tree 9e7c2243752bd484a30868dacb22c5cebb892f4c
parent 817fd33836e73812df2f1907612b57750fcb9491
author Helge Deller <deller@gmx.de> 1670240305 +0100
committer Laurent Vivier <laurent@vivier.eu> 1678477290 +0100

linux-user: Fix access to /proc/self/exe

When accsssing /proc/self/exe from a userspace program, linux-user tries
to resolve the name via realpath(), which may fail if the process
changed the working directory in the meantime.

An example:
- a userspace program ist started with ./testprogram
- the program runs chdir("/tmp")
- then the program calls readlink("/proc/self/exe")
- linux-user tries to run realpath("./testprogram") which fails
  because ./testprogram isn't in /tmp
- readlink() will return -ENOENT back to the program

Avoid this issue by resolving the full path name of the started process
at startup of linux-user and store it in real_exec_path[]. This then
simplifies the emulation of readlink() and readlinkat() as well, because
they can simply copy the path string to userspace.

I noticed this bug because the testsuite of the debian package "pandoc"
failed on linux-user while it succeeded on real hardware.  The full log
is here:
https://buildd.debian.org/status/fetch.php?pkg=pandoc&arch=hppa&ver=2.17.1.1-1.1%2Bb1&stamp=1670153210&raw=0

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20221205113825.20615-1-deller@gmx.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>