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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/common/process_watcher.h"
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "base/platform_thread.h"
// Return true if the given child is dead. This will also reap the process.
// Doesn't block.
static bool IsChildDead(pid_t child) {
const int result = waitpid(child, NULL, WNOHANG);
if (result == -1) {
NOTREACHED();
} else if (result > 0) {
// The child has died.
return true;
}
return false;
}
// A thread class which waits for the given child to exit and reaps it.
// If the child doesn't exit within a couple of seconds, kill it.
class BackgroundReaper : public PlatformThread::Delegate {
public:
explicit BackgroundReaper(pid_t child)
: child_(child) {
}
void ThreadMain() {
WaitForChildToDie();
delete this;
}
void WaitForChildToDie() {
// There's no good way to wait for a specific child to exit in a timed
// fashion. (No kqueue on Linux), so we just loop and sleep.
// Waits 0.5 * 4 = 2 seconds.
for (unsigned i = 0; i < 4; ++i) {
PlatformThread::Sleep(500); // 0.5 seconds
if (IsChildDead(child_))
return;
}
if (kill(child_, SIGKILL) == 0) {
// SIGKILL is uncatchable. Since the signal was delivered, we can
// just wait for the process to die now in a blocking manner.
int result;
do {
result = waitpid(child_, NULL, 0);
} while (result == -1 && errno == EINTR);
} else {
LOG(ERROR) << "While waiting for " << child_ << " to terminate we"
<< " failed to deliver a SIGKILL signal (" << errno << ").";
}
}
private:
const pid_t child_;
DISALLOW_COPY_AND_ASSIGN(BackgroundReaper);
};
// static
void ProcessWatcher::EnsureProcessTerminated(base::ProcessHandle process) {
// If the child is already dead, then there's nothing to do
if (IsChildDead(process))
return;
BackgroundReaper* reaper = new BackgroundReaper(process);
PlatformThread::CreateNonJoinable(0, reaper);
}
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