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https://github.com/fish-shell/fish-shell.git
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78 lines
2.5 KiB
Rust
78 lines
2.5 KiB
Rust
use crate::wutil::{wstat, wstr};
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use std::cmp::Ordering;
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use std::fs::{File, Metadata};
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use std::os::unix::prelude::*;
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/// Struct for representing a file's inode. We use this to detect and avoid symlink loops, among
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/// other things. While an inode / dev pair is sufficient to distinguish co-existing files, Linux
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/// seems to aggressively re-use inodes, so it cannot determine if a file has been deleted (ABA
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/// problem). Therefore we include richer information.
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#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
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pub struct FileId {
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pub device: u64,
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pub inode: u64,
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pub size: u64,
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pub change_seconds: i64,
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pub change_nanoseconds: i64,
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pub mod_seconds: i64,
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pub mod_nanoseconds: i64,
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}
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impl FileId {
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pub fn from_stat(buf: Metadata) -> Self {
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// These "into()" calls are because the various fields have different types
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// on different platforms.
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#[allow(clippy::useless_conversion)]
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FileId {
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device: buf.dev(),
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inode: buf.ino(),
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size: buf.size(),
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change_seconds: buf.ctime().into(),
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change_nanoseconds: buf.ctime_nsec().into(),
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mod_seconds: buf.mtime().into(),
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mod_nanoseconds: buf.mtime_nsec().into(),
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}
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}
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pub fn older_than(&self, rhs: &FileId) -> bool {
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match (self.change_seconds, self.change_nanoseconds)
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.cmp(&(rhs.change_seconds, rhs.change_nanoseconds))
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{
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Ordering::Less => true,
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Ordering::Equal | Ordering::Greater => false,
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}
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}
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}
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pub const INVALID_FILE_ID: FileId = FileId {
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device: u64::MAX,
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inode: u64::MAX,
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size: u64::MAX,
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change_seconds: i64::MIN,
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change_nanoseconds: -1,
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mod_seconds: i64::MIN,
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mod_nanoseconds: -1,
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};
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/// Get a FileID corresponding to a raw file descriptor, or INVALID_FILE_ID if it fails.
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pub fn file_id_for_fd(fd: RawFd) -> FileId {
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// Safety: we just want fstat(). Rust makes this stupidly hard.
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// The only way to get fstat from an fd is to use a File as an intermediary,
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// but File assumes ownership; so we have to use into_raw_fd() to release it.
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let file = unsafe { File::from_raw_fd(fd) };
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let res = file
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.metadata()
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.map(FileId::from_stat)
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.unwrap_or(INVALID_FILE_ID);
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let fd2 = file.into_raw_fd();
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assert_eq!(fd, fd2);
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res
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}
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/// Get a FileID corresponding to a path, or INVALID_FILE_ID if it fails.
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pub fn file_id_for_path(path: &wstr) -> FileId {
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wstat(path)
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.map(FileId::from_stat)
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.unwrap_or(INVALID_FILE_ID)
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}
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