[gimp] plug-ins: Only enable darktable loading when it's installed

[Tobias Ellinghaus <et src gnome org>]

commit 24b9a24a66abcc9214b119d5546b6dc7ebc7cdac
Author: Tobias Ellinghaus <me houz org>
Date:   Thu Apr 21 11:40:45 2016 +0200

    plug-ins: Only enable darktable loading when it's installed
    
    For now we only check if darktable is in PATH, of the right version and
    supporting the featuers we need (i.e., Lua scripting). We still want to
    have a way to manually specify the path to the darktable installation in
    preferences I guess.

 plug-ins/file-darktable/file-darktable.c |   29 +++++++++++++++++++++++++++--
 1 files changed, 27 insertions(+), 2 deletions(-)
---
diff --git a/plug-ins/file-darktable/file-darktable.c b/plug-ins/file-darktable/file-darktable.c
index d778e35..d90a36c 100644
--- a/plug-ins/file-darktable/file-darktable.c
+++ b/plug-ins/file-darktable/file-darktable.c
@@ -111,8 +111,33 @@ query (void)
 
   gint i;
 
-  // TODO: check if darktable is installed
-  gboolean have_darktable = TRUE;
+  /* check if darktable is installed */
+  /* TODO: allow setting the location of the executable in preferences */
+  gboolean have_darktable = FALSE;
+  gchar *argv[] = { "darktable", "--version", NULL };
+  gchar *darktable_stdout = NULL;
+
+  if (g_spawn_sync (NULL,
+                    argv,
+                    NULL,
+                    G_SPAWN_STDERR_TO_DEV_NULL |
+                    G_SPAWN_SEARCH_PATH,
+                    NULL,
+                    NULL,
+                    &darktable_stdout,
+                    NULL,
+                    NULL,
+                    NULL))
+    {
+      int n, major, minor, patch;
+      char *lua_support;
+      n = sscanf (darktable_stdout, "this is darktable %d.%d.%d", &major, &minor, &patch);
+      lua_support = g_strstr_len (darktable_stdout, -1, "Lua support enabled");
+      if (n == 3 && ((major == 1 && minor >= 7) || major >= 2) && lua_support)
+        have_darktable = TRUE;
+    }
+
+  g_free (darktable_stdout);
 
   if (! have_darktable)
     return;