[gimp] plug-ins: Use Windows registry to find darktable

[Tobias Ellinghaus <et src gnome org>]

commit bc05ec52e862866f3f128e3e423f8b461e92cd20
Author: Tobias Ellinghaus <me houz org>
Date:   Wed Jul 5 00:50:54 2017 +0200

    plug-ins: Use Windows registry to find darktable
    
    There are now (up to) three steps to locate an installed darktable used
    to load raw files:
    
    1. The environment variable DARKTABLE_EXECUTABLE. It should point to the
    main darktable executable without any file extension. So on Windows
    leave the ".exe" away!
    2. If the environment variable isn't set there is a platform dependent
    part. On OSX it uses Kris' code to look for installed app bundles, on
    Windows it checks for the registry key written by darktable's installer.
    3. Last but not least we fall back to crossing our fingers and hoping
    that darktable is in PATH.

 plug-ins/file-darktable/file-darktable.c |  152 +++++++++++++++++++++---------
 1 files changed, 106 insertions(+), 46 deletions(-)
---
diff --git a/plug-ins/file-darktable/file-darktable.c b/plug-ins/file-darktable/file-darktable.c
index f32d38c..e16521b 100644
--- a/plug-ins/file-darktable/file-darktable.c
+++ b/plug-ins/file-darktable/file-darktable.c
@@ -37,6 +37,10 @@
 #include <CoreServices/CoreServices.h>
 #endif
 
+#ifdef GDK_WINDOWING_WIN32
+#include <Windows.h>
+#endif
+
 #define LOAD_THUMB_PROC "file-darktable-load-thumb"
 
 static gchar   *get_executable_path  (const gchar      *suffix,
@@ -73,53 +77,93 @@ static gchar *
 get_executable_path (const gchar *suffix,
                      gboolean    *search_path)
 {
-  /* TODO: allow setting the location of the executable in preferences
+  /*
+   * First check for the environment variable DARKTABLE_EXECUTABLE.
+   * Next do platform specific checks (bundle lookup on Mac, registry stuff
+   * on Windows).
+   * Last resort is hoping for darktable to be in PATH.
    */
 
-#ifdef GDK_WINDOWING_QUARTZ
-  OSStatus status;
-  CFURLRef bundle_url = NULL;
+  /*
+   * Look for env variable. That can be set directly or via an environ file.
+   * We assume that just appendign the suffix to that value will work.
+   * That means that on Windows there should be no ".exe"!
+   */
+  const gchar *dt_env = g_getenv ("DARKTABLE_EXECUTABLE");
+  if (dt_env)
+    return g_strconcat (dt_env, suffix, NULL);
 
-  /* For macOS, attempt searching for a darktable app bundle first. */
-  status = LSFindApplicationForInfo (kLSUnknownCreator,
-                                     CFSTR ("org.darktable"),
-                                     NULL, NULL, &bundle_url);
+#if defined (GDK_WINDOWING_QUARTZ)
+  {
+    OSStatus status;
+    CFURLRef bundle_url = NULL;
+
+    /* For macOS, attempt searching for a darktable app bundle first. */
+    status = LSFindApplicationForInfo (kLSUnknownCreator,
+                                      CFSTR ("org.darktable"),
+                                      NULL, NULL, &bundle_url);
+
+    if (status >= 0)
+      {
+        CFBundleRef bundle;
+        CFURLRef exec_url, absolute_url;
+        CFStringRef path;
+        gchar *ret;
+        CFIndex len;
+
+        bundle = CFBundleCreate (kCFAllocatorDefault, bundle_url);
+        CFRelease (bundle_url);
+
+        exec_url = CFBundleCopyExecutableURL (bundle);
+        absolute_url = CFURLCopyAbsoluteURL (exec_url);
+        path = CFURLCopyFileSystemPath (absolute_url, kCFURLPOSIXPathStyle);
+
+        /* This gets us the length in UTF16 characters, we multiply by 2
+        * to make sure we have a buffer big enough to fit the UTF8 string.
+        */
+        len = CFStringGetLength (path);
+        ret = g_malloc0 (len * 2 * sizeof (gchar));
+        if (!CFStringGetCString (path, ret, 2 * len * sizeof (gchar),
+                                kCFStringEncodingUTF8))
+          ret = NULL;
+
+        CFRelease (path);
+        CFRelease (absolute_url);
+        CFRelease (exec_url);
+        CFRelease (bundle);
+
+        if (ret)
+          return ret;
+      }
+    /* else, app bundle was not found, try path search as last resort. */
+  }
+#elif defined (GDK_WINDOWING_WIN32)
+  {
+    /* Look for darktable in the Windows registry. */
 
-  if (status >= 0)
-    {
-      CFBundleRef bundle;
-      CFURLRef exec_url, absolute_url;
-      CFStringRef path;
-      gchar *ret;
-      CFIndex len;
-
-      bundle = CFBundleCreate (kCFAllocatorDefault, bundle_url);
-      CFRelease (bundle_url);
-
-      exec_url = CFBundleCopyExecutableURL (bundle);
-      absolute_url = CFURLCopyAbsoluteURL (exec_url);
-      path = CFURLCopyFileSystemPath (absolute_url, kCFURLPOSIXPathStyle);
-
-      /* This gets us the length in UTF16 characters, we multiply by 2
-       * to make sure we have a buffer big enough to fit the UTF8 string.
-       */
-      len = CFStringGetLength (path);
-      ret = g_malloc0 (len * 2 * sizeof (gchar));
-      if (!CFStringGetCString (path, ret, 2 * len * sizeof (gchar),
-                               kCFStringEncodingUTF8))
-        ret = NULL;
-
-      CFRelease (path);
-      CFRelease (absolute_url);
-      CFRelease (exec_url);
-      CFRelease (bundle);
-
-      if (ret)
-        return ret;
-    }
-  /* else, app bundle was not found, try path search as last resort. */
+    char *registry_key;
+    const char *registry_key_base = "SOFTWARE\\Microsoft\\Windows\\"
+                                    "CurrentVersion\\App Paths\\darktable";
+    char path[MAX_PATH];
+    DWORD buffer_size = sizeof (path);
+    long status;
+
+    if (suffix)
+      registry_key = g_strconcat (registry_key_base, suffix, ".exe", NULL);
+    else
+      registry_key = g_strconcat (registry_key_base, ".exe", NULL);
+
+    status = RegGetValue (HKEY_LOCAL_MACHINE, registry_key, "", RRF_RT_ANY,
+                          NULL, (PVOID)&path, &buffer_size);
+
+    g_free (registry_key);
+
+    if (status == ERROR_SUCCESS)
+      return g_strdup (path);
+  }
 #endif
 
+  /* Finally, the last resort. */
   *search_path = TRUE;
   if (suffix)
     return g_strconcat ("darktable", suffix, NULL);
@@ -160,20 +204,23 @@ init (void)
   gchar    *exec_path        = get_executable_path (NULL, &search_path);
   gchar    *argv[]           = { exec_path, "--version", NULL };
   gchar    *darktable_stdout = NULL;
+  gchar    *darktable_stderr = NULL;
   gboolean  have_darktable   = FALSE;
+  GError   *error            = NULL;
   gint      i;
 
+  printf ("[%s] trying to call '%s'\n", __FILE__, exec_path);
+
   if (g_spawn_sync (NULL,
                     argv,
                     NULL,
-                    G_SPAWN_STDERR_TO_DEV_NULL |
                     (search_path ? G_SPAWN_SEARCH_PATH : 0),
                     NULL,
                     NULL,
                     &darktable_stdout,
+                    &darktable_stderr,
                     NULL,
-                    NULL,
-                    NULL))
+                    &error))
     {
       gint major, minor, patch;
 
@@ -190,10 +237,23 @@ init (void)
                 }
             }
         }
+    }
+  else
+    printf ("[%s] g_spawn_sync failed\n", __FILE__);
 
-      g_free (darktable_stdout);
+  if (error)
+    {
+      printf ("[%s] error: %s\n", __FILE__, error->message);
+      g_error_free (error);
     }
+  if (darktable_stdout && *darktable_stdout)
+    printf ("[%s] stdout:\n%s\n", __FILE__, darktable_stdout);
+  if (darktable_stderr && *darktable_stderr)
+    printf ("[%s] stderr:\n%s\n", __FILE__, darktable_stderr);
+  printf ("[%s] have_darktable: %d\n", __FILE__, have_darktable);
 
+  g_free (darktable_stdout);
+  g_free (darktable_stderr);
   g_free (exec_path);
 
   if (! have_darktable)