Reserve some third-party API messages to debug logging

FFmpegthumbnailer is known to be really verbose, and we don't have a
priori control on the messages that can be displayed by external
thumbnailers (it can be in particular FFmpegthumbnailer).

Fixes #10, related to #29.

5 files changed, 56 insertions, 4 deletions

diff --git a/docs/reference/tumbler/tumbler-sections.txt b/docs/reference/tumbler/tumbler-sections.txt
index 8a39e48..1d41b50 100644
--- a/docs/reference/tumbler/tumbler-sections.txt
+++ b/docs/reference/tumbler/tumbler-sections.txt
@@ -259,6 +259,7 @@ tumbler_thumbnailer_provider_get_type
 <FILE>tumbler-util</FILE>
 tumbler_util_is_debug_logging_enabled
 tumbler_util_dump_strv
+tumbler_util_toggle_stderr
 tumbler_util_get_supported_uri_schemes
 tumbler_util_get_settings
 tumbler_util_guess_is_sparse
diff --git a/plugins/desktop-thumbnailer/desktop-thumbnailer.c b/plugins/desktop-thumbnailer/desktop-thumbnailer.c
index 96e357e..05c4433 100644
--- a/plugins/desktop-thumbnailer/desktop-thumbnailer.c
+++ b/plugins/desktop-thumbnailer/desktop-thumbnailer.c
@@ -263,7 +263,7 @@ desktop_thumbnailer_load_thumbnail (DesktopThumbnailer *thumbnailer,
 {
   GFileIOStream *stream;
   GFile     *tmpfile;
-  gchar     *exec;
+  gchar     *exec, *std_err;
   gchar    **cmd_argv;
   const gchar *tmpfilepath;
   gboolean   res;
@@ -271,6 +271,7 @@ desktop_thumbnailer_load_thumbnail (DesktopThumbnailer *thumbnailer,
   gint       size;
   gchar     *working_directory = NULL;
   GdkPixbuf *source, *pixbuf = NULL;
+  gboolean verbose;
 
   g_object_get (G_OBJECT (thumbnailer), "exec", &exec, NULL);
 
@@ -295,13 +296,20 @@ desktop_thumbnailer_load_thumbnail (DesktopThumbnailer *thumbnailer,
         {
           working_directory = g_path_get_dirname (path);
 
+          verbose = tumbler_util_is_debug_logging_enabled (G_LOG_DOMAIN);
           res = g_spawn_sync (working_directory,
                               cmd_argv, NULL,
-                              G_SPAWN_SEARCH_PATH,
-                              NULL, NULL,
+                              verbose ? G_SPAWN_SEARCH_PATH
+                                      : G_SPAWN_SEARCH_PATH | G_SPAWN_STDERR_TO_DEV_NULL,
                               NULL, NULL,
+                              NULL, verbose ? &std_err : NULL,
                               NULL,
                               error);
+          if (verbose)
+            {
+              g_printerr ("%s", std_err);
+              g_free (std_err);
+            }
 
           if (G_LIKELY (res))
             {
diff --git a/plugins/ffmpeg-thumbnailer/ffmpeg-thumbnailer.c b/plugins/ffmpeg-thumbnailer/ffmpeg-thumbnailer.c
index 3b3494e..c6bf337 100644
--- a/plugins/ffmpeg-thumbnailer/ffmpeg-thumbnailer.c
+++ b/plugins/ffmpeg-thumbnailer/ffmpeg-thumbnailer.c
@@ -143,6 +143,7 @@ ffmpeg_thumbnailer_create (TumblerAbstractThumbnailer *thumbnailer,
   gint                    dest_height;
   gchar                  *path;
   const gchar            *uri;
+  gint                    res;
 
   g_return_if_fail (IS_FFMPEG_THUMBNAILER (thumbnailer));
   g_return_if_fail (cancellable == NULL || G_IS_CANCELLABLE (cancellable));
@@ -206,7 +207,10 @@ ffmpeg_thumbnailer_create (TumblerAbstractThumbnailer *thumbnailer,
     }
 
   /* try to generate a thumbnail */
-  if (video_thumbnailer_generate_thumbnail_to_buffer (ffmpeg_thumbnailer->video, path, v_data) != 0)
+  tumbler_util_toggle_stderr (G_LOG_DOMAIN);
+  res = video_thumbnailer_generate_thumbnail_to_buffer (ffmpeg_thumbnailer->video, path, v_data);
+  tumbler_util_toggle_stderr (G_LOG_DOMAIN);
+  if (res != 0)
     {
       /* there was an error, emit error signal */
       g_set_error (&error, TUMBLER_ERROR, TUMBLER_ERROR_INVALID_FORMAT,
diff --git a/tumbler/tumbler-util.c b/tumbler/tumbler-util.c
index 04c434d..cfc1172 100644
--- a/tumbler/tumbler-util.c
+++ b/tumbler/tumbler-util.c
@@ -85,6 +85,43 @@ tumbler_util_dump_strv (const gchar *log_domain,
 
 
 
+/*
+ * This is intended to be used around too verbose third-party APIs we can't silence by
+ * another means:
+ *   tumbler_util_toggle_stderr (G_LOG_DOMAIN);
+ *   … = too_verbose_api (…);
+ *   tumbler_util_toggle_stderr (G_LOG_DOMAIN);
+ * When debug logging is enabled, it does nothing.
+ */
+void
+tumbler_util_toggle_stderr (const gchar *log_domain)
+{
+  static gint stderr_save = -2;
+
+  /* do nothing in case of previous error or if debug logging is enabled */
+  if (stderr_save == -1 || tumbler_util_is_debug_logging_enabled (log_domain))
+    return;
+
+  /* redirect stderr to /dev/null */
+  if (stderr_save == -2)
+    {
+      fflush (stderr);
+      stderr_save = dup (STDERR_FILENO);
+      if (stderr_save != -1 && freopen ("/dev/null", "a", stderr) == NULL)
+        stderr_save = -1;
+    }
+  /* restore stderr to stderr_save */
+  else
+    {
+      fflush (stderr);
+      stderr_save = dup2 (stderr_save, STDERR_FILENO);
+      if (stderr_save != -1)
+        stderr_save = -2;
+    }
+}
+
+
+
 gchar **
 tumbler_util_get_supported_uri_schemes (void)
 {
diff --git a/tumbler/tumbler-util.h b/tumbler/tumbler-util.h
index 20a0cc3..24c7d29 100644
--- a/tumbler/tumbler-util.h
+++ b/tumbler/tumbler-util.h
@@ -34,6 +34,8 @@ void tumbler_util_dump_strv (const gchar *log_domain,
                              const gchar *label,
                              const gchar *const *strv);
 
+void tumbler_util_toggle_stderr (const gchar *log_domain);
+
 gchar **tumbler_util_get_supported_uri_schemes (void) G_GNUC_MALLOC;
 
 GKeyFile *tumbler_util_get_settings (void) G_GNUC_MALLOC;