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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/event.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "base/eintr_wrapper.h"
#include "base/file_util.h"
#include "base/time.h"
namespace {
// Reap |child| process.
// This call blocks until completion.
void BlockingReap(pid_t child) {
const pid_t result = HANDLE_EINTR(waitpid(child, NULL, 0));
if (result == -1) {
PLOG(ERROR) << "waitpid(" << child << ")";
NOTREACHED();
}
}
// Waits for |timeout| seconds for the given |child| to exit and reap it.
// If the child doesn't exit within a couple of seconds, kill it.
void WaitForChildToDie(pid_t child, unsigned timeout) {
int kq = HANDLE_EINTR(kqueue());
file_util::ScopedFD auto_close(&kq);
if (kq == -1) {
PLOG(ERROR) << "Failed to create kqueue";
return;
}
struct kevent event_to_add = {0};
EV_SET(&event_to_add, child, EVFILT_PROC, EV_ADD, NOTE_EXIT, 0, NULL);
// Register interest with kqueue.
int result = HANDLE_EINTR(kevent(kq, &event_to_add, 1, NULL, 0, NULL));
if (result == -1 && errno == ESRCH) {
// A "No Such Process" error is fine, the process may have died already
// and been reaped by someone else. But make sure that it was/is reaped.
// Don't report an error in case it was already reaped.
HANDLE_EINTR(waitpid(child, NULL, WNOHANG));
return;
}
if (result == -1) {
PLOG(ERROR) << "Failed to register event to listen for death of pid "
<< child;
return;
}
struct kevent event = {0};
DCHECK(timeout != 0);
int num_processes_that_died = -1;
using base::Time;
using base::TimeDelta;
// We need to keep track of the elapsed time - if kevent() returns
// EINTR in the middle of blocking call we want to make up what's left
// of the timeout.
TimeDelta time_left = TimeDelta::FromSeconds(timeout);
Time wakeup = Time::Now() + time_left;
while(time_left.InMilliseconds() > 0) {
const struct timespec timeout = time_left.ToTimeSpec();
num_processes_that_died = kevent(kq, NULL, 0, &event, 1, &timeout);
if (num_processes_that_died >= 0)
break;
if (num_processes_that_died == -1 && errno == EINTR) {
time_left = wakeup - Time::Now();
continue;
}
// If we got here, kevent() must have returned -1.
PLOG(ERROR) << "kevent() failed";
break;
}
if (num_processes_that_died == -1) {
PLOG(ERROR) << "kevent failed";
return;
}
if (num_processes_that_died == 1) {
if (event.fflags & NOTE_EXIT &&
event.ident == static_cast<uintptr_t>(child)) {
// Process died, it's safe to make a blocking call here since the
// kqueue() notification occurs when the process is already zombified.
BlockingReap(child);
return;
} else {
PLOG(ERROR) << "kevent() returned unexpected result - ke.fflags ="
<< event.fflags
<< " ke.ident ="
<< event.ident
<< " while listening for pid="
<< child;
}
}
// If we got here the child is still alive so kill it...
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.
BlockingReap(child);
} else {
PLOG(ERROR) << "While waiting for " << child << " to terminate we"
<< " failed to deliver a SIGKILL signal";
}
}
} // namespace
void ProcessWatcher::EnsureProcessTerminated(base::ProcessHandle process) {
WaitForChildToDie(process, 2);
}
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