Fix list duplication error in define_image_type.

* image.c (define_image_type): Avoid adding duplicate types to
image_types.  Suggested by Jörg Walter.

Fixes: debbugs:12463

2 files changed, 12 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index f3b8b2108e1..31db282c6e3 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2012-09-21  Chong Yidong  <cyd@gnu.org>
+
+        * image.c (define_image_type): Avoid adding duplicate types to
+        image_types (Bug#12463).  Suggested by Jörg Walter.
+
 2012-09-21  YAMAMOTO Mitsuharu  <mituharu@math.s.chiba-u.ac.jp>
 
         * unexmacosx.c: Define LC_DATA_IN_CODE if not defined.
diff --git a/src/image.c b/src/image.c
index 8fc1c8637eb..8d690df8abb 100644
--- a/src/image.c
+++ b/src/image.c
@@ -590,9 +590,15 @@ define_image_type (struct image_type *type, int loaded)
     success = Qnil;
   else
     {
+      struct image_type *p;
+      Lisp_Object target_type = *(type->type);
+      for (p = image_types; p; p = p->next)
+        if (EQ (*(p->type), target_type))
+          return Qt;
+
       /* Make a copy of TYPE to avoid a bus error in a dumped Emacs.
          The initialized data segment is read-only.  */
-      struct image_type *p = xmalloc (sizeof *p);
+      p = xmalloc (sizeof *p);
       *p = *type;
       p->next = image_types;
       image_types = p;