On 2023-09-01 08:09, Bruno Haible wrote:
It applies to all 4 variants, as can be seen from applying it to a directory:
$ ./a.out /media/nas/bruno/dir1
lchown: Permission denied
fchownat: Permission denied
chown: Permission denied
fchown: Permission denied
Thanks, for coreutils it'd be helpful to now whether there's a similar
problem with chmod-related syscalls. If you compile and run the attached
program on a file that you don't own (e.g., './a.out /'), does it
incorrectly issue "Permission denied" instead of "Operation not
permitted" diagnostics?#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>
int
main (int argc, char **argv)
{
char const *file = argv[1] ? argv[1] : ".";
struct stat st;
if (lstat (file, &st) < 0)
return perror ("lstat"), 1;
mode_t mode = st.st_mode & 07777;
int status = 0;
if (lchmod (file, mode) < 0)
perror ("lchmod"), status = 1;
if (fchmodat (AT_FDCWD, file, mode, AT_SYMLINK_NOFOLLOW) < 0)
perror ("fchmodat"), status = 1;
if (!S_ISLNK (st.st_mode))
{
if (chmod (file, mode) < 0)
perror ("chmod"), status = 1;
int fd = openat (AT_FDCWD, file, O_RDONLY | O_NOFOLLOW);
if (fd < 0)
perror ("openat"), status = 1;
else if (fchmod (fd, mode) < 0)
perror ("fchmod"), status = 1;
}
return status;
}
