core.fs: Not changing into drive directory, sometimes

[obiwac]

It seems opening a file may sometimes fail because the current process is not in the right drive directory. This is likely due to a race condition. Relevant code from core.fs:

if (chdir(dir) < 0) {
	LOG_WARN("Couldn't change into drive directory of '%s:%s' ('%s')", drive, path, dir)
	goto chdir_error;
}

... // between when we changed into dir and when realpath is called, we may have changed directories on another thread

char* abs_path = realpath(path, NULL); // abs_path is NULL, realpath fails with "No such file or directory"

Example log:

[VERBOSE core.fs -> ./core.fs/functions.h:130 -> fs_open] realpath("cfg:cursors/drag.svg") (from within "/home/obiwac/.aqua//conf"): No such file or directory
[WARN core.fs -> ./core.fs/functions.h:224 -> fs_mmap] Descriptor pointer is NULL
[INFO aquabsd.alps.svg -> ./aquabsd.alps.svg/functions.h:23 -> load_svg] Load SVG (0x0)
[VERBOSE aquabsd.alps.svg -> ./aquabsd.alps.svg/functions.h:42 -> load_svg] SVG hash is aa8f1bc7fdb8e660

This kind of problem wouldn't happen if POSIX had a proper way of checking path hierarchy ;)