[cairo-png] Propagate error from read and write funcs.

Use the png_struct->error_ptr to propagate the error status from the
user/stdio read and write functions through the png_error() to the
cairo_surface_write_to_png*() and cairo_surface_read_from_png*()
functions. From there the error is returned back to the user either
directly or as the most appropriate error surface.

(Fixes https://bugs.freedesktop.org/show_bug.cgi?id=6909)

1 files changed, 75 insertions, 9 deletions

diff --git a/test/create-from-png.c b/test/create-from-png.c
index 4aefc34ca..fe08b308d 100644
--- a/test/create-from-png.c
+++ b/test/create-from-png.c
@@ -39,6 +39,18 @@ cairo_test_t test = {
     draw
 };
 
+static cairo_status_t
+no_memory_error (void *closure, unsigned char *data, unsigned int size)
+{
+    return CAIRO_STATUS_NO_MEMORY;
+}
+
+static cairo_status_t
+read_error (void *closure, unsigned char *data, unsigned int size)
+{
+    return CAIRO_STATUS_READ_ERROR;
+}
+
 static cairo_test_status_t
 draw (cairo_t *cr, int width, int height)
 {
@@ -46,18 +58,10 @@ draw (cairo_t *cr, int width, int height)
     char *filename;
     cairo_surface_t *surface;
 
-    surface = cairo_image_surface_create_from_png ("___THIS_FILE_DOES_NOT_EXIST___");
-    if (cairo_surface_status (surface) != CAIRO_STATUS_FILE_NOT_FOUND) {
-	cairo_test_log ("Error: expected \"file not found\", but got: %s\n",
-			cairo_status_to_string (cairo_surface_status (surface)));
-	return CAIRO_TEST_FAILURE;
-    }
-
     xasprintf (&filename, "%s/%s", srcdir ? srcdir : ".",
 	       "create-from-png-ref.png");
 
     surface = cairo_image_surface_create_from_png (filename);
-
     if (cairo_surface_status (surface)) {
 	cairo_test_log ("Error reading PNG image %s: %s\n",
 			filename,
@@ -65,7 +69,6 @@ draw (cairo_t *cr, int width, int height)
 	free (filename);
 	return CAIRO_TEST_FAILURE;
     }
-
     free (filename);
 
     cairo_set_source_surface (cr, surface, 0, 0);
@@ -79,5 +82,68 @@ draw (cairo_t *cr, int width, int height)
 int
 main (void)
 {
+    char *srcdir = getenv ("srcdir");
+    char *filename;
+    cairo_surface_t *surface;
+    cairo_status_t status;
+
+    surface = cairo_image_surface_create_from_png ("___THIS_FILE_DOES_NOT_EXIST___");
+    if (cairo_surface_status (surface) != CAIRO_STATUS_FILE_NOT_FOUND) {
+	cairo_test_log ("Error: expected \"file not found\", but got: %s\n",
+			cairo_status_to_string (cairo_surface_status (surface)));
+	cairo_surface_destroy (surface);
+	return CAIRO_TEST_FAILURE;
+    }
+
+    surface = cairo_image_surface_create_from_png_stream (no_memory_error, NULL);
+    if (cairo_surface_status (surface) != CAIRO_STATUS_NO_MEMORY) {
+	cairo_test_log ("Error: expected \"out of memory\", but got: %s\n",
+			cairo_status_to_string (cairo_surface_status (surface)));
+	cairo_surface_destroy (surface);
+	return CAIRO_TEST_FAILURE;
+    }
+
+    surface = cairo_image_surface_create_from_png_stream (read_error, NULL);
+    if (cairo_surface_status (surface) != CAIRO_STATUS_READ_ERROR) {
+	cairo_test_log ("Error: expected \"read error\", but got: %s\n",
+			cairo_status_to_string (cairo_surface_status (surface)));
+	cairo_surface_destroy (surface);
+	return CAIRO_TEST_FAILURE;
+    }
+
+    /* cheekily test error propagation from the user write funcs as well ... */
+    xasprintf (&filename, "%s/%s", srcdir ? srcdir : ".",
+	       "create-from-png-ref.png");
+
+    surface = cairo_image_surface_create_from_png (filename);
+    if (cairo_surface_status (surface)) {
+	cairo_test_log ("Error reading PNG image %s: %s\n",
+			filename,
+			cairo_status_to_string (cairo_surface_status (surface)));
+	free (filename);
+	return CAIRO_TEST_FAILURE;
+    }
+    free (filename);
+
+    status = cairo_surface_write_to_png_stream (surface,
+	                                   (cairo_write_func_t) no_memory_error,
+					   NULL);
+    if (status != CAIRO_STATUS_NO_MEMORY) {
+	cairo_test_log ("Error: expected \"out of memory\", but got: %s\n",
+			cairo_status_to_string (status));
+	cairo_surface_destroy (surface);
+	return CAIRO_TEST_FAILURE;
+    }
+    status = cairo_surface_write_to_png_stream (surface,
+	                                        (cairo_write_func_t) read_error,
+						NULL);
+    if (status != CAIRO_STATUS_READ_ERROR) {
+	cairo_test_log ("Error: expected \"read error\", but got: %s\n",
+			cairo_status_to_string (status));
+	cairo_surface_destroy (surface);
+	return CAIRO_TEST_FAILURE;
+    }
+    cairo_surface_destroy (surface);
+
     return cairo_test (&test);
 }