[gtk/cherry-pick-a76f5155] cssimagecrossfade: Don't abort() when failing to parse image

[Benjamin Otte <otte src gnome org>]

commit a5b1a86ab74374d1941769337e1bf50c6713c8f6
Author: Benjamin Otte <otte redhat com>
Date:   Fri Jul 16 17:48:25 2021 +0200

    cssimagecrossfade: Don't abort() when failing to parse image
    
    The code wasn't checking if parsing an image failed and just returning
    success.
    
    Testcase from bug is attached.
    
    Fixes #4101
    
    
    (cherry picked from commit a76f515569822d2261fc829e834404c8ed878608)

 gtk/gtkcssimagecrossfade.c                         | 16 +++++++++++-----
 testsuite/css/parser/cross-fade-crash-4101.css     |  3 +++
 testsuite/css/parser/cross-fade-crash-4101.errors  |  1 +
 testsuite/css/parser/cross-fade-crash-4101.ref.css |  0
 testsuite/css/parser/meson.build                   |  3 +++
 5 files changed, 18 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkcssimagecrossfade.c b/gtk/gtkcssimagecrossfade.c
index fadd11331d..6953606c8e 100644
--- a/gtk/gtkcssimagecrossfade.c
+++ b/gtk/gtkcssimagecrossfade.c
@@ -312,7 +312,13 @@ parse_image (GtkCssParser *parser,
   GtkCssImage **image = option_data;
 
   if (_gtk_css_image_can_parse (parser))
-    *image = _gtk_css_image_new_parse (parser);
+    {
+      *image = _gtk_css_image_new_parse (parser);
+      if (*image == NULL)
+        return FALSE;
+
+      return TRUE;
+    }
   else if (gtk_css_color_value_can_parse (parser))
     {
       GtkCssValue *color;
@@ -322,11 +328,11 @@ parse_image (GtkCssParser *parser,
         return FALSE;
 
       *image = _gtk_css_image_fallback_new_for_color (color);
-    }
-  else
-    return FALSE;
 
-  return TRUE;
+      return TRUE;
+    }
+  
+  return FALSE;
 }
 
 static guint
diff --git a/testsuite/css/parser/cross-fade-crash-4101.css b/testsuite/css/parser/cross-fade-crash-4101.css
new file mode 100644
index 0000000000..79180f9232
--- /dev/null
+++ b/testsuite/css/parser/cross-fade-crash-4101.css
@@ -0,0 +1,3 @@
+a {
+  background: cross-fade(8% -gtk-icontheme("system-run-symbolic"), image());
+}
diff --git a/testsuite/css/parser/cross-fade-crash-4101.errors 
b/testsuite/css/parser/cross-fade-crash-4101.errors
new file mode 100644
index 0000000000..25d4bec65f
--- /dev/null
+++ b/testsuite/css/parser/cross-fade-crash-4101.errors
@@ -0,0 +1 @@
+cross-fade-crash-4101.css:2:74-75: error: GTK_CSS_PARSER_ERROR_SYNTAX
diff --git a/testsuite/css/parser/cross-fade-crash-4101.ref.css 
b/testsuite/css/parser/cross-fade-crash-4101.ref.css
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/testsuite/css/parser/meson.build b/testsuite/css/parser/meson.build
index 2d476f018d..e161d48835 100644
--- a/testsuite/css/parser/meson.build
+++ b/testsuite/css/parser/meson.build
@@ -212,6 +212,9 @@ test_data = [
   'comment-detection.css',
   'comment-detection.ref.css',
   'cross-fade-basic.css',
+  'cross-fade-crash-4101.css',
+  'cross-fade-crash-4101.errors',
+  'cross-fade-crash-4101.ref.css',
   'css-21-malformed-declarations.css',
   'css-21-malformed-declarations.errors',
   'css-21-malformed-declarations.ref.css',