fix failure of fchmodat to report EOPNOTSUPP in the race path

in the case where a non-symlink file was replaced by a symlink during
the fchmodat operation with AT_SYMLINK_NOFOLLOW, mode change on the
new symlink target was successfully suppressed, but the error was not
reported. instead, fchmodat simply returned 0.

diff --git a/src/stat/fchmodat.c b/src/stat/fchmodat.c
index a894cb6..d94667a 100644 (file)
--- a/src/stat/fchmodat.c
+++ b/src/stat/fchmodat.c
@@ -29,8 +29,10 @@ int fchmodat(int fd, const char *path, mode_t mode, int flag)
 
        __procfdname(proc, fd2);
        ret = __syscall(SYS_fstatat, AT_FDCWD, proc, &st, 0);
-       if (!ret && !S_ISLNK(st.st_mode))
-               ret = __syscall(SYS_fchmodat, AT_FDCWD, proc, mode);
+       if (!ret) {
+               if (S_ISLNK(st.st_mode)) ret = -EOPNOTSUPP;
+               else ret = __syscall(SYS_fchmodat, AT_FDCWD, proc, mode);
+       }
 
        __syscall(SYS_close, fd2);
        return __syscall_ret(ret);