Following Linux, allow the pathname argument to be empty if the
AT_EMPTY_PATH is specified. In this case the dirfd argument can refer
to any type of file, not just a directory, and the call operates on
that file. In particular, dirfd can refer to a symlink that was
opened with O_PATH and O_NOFOLLOW.
---
winsup/cygwin/syscalls.cc | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 3d87fd685..e7298fd43 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -4823,14 +4823,27 @@ fstatat (int dirfd, const char *__restrict pathname,
struct stat *__restrict st,
tmp_pathbuf tp;
__try
{
- if (flags & ~AT_SYMLINK_NOFOLLOW)
+ if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
{
set_errno (EINVAL);
__leave;
}
char *path = tp.c_get ();
- if (gen_full_path_at (path, dirfd, pathname))
- __leave;
+ int res = gen_full_path_at (path, dirfd, pathname);
+ if (res)
+ {
+ if (!(errno == ENOENT && (flags & AT_EMPTY_PATH)))
+ __leave;
+ /* pathname is an empty string. Operate on dirfd. */
+ if (dirfd == AT_FDCWD)
+ {
+ cwdstuff::cwd_lock.acquire ();
+ strcpy (path, cygheap->cwd.get_posix ());
+ cwdstuff::cwd_lock.release ();
+ }
+ else
+ return fstat (dirfd, st);
+ }
path_conv pc (path, ((flags & AT_SYMLINK_NOFOLLOW)
? PC_SYM_NOFOLLOW : PC_SYM_FOLLOW)
| PC_POSIX | PC_KEEP_HANDLE, stat_suffixes);
--
2.21.0
