acl: Don't use GETACLCNT and similar ops, since they are unreliable.
- There were several instances of this pattern:
for (;;) {
n = acl (f, GETACLCNT, 0, NULL);
[ allocate an array A of size N ]
if (acl (f, GETACL, n, a) == n)
break;
}
This loop might never terminate if some other process is constantly
manipulating the file's ACL. The loop should be rewritten to
terminate.
- The acl (... GETACLNT ...) call is merely an optimization; its value
is merely a hint as to how big to make the array. A better
optimization is to avoid the acl (... GETACLNT ...) call entirely,
and just guess a reasonably-big size, growing the size and trying
again if it's not large enough. This guarantees termination, and
saves a system call.
* lib/acl-internal.h: Include <limits.h>.
(MIN, SIZE_MAX): New macros.
* lib/file-has-acl.c (file_has_acl) [Solaris]: Read the entries into
a stack-allocated buffer, and use malloc if it does not fit. Don't
use GETACLCNT.
* lib/set-mode-acl.c (qset_acl) [Solaris]: Likewise.