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Add a wrapper that sets LD_PRELOAD=.../shmoverride.so. Since suid binaries are not involved with Xwayland, it can be a simple shell script. Place the wrapper as Xwayland in /usr/libexec/qubes/wrappers. Processes that are supposed to use it need to have /usr/libexec/qubes/wrappers prepended to PATH. QubesOS/qubes-issues#8515
If shmoverride init fails to take the lock, it likely means it is used by currently running process - do _not_ remove the file in such a case. This may happen if LD_PRELOAD leaks to child processes (which seems to happend on Xwayland when shmoverride is linked with -z initfirst). But also, if X server is started several times for some reason (for example user calls it manually), it will abort, but not early enough to skip shmoverride init. QubesOS/qubes-issues#8515
Look for display number as the first thing after stuff necessary to work in passive mode. This will be relevant for filtering which process gets shmoverride enabled. QubesOS/qubes-issues#8515
This allows setting LD_PRELOAD earlier for some parent process, and have it actually applied to selected child process. This is especially helpful for Xwayland that is started by the wayland compositor and rarely has an option to change binary path (contrary to display managers starting Xorg). This feature allows setting LD_PRELOAD on the compositor itself, and have it affected only Xwayland process. Note, this feature does not work if shmoverride is linked with -z initfirst, as getenv()/unsetenv() are not working in that case. QubesOS/qubes-issues#8515
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This does not work with kwin. |
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Support adding LD_PRELOAD to a parent process too (for example wayland compositor that only later will start Xwayland). See commit messages for details.
Note, this approach does not work together with linking with -z initfirst.
Built on top of #151