Add manual POSIX fork handling support (Android)

* include/gc.h (GC_set_handle_fork): Update comment.
* include/gc.h (GC_atfork_prepare, GC_atfork_parent, GC_atfork_child):
New API proto.
* include/private/gc_priv.h (GC_handle_fork): Change type from GC_bool
to int (to hold a value of -1).
* misc.c (GC_handle_fork): Likewise.
* include/private/gc_priv.h (GC_handle_fork): Add comment.
* misc.c (GC_set_handle_fork): Likewise.
* include/private/gcconfig.h (CAN_HANDLE_FORK): Define also for HURD
and PLATFORM_ANDROID; do not define if HAVE_NO_FORK already defined.
* include/private/gcconfig.h (CAN_CALL_ATFORK): New macro (defined if
CAN_HANDLE_FORK but not HURD or PLATFORM_ANDROID).
* include/private/gcconfig.h (HAVE_NO_FORK): New macro (defined for
Win32, OS/2 and others).
* misc.c (GC_atfork_prepare, GC_atfork_parent, GC_atfork_child): New
API function definition (only if not CAN_HANDLE_FORK and not
HAVE_NO_FORK).
* misc.c (GC_handle_fork): Map all negative values of argument except
for -1 to a positive one stored to GC_handle_fork; call GC_init to
initialize GC_stderr before ABORT invocation (only if not
SMALL_CONFIG).
* pthread_support.c (GC_atfork_prepare, GC_atfork_parent,
GC_atfork_child): New API function definition (only if
CAN_HANDLE_FORK).
* win32_threads.c (GC_atfork_prepare, GC_atfork_parent,
GC_atfork_child): Likewise.
* pthread_support.c (GC_thr_init): No pthread_atfork call if not
CAN_CALL_ATFORK; adjust GC_handle_fork value if pthread_atfork
succeeds; do not about in case of pthread_atfork failure provided
GC_handle_fork is -1 (only if CAN_HANDLE_FORK).
* win32_threads.c (GC_thr_init): Likewise.
* tests/test.c (TEST_FORK_WITHOUT_ATFORK): Recognize new macro (do not
define NO_TEST_HANDLE_FORK in this case and set INIT_FORK_SUPPORT to
no-op).
* tests/test.c (INIT_FORK_SUPPORT): Define to GC_set_handle_fork(-1)
unless HANDLE_FORK, or NO_TEST_HANDLE_FORK or TEST_FORK_WITHOUT_ATFORK.
* tests/test.c (run_one_test): Surround fork() invocation with
GC_atfork_prepare, GC_atfork_parent, GC_atfork_child calls.
* win32_threads.c: Include unistd.h if CAN_CALL_ATFORK defined
(instead of CAN_HANDLE_FORK) to get pthread_atfork prototype.

1 files changed, 31 insertions, 5 deletions

diff --git a/win32_threads.c b/win32_threads.c
index 4e25bc71..83b2c420 100644
--- a/win32_threads.c
+++ b/win32_threads.c
@@ -60,7 +60,7 @@
   STATIC void GC_thread_exit_proc(void *arg);
 
 # include <pthread.h>
-# ifdef CAN_HANDLE_FORK
+# ifdef CAN_CALL_ATFORK
 #   include <unistd.h>
 # endif
 
@@ -1085,6 +1085,25 @@ GC_API void * GC_CALL GC_call_with_gc_active(GC_fn_type fn,
       GC_remove_all_threads_but_me();
       UNLOCK();
     }
+
+  /* Routines for fork handling by client (no-op if pthread_atfork works). */
+  GC_API void GC_CALL GC_atfork_prepare(void)
+  {
+    if (GC_handle_fork <= 0)
+      fork_prepare_proc();
+  }
+
+  GC_API void GC_CALL GC_atfork_parent(void)
+  {
+    if (GC_handle_fork <= 0)
+      fork_parent_proc();
+  }
+
+  GC_API void GC_CALL GC_atfork_child(void)
+  {
+    if (GC_handle_fork <= 0)
+      fork_child_proc();
+  }
 #endif /* CAN_HANDLE_FORK */
 
 void GC_push_thread_structures(void)
@@ -2404,10 +2423,17 @@ GC_INNER void GC_thr_init(void)
 
 # ifdef CAN_HANDLE_FORK
     /* Prepare for forks if requested.  */
-    if (GC_handle_fork
-          && pthread_atfork(fork_prepare_proc, fork_parent_proc,
-                            fork_child_proc) != 0)
-      ABORT("pthread_atfork failed");
+    if (GC_handle_fork) {
+#     ifdef CAN_CALL_ATFORK
+        if (pthread_atfork(fork_prepare_proc, fork_parent_proc,
+                           fork_child_proc) == 0) {
+          /* Handlers successfully registered.  */
+          GC_handle_fork = 1;
+        } else
+#     endif
+      /* else */ if (GC_handle_fork != -1)
+        ABORT("pthread_atfork failed");
+    }
 # endif
 
   /* Add the initial thread, so we can stop it. */