Hi, everyone. When the Arch Linux-based package 'qt5-styleplugins' is used and the environment variable QT_QPA_PLATFORMTHEME= is set on "gtk2", or "qt5ct" with its interface set on Appearance > Style: gtk2, the Dolphin file-manager will not create new thumbnails, although thumbnails that were previously created (such as with Thunar, or Dolphin not using "gtk2") will be shown. This problem doesn't occur with the other styles of 'qtstyleplugins'. I traced this problem back to GLib. The problem was introduced with the following package, and remains in later versions: glib2-2.62.1-1-x86_64.pkg.tar.xz The following version and previous versions work properly: glib2-2.60.6-1-x86_64.pkg.tar.xz However, using this previous version breaks some (but not all) GTK+ 3 programs. How I tracked the problem to GLib was that I replaced (using 'downgrade') with previous known working versions any package that I thought might be connected to Dolphin's thumbnailing or its theming (including Dolphin itself), yet nothing had any effect. Then I thought to start Dolphin in a 'uxterm' in order to see the output. That's when I saw that GLib was outputting errors that were causing '/usr/lib/qt/plugins/kf5/kio/thumbnail.so' to crash. Upon seeing that, when I replaced the GLib package as related above, thumbnailing worked. What I take the GLib error messages (involving 'platform_get_argv0' in the output) to mean is that GLib doesn't recognize the platform "gtk2", and that then causes 'thumbnail.so' to crash. Thus, in order for 'thumbnail.so' to work, apparently it requires GLib not to exit with error messages like that upon not recognizing the platform. I here provide links to three PNGs of 'uxterm' output when Dolphin is started in it. 'Dolphin-thumbnailing-working-Windows-style-via-qt5ct.png' is when the 'qt5ct' program is set on the "Windows" style, and thumbnailing works. 'Dolphin-thumbnailing-failing-gtk2-style-via-qt5ct.png' is when the 'qt5ct' program is set on the "gtk2" style, and thumbnailing doesn't work. 'Dolphin-thumbnailing-failing-gtk2-style-direct.png' is when QT_QPA_PLATFORMTHEME= is directly set on "gtk2", and thumbnailing doesn't work. * Dolphin-thumbnailing-working-Windows-style-via-qt5ct.png , https://ibb.co/TWBqj4f , https://archive.is/VTMQO . * Dolphin-thumbnailing-failing-gtk2-style-via-qt5ct.png , https://ibb.co/VYd1145 , https://archive.is/5As1p . * Dolphin-thumbnailing-failing-gtk2-style-direct.png , https://ibb.co/7ypN042 , https://archive.is/lPQkw . Whether the style is set via the 'qt5ct' program or is directly set with QT_QPA_PLATFORMTHEME= doesn't matter to this problem. If "gtk2" is the style, thumbnailing fails either way, yet every other style works. This problem is quite unfortunate because I use the "gtk2" style for Qt 5 programs, and Dolphin is my primary file-manager. Further, this breaks my Computing Machine desktop-environment theme ( https://www.pling.com/p/1315191/ ). Can this problem please be fixed? Thank you for your time on this matter!
Please try it with a style which works fine and post the output of "hexdump -C /proc/$(pgrep -n thumbnail.so)/cmdline". I cannot reproduce the issue here with glib2 2.62.1 here on Tumbleweed, cmdline is always terminated with a nullbyte.
(In reply to Fabian Vogt from comment #1) > Please try it with a style which works fine and post the output of "hexdump > -C /proc/$(pgrep -n thumbnail.so)/cmdline". > > I cannot reproduce the issue here with glib2 2.62.1 here on Tumbleweed, > cmdline is always terminated with a nullbyte. Hi, Fabian Vogt. My apologies for not responding sooner. Here is the output of your command: $ hexdump -C /proc/$(pgrep -n thumbnail.so)/cmdline 00000000 42 4f 4f 54 5f 49 4d 41 47 45 3d 2f 62 6f 6f 74 |BOOT_IMAGE=/boot| 00000010 2f 76 6d 6c 69 6e 75 7a 2d 34 2e 31 34 2d 78 38 |/vmlinuz-4.14-x8| 00000020 36 5f 36 34 20 72 6f 6f 74 3d 55 55 49 44 3d 32 |6_64 root=UUID=2| 00000030 61 63 38 31 65 36 34 2d 66 30 61 39 2d 34 66 64 |ac81e64-f0a9-4fd| 00000040 64 2d 61 38 65 63 2d 63 66 34 36 37 36 33 33 31 |d-a8ec-cf4676331| 00000050 66 62 61 20 72 77 20 71 75 69 65 74 20 63 72 79 |fba rw quiet cry| 00000060 70 74 64 65 76 69 63 65 3d 55 55 49 44 3d 39 62 |ptdevice=UUID=9b| 00000070 38 66 35 33 33 30 2d 62 39 61 31 2d 34 34 62 37 |8f5330-b9a1-44b7| 00000080 2d 62 63 64 31 2d 36 35 37 36 38 37 30 30 34 39 |-bcd1-6576870049| 00000090 32 66 3a 6c 75 6b 73 2d 39 62 38 66 35 33 33 30 |2f:luks-9b8f5330| 000000a0 2d 62 39 61 31 2d 34 34 62 37 2d 62 63 64 31 2d |-b9a1-44b7-bcd1-| 000000b0 36 35 37 36 38 37 30 30 34 39 32 66 20 72 6f 6f |65768700492f roo| 000000c0 74 3d 2f 64 65 76 2f 6d 61 70 70 65 72 2f 6c 75 |t=/dev/mapper/lu| 000000d0 6b 73 2d 39 62 38 66 35 33 33 30 2d 62 39 61 31 |ks-9b8f5330-b9a1| 000000e0 2d 34 34 62 37 2d 62 63 64 31 2d 36 35 37 36 38 |-44b7-bcd1-65768| 000000f0 37 30 30 34 39 32 66 20 72 65 73 75 6d 65 3d 2f |700492f resume=/| 00000100 64 65 76 2f 6d 61 70 70 65 72 2f 6c 75 6b 73 2d |dev/mapper/luks-| 00000110 39 62 38 66 35 33 33 30 2d 62 39 61 31 2d 34 34 |9b8f5330-b9a1-44| 00000120 62 37 2d 62 63 64 31 2d 36 35 37 36 38 37 30 30 |b7-bcd1-65768700| 00000130 34 39 32 66 0a |492f.| 00000135 Also, the following threads are relevant to this problem: * Jamie Michelle, "Recent Versions of GLib Break Dolphin File-Manager's Thumbnailing when Using 'gtk2' Style", Oct. 29, 2019, https://gitlab.gnome.org/GNOME/glib/issues/1923 . Simon McVittie, "goption: Relax assertion to avoid being broken by kdeinit5", Oct. 31, 2019, https://gitlab.gnome.org/GNOME/glib/commit/15a5c2dcf8edacbf7e105c97bd1f34295b1f2a98 .
(In reply to Jamie Michelle from comment #2) > (In reply to Fabian Vogt from comment #1) > > Please try it with a style which works fine and post the output of "hexdump > > -C /proc/$(pgrep -n thumbnail.so)/cmdline". > > > > I cannot reproduce the issue here with glib2 2.62.1 here on Tumbleweed, > > cmdline is always terminated with a nullbyte. > > Hi, Fabian Vogt. My apologies for not responding sooner. Here is the output > of your command: > > $ hexdump -C /proc/$(pgrep -n thumbnail.so)/cmdline > 00000000 42 4f 4f 54 5f 49 4d 41 47 45 3d 2f 62 6f 6f 74 > |BOOT_IMAGE=/boot| Unfortunately thumbnail.so was not running at that point so you dumped /proc/cmdline instead... Can you try again? You should get different output. > Also, the following threads are relevant to this problem: > > * Jamie Michelle, "Recent Versions of GLib Break Dolphin File-Manager's > Thumbnailing when Using 'gtk2' Style", Oct. 29, 2019, > https://gitlab.gnome.org/GNOME/glib/issues/1923 . Apparently a GLib dev had a look at our code as well: > More specifically, it looks like kdeinit5 overwrites the memory occupied by the elements of argv, which in turn changes /proc/self/cmdline (although I can't see how it would end up non-terminated). So he can't spot the bug either... > Simon McVittie, "goption: Relax assertion to avoid being broken by > kdeinit5", Oct. 31, 2019, > https://gitlab.gnome.org/GNOME/glib/commit/ > 15a5c2dcf8edacbf7e105c97bd1f34295b1f2a98 . Ok, so it's fixed upstream in glib, that's good news.
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This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging Thank you for helping us make KDE software even better for everyone!