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std: prevent `CreateProcess()` race on Windows 

Believe or not, `CreateProcess()` is racy if several threads create
child processes: [0], [1], [2].

This caused some tests show crash dialogs during
`make check-stage#-rpass`.

More explanation:

On Windows, `SetErrorMode()` controls display of error dialogs: it
accepts new error mode and returns old error mode.
The error mode is process-global and automatically inherited to child
process when created.

MSYS2 bash shell internally sets it to not show error dialogs, therefore
`make check-stage#-rpass` should not show them either.

However, [1] says that `CreateProcess()` internally invokes
`SetErrorMode()` twice: at first it sets mode `0x8001` and saves
original mode, and at second it restores original mode.
So if two threads simultaneously call `CreateProcess()`, the first
thread sets error mode to `0x8001` then the second thread recognizes
that current error mode is `0x8001`. Therefore, The second thread will
create process with wrong error mode.

This really occurs inside `compiletest`: it creates several processes on
each thread, so some `run-pass` tests are invoked with wrong error mode
therefore show crash dialog.

This commit adds `StaticMutex` for `CreateProcess()` call. This seems
to fix the "dialog annoyance" issue.

[0]: http://support.microsoft.com/kb/315939
[1]: https://code.google.com/p/nativeclient/issues/detail?id=2968
[2]: https://ghc.haskell.org/trac/ghc/ticket/2650
This commit is contained in:
klutzy 2015-01-07 00:42:26 +09:00
parent 8efd9901b6
commit 68cb17097a
1 changed files with 7 additions and 0 deletions
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7
src/libstd/sys/windows/process.rs
View File

@ -25,6 +25,8 @@ use path::BytesContainer;
use ptr;
use str;
use sys::fs::FileDesc;
use sync::{StaticMutex, MUTEX_INIT};
use sys::fs;
use sys::{self, retry, c, wouldblock, set_nonblocking, ms_to_timeval, timer};
use sys_common::helper_thread::Helper;
@ -32,6 +34,10 @@ use sys_common::{AsInner, mkerr_libc, timeout};
pub use sys_common::ProcessConfig;
// `CreateProcess` is racy!
// http://support.microsoft.com/kb/315939
static CREATE_PROCESS_LOCK: StaticMutex = MUTEX_INIT;
/// A value representing a child process.
///
/// The lifetime of this value is linked to the lifetime of the actual
@ -224,6 +230,7 @@ impl Process {
with_dirp(cfg.cwd(), |dirp| {
let mut cmd_str: Vec<u16> = cmd_str.utf16_units().collect();
cmd_str.push(0);
let _lock = CREATE_PROCESS_LOCK.lock().unwrap();
let created = CreateProcessW(ptr::null(),
cmd_str.as_mut_ptr(),
ptr::null_mut(),