Linux: Use _exit() instead of exit() in the child after fork() in failure conditions.

TEST=none
BUG=none

Review URL: http://codereview.chromium.org/159275

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21418 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 12 insertions, 2 deletions

diff --git a/base/process_util_linux.cc b/base/process_util_linux.cc
index b784803..50eb4a2 100644
--- a/base/process_util_linux.cc
+++ b/base/process_util_linux.cc
@@ -113,8 +113,13 @@ bool LaunchApp(const std::vector<std::string>& argv,
       }
     }
 
+    // Obscure fork() rule: in the child, if you don't end up doing exec*(),
+    // you call _exit() instead of exit(). This is because _exit() does not
+    // call any previously-registered (in the parent) exit handlers, which
+    // might do things like block waiting for threads that don't even exist
+    // in the child.
     if (!ShuffleFileDescriptors(fd_shuffle))
-      exit(127);
+      _exit(127);
 
     // If we are using the SUID sandbox, it sets a magic environment variable
     // ("SBX_D"), so we remove that variable from the environment here on the
@@ -130,7 +135,7 @@ bool LaunchApp(const std::vector<std::string>& argv,
     execvp(argv_cstr[0], argv_cstr.get());
     LOG(ERROR) << "LaunchApp: exec failed!, argv_cstr[0] " << argv_cstr[0]
         << ", errno " << errno;
-    exit(127);
+    _exit(127);
   } else {
     // Parent process
     if (wait)
diff --git a/base/process_util_posix.cc b/base/process_util_posix.cc
index a03b45c..6ff660f 100644
--- a/base/process_util_posix.cc
+++ b/base/process_util_posix.cc
@@ -441,6 +441,11 @@ bool GetAppOutput(const CommandLine& cl, std::string* output) {
       return false;
     case 0:  // child
       {
+        // Obscure fork() rule: in the child, if you don't end up doing exec*(),
+        // you call _exit() instead of exit(). This is because _exit() does not
+        // call any previously-registered (in the parent) exit handlers, which
+        // might do things like block waiting for threads that don't even exist
+        // in the child.
         int dev_null = open("/dev/null", O_WRONLY);
         if (dev_null < 0)
           _exit(127);