Make sources thread-safe

1 files changed, 15 insertions, 3 deletions

diff --git a/src/backend_libpng.c b/src/backend_libpng.c
index 2c3b1d7..3713ae8 100644
--- a/src/backend_libpng.c
+++ b/src/backend_libpng.c
@@ -18,6 +18,7 @@ struct private {
 
 static void source_free(struct imv_source *src)
 {
+  pthread_mutex_lock(&src->busy);
   free(src->name);
   src->name = NULL;
 
@@ -30,6 +31,8 @@ static void source_free(struct imv_source *src)
   free(src->private);
   src->private = NULL;
 
+  pthread_mutex_unlock(&src->busy);
+  pthread_mutex_destroy(&src->busy);
   free(src);
 }
 
@@ -57,6 +60,7 @@ static void report_error(struct imv_source *src)
   msg.bitmap = NULL;
   msg.error = "Internal error";
 
+  pthread_mutex_unlock(&src->busy);
   src->callback(&msg);
 }
 
@@ -76,16 +80,22 @@ static void send_bitmap(struct imv_source *src, void *bitmap)
   msg.frametime = 0;
   msg.error = NULL;
 
+  pthread_mutex_unlock(&src->busy);
   src->callback(&msg);
 }
 
-static void load_image(struct imv_source *src)
+static int load_image(struct imv_source *src)
 {
+  /* Don't run if this source is already active */
+  if (pthread_mutex_trylock(&src->busy)) {
+    return -1;
+  }
+
   struct private *private = src->private;
 
   if (setjmp(png_jmpbuf(private->png))) {
     report_error(src);
-    return;
+    return -1;
   }
 
   png_bytep *rows = alloca(sizeof(png_bytep) * src->height);
@@ -98,13 +108,14 @@ static void load_image(struct imv_source *src)
   if (setjmp(png_jmpbuf(private->png))) {
     free(rows[0]);
     report_error(src);
-    return;
+    return -1;
   }
 
   png_read_image(private->png, rows);
   fclose(private->file);
   private->file = NULL;
   send_bitmap(src, rows[0]);
+  return 0;
 }
 
 static enum backend_result open_path(const char *path, struct imv_source **src)
@@ -169,6 +180,7 @@ static enum backend_result open_path(const char *path, struct imv_source **src)
   source->height = png_get_image_height(private->png, private->info);
   source->num_frames = 1;
   source->next_frame = 1;
+  pthread_mutex_init(&source->busy, NULL);
   source->load_first_frame = &load_image;
   source->load_next_frame = NULL;
   source->free = &source_free;