bug#65599: mv and cp give a pointless warning when moving/copying a directory

[Bruno Haible]

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 +++