filetime/unix/
linux.rs

Help
1//! On Linux we try to use the more accurate `utimensat` syscall but this isn't
2//! always available so we also fall back to `utimes` if we couldn't find
3//! `utimensat` at runtime.
4
5use crate::FileTime;
6use std::ffi::CString;
7use std::fs;
8use std::io;
9use std::os::unix::prelude::*;
10use std::path::Path;
11use std::ptr;
12use std::sync::atomic::AtomicBool;
13use std::sync::atomic::Ordering::SeqCst;
14
15pub fn set_file_times(p: &Path, atime: FileTime, mtime: FileTime) -> io::Result<()> {
16    set_times(p, Some(atime), Some(mtime), false)
17}
18
19pub fn set_file_mtime(p: &Path, mtime: FileTime) -> io::Result<()> {
20    set_times(p, None, Some(mtime), false)
21}
22
23pub fn set_file_atime(p: &Path, atime: FileTime) -> io::Result<()> {
24    set_times(p, Some(atime), None, false)
25}
26
27pub fn set_file_handle_times(
28    f: &fs::File,
29    atime: Option<FileTime>,
30    mtime: Option<FileTime>,
31) -> io::Result<()> {
32    // Attempt to use the `utimensat` syscall, but if it's not supported by the
33    // current kernel then fall back to an older syscall.
34    static INVALID: AtomicBool = AtomicBool::new(false);
35    if !INVALID.load(SeqCst) {
36        let times = [super::to_timespec(&atime), super::to_timespec(&mtime)];
37
38        // We normally use a syscall because the `utimensat` function is documented
39        // as not accepting a file descriptor in the first argument (even though, on
40        // Linux, the syscall itself can accept a file descriptor there).
41        #[cfg(not(target_env = "musl"))]
42        let rc = unsafe {
43            libc::syscall(
44                libc::SYS_utimensat,
45                f.as_raw_fd(),
46                ptr::null::<libc::c_char>(),
47                times.as_ptr(),
48                0,
49            )
50        };
51        // However, on musl, we call the musl libc function instead. This is because
52        // on newer musl versions starting with musl 1.2, `timespec` is always a 64-bit
53        // value even on 32-bit targets. As a result, musl internally converts their
54        // `timespec` values to the correct ABI before invoking the syscall. Since we
55        // use `timespec` from the libc crate, it matches musl's definition and not
56        // the Linux kernel's version (for some platforms) so we must use musl's
57        // `utimensat` function to properly convert the value. musl's `utimensat`
58        // function allows file descriptors in the path argument so this is fine.
59        #[cfg(target_env = "musl")]
60        let rc = unsafe {
61            libc::utimensat(
62                f.as_raw_fd(),
63                ptr::null::<libc::c_char>(),
64                times.as_ptr(),
65                0,
66            )
67        };
68
69        if rc == 0 {
70            return Ok(());
71        }
72        let err = io::Error::last_os_error();
73        if err.raw_os_error() == Some(libc::ENOSYS) {
74            INVALID.store(true, SeqCst);
75        } else {
76            return Err(err);
77        }
78    }
79
80    super::utimes::set_file_handle_times(f, atime, mtime)
81}
82
83pub fn set_symlink_file_times(p: &Path, atime: FileTime, mtime: FileTime) -> io::Result<()> {
84    set_times(p, Some(atime), Some(mtime), true)
85}
86
87fn set_times(
88    p: &Path,
89    atime: Option<FileTime>,
90    mtime: Option<FileTime>,
91    symlink: bool,
92) -> io::Result<()> {
93    let flags = if symlink {
94        libc::AT_SYMLINK_NOFOLLOW
95    } else {
96        0
97    };
98
99    // Same as the `if` statement above.
100    static INVALID: AtomicBool = AtomicBool::new(false);
101    if !INVALID.load(SeqCst) {
102        let p = CString::new(p.as_os_str().as_bytes())?;
103        let times = [super::to_timespec(&atime), super::to_timespec(&mtime)];
104        let rc = unsafe { libc::utimensat(libc::AT_FDCWD, p.as_ptr(), times.as_ptr(), flags) };
105        if rc == 0 {
106            return Ok(());
107        }
108        let err = io::Error::last_os_error();
109        if err.raw_os_error() == Some(libc::ENOSYS) {
110            INVALID.store(true, SeqCst);
111        } else {
112            return Err(err);
113        }
114    }
115
116    super::utimes::set_times(p, atime, mtime, symlink)
117}
filetime/unix/linux.rs

filetime/unix/
linux.rs
