NAME

acl_valid, acl_valid_fd_np, acl_valid_file_np, acl_valid_link_np —

validate an ACL

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/types.h>
#include <sys/acl.h>

int
acl_valid(acl_t acl);

int
acl_valid_fd_np(int fd, acl_type_t type, acl_t acl);

int
acl_valid_file_np(const char *path_p, acl_type_t type, acl_t acl);

int
acl_valid_link_np(const char *path_p, acl_type_t type, acl_t acl);

DESCRIPTION

These functions check that the ACL referred to by the argument acl is valid. The POSIX.1e routine, acl_valid(), checks this validity only with POSIX.1e ACL semantics, and irrespective of the context in which the ACL is to be used. The non-portable forms, acl_valid_fd_np(), acl_valid_file_np(), and acl_valid_link_np() allow an ACL to be checked in the context of a specific acl type, type, and file system object. In environments where additional ACL types are supported than just POSIX.1e, this makes more sense. Whereas acl_valid_file_np() will follow the symlink if the specified path is to a symlink, acl_valid_link_np() will not.

For POSIX.1e semantics, the checks include:

The three required entries (ACL_USER_OBJ, ACL_GROUP_OBJ, and ACL_OTHER) shall exist exactly once in the ACL. If the ACL contains any ACL_USER, ACL_GROUP, or any other implementation-defined entries in the file group class then one ACL_MASK entry shall also be required. The ACL shall contain at most one ACL_MASK entry.
The qualifier field shall be unique among all entries of the same POSIX.1e ACL facility defined tag type. The tag type field shall contain valid values including any implementation-defined values. Validation of the values of the qualifier field is implementation-defined.

The POSIX.1e acl_valid() function may reorder the ACL for the purposes of verification; the non-portable validation functions will not.

IMPLEMENTATION NOTES

FreeBSD's support for POSIX.1e interfaces and features is still under development at this time.

RETURN VALUES

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

ERRORS

If any of the following conditions occur, these functions shall return -1 and set errno to the corresponding value:

[EACCES]

Search permission is denied for a component of the path prefix, or the object exists and the process does not have appropriate access rights.

[EBADF]

The fd argument is not a valid file descriptor.

[EINVAL]

Argument acl does not point to a valid ACL.

One or more of the required ACL entries is not present in acl.

The ACL contains entries that are not unique.

The file system rejects the ACL based on fs-specific semantics issues.

[ENAMETOOLONG]

A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

[ENOENT]

The named object does not exist, or the path_p argument points to an empty string.

[ENOMEM]

Insufficient memory available to fulfill request.

[EOPNOTSUPP]

The file system does not support ACL retrieval.

STANDARDS

POSIX.1e is described in IEEE POSIX.1e draft 17. Discussion of the draft continues on the cross-platform POSIX.1e implementation mailing list. To join this list, see the FreeBSD POSIX.1e implementation page for more information.

HISTORY

POSIX.1e support was introduced in FreeBSD 4.0, and development continues.

AUTHORS

Robert N M Watson