compiler/rustc_data_structures/src/flock/unix.rs

   1 use std::fs::{File, OpenOptions};
   2 use std::io;
   3 use std::mem;
   4 use std::os::unix::prelude::*;
   5 use std::path::Path;
   6
   7 #[derive(Debug)]
   8 pub struct Lock {
   9     file: File,
  10 }
  11
  12 impl Lock {
  13     pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
  14         let file = OpenOptions::new()
  15             .read(true)
  16             .write(true)
  17             .create(create)
  18             .mode(libc::S_IRWXU as u32)
  19             .open(p)?;
  20
  21         let lock_type = if exclusive { libc::F_WRLCK } else { libc::F_RDLCK };
  22
  23         let mut flock: libc::flock = unsafe { mem::zeroed() };
  24         #[cfg(not(all(target_os = "hurd", target_arch = "x86")))]
  25         {
  26             flock.l_type = lock_type as libc::c_short;
  27             flock.l_whence = libc::SEEK_SET as libc::c_short;
  28         }
  29         #[cfg(all(target_os = "hurd", target_arch = "x86"))]
  30         {
  31             flock.l_type = lock_type as libc::c_int;
  32             flock.l_whence = libc::SEEK_SET as libc::c_int;
  33         }
  34         flock.l_start = 0;
  35         flock.l_len = 0;
  36
  37         let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
  38         let ret = unsafe { libc::fcntl(file.as_raw_fd(), cmd, &flock) };
  39         if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { file }) }
  40     }
  41
  42     pub fn error_unsupported(err: &io::Error) -> bool {
  43         matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
  44     }
  45 }
  46
  47 impl Drop for Lock {
  48     fn drop(&mut self) {
  49         let mut flock: libc::flock = unsafe { mem::zeroed() };
  50         #[cfg(not(all(target_os = "hurd", target_arch = "x86")))]
  51         {
  52             flock.l_type = libc::F_UNLCK as libc::c_short;
  53             flock.l_whence = libc::SEEK_SET as libc::c_short;
  54         }
  55         #[cfg(all(target_os = "hurd", target_arch = "x86"))]
  56         {
  57             flock.l_type = libc::F_UNLCK as libc::c_int;
  58             flock.l_whence = libc::SEEK_SET as libc::c_int;
  59         }
  60         flock.l_start = 0;
  61         flock.l_len = 0;
  62
  63         unsafe {
  64             libc::fcntl(self.file.as_raw_fd(), libc::F_SETLK, &flock);
  65         }
  66     }
  67 }