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-rw-r--r--src/pty.rs15
-rw-r--r--src/unistd.rs34
2 files changed, 45 insertions, 4 deletions
diff --git a/src/pty.rs b/src/pty.rs
index 88c9cc14..fd8ad98e 100644
--- a/src/pty.rs
+++ b/src/pty.rs
@@ -45,10 +45,17 @@ impl IntoRawFd for PtyMaster {
impl Drop for PtyMaster {
fn drop(&mut self) {
- // Errors when closing are ignored because we don't actually know if the file descriptor
- // was closed. If we retried, it's possible that descriptor was reallocated in the mean
- // time and the wrong file descriptor could be closed.
- let _ = ::unistd::close(self.0);
+ // On drop, we ignore errors like EINTR and EIO because there's no clear
+ // way to handle them, we can't return anything, and (on FreeBSD at
+ // least) the file descriptor is deallocated in these cases. However,
+ // we must panic on EBADF, because it is always an error to close an
+ // invalid file descriptor. That frequently indicates a double-close
+ // condition, which can cause confusing errors for future I/O
+ // operations.
+ let e = ::unistd::close(self.0);
+ if e == Err(Error::Sys(Errno::EBADF)) {
+ panic!("Closing an invalid file descriptor!");
+ };
}
}
diff --git a/src/unistd.rs b/src/unistd.rs
index 3209bb98..196232b6 100644
--- a/src/unistd.rs
+++ b/src/unistd.rs
@@ -670,6 +670,40 @@ pub fn gethostname<'a>(buffer: &'a mut [u8]) -> Result<&'a CStr> {
})
}
+/// Close a raw file descriptor
+///
+/// Be aware that many Rust types implicitly close-on-drop, including
+/// `std::fs::File`. Explicitly closing them with this method too can result in
+/// a double-close condition, which can cause confusing `EBADF` errors in
+/// seemingly unrelated code. Caveat programmer.
+///
+/// # Examples
+///
+/// ```no_run
+/// extern crate tempfile;
+/// extern crate nix;
+///
+/// use std::os::unix::io::AsRawFd;
+/// use nix::unistd::close;
+///
+/// fn main() {
+/// let mut f = tempfile::tempfile().unwrap();
+/// close(f.as_raw_fd()).unwrap(); // Bad! f will also close on drop!
+/// }
+/// ```
+///
+/// ```rust
+/// extern crate tempfile;
+/// extern crate nix;
+///
+/// use std::os::unix::io::IntoRawFd;
+/// use nix::unistd::close;
+///
+/// fn main() {
+/// let mut f = tempfile::tempfile().unwrap();
+/// close(f.into_raw_fd()).unwrap(); // Good. into_raw_fd consumes f
+/// }
+/// ```
pub fn close(fd: RawFd) -> Result<()> {
let res = unsafe { libc::close(fd) };
Errno::result(res).map(drop)