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/// On success, a list of match pattern is returned as well as the raw file
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/// byte buffer together with the files stats.
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/// This is done in order to avoid reading the file more than once during
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/// encoding of the archive.
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pub fn from_file<P: ?Sized + NixPath>(
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parent_fd: RawFd,
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filename: &P,
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) -> Result<Option<(Vec<MatchPattern>, Vec<u8>, FileStat)>, Error> {
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let stat = match stat::fstatat(parent_fd, filename, AtFlags::AT_SYMLINK_NOFOLLOW) {
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Ok(stat) => stat,
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Err(nix::Error::Sys(Errno::ENOENT)) => return Ok(None),
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Err(err) => bail!("stat failed - {}", err),
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};
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let filefd = fcntl::openat(parent_fd, filename, OFlag::O_NOFOLLOW, Mode::empty())?;
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let mut file = unsafe { File::from_raw_fd(filefd) };
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let mut content_buffer = Vec::new();
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let _bytes = file.read_to_end(&mut content_buffer)?;
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let mut match_pattern = Vec::new();
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for line in content_buffer.split(|&c| c == b'\n') {
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if line.is_empty() {
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continue;
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}
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if let Some(pattern) = Self::from_line(line)? {
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match_pattern.push(pattern);
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}
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}
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Ok(Some((match_pattern, content_buffer, stat)))
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}
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/// Interprete a byte buffer as a sinlge line containing a valid
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/// `MatchPattern`.
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/// Pattern starting with `#` are interpreted as comments, returning `Ok(None)`.
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/// Pattern starting with '!' are interpreted as negative match pattern.
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/// Pattern with trailing `/` match only against directories.
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/// `.` as well as `..` and any pattern containing `\0` are invalid and will
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/// result in an error.
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pub fn from_line(line: &[u8]) -> Result<Option<MatchPattern>, Error> {
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let mut input = line;
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if input.starts_with(b"#") {
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return Ok(None);
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}
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let match_positive = if input.starts_with(b"!") {
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// Reduce slice view to exclude "!"
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input = &input[1..];
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false
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} else {
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true
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};
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// Paths ending in / match only directory names (no filenames)
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let match_dir_only = if input.ends_with(b"/") {
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let len = input.len();
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input = &input[..len - 1];
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true
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} else {
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false
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};
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// Ignore initial slash
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if input.starts_with(b"/") {
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input = &input[1..];
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}
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if input.is_empty() || input == b"." || input == b".." || input.contains(&b'\0') {
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bail!("invalid path component encountered");
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}
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// This will fail if the line contains b"\0"
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let pattern = CString::new(input)?;
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let split_pattern = split_at_slash(&pattern);
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Ok(Some(MatchPattern {
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pattern,
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match_positive,
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match_dir_only,
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split_pattern,
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}))
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}
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/// Returns the pattern before the first `/` encountered as `MatchPattern`.
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/// If no slash is encountered, the `MatchPattern` will be a copy of the
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/// original pattern.
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/// ```
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/// # use self::proxmox_backup::pxar::{MatchPattern, MatchType};
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/// # fn main() -> Result<(), failure::Error> {
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/// let pattern = MatchPattern::from_line(b"some/match/pattern/")?.unwrap();
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/// let front = pattern.get_front_pattern();
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/// /// ... will be the same as ...
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/// let front_pattern = MatchPattern::from_line(b"some")?.unwrap();
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/// # Ok(())
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/// # }
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/// ```
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pub fn get_front_pattern(&self) -> MatchPattern {
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let pattern = split_at_slash(&self.split_pattern.0);
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MatchPattern {
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pattern: self.split_pattern.0.clone(),
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match_positive: self.match_positive,
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match_dir_only: self.match_dir_only,
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split_pattern: pattern,
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}
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}
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/// Returns the pattern after the first encountered `/` as `MatchPattern`.
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/// If no slash is encountered, the `MatchPattern` will be empty.
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/// ```
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/// # use self::proxmox_backup::pxar::{MatchPattern, MatchType};
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/// # fn main() -> Result<(), failure::Error> {
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/// let pattern = MatchPattern::from_line(b"some/match/pattern/")?.unwrap();
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/// let rest = pattern.get_rest_pattern();
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/// /// ... will be the same as ...
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/// let rest_pattern = MatchPattern::from_line(b"match/pattern/")?.unwrap();
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/// # Ok(())
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/// # }
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/// ```
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pub fn get_rest_pattern(&self) -> MatchPattern {
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let pattern = split_at_slash(&self.split_pattern.1);
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MatchPattern {
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pattern: self.split_pattern.1.clone(),
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match_positive: self.match_positive,
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match_dir_only: self.match_dir_only,
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split_pattern: pattern,
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}
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}
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/// Dump the content of the `MatchPattern` to stdout.
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/// Intended for debugging purposes only.
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pub fn dump(&self) {
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match (self.match_positive, self.match_dir_only) {
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(true, true) => println!("{:#?}/", self.pattern),
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(true, false) => println!("{:#?}", self.pattern),
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(false, true) => println!("!{:#?}/", self.pattern),
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(false, false) => println!("!{:#?}", self.pattern),
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}
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}
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/// Convert a list of MatchPattern to bytes in order to write them to e.g.
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/// a file.
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pub fn to_bytes(patterns: &[MatchPattern]) -> Vec<u8> {
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let mut buffer = Vec::new();
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for pattern in patterns {
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if !pattern.match_positive { buffer.push(b'!'); }
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buffer.extend_from_slice( pattern.pattern.as_bytes());
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if pattern.match_dir_only { buffer.push(b'/'); }
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buffer.push(b'\n');
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}
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buffer
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}
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/// Match the given filename against this `MatchPattern`.
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/// If the filename matches the pattern completely, `MatchType::Positive` or
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/// `MatchType::Negative` is returned, depending if the match pattern is was
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/// declared as positive (no `!` prefix) or negative (`!` prefix).
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/// If the pattern matched only up to the first slash of the pattern,
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/// `MatchType::PartialPositive` or `MatchType::PartialNegatie` is returned.
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/// If the pattern was postfixed by a trailing `/` a match is only valid if
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/// the parameter `is_dir` equals `true`.
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/// No match results in `MatchType::None`.
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pub fn matches_filename(&self, filename: &CStr, is_dir: bool) -> Result<MatchType, Error> {
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let mut res = MatchType::None;
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let (front, _) = &self.split_pattern;
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let fnmatch_res = unsafe {
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let front_ptr = front.as_ptr() as *const libc::c_char;
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let filename_ptr = filename.as_ptr() as *const libc::c_char;
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fnmatch(front_ptr, filename_ptr, 0)
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};
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if fnmatch_res < 0 {
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bail!("error in fnmatch inside of MatchPattern");
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}
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if fnmatch_res == 0 {
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res = if self.match_positive {
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MatchType::PartialPositive
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} else {
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MatchType::PartialNegative
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};
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}
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let full = if self.pattern.to_bytes().starts_with(b"**/") {
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CString::new(&self.pattern.to_bytes()[3..]).unwrap()
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} else {
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CString::new(&self.pattern.to_bytes()[..]).unwrap()
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};
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let fnmatch_res = unsafe {
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let full_ptr = full.as_ptr() as *const libc::c_char;
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let filename_ptr = filename.as_ptr() as *const libc::c_char;
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fnmatch(full_ptr, filename_ptr, 0)
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};
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if fnmatch_res < 0 {
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bail!("error in fnmatch inside of MatchPattern");
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}
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if fnmatch_res == 0 {
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res = if self.match_positive {
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MatchType::Positive
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} else {
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MatchType::Negative
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};
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}
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if !is_dir && self.match_dir_only {
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res = MatchType::None;
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}
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if !is_dir && (res == MatchType::PartialPositive || res == MatchType::PartialNegative) {
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res = MatchType::None;
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}
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Ok(res)
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}
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}
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// Splits the `CStr` slice at the first slash encountered and returns the
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// content before (front pattern) and after the slash (rest pattern),
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// omitting the slash itself.
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// Slices starting with `**/` are an exception to this, as the corresponding
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// `MatchPattern` is intended to match multiple directories.
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// These pattern slices therefore return a `*` as front pattern and the original
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// pattern itself as rest pattern.
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fn split_at_slash(match_pattern: &CStr) -> (CString, CString) {
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let match_pattern = match_pattern.to_bytes();
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let pattern = if match_pattern.starts_with(b"./") {
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&match_pattern[2..]
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} else {
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match_pattern
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};
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let (mut front, mut rest) = match pattern.iter().position(|&c| c == b'/') {
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Some(ind) => {
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let (front, rest) = pattern.split_at(ind);
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(front, &rest[1..])
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}
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None => (pattern, &pattern[0..0]),
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};
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// '**' is treated such that it maches any directory
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if front == b"**" {
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front = b"*";
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rest = pattern;
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}
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// Pattern where valid CStrings before, so it is safe to unwrap the Result
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let front_pattern = CString::new(front).unwrap();
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let rest_pattern = CString::new(rest).unwrap();
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(front_pattern, rest_pattern)
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}
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