Gnulib module: readlinkat
Portability problems fixed by Gnulib:
- This function is missing on some platforms:
glibc 2.3.6, Mac OS X 10.9, FreeBSD 6.0, NetBSD 5.0, OpenBSD 3.8, Minix 3.1.8, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 10, Cygwin 1.5.x, mingw, MSVC 14, Android 4.4.
But the replacement function is not safe to be used in libraries and is not multithread-safe.
- Some platforms mistakenly succeed on file names ending in /:
OS X 10.10.
- On some platforms, this function returns
int instead of
Portability problems mostly fixed by Gnulib:
- On some platforms, this function fails and sets
ERANGE rather than returning truncated contents:
The Gnulib replacement normally works as POSIX requires by returning
the truncated contents. However, if the full link contents are
unreasonably large (more than 4000 bytes) the replacement clears the
entire buffer and returns the buffer size; although this is not a
complete fix, it suffices for typical callers, which ignore the buffer
Portability problems not fixed by Gnulib:
- This function always fails on platforms that don’t support symlinks:
mingw, MSVC 14.
- When this function is called on a directory: In the case of NFS mounted
directories, Cygwin sets
EIO instead of
EINVAL. To avoid this problem, check for a directory before calling
- When this function is called on a file that is not a symbolic link:
IRIX may set
ENXIO instead of
may set errno to
EACCES instead of
- When this function fails because it is called on an existing
non-directory’s name concatenated to /,
- Symlink contents do not always have a trailing null byte, and there is
no indication if symlink contents were truncated if the return value
matches the length. Furthermore,
EINVAL if the
requested length is zero. Use the gnulib module
improved ability to read symlink contents.