Linux: inform the Zygote when it's waiting on a dead process

If the browser calls ProcessDied() and asks the Zygote to wait (without blocking)
on a dead process, the kernel might not be done destroying it and the Zygote may
mistakenly claim that the process is alive.

We now inform the Zygote over the IPC that the process is already dead so
that it can wait synchroneously.

BUG=157458
NOTRY=true


Review URL: https://chromiumcodereview.appspot.com/11316261

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171450 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 49 insertions, 37 deletions

diff --git a/base/process_util_posix.cc b/base/process_util_posix.cc
index a19cc2a..284d00f 100644
--- a/base/process_util_posix.cc
+++ b/base/process_util_posix.cc
@@ -152,6 +152,50 @@ void ResetChildSignalHandlersToDefaults() {
   signal(SIGTERM, SIG_DFL);
 }
 
+TerminationStatus GetTerminationStatusImpl(ProcessHandle handle,
+                                           bool can_block,
+                                           int* exit_code) {
+  int status = 0;
+  const pid_t result = HANDLE_EINTR(waitpid(handle, &status,
+                                            can_block ? 0 : WNOHANG));
+  if (result == -1) {
+    DPLOG(ERROR) << "waitpid(" << handle << ")";
+    if (exit_code)
+      *exit_code = 0;
+    return TERMINATION_STATUS_NORMAL_TERMINATION;
+  } else if (result == 0) {
+    // the child hasn't exited yet.
+    if (exit_code)
+      *exit_code = 0;
+    return TERMINATION_STATUS_STILL_RUNNING;
+  }
+
+  if (exit_code)
+    *exit_code = status;
+
+  if (WIFSIGNALED(status)) {
+    switch (WTERMSIG(status)) {
+      case SIGABRT:
+      case SIGBUS:
+      case SIGFPE:
+      case SIGILL:
+      case SIGSEGV:
+        return TERMINATION_STATUS_PROCESS_CRASHED;
+      case SIGINT:
+      case SIGKILL:
+      case SIGTERM:
+        return TERMINATION_STATUS_PROCESS_WAS_KILLED;
+      default:
+        break;
+    }
+  }
+
+  if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
+    return TERMINATION_STATUS_ABNORMAL_TERMINATION;
+
+  return TERMINATION_STATUS_NORMAL_TERMINATION;
+}
+
 }  // anonymous namespace
 
 ProcessId GetCurrentProcId() {
@@ -754,44 +798,12 @@ void RaiseProcessToHighPriority() {
 }
 
 TerminationStatus GetTerminationStatus(ProcessHandle handle, int* exit_code) {
-  int status = 0;
-  const pid_t result = HANDLE_EINTR(waitpid(handle, &status, WNOHANG));
-  if (result == -1) {
-    DPLOG(ERROR) << "waitpid(" << handle << ")";
-    if (exit_code)
-      *exit_code = 0;
-    return TERMINATION_STATUS_NORMAL_TERMINATION;
-  } else if (result == 0) {
-    // the child hasn't exited yet.
-    if (exit_code)
-      *exit_code = 0;
-    return TERMINATION_STATUS_STILL_RUNNING;
-  }
-
-  if (exit_code)
-    *exit_code = status;
-
-  if (WIFSIGNALED(status)) {
-    switch (WTERMSIG(status)) {
-      case SIGABRT:
-      case SIGBUS:
-      case SIGFPE:
-      case SIGILL:
-      case SIGSEGV:
-        return TERMINATION_STATUS_PROCESS_CRASHED;
-      case SIGINT:
-      case SIGKILL:
-      case SIGTERM:
-        return TERMINATION_STATUS_PROCESS_WAS_KILLED;
-      default:
-        break;
-    }
-  }
-
-  if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
-    return TERMINATION_STATUS_ABNORMAL_TERMINATION;
+  return GetTerminationStatusImpl(handle, false /* can_block */, exit_code);
+}
 
-  return TERMINATION_STATUS_NORMAL_TERMINATION;
+TerminationStatus WaitForTerminationStatus(ProcessHandle handle,
+                                           int* exit_code) {
+  return GetTerminationStatusImpl(handle, true /* can_block */, exit_code);
 }
 
 bool WaitForExitCode(ProcessHandle handle, int* exit_code) {