ffi: Treat enums as 32 bit signed values to fix PPC64

To call a function dynamically using ffi, the caller
first has to tell ffi the size of all the input arguments
of the function. On little endian architectures (like x86_64)
specifying a size that's too large will happen to work because
of how the bits are laid out in memory.  On big endian architectures,
however, specifying the wrong size can lead to reading the wrong
bits.

The function g_type_info_get_ffi_type maps input giargument types to
specific sizes. It was assuming enums were word (pointer) sized; in
fact they can be in theory any size (1,2,4,8 bytes), but in practice
in introspection (via GIArgument) as well as GValue we're limited to 4
byte enums.

This commit fixes PPC64 (big endian, 64 bit).

Signed-off-by: Colin Walters <walters@verbum.org>

https://bugzilla.gnome.org/show_bug.cgi?id=665150

1 files changed, 48 insertions, 12 deletions

diff --git a/girepository/girffi.c b/girepository/girffi.c
index aae1dcc3..1fa48396 100644
--- a/girepository/girffi.c
+++ b/girepository/girffi.c
@@ -30,16 +30,10 @@
 #include "girepository.h"
 #include "girepository-private.h"
 
-/**
- * gi_type_tag_get_ffi_type:
- * @tag: A #GITypeTag
- * @is_pointer: Whether or not this is a pointer type
- *
- * Returns: A #ffi_type corresponding to the platform default C ABI for @tag and @is_pointer.
- */
-ffi_type *
-gi_type_tag_get_ffi_type (GITypeTag   tag,
-			  gboolean    is_pointer)
+static ffi_type *
+gi_type_tag_get_ffi_type_internal (GITypeTag   tag,
+                                   gboolean    is_pointer,
+				   gboolean    is_enum)
 {
   switch (tag)
     {
@@ -77,12 +71,21 @@ gi_type_tag_get_ffi_type (GITypeTag   tag,
     case GI_TYPE_TAG_UTF8:
     case GI_TYPE_TAG_FILENAME:
     case GI_TYPE_TAG_ARRAY:
-    case GI_TYPE_TAG_INTERFACE:
     case GI_TYPE_TAG_GLIST:
     case GI_TYPE_TAG_GSLIST:
     case GI_TYPE_TAG_GHASH:
     case GI_TYPE_TAG_ERROR:
       return &ffi_type_pointer;
+    case GI_TYPE_TAG_INTERFACE:
+      {
+	/* We need to handle enums specially:
+	 * https://bugzilla.gnome.org/show_bug.cgi?id=665150
+	 */
+        if (!is_enum)
+          return &ffi_type_pointer;
+	else
+	  return &ffi_type_sint32;
+      }
     case GI_TYPE_TAG_VOID:
       if (is_pointer)
         return &ffi_type_pointer;
@@ -96,6 +99,20 @@ gi_type_tag_get_ffi_type (GITypeTag   tag,
 }
 
 /**
+ * gi_type_tag_get_ffi_type:
+ * @tag: A #GITypeTag
+ * @is_pointer: Whether or not this is a pointer type
+ *
+ * Returns: A #ffi_type corresponding to the platform default C ABI for @tag and @is_pointer.
+ */
+ffi_type *
+gi_type_tag_get_ffi_type (GITypeTag   tag,
+			  gboolean    is_pointer)
+{
+  return gi_type_tag_get_ffi_type_internal (tag, is_pointer, FALSE);
+}
+
+/**
  * g_type_info_get_ffi_type:
  * @info: A #GITypeInfo
  *
@@ -104,7 +121,26 @@ gi_type_tag_get_ffi_type (GITypeTag   tag,
 ffi_type *
 g_type_info_get_ffi_type (GITypeInfo *info)
 {
-  return gi_type_tag_get_ffi_type (g_type_info_get_tag (info), g_type_info_is_pointer (info));
+  gboolean is_enum;
+  GIBaseInfo *iinfo;
+
+  if (g_type_info_get_tag (info) == GI_TYPE_TAG_INTERFACE)
+    {
+      iinfo = g_type_info_get_interface (info);
+      switch (g_base_info_get_type (iinfo))
+	{
+	case GI_INFO_TYPE_ENUM:
+	case GI_INFO_TYPE_FLAGS:
+	  is_enum = TRUE;
+	  break;
+	default:
+	  is_enum = FALSE;
+	  break;
+	}
+      g_base_info_unref (iinfo);
+    }
+
+  return gi_type_tag_get_ffi_type_internal (g_type_info_get_tag (info), g_type_info_is_pointer (info), is_enum);
 }
 
 /**