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std: Unconditionally close all file descriptors

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The logic for only closing file descriptors >= 3 was inherited from quite some
time ago and ends up meaning that some internal APIs are less consistent than
they should be. By unconditionally closing everything entering a `FileDesc` we
ensure that we're consistent in our behavior as well as robustly handling the
stdio case.
This commit is contained in:
Alex Crichton
2015-04-03 15:44:14 -07:00
parent 33a2191d0b
commit eadc3bcd67
5 changed files with 86 additions and 67 deletions
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59
src/libstd/sys/unix/process2.rs
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@@ -119,6 +119,12 @@ pub struct Process {
pid: pid_t
}
pub enum Stdio {
Inherit,
Piped(AnonPipe),
None,
}
const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX";
impl Process {
@@ -128,9 +134,9 @@ impl Process {
}
pub fn spawn(cfg: &Command,
in_fd: Option<AnonPipe>,
out_fd: Option<AnonPipe>,
err_fd: Option<AnonPipe>) -> io::Result<Process> {
in_fd: Stdio,
out_fd: Stdio,
err_fd: Stdio) -> io::Result<Process> {
let dirp = cfg.cwd.as_ref().map(|c| c.as_ptr()).unwrap_or(ptr::null());
let (envp, _a, _b) = make_envp(cfg.env.as_ref());
@@ -224,9 +230,9 @@ impl Process {
argv: *const *const libc::c_char,
envp: *const libc::c_void,
dirp: *const libc::c_char,
in_fd: Option<AnonPipe>,
out_fd: Option<AnonPipe>,
err_fd: Option<AnonPipe>) -> ! {
in_fd: Stdio,
out_fd: Stdio,
err_fd: Stdio) -> ! {
fn fail(output: &mut AnonPipe) -> ! {
let errno = sys::os::errno() as u32;
let bytes = [
@@ -244,23 +250,30 @@ impl Process {
unsafe { libc::_exit(1) }
}
// If a stdio file descriptor is set to be ignored, we don't
// actually close it, but rather open up /dev/null into that
// file descriptor. Otherwise, the first file descriptor opened
// up in the child would be numbered as one of the stdio file
// descriptors, which is likely to wreak havoc.
let setup = |src: Option<AnonPipe>, dst: c_int| {
src.map(|p| p.into_fd()).or_else(|| {
let mut opts = OpenOptions::new();
opts.read(dst == libc::STDIN_FILENO);
opts.write(dst != libc::STDIN_FILENO);
let devnull = CStr::from_ptr(b"/dev/null\0".as_ptr()
as *const _);
File::open_c(devnull, &opts).ok().map(|f| f.into_fd())
}).map(|fd| {
fd.unset_cloexec();
retry(|| libc::dup2(fd.raw(), dst)) != -1
}).unwrap_or(false)
let setup = |src: Stdio, dst: c_int| {
let fd = match src {
Stdio::Inherit => return true,
Stdio::Piped(pipe) => pipe.into_fd(),
// If a stdio file descriptor is set to be ignored, we open up
// /dev/null into that file descriptor. Otherwise, the first
// file descriptor opened up in the child would be numbered as
// one of the stdio file descriptors, which is likely to wreak
// havoc.
Stdio::None => {
let mut opts = OpenOptions::new();
opts.read(dst == libc::STDIN_FILENO);
opts.write(dst != libc::STDIN_FILENO);
let devnull = CStr::from_ptr(b"/dev/null\0".as_ptr()
as *const _);
if let Ok(f) = File::open_c(devnull, &opts) {
f.into_fd()
} else {
return false
}
}
};
retry(|| libc::dup2(fd.raw(), dst)) != -1
};
if !setup(in_fd, libc::STDIN_FILENO) { fail(&mut output) }