Paul Eggert wrote:
> > 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?
and I replied:
> In this case, the diagnostic is "Operation not permitted" (from EPERM):
>
> $ ./a.out /
> lchown: Operation not permitted
> fchownat: Operation not permitted
> chown: Operation not permitted
> fchown: Operation not permitted
Oops, I mistakenly compiled and ran the wrong test program. Here are the
results for the test program you meant:
$ ./a.out /
lchmod: Operation not permitted
fchmodat: Operation not permitted
chmod: Operation not permitted
fchmod: Operation not permitted
$ strace ./a.out /
...
chmod("/proc/self/fd/3", 0755) = -1 EPERM (Operation not permitted)
close(3) = 0
dup(2) = 3
fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
getrandom("\xd5\xae\x46\x10\x0d\x5a\x98\x9a", 8, GRND_NONBLOCK) = 8
brk(NULL) = 0x5575761c2000
brk(0x5575761e3000) = 0x5575761e3000
newfstatat(3, "", {st_mode=S_IFCHR|0600, st_rdev=makedev(0x88, 0xd), ...},
AT_EMPTY_PATH) = 0
write(3, "lchmod: Operation not permitted\n", 32lchmod: Operation not permitted
) = 32
close(3) = 0
openat(AT_FDCWD, "/", O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH) = 3
newfstatat(3, "", {st_mode=S_IFDIR|0755, st_size=4096, ...}, AT_EMPTY_PATH) = 0
chmod("/proc/self/fd/3", 0755) = -1 EPERM (Operation not permitted)
close(3) = 0
dup(2) = 3
fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
newfstatat(3, "", {st_mode=S_IFCHR|0600, st_rdev=makedev(0x88, 0xd), ...},
AT_EMPTY_PATH) = 0
write(3, "fchmodat: Operation not permitte"..., 34fchmodat: Operation not
permitted
) = 34
close(3) = 0
chmod("/", 0755) = -1 EPERM (Operation not permitted)
dup(2) = 3
fcntl(3, F_GETFL) = 0x2 (flags O_RDWR)
newfstatat(3, "", {st_mode=S_IFCHR|0600, st_rdev=makedev(0x88, 0xd), ...},
AT_EMPTY_PATH) = 0
write(3, "chmod: Operation not permitted\n", 31chmod: Operation not permitted
) = 31
close(3) = 0
openat(AT_FDCWD, "/", O_RDONLY|O_NOFOLLOW) = 3
fchmod(3, 0755) = -1 EPERM (Operation not permitted)
dup(2) = 4
fcntl(4, F_GETFL) = 0x2 (flags O_RDWR)
newfstatat(4, "", {st_mode=S_IFCHR|0600, st_rdev=makedev(0x88, 0xd), ...},
AT_EMPTY_PATH) = 0
write(4, "fchmod: Operation not permitted\n", 32fchmod: Operation not permitted
) = 32
close(4) = 0
exit_group(1) = ?
+++ exited with 1 +++
