Useless call of xdg-mime that is not working properly and slow down startup

[avi9526]

• Operating System (Linux/Mac/Windows/iOS/Android): Linux
• Delta Chat Version: deltachat-desktop 1.46.8-1
• Expected behavior: Fast startup
• Actual behavior: Slow startup with freezing desktop (Plasma) for 1..2 seconds
• Steps to reproduce the problem: Install Arch Linux, update it, install Plasma desktop, install DeltaChat, launch it and login, close, launch it as:

strace -c electron30 /usr/lib/deltachat-desktop/app.asar

close DeltaChat from tray icon after main window appears

strace report include:

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ------------------
 90.08    0.388022       29847        13         1 wait4
  2.64    0.011358           7      1577           ppoll
  …

became root and do:

cd /bin/
mv xdg-mime /root/
cp -r echo xdg-mime

repeat strace run from above, output is:

% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ------------------
 38.23    0.021738        1672        13         1 wait4
 16.67    0.009478           5      1591           ppoll
 …

Changes in launch time is visually noticeable - it opens almost instantly

• Screenshots:
  null
• Logs:
  strace logs include

04:19:54 wait4(33498, xdg-mime: application argument missing
Try 'xdg-mime --help' for more information.
[{WIFEXITED(s) && WEXITSTATUS(s) == 4}], 0, NULL) = 33498 <0.273471>

It seems xdg-mime is not doing anything useful and quits with an error.

Fast workaround is:
/usr/bin/bash -c 'function xdg-mime { echo ; }; export -f xdg-mime; /usr/bin/deltachat-desktop --minimized'

[Simon-Laux]

I think on linux it is only ever useful in appImage because in other cases uri scheme association is already done via desktop file. But even there we could live without it, also not setting file/uri association could be seen as feature for people using app images as portable apps. So I think just disabling the code on linux is fine.