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"fix" a nasty race condition

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10860 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-01-14 21:18:03 +00:00
parent de31b76784
commit 411a9a6f07
1 changed files with 20 additions and 1 deletions
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21
lib/Debugger/UnixLocalInferiorProcess.cpp
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@ -419,6 +419,9 @@ void IP::writeToChild(void *Buffer, unsigned Size) const {
void IP::killChild() const {
assert(ChildPID != 0 && "Child has already been reaped!");
// If the process terminated on its own accord, closing the pipe file
// descriptors, we will get here. Check to see if the process has already
// died in this manner, gracefully.
int Status = 0;
int PID;
do {
@ -426,7 +429,23 @@ void IP::killChild() const {
} while (PID < 0 && errno == EINTR);
if (PID < 0) throw "Error waiting for child to exit!";
// If the child process was already dead, then it died unexpectedly.
// Ok, there is a slight race condition here. It's possible that we will find
// out that the file descriptor closed before waitpid will indicate that the
// process gracefully died. If we don't know that the process gracefully
// died, wait a bit and try again. This is pretty nasty.
if (PID == 0) {
usleep(10000); // Wait a bit.
// Try again.
Status = 0;
do {
PID = waitpid(ChildPID, &Status, WNOHANG);
} while (PID < 0 && errno == EINTR);
if (PID < 0) throw "Error waiting for child to exit!";
}
// If the child process was already dead, then indicate that the process
// terminated on its own.
if (PID) {
assert(PID == ChildPID && "Didn't reap child?");
ChildPID = 0; // Child has been reaped