feature/android 46c603be5a8 5/5: Update Android port

[Po Lu]

branch: feature/android
commit 46c603be5a81f175b8003d3b5b6c4e73695f1002
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Update Android port
    
    * src/android.c (android_run_in_emacs_thread): Behave more
    robustly if SIGIO arrives too late Emacs for Emacs to check for
    signals, but too early to preempt a long running syscall.
---
 src/android.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/android.c b/src/android.c
index b1d7b75c129..d8b264a8491 100644
--- a/src/android.c
+++ b/src/android.c
@@ -6385,6 +6385,8 @@ android_run_in_emacs_thread (void (*proc) (void *), void 
*closure)
       __atomic_store_n (&android_urgent_query, true,
                        __ATOMIC_RELEASE);
 
+    kill_again:
+
       /* And raise SIGIO.  Now that the query is considered urgent,
         the main thread will reply while reading async input.
 
@@ -6396,9 +6398,27 @@ android_run_in_emacs_thread (void (*proc) (void *), void 
*closure)
       /* Wait for the query to complete.  `android_urgent_query' is
         only cleared by either `android_select' or
         `android_check_query', so there's no need to worry about the
-        flag being cleared before the query is processed.  */
-      while (sem_wait (&android_query_sem) < 0)
-       ;;
+        flag being cleared before the query is processed.
+
+        Send SIGIO again periodically until the query is answered, on
+        the off chance that SIGIO arrived too late to preempt a
+        system call, but too early for it to return EINTR.  */
+
+      timeout.tv_sec = 4;
+      timeout.tv_nsec = 0;
+      timeout = timespec_add (current_timespec (), timeout);
+
+      while (sem_timedwait (&android_query_sem, &timeout) < 0)
+       {
+         /* If waiting timed out, send SIGIO to the main thread
+            again.  */
+
+         if (errno == ETIMEDOUT)
+           goto kill_again;
+
+         /* Otherwise, continue waiting.  */
+         eassert (errno == EINTR);
+       }
     }
 
   /* At this point, `android_servicing_query' should either be zero if