gnu: gdk-pixbuf: Honor GUIX_GDK_PIXBUF_MODULE_FILES search path.

* gnu/packages/patches/gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch:
New file.
* gnu/local.mk (dist_patch_DATA): Register patch.
* gnu/packages/gtk.scm (gdk-pixbuf)[source]: Add patch.
[native-search-paths]: Replace GDK_PIXBUF_MODULE_FILE with GUIX_GDK_PIXBUF_MODULE_FILES.

Change-Id: Ibcf6ebf33f5de2c889bc27a88d59a5f444b77906
Fixes: GDK_PIXBUF_MODULE_FILE conflicts on foreign distros
  <https://issues.guix.gnu.org/75523>
Reviewed-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Signed-off-by: Liliana Marie Prikler <liliana.prikler@gmail.com>

3 files changed, 40 insertions, 3 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index 326875133f..a7a3238669 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1408,6 +1408,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gd-fix-tests-on-i686.patch		\
   %D%/packages/patches/gd-brect-bounds.patch			\
   %D%/packages/patches/gdb-hurd64.patch				\
+  %D%/packages/patches/gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch	\
   %D%/packages/patches/gdm-default-session.patch		\
   %D%/packages/patches/gdm-remove-hardcoded-xwayland-path.patch	\
   %D%/packages/patches/gdm-wayland-session-wrapper-from-env.patch	\
diff --git a/gnu/packages/gtk.scm b/gnu/packages/gtk.scm
index 35baf938fe..15b43da636 100644
--- a/gnu/packages/gtk.scm
+++ b/gnu/packages/gtk.scm
@@ -726,7 +726,10 @@ highlighting and other features typical of a source code editor.")
                                   name "-" version ".tar.xz"))
               (sha256
                (base32
-                "1iz392vrlrnb92hrak697bgndsbkrcxhqxilxn6f99xr8ls5nl5r"))))
+                "1iz392vrlrnb92hrak697bgndsbkrcxhqxilxn6f99xr8ls5nl5r"))
+              (patches
+               (search-patches
+                "gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch"))))
     (build-system meson-build-system)
     (outputs '("out" "debug"))
     (arguments
@@ -780,9 +783,8 @@ highlighting and other features typical of a source code editor.")
      ;; This file is produced by the gdk-pixbuf-loaders-cache-file
      ;; profile hook.
      (list (search-path-specification
-            (variable "GDK_PIXBUF_MODULE_FILE")
+            (variable "GUIX_GDK_PIXBUF_MODULE_FILES")
             (files (list %gdk-pixbuf-loaders-cache-file))
-            (separator #f)              ;single valued
             (file-type 'regular))))
     (synopsis "Image loading library")
     (description "GdkPixbuf is a library that loads image data in various
diff --git a/gnu/packages/patches/gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch b/gnu/packages/patches/gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch
new file mode 100644
index 0000000000..4e97d3aa5b
--- /dev/null
+++ b/gnu/packages/patches/gdk-pixbuf-honor-GUIX_GDK_PIXBUF_MODULE_FILES.patch
@@ -0,0 +1,34 @@
+This patch makes gdk-pixbuf look for additional modules in a list of files
+specified by the environment variable "GUIX_GDK_PIXBUF_MODULE_FILES".
+
+A similiar patch for "GDK_PIXBUF_MODULE_FILES" had been sent to upstream:
+  https://gitlab.gnome.org/GNOME/gdk-pixbuf/-/merge_requests/180
+
+We use a "GUIX_" prefixed one to avoid breaking foreign programs:
+  https://issues.guix.gnu.org/63853
+  https://issues.guix.gnu.org/75523
+
+Upstream-status: N/A
+---
+diff --git a/gdk-pixbuf/gdk-pixbuf-io.c b/gdk-pixbuf/gdk-pixbuf-io.c
+index e1df590..913ce89 100644
+--- a/gdk-pixbuf/gdk-pixbuf-io.c
++++ b/gdk-pixbuf/gdk-pixbuf-io.c
+@@ -670,6 +670,17 @@ gdk_pixbuf_io_init (void)
+ 	gboolean ret;
+ 
+ 	gdk_pixbuf_io_init_builtin ();
++
++        /* Load modules from GUIX_GDK_PIXBUF_MODULE_FILES. */
++        gchar *module_files_env = g_getenv ("GUIX_GDK_PIXBUF_MODULE_FILES");
++        if (module_files_env) {
++            gchar **module_files = g_strsplit (module_files_env,
++                                               G_SEARCHPATH_SEPARATOR_S, 0);
++            for (int i = 0; module_files[i] != NULL; i++)
++                gdk_pixbuf_io_init_modules (module_files[i], NULL);
++            g_strfreev (module_files);
++        }
++
+ #ifdef USE_GMODULE
+ 	module_file = gdk_pixbuf_get_module_file ();
+ #endif