From fc2925def0cb11c601ee7e0dc334eaf66c2e8afd Mon Sep 17 00:00:00 2001
From: Jehan <jehan@girinstud.io>
Date: Mon, 13 Feb 2023 21:23:47 +0100
Subject: [PATCH] app, libgimp, pdb: gimp_image_set_file() only works for XCF
 files.

This is not made to set the imported or exported file, but only the XCF file.
See previous commit to see what happens when this API is used to set non-XCF
file extensions (saving fails unless one edits the filename).
---
 app/pdb/image-cmds.c    | 35 ++++++++++++++++++++++++++++++++---
 libgimp/gimpimage_pdb.c |  5 ++++-
 pdb/groups/image.pdb    | 36 ++++++++++++++++++++++++++++++++++--
 3 files changed, 70 insertions(+), 6 deletions(-)

diff --git a/app/pdb/image-cmds.c b/app/pdb/image-cmds.c
index 5086deaff8..42c9b6c591 100644
--- a/app/pdb/image-cmds.c
+++ b/app/pdb/image-cmds.c
@@ -2263,7 +2263,35 @@ image_set_file_invoker (GimpProcedure         *procedure,
 
   if (success)
     {
-      gimp_image_set_file (image, file);
+      gchar *uri;
+      gchar *folded_uri;
+      gchar *folded_ext;
+
+      uri        = g_file_get_uri (file);
+      folded_uri = g_utf8_casefold (uri, -1);
+      folded_ext = g_utf8_casefold (".xcf", -1);
+
+      if (! g_str_has_suffix (folded_uri, folded_ext))
+        {
+          gchar *dot = g_strrstr (uri, ".");
+
+          if (dot != NULL && strstr (dot + 1, G_DIR_SEPARATOR_S) == NULL)
+            g_printerr ("%s: failure to set file '%s' with extension '%s'. "
+                        "The extension must be '.xcf'.\n",
+                        "gimp_image_set_file", uri, dot + 1);
+          else
+            g_printerr ("%s: failure to set file '%s' without extension. "
+                        "The extension must be '.xcf'.\n",
+                        "gimp_image_set_file", uri);
+
+          success = FALSE;
+        }
+      if (success)
+        gimp_image_set_file (image, file);
+
+      g_free (uri);
+      g_free (folded_uri);
+      g_free (folded_ext);
     }
 
   return gimp_procedure_get_return_values (procedure, success,
@@ -4968,8 +4996,9 @@ register_image_procs (GimpPDB *pdb)
   gimp_object_set_static_name (GIMP_OBJECT (procedure),
                                "gimp-image-set-file");
   gimp_procedure_set_static_help (procedure,
-                                  "Sets the specified image's file.",
-                                  "This procedure sets the specified image's file.",
+                                  "Sets the specified XCF image's file.",
+                                  "This procedure sets the specified image's file.\n"
+                                  "This is to set the XCF file associated with your image. In particular, do not use this function to set the imported file in file import plug-ins. This is done by the core process.",
                                   NULL);
   gimp_procedure_set_static_attribution (procedure,
                                          "Spencer Kimball & Peter Mattis",
diff --git a/libgimp/gimpimage_pdb.c b/libgimp/gimpimage_pdb.c
index 4a3d9d19ec..9c59564c52 100644
--- a/libgimp/gimpimage_pdb.c
+++ b/libgimp/gimpimage_pdb.c
@@ -2615,9 +2615,12 @@ gimp_image_get_file (GimpImage *image)
  * @image: The image.
  * @file: The new image file.
  *
- * Sets the specified image's file.
+ * Sets the specified XCF image's file.
  *
  * This procedure sets the specified image's file.
+ * This is to set the XCF file associated with your image. In
+ * particular, do not use this function to set the imported file in
+ * file import plug-ins. This is done by the core process.
  *
  * Returns: TRUE on success.
  **/
diff --git a/pdb/groups/image.pdb b/pdb/groups/image.pdb
index 26abaa43f6..8d228b4ab3 100644
--- a/pdb/groups/image.pdb
+++ b/pdb/groups/image.pdb
@@ -2322,10 +2322,14 @@ CODE
 }
 
 sub image_set_file {
-    $blurb = "Sets the specified image's file.";
+    $blurb = "Sets the specified XCF image's file.";
 
     $help = <<'HELP';
 This procedure sets the specified image's file.
+
+This is to set the XCF file associated with your image. In particular, do not
+use this function to set the imported file in file import plug-ins. This is done
+by the core process.
 HELP
 
     &std_pdb_misc;
@@ -2340,7 +2344,35 @@ HELP
     %invoke = (
         code => <<'CODE'
 {
-  gimp_image_set_file (image, file);
+  gchar *uri;
+  gchar *folded_uri;
+  gchar *folded_ext;
+
+  uri        = g_file_get_uri (file);
+  folded_uri = g_utf8_casefold (uri, -1);
+  folded_ext = g_utf8_casefold (".xcf", -1);
+
+  if (! g_str_has_suffix (folded_uri, folded_ext))
+    {
+      gchar *dot = g_strrstr (uri, ".");
+
+      if (dot != NULL && strstr (dot + 1, G_DIR_SEPARATOR_S) == NULL)
+        g_printerr ("%s: failure to set file '%s' with extension '%s'. "
+                    "The extension must be '.xcf'.\n",
+                    "gimp_image_set_file", uri, dot + 1);
+      else
+        g_printerr ("%s: failure to set file '%s' without extension. "
+                    "The extension must be '.xcf'.\n",
+                    "gimp_image_set_file", uri);
+
+      success = FALSE;
+    }
+  if (success)
+    gimp_image_set_file (image, file);
+
+  g_free (uri);
+  g_free (folded_uri);
+  g_free (folded_ext);
 }
 CODE
     );