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maxmind_db: Close our pipe FDs inside a lock. 

Lock our pipe mutex before closing its file descriptors. This should
hopefully fix some infrequent crashes that I'm seeing on my Windows 7 VM.

Add a note about GRWLock behavior on Windows which doesn't appear to be
related to this issue, but which is nevertheless important.

Ping-Bug: 14701
Change-Id: I32e66a24258264fa65a907f319755594f90c0177
Reviewed-on: https://code.wireshark.org/review/31375
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>
This commit is contained in:
Gerald Combs 2019-01-04 13:24:10 -08:00 committed by Anders Broman
parent 5fa9257704
commit f100f7f122
1 changed files with 15 additions and 4 deletions
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19
epan/maxmind_db.c
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@ -43,6 +43,14 @@ static mmdb_lookup_t mmdb_not_found;
static GThread *write_mmdbr_stdin_thread;
static GAsyncQueue *mmdbr_request_q; // g_allocated char *
// The GLib documentation says that g_rw_lock_reader_lock can be called
// recursively:
// https://developer.gnome.org/glib/stable/glib-Threads.html#g-rw-lock-reader-lock
// However, g_rw_lock_reader_lock calls AcquireSRWLockShared
// https://gitlab.gnome.org/GNOME/glib/blob/master/glib/gthread-win32.c#L206
// and SRW locks "cannot be acquired recursively"
// https://docs.microsoft.com/en-us/windows/desktop/Sync/slim-reader-writer--srw--locks
// https://blogs.msdn.microsoft.com/oldnewthing/20160506-00/?p=93416
static GRWLock mmdbr_pipe_mtx;
// Hashes of mmdb_lookup_t
@ -332,7 +340,7 @@ read_mmdbr_stdout_worker(gpointer data _U_) {
/**
* Stop our mmdbresolve process.
* Can be called from any thread.
* Main thread only.
*/
static void mmdb_resolve_stop(void) {
char *request;
@ -347,12 +355,15 @@ static void mmdb_resolve_stop(void) {
return;
}
g_rw_lock_writer_lock(&mmdbr_pipe_mtx);
MMDB_DEBUG("closing pid %d", mmdbr_pipe.pid);
ws_pipe_close(&mmdbr_pipe);
MMDB_DEBUG("closing pipe FDs");
ws_close(mmdbr_pipe.stdin_fd);
ws_close(mmdbr_pipe.stdout_fd);
g_rw_lock_writer_lock(&mmdbr_pipe_mtx);
MMDB_DEBUG("closing pid %d", mmdbr_pipe.pid);
ws_pipe_close(&mmdbr_pipe);
g_rw_lock_writer_unlock(&mmdbr_pipe_mtx);
g_thread_join(write_mmdbr_stdin_thread);