[gimp/muks/openjpeg] plug-ins: test for image types in a more robust way.

[Jehan Pagès <jehanp src gnome org>]

commit c51fc6e2680f55d9f31ddbf5e4e8fe0147c653d5
Author: Jehan <jehan girinstud io>
Date:   Sun Mar 4 16:25:39 2018 +0100

    plug-ins: test for image types in a more robust way.
    
    Rather than just assuming all non-gray images are RGB, do a bit more
    robust check and reject unknown formats. Indeed even though I see we
    took care of YUV, e-YCC and CMYK images above (and normally either
    converted them to RGB or already exited with an error), I can see that
    the OpenJPEG library could still return OPJ_CLRSPC_UNKNOWN or
    OPJ_CLRSPC_UNSPECIFIED. Let's be thorough and not assume we got a SRGB
    here.
    Also add the alpha-variant tests inside their parent image type
    respective test. This should not change anything by any logics, but
    let's not leave anything for chance to strike us.

 plug-ins/common/file-jp2-load.c |   23 +++++++++++++----------
 1 files changed, 13 insertions(+), 10 deletions(-)
---
diff --git a/plug-ins/common/file-jp2-load.c b/plug-ins/common/file-jp2-load.c
index 05cc38d..6bf172a 100644
--- a/plug-ins/common/file-jp2-load.c
+++ b/plug-ins/common/file-jp2-load.c
@@ -913,27 +913,30 @@ load_image (const gchar  *filename,
         }
     }
 
+  num_components = image->numcomps;
+
   if (image->color_space == OPJ_CLRSPC_GRAY)
     {
       base_type  = GIMP_GRAY;
       image_type = GIMP_GRAY_IMAGE;
+
+      if (num_components == 2)
+        image_type = GIMP_GRAYA_IMAGE;
     }
-  else
+  else if (image->color_space == OPJ_CLRSPC_SRGB)
     {
       base_type  = GIMP_RGB;
       image_type = GIMP_RGB_IMAGE;
 
+      if (num_components == 4)
+        image_type = GIMP_RGBA_IMAGE;
     }
-
-  num_components = image->numcomps;
-
-  if (num_components == 2)
-    {
-      image_type = GIMP_GRAYA_IMAGE;
-    }
-  else if (num_components == 4)
+  else
     {
-      image_type = GIMP_RGBA_IMAGE;
+      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                   _("Couldn't decode JP2 image in '%s'."),
+                   gimp_filename_to_utf8 (filename));
+      goto out;
     }
 
   /* FIXME */