[gvfs] mtp: Allow toggling libmtp debug output

[Ondrej Holy <oholy src gnome org>]

commit eb976998228321df52454930606aaac3a9e6e52c
Author: Ondrej Holy <oholy redhat com>
Date:   Wed Nov 29 09:55:20 2017 +0100

    mtp: Allow toggling libmtp debug output
    
    libmtp provides LIBMTP_DEBUG environment variable already, but with
    binary flags. Let's introduce GVFS_MTP_DEBUG environment variable as
    has other backends to toggle libmtp debug output with string values.
    Possible values are "all", "data", "usb", or "ptp".

 daemon/gvfsbackendmtp.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)
---
diff --git a/daemon/gvfsbackendmtp.c b/daemon/gvfsbackendmtp.c
index a606ec2..556a197 100644
--- a/daemon/gvfsbackendmtp.c
+++ b/daemon/gvfsbackendmtp.c
@@ -378,6 +378,7 @@ g_vfs_backend_mtp_init (GVfsBackendMtp *backend)
 {
   g_debug ("(I) g_vfs_backend_mtp_init\n");
   GMountSpec *mount_spec;
+  const char *debug;
 
   g_mutex_init (&backend->mutex);
   g_vfs_backend_set_display_name (G_VFS_BACKEND (backend), "mtp");
@@ -394,6 +395,22 @@ g_vfs_backend_mtp_init (GVfsBackendMtp *backend)
                                            backend, 1, FALSE, NULL);
 #endif
 
+  debug = g_getenv ("GVFS_MTP_DEBUG");
+  if (debug != NULL) {
+    int level;
+
+    if (g_ascii_strcasecmp ("ptp", debug) == 0)
+      level = LIBMTP_DEBUG_PTP;
+    else if (g_ascii_strcasecmp ("usb", debug) == 0)
+      level = LIBMTP_DEBUG_USB | LIBMTP_DEBUG_PTP;
+    else if (g_ascii_strcasecmp ("data", debug) == 0)
+      level = LIBMTP_DEBUG_DATA | LIBMTP_DEBUG_USB | LIBMTP_DEBUG_PTP;
+    else /* "all" */
+      level = LIBMTP_DEBUG_ALL;
+
+    LIBMTP_Set_Debug (level);
+  }
+
   g_debug ("(I) g_vfs_backend_mtp_init done.\n");
 }