cd fails for directory without read permission, displays Permission denied

[TheJonny]

cd or pushd into a directory without read permission (but with x permission) does not work in fish.

jonny@charon /> sh -c 'env HOME=$(mktemp -d) XDG_CONFIG_HOME= fish'
Welcome to fish, the friendly interactive shell
Type help for instructions on how to use fish
jonny@charon /> echo $version
3.7.1
jonny@charon /> ls -ld /srv
drwxr-x--x 1 root root 48 14. Jan 23:51 /srv/
jonny@charon /> cd /srv
cd: Permission denied: '/srv'
jonny@charon / [1]> bash
[jonny@charon /]$ cd /srv
[jonny@charon srv]$ pwd
/srv

This transscript was on archlinux. The same behaviour on debian stable with fish 3.6.0

it is possible to cd through the directory, if I have read permission in the target, e.g. cd /srv/www.

[TheJonny]

here an strace.

strace.log

the only EACCES occurs in line 2947, followed by printing the error message:

2947 openat(AT_FDCWD, "/srv", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)
2948 write(2, "cd: Permission denied: '/srv'\n", 30) = 30

[TheJonny]

builtins/cd.rs calls fds::wopen_dir, which calls fds::open_dir, which sets O_RDONLY. changing it to O_PATH works for me on Linux, but is neither portable nor correct for a function called open_dir

But it looks like open_dir is only used in cd and in the parser to initialize LibraryData::cwd_fd.
It also seems like cwd_fd is never read (grep does not find usages, and it still builds when changing it to pub(crate) in struct LibraryData.)

so can we just remove the functions, skip the filedescriptor and directly chdir? this would be portable to platforms without O_PATH (like it seems, macos) or O_SEARCH (all platforms, even if this is specified by posix)

[TheJonny]

If we want to keep cwd_fd, we can first chdir and then open(".", ...) (as done in the Parser's constructor).
As cwd_fd is an Option, this would be ok to fail.

The flag can be O_SEARCH, O_SEARCH or O_RDONLY, whatever is supported on the platform.