Merge #638

638: Make aio, chdir, and wait tests thread safe r=Susurrus

Fix thread safety issues in aio, chdir, and wait tests
    
They have four problems:
    
* The chdir tests change the process's cwd, which is global.  Protect them all with a mutex.
    
* The wait tests will reap any subprocess, and several tests create subprocesses.  Protect them all with a mutex so only one subprocess-creating test will run at a time.
    
* When a multithreaded test forks, the child process can sometimes block in the stack unwinding code.  It blocks on a mutex that was held by a different thread in the parent, but that thread doesn't exist in the child, so a deadlock results.  Fix this by immediately calling `std::process:;exit` in the child processes.
    
* My previous attempt at thread safety in the aio tests didn't work, because anonymous MutexGuards drop immediately.  Fix this by naming the SIGUSR2_MTX MutexGuards.

Fixes #251 

1 files changed, 6 insertions, 0 deletions

diff --git a/test/sys/test_wait.rs b/test/sys/test_wait.rs
index d8ac94e4..2e28d9e7 100644
--- a/test/sys/test_wait.rs
+++ b/test/sys/test_wait.rs
@@ -6,6 +6,9 @@ use libc::exit;
 
 #[test]
 fn test_wait_signal() {
+    #[allow(unused_variables)]
+    let m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");
+
     match fork() {
       Ok(Child) => pause().unwrap_or(()),
       Ok(Parent { child }) => {
@@ -19,6 +22,9 @@ fn test_wait_signal() {
 
 #[test]
 fn test_wait_exit() {
+    #[allow(unused_variables)]
+    let m = ::FORK_MTX.lock().expect("Mutex got poisoned by another test");
+
     match fork() {
       Ok(Child) => unsafe { exit(12); },
       Ok(Parent { child }) => {