Symlink loop crashes (freezes) EmulationStation

[sleve_mcdichael]

I'm on RPi4 using emulationstation-dev 08d74d3.

With screensaver set to slideshow, custom media source and recursive set to true (es_settings.cfg, excerpt):

<bool name="SlideshowScreenSaverCustomMediaSource" value="true" />
<bool name="SlideshowScreenSaverRecurse" value="true" />

<string name="ScreenSaverBehavior" value="slideshow" />
<string name="SlideshowScreenSaverMediaDir" value="/home/pi/.emulationstation/slideshow/image" />

...if the media dir contains two (2) separate paths that link back to itself (these can be in the media dir or in subdirs, the simplest example being):

pi@retropie:~/.emulationstation/slideshow/image $ ls -l
total 0
lrwxrwxrwx 1 pi pi 42 May 29 11:32 link_a -> /home/pi/.emulationstation/slideshow/image
lrwxrwxrwx 1 pi pi 42 May 29 11:32 link_b -> /home/pi/.emulationstation/slideshow/image

...then when the screensaver is engaged, EmulationStation will lock up:

• screen freezes with the system carousel or gamelist menu displayed
• keyboard and gamepad become unresponsive
• (num lock lamp does not illuminate when key pressed)
• background music (scripted using mpg123) continues to play
• I can connect via SSH
• when I pkill emulationstatio via SSH, the .bashrc is ran and kills the music.
• when I run my custom "logmeout" script via SSH (kills the oldest local TTY1 instance of bash; then autostart will log me back in), the music (and, presumably, ES, though I can't see it behind the frozen screen) are restarted.
• This whole time, the ES system carousel remains frozen onscreen.
• I can reboot over SSH.
• Alternatively, I can regain full control locally with Alt + SysRq + E (term all processes except init.) This will clear the screen and I see a quick scroll of text before ES and background music restart.

It seems to only happen with this dual-infinite-loop scenario. If I remove one of the symlinks, leaving the other and creating a single infinite loop, or if I turn off "recursive", the freeze doesn't happen & the slideshow works normally.

[mitu]

It probably happens because of an infinite loop when EmulationStation tries to 'normalize' the path for those links. Is there a real use case for this scenario of re-cursive links ?

[sleve_mcdichael]

@mitu said in Symlink loop crashes (freezes) EmulationStation:

Is there a real use case for this scenario of re-cursive links ?

Not at all, I only noticed it when I had accidentally placed some links wrong while trying to do something else. I'm not savvy enough to know whether this is a legitimate bug to be addressed in ES, or if the loop itself is just a cursed object that should never be allowed to exist in the first place.

[mitu]

It's a bug, but something that shouldn't affect many users since it wouldn't occur without this symlink loop. It's probably affecting also the reading of the ROM/game folders, which would make EmulationStation freeze on start-up in this kind of scenario.