No st_mode from stat?

The internal struct used by stat calls does not have a field for the mode of the file (read/write/execute bits), and stat, lstat, fstat, fstatat all return zeros for these bits.
The implementer of the API has no control over that.

https://github.com/CraneStation/wasi-libc/blob/12f5832b45c7450f8320db271334081247191d58/libc-bottom-half/headers/public/wasi/api.h#L955

Most of the time it's alright, but some code checks file permissions occasionally (esp. execute permission) and behaves unexpectedly when the permissions set in st_mode are in fact lower than the actual permissions for the file.

E.g. excerpt from kpathsea:

      if (stat (name, &s) == 0 && s.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)
                               /* Do not stop at directories. */
                               && !S_ISDIR(s.st_mode))
        self = name;
      else
        free (name);

Start with the WASI API definition linked at libc-bottom-half/headers/public/wasi/api.h around line 955, then trace how stat, lstat, fstat, and fstatat populate their internal result. Confirm the current zero mode bits and determine the API change needed so permission and file-type information is represented accurately; done means affected callers receive correct st_mode bits.