Bug#781480: MTP: stream API not usable

[Yves-Alexis Perez]

Package: gvfs-backends
Version: 1.23.92-1
Severity: normal

Hi,

trying to investigate why my media player (parole) could play videos on
a smb share and not on my android phone (MTP) share, I might have
experienced a bug in the gvfs MTP backend.

I've first tried to debug this with gstreamer people, since the media
player uses gstreamer. Basically we noticed that:

- parole doesn't play
- gst-play-1.0 doesn't play
- gst-launch-1.0 giosrc location=mtp://... ! filesink location=foo
  doesn't copy the file
- gvfs-copy does copy the file
- gvfs-cat doesn't output the file

gvfs-copy apparently uses g_file_copy() while gvfs-cat (and the gst
pipeline) use g_input_stream_read().

I know MTP is a bit special, but Android supports some extensions to
make files seekable, and it seems that g_seekable_can_seek() returns
TRUE.

So there might be an issue in the gvfs mtp backend. I tried both on sid
and experimental version.

If there's any information I can provide, please ask.

Regards,
-- 
Yves-Alexis

-- System Information:
Debian Release: 8.0
  APT prefers unstable
  APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable'), (450, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.utf8, LC_CTYPE=fr_FR.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages gvfs-backends depends on:
ii  dconf-gsettings-backend [gsettings-backend]  0.22.0-1
ii  gvfs                                         1.23.92-1
ii  gvfs-common                                  1.23.92-1
ii  gvfs-daemons                                 1.23.92-1
ii  gvfs-libs                                    1.23.92-1
ii  libarchive13                                 3.1.2-11
ii  libatk1.0-0                                  2.14.0-1
ii  libavahi-client3                             0.6.31-4+b2
ii  libavahi-common3                             0.6.31-4+b2
ii  libavahi-glib1                               0.6.31-4+b2
ii  libbluetooth3                                5.23-2+b1
ii  libbluray1                                   1:0.6.2-1
ii  libc6                                        2.19-17
ii  libcairo-gobject2                            1.14.0-2.1
ii  libcairo2                                    1.14.0-2.1
ii  libcdio-cdda1                                0.83-4.2
ii  libcdio-paranoia1                            0.83-4.2
ii  libcdio13                                    0.83-4.2
ii  libdbus-1-3                                  1.8.16-1
ii  libdbus-glib-1-2                             0.102-1
ii  libexif12                                    0.6.21-2
ii  libexpat1                                    2.1.0-6+b3
ii  libgcrypt20                                  1.6.3-2
ii  libgdk-pixbuf2.0-0                           2.31.1-2+b1
ii  libglib2.0-0                                 2.43.92-1
ii  libgoa-1.0-0b                                3.14.2-1
ii  libgphoto2-6                                 2.5.4-1.1+b2
ii  libgphoto2-port10                            2.5.4-1.1+b2
ii  libgtk-3-0                                   3.14.5-1
ii  libgudev-1.0-0                               215-13
ii  libimobiledevice4                            1.1.6+dfsg-3.1
ii  libmtp9                                      1.1.8-1+b1
ii  libpango-1.0-0                               1.36.8-3
ii  libpangocairo-1.0-0                          1.36.8-3
ii  libplist2                                    1.11-3
ii  libsecret-1-0                                0.18-1+b1
ii  libsmbclient                                 2:4.1.17+dfsg-2
ii  libsoup2.4-1                                 2.48.0-1
ii  libusb-1.0-0                                 2:1.0.19-1
ii  libxml2                                      2.9.2+dfsg1-3
ii  psmisc                                       22.21-2

Versions of packages gvfs-backends recommends:
ii  gnome-keyring  3.14.0-1+b1

Versions of packages gvfs-backends suggests:
ii  obex-data-server  0.4.5-1+b4
ii  samba-common      2:4.1.17+dfsg-2

-- no debconf information