crash_dump: fork a copy of the target's address space.

Reduce the amount of time that a process remains paused by pausing its
threads, fetching their registers, and then performing unwinding on a
copy of its address space. This also works around a kernel change
that's in 4.9 that prevents ptrace from reading memory of processes
that we don't have immediate permissions to ptrace (even if we
previously ptraced them).

Bug: http://b/62112103
Bug: http://b/63989615
Test: treehugger
Change-Id: I7b9cc5dd8f54a354bc61f1bda0d2b7a8a55733c4

1 files changed, 12 insertions, 22 deletions

diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index 8d0c98bb0..0d17a3b5c 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -245,6 +245,8 @@ void CrasherTest::AssertDeath(int signo) {
   int status;
   pid_t pid = TIMEOUT(5, waitpid(crasher_pid, &status, 0));
   if (pid != crasher_pid) {
+    printf("failed to wait for crasher (pid %d)\n", crasher_pid);
+    sleep(100);
     FAIL() << "failed to wait for crasher: " << strerror(errno);
   }
 
@@ -341,13 +343,12 @@ TEST_F(CrasherTest, signal) {
   int intercept_result;
   unique_fd output_fd;
   StartProcess([]() {
-    abort();
+    while (true) {
+      sleep(1);
+    }
   });
   StartIntercept(&output_fd);
-
-  // Wait for a bit, or we might end up killing the process before the signal
-  // handler even gets a chance to be registered.
-  std::this_thread::sleep_for(100ms);
+  FinishCrasher();
   ASSERT_EQ(0, kill(crasher_pid, SIGSEGV));
 
   AssertDeath(SIGSEGV);
@@ -439,19 +440,6 @@ TEST_F(CrasherTest, wait_for_gdb) {
   AssertDeath(SIGABRT);
 }
 
-// wait_for_gdb shouldn't trigger on manually sent signals.
-TEST_F(CrasherTest, wait_for_gdb_signal) {
-  if (!android::base::SetProperty(kWaitForGdbKey, "1")) {
-    FAIL() << "failed to enable wait_for_gdb";
-  }
-
-  StartProcess([]() {
-    abort();
-  });
-  ASSERT_EQ(0, kill(crasher_pid, SIGSEGV)) << strerror(errno);
-  AssertDeath(SIGSEGV);
-}
-
 TEST_F(CrasherTest, backtrace) {
   std::string result;
   int intercept_result;
@@ -596,15 +584,13 @@ TEST_F(CrasherTest, competing_tracer) {
   int intercept_result;
   unique_fd output_fd;
   StartProcess([]() {
-    while (true) {
-    }
+    raise(SIGABRT);
   });
 
   StartIntercept(&output_fd);
-  FinishCrasher();
 
   ASSERT_EQ(0, ptrace(PTRACE_SEIZE, crasher_pid, 0, 0));
-  ASSERT_EQ(0, kill(crasher_pid, SIGABRT));
+  FinishCrasher();
 
   int status;
   ASSERT_EQ(crasher_pid, waitpid(crasher_pid, &status, 0));
@@ -622,6 +608,10 @@ TEST_F(CrasherTest, competing_tracer) {
   regex += R"( \(.+debuggerd_test)";
   ASSERT_MATCH(result, regex.c_str());
 
+  ASSERT_EQ(crasher_pid, waitpid(crasher_pid, &status, 0));
+  ASSERT_TRUE(WIFSTOPPED(status));
+  ASSERT_EQ(SIGABRT, WSTOPSIG(status));
+
   ASSERT_EQ(0, ptrace(PTRACE_DETACH, crasher_pid, 0, SIGABRT));
   AssertDeath(SIGABRT);
 }