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ACL_GET_FILE

Section: C Library Functions (3)
Index Return to Main Contents

BSD mandoc
Linux ACL

NAME

acl_get_file acl_get_file_at - get an ACL by filename

LIBRARY

Linux Access Control Lists library (libacl, -lacl).

SYNOPSIS

In sys/types.h In sys/acl.h Ft acl_t Fo acl_get_file Fa const char *path_p Fa acl_type_t type Fc Ft acl_t Fo acl_get_file_at Fa int dirfd Fa const char *path_p Fa int at_flags Fa acl_type_t type Fc

DESCRIPTION

The Fn acl_get_file function retrieves the access ACL associated with a file or directory, or the default ACL associated with a directory. The pathname for the file or directory is given in the argument path_p If path_p is a symbolic link, Fn acl_get_file returns information about the file or directory the link refers to.

The ACL is placed into working storage and Fn acl_get_file returns a pointer to that storage.

In order to read an ACL from an object, a process must have read access to the object's attributes.

The value of the argument type is used to indicate whether the access ACL or the default ACL associated with path_p is returned. If type is ACL_TYPE_ACCESS the access ACL of path_p is returned. If type is ACL_TYPE_DEFAULT the default ACL of path_p is returned. If type is ACL_TYPE_DEFAULT and no default ACL is associated with the directory path_p then an ACL containing zero ACL entries is returned. If type specifies a type of ACL that cannot be associated with path_p then the function fails.

This function may cause memory to be allocated. The caller should free any releasable memory, when the new ACL is no longer required, by calling acl_free3 with the (void*)acl_t returned by Fn acl_get_file as an argument.

Fn acl_get_file_at

The Fn acl_get_file_at function operates in exactly the same way as Fn acl_get_file , except for the differences described here.

If the pathname given in path_p is relative, then it is interpreted relative to the directory referred to by the file descriptor dirfd (rather than relative to the current working directory of the calling process, as is done by Fn acl_get_file ) .

If path_p is relative and dirfd is the special value AT_FDCWD then path_p is interpreted relative to the current working directory of the calling process (like Fn acl_get_file ) .

If path_p is absolute, then dirfd is ignored.

The at_flags argument can either be 0, or include one or more of the following flags ORed:

AT_EMPTY_PATH: If path_p is an empty string, operate on the file referred to by dirfd (which may have been obtained using the open(2) O_PATH flag). In this case, dirfd can refer to any type of file, not just a directory, and the behavior of Fn acl_get_file_at is similar to that of Fn acl_get_fd .
AT_SYMLINK_NOFOLLOW: If path_p refers to a symbolic link, do not dereference it: instead, fail the operation and set the global variable errno to Er ENOTSUP . This indicates that the symbolic link cannot have ACLs.

RETURN VALUE

On success, the Fn acl_get_file and Fn acl_get_file_at functions return a pointer to the working storage. On error, a value of (acl_t)NULL is returned, and errno is set appropriately.

ERRORS

If any of the following conditions occur, the Fn acl_get_file and Fn acl_get_file_at functions return a value of (acl_t)NULL and set errno to the corresponding value:

Bq Er 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.
Argument type specifies a type of ACL that cannot be associated with path_p
Bq Er EBADF: The argument path_p is relative but the argument dirfd is neither AT_FDCWD nor a valid file descriptor.
Bq Er EINVAL: The argument type is not ACL_TYPE_ACCESS or ACL_TYPE_DEFAULT
An invalid flag was specified in the at_flags argument.
Bq Er ENAMETOOLONG: The length of the argument path_p is too long.
Bq Er ENOENT: The named object does not exist or the argument path_p points to an empty string.
Bq Er ENOMEM: The ACL working storage requires more memory than is allowed by the hardware or syste-imposed memory management constraints.
Bq Er ENOTDIR: A component of the path prefix is not a directory.
The argument path_p is relative and the argument dirfd is a file descriptor referring to a file other than a directory.
Bq Er ENOTSUP: The argument at_flags includes the flag AT_SYMLINK_NOFOLLOW and path_p is a symbolic link.
The file system on which the file identified by path_p is located does not support ACLs, or ACLs are disabled.

STANDARDS

IEEE Std 1003.1e draft 17 (lqPOSIX.1erq, abandoned)

Function Fn acl_get_file_at is a Linux specific extension.

AUTHOR

Derived from the FreeBSD manual pages written by An Robert N M Watson Aq rwatson@FreeBSD.org , and adapted for Linux by An Andreas Gruenbacher Aq andreas.gruenbacher@gmail.com .