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Fix file descriptors leak in do_exec #147656

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Fix file descriptors leak in do_exec #147656

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4 changes: 2 additions & 2 deletions library/std/src/sys/process/unix/common.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -105,15 +105,15 @@ pub struct Command {
setsid: bool,
}

// passed to do_exec() with configuration of what the child stdio should look
// like
// passed to do_exec() with configuration of what the child stdio should look like
#[cfg_attr(target_os = "vita", allow(dead_code))]
pub struct ChildPipes {
pub stdin: ChildStdio,
pub stdout: ChildStdio,
pub stderr: ChildStdio,
}

// SAFETY: ChildPipes does not involve heap memory allocations
pub enum ChildStdio {
Inherit,
Explicit(c_int),
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10 changes: 5 additions & 5 deletions library/std/src/sys/process/unix/unix.rs
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Expand Up @@ -269,11 +269,6 @@ impl Command {
// For this reason, the block of code below should contain 0
// invocations of either malloc of free (or their related friends).
//
// As an example of not having malloc/free traffic, we don't close
// this file descriptor by dropping the FileDesc (which contains an
// allocation). Instead we just close it manually. This will never
// have the drop glue anyway because this code never returns (the
// child will either exec() or invoke libc::exit)
#[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
unsafe fn do_exec(
&mut self,
Expand All @@ -292,6 +287,11 @@ impl Command {
cvt_r(|| libc::dup2(fd, libc::STDERR_FILENO))?;
}

// SAFETY: Dropping `stdio` (ChildPipes) is safe here since ChildPipes
// does not involve heap memory allocations
debug_assert!(size_of::<ChildPipes>() <= 24);
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the intension is make sure ChildPipes does not involve heap allocations,
mem::needs_drop does not work here, since ChildPipes -> ChildStdio -> FileDesc,
and FileDesc impl Drop.

any better way to achieve the assertion?

drop(stdio);

#[cfg(not(target_os = "l4re"))]
{
if let Some(_g) = self.get_groups() {
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