Fix error handling when reading binary path from /proc

On Linux, Hurd, Cygwin, DragonFly BSD and Solaris/Illumos, Kakoune obtains
a path to its binary by reading the appropriate /proc symlink target.
readlink() can fail or it can fill the entire buffer, silently truncating
the path if the buffer is too small.

kak_assert() is compiled out in non-debug builds so we ignore a readlink()
failure, corrupt the stack by writing to buffer[-1] then return a string
from the uninitialised buffer.

If readlink() succeeds and the binary path is sizeof(buffer) long, we write
a \0 terminator beyond its end. If it is longer, we also truncate the path.

Throw a fatal error on startup in all these unlikely failure cases.

0 files changed, 0 insertions, 0 deletions