[user-font] Review locks under error conditions.

Simplify the error handling by only relinquishing the global
scaled_font_map mutex if we successfully insert the placeholder font. The
result is that on the error path, there are no changes to global state and
thus we can entirely skip the user-font initialisation and
re-registration.

1 files changed, 23 insertions, 16 deletions

diff --git a/src/cairo-user-font.c b/src/cairo-user-font.c
index 2a12df723..5645287a4 100644
--- a/src/cairo-user-font.c
+++ b/src/cairo-user-font.c
@@ -151,9 +151,14 @@ _cairo_user_scaled_glyph_init (void			 *abstract_font,
 	    null_surface = _cairo_null_surface_create (cairo_surface_get_content (meta_surface));
 	    analysis_surface = _cairo_analysis_surface_create (null_surface, -1, -1);
 	    cairo_surface_destroy (null_surface);
+	    status = analysis_surface->status;
+	    if (status)
+		return status;
 
-	    _cairo_analysis_surface_set_ctm (analysis_surface, &scaled_font->extent_scale);
-	    status = _cairo_meta_surface_replay (meta_surface, analysis_surface);
+	    _cairo_analysis_surface_set_ctm (analysis_surface,
+					     &scaled_font->extent_scale);
+	    status = _cairo_meta_surface_replay (meta_surface,
+						 analysis_surface);
 	    _cairo_analysis_surface_get_bounding_box (analysis_surface, &bbox);
 	    cairo_surface_destroy (analysis_surface);
 
@@ -399,7 +404,7 @@ _cairo_user_font_face_scaled_font_create (void                        *abstract_
 
     user_scaled_font = malloc (sizeof (cairo_user_scaled_font_t));
     if (user_scaled_font == NULL)
-	return CAIRO_STATUS_NO_MEMORY;
+	return _cairo_error (CAIRO_STATUS_NO_MEMORY);
 
     status = _cairo_scaled_font_init (&user_scaled_font->base,
 				      &font_face->base,
@@ -444,29 +449,31 @@ _cairo_user_font_face_scaled_font_create (void                        *abstract_
 	}
     }
 
-    if (status == CAIRO_STATUS_SUCCESS && font_face->scaled_font_methods.init != NULL) {
-
-	cairo_t *cr;
-
+    if (status == CAIRO_STATUS_SUCCESS &&
+	font_face->scaled_font_methods.init != NULL)
+    {
 	/* Lock the scaled_font mutex such that user doesn't accidentally try
          * to use it just yet. */
 	CAIRO_MUTEX_LOCK (user_scaled_font->base.mutex);
 
 	/* Give away fontmap lock such that user-font can use other fonts */
-	_cairo_scaled_font_register_placeholder_and_unlock_font_map (&user_scaled_font->base);
+	status = _cairo_scaled_font_register_placeholder_and_unlock_font_map (&user_scaled_font->base);
+	if (status == CAIRO_STATUS_SUCCESS) {
+	    cairo_t *cr;
 
-	cr = _cairo_user_scaled_font_create_meta_context (user_scaled_font);
+	    cr = _cairo_user_scaled_font_create_meta_context (user_scaled_font);
 
-	status = font_face->scaled_font_methods.init (&user_scaled_font->base,
-						      cr,
-						      &font_extents);
+	    status = font_face->scaled_font_methods.init (&user_scaled_font->base,
+							  cr,
+							  &font_extents);
 
-	if (status == CAIRO_STATUS_SUCCESS)
-	    status = cairo_status (cr);
+	    if (status == CAIRO_STATUS_SUCCESS)
+		status = cairo_status (cr);
 
-	cairo_destroy (cr);
+	    cairo_destroy (cr);
 
-	_cairo_scaled_font_unregister_placeholder_and_lock_font_map (&user_scaled_font->base);
+	    _cairo_scaled_font_unregister_placeholder_and_lock_font_map (&user_scaled_font->base);
+	}
 
 	CAIRO_MUTEX_UNLOCK (user_scaled_font->base.mutex);
     }