Fix ProcessUtilTest.GetTerminationStatusCrash on Android L+

On Android L+, signal and sigaction symbols are provided by libsigchain
that override the system's versions. There is a bug in these functions
where they essentially ignore requests to install SIG_DFL. This causes
ProcessUtilTest.GetTerminationStatusCrash to fail (as
CrashingChildProcess goes into infinite loop instead of crashing).

Workaround this issue by explicitly performing a syscall to
__NR_rt_sigaction to install SIG_DFL on Android, as breakpad does
(see https://breakpad.appspot.com/1804002/).

BUG=512255
TEST=ProcessUtilTest.GetTerminationStatusCrash

Review URL: https://codereview.chromium.org/1241333002

Cr-Commit-Position: refs/heads/master@{#339584}

2 files changed, 17 insertions, 1 deletions

diff --git a/base/DEPS b/base/DEPS
index c632e35..6d91c8d 100644
--- a/base/DEPS
+++ b/base/DEPS
@@ -4,6 +4,7 @@ include_rules = [
   "+third_party/apple_apsl",
   "+third_party/libevent",
   "+third_party/dmg_fp",
+  "+third_party/lss",
   "+third_party/mach_override",
   "+third_party/modp_b64",
   "+third_party/tcmalloc",
diff --git a/base/process/process_util_unittest.cc b/base/process/process_util_unittest.cc
index 6c1a3f1..0ca4e3a 100644
--- a/base/process/process_util_unittest.cc
+++ b/base/process/process_util_unittest.cc
@@ -59,6 +59,9 @@
 #include <malloc/malloc.h>
 #include "base/mac/mac_util.h"
 #endif
+#if defined(OS_ANDROID)
+#include "third_party/lss/linux_syscall_support.h"
+#endif
 
 using base::FilePath;
 
@@ -226,7 +229,19 @@ const char kSignalFileCrash[] = "CrashingChildProcess.die";
 
 MULTIPROCESS_TEST_MAIN(CrashingChildProcess) {
   WaitToDie(ProcessUtilTest::GetSignalFilePath(kSignalFileCrash).c_str());
-#if defined(OS_POSIX)
+#if defined(OS_ANDROID)
+  // Android L+ expose signal and sigaction symbols that override the system
+  // ones. There is a bug in these functions where a request to set the handler
+  // to SIG_DFL is ignored. In that case, an infinite loop is entered as the
+  // signal is repeatedly sent to the crash dump signal handler.
+  // To work around this, directly call the system's sigaction.
+  struct kernel_sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sys_sigemptyset(&sa.sa_mask);
+  sa.sa_handler_ = SIG_DFL;
+  sa.sa_flags = SA_RESTART;
+  sys_rt_sigaction(SIGSEGV, &sa, NULL, sizeof(kernel_sigset_t));
+#elif defined(OS_POSIX)
   // Have to disable to signal handler for segv so we can get a crash
   // instead of an abnormal termination through the crash dump handler.
   ::signal(SIGSEGV, SIG_DFL);