debuggerd: wait for dump completion on crashes.

When a process crashes, both ActivityManager and init will try to kill
its process group when they notice. The recent change to minimize the
amount of time a process is paused results in crash dumps being killed
before they finish as a result of this. Since anything that needs to be
low-latency is probably not going to be too happy if it crashes, just
wait for completion whenever we're processing a real crash.

Bug: http://b/70343110
Test: debuggerd_test
Change-Id: I894bb06efd264b1ba005df06f7326a72f4b767bb

1 files changed, 8 insertions, 3 deletions

diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 02bc4b84f..96f3c7c54 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -395,9 +395,6 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
   // crash_dump is ptracing us, fork off a copy of our address space for it to use.
   create_vm_process();
 
-  input_read.reset();
-  input_write.reset();
-
   // Don't leave a zombie child.
   int status;
   if (TEMP_FAILURE_RETRY(waitpid(crash_dump_pid, &status, 0)) == -1) {
@@ -406,6 +403,14 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
   } else if (WIFSTOPPED(status) || WIFSIGNALED(status)) {
     async_safe_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper crashed or stopped");
   }
+
+  if (thread_info->siginfo->si_signo != DEBUGGER_SIGNAL) {
+    // For crashes, we don't need to minimize pause latency.
+    // Wait for the dump to complete before having the process exit, to avoid being murdered by
+    // ActivityManager or init.
+    TEMP_FAILURE_RETRY(read(input_read, &buf, sizeof(buf)));
+  }
+
   return 0;
 }