access(2) access(2)
NAME
access - determine accessibility of a file
SYNOPSIS
#include <unistd.h>
int access(char *path, int amode);
DESCRIPTION
The access() system call checks the file pointed to by path for
accessibility according to the bit pattern contained in amode.
access() uses the real user ID, not the effective user ID, and the
real group ID, not the effective group ID.
The value of amode is either the bit-wise inclusive OR of the access
permissions to be checked, or the existence test. You can use the
following symbolic constants, defined in <unistd.h>, to test for
permissions:
R_OK Read access
W_OK Write access
X_OK Execute (search) access
F_OK Check existence of file
The owner of a file has permission checked with respect to the "user"
read, write, and execute mode bits. Members of the file's group other
than the owner have permissions checked with respect to the "group"
mode bits. All others have permissions checked with respect to the
"other" mode bits.
If a file is currently open for execution, access() reports that it is
not writable, regardless of the setting of its mode.
Access Control Lists - HFS File Systems Only
Read, write, and execute/search permissions are checked against the
file's access control list (ACL). Each mode is checked separately
since different ACL entries can grant different permissions. The real
user ID is combined with the process's real group ID and each group in
its supplementary groups list, and the access control list is searched
for a match. Search proceeds in order of specificity and ends when
one or more matching entries are found at a specific level. More than
one user.group or %.group entry can match a user if that user has a
nonnull supplementary groups list. If any matching entry has the
appropriate permission bit set, access is permitted.
If a shared text file is currently open for execution, access()
reports that it is not writable, regardless of its access control
list. However, access() does not report that a shared text file open
for writing is not executable, since the check is not easily done.
Hewlett-Packard Company - 1 - HP-UX Release 11.00: October 1997
access(2) access(2)
It also reports that a file on a read-only file system is not
writable.
RETURN VALUE
access() returns the following values:
0 Successful completion. The requested access is permitted.
If the path is valid and the real user ID is superuser,
access() always returns 0, except when amode includes X_OK,
the path is not a directory, and none of the execute bits
are set in the file's mode.
-1 Failure. errno is set to indicate the error.
ERRORS
If access() fails, errno is set to one of the following values.
[EACCES] Search permission is denied on a component of the
path prefix.
[EACCES] The access control list does not permit the
requested access and the real user ID is not a
user with appropriate privileges.
[EFAULT] path points outside the allocated address space
for the process. The reliable detection of this
error is implementation dependent.
[ELOOP] Too many symbolic links were encountered in
translating the path name.
[ENAMETOOLONG] The length of the specified path name exceeds
PATH_MAX bytes, or the length of a component of
the path name exceeds NAME_MAX bytes while
_POSIX_NO_TRUNC is in effect.
[ENOENT] Read, write, or execute (search) permission is
requested for a null path name.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
[EROFS] Write access is requested for a file on a read-
only file system.
[ETXTBSY] Write access is requested for a pure procedure
(shared text) file that is being executed.
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access(2) access(2)
SEE ALSO
chmod(2), stat(2), setacl(2), acl(5), unistd(5).
STANDARDS CONFORMANCE
access(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
Hewlett-Packard Company - 3 - HP-UX Release 11.00: October 1997
Il n'est pas dit que access ne modifie pas la chaine qui lui est passe, et s'il ne la modifiait pas ne devrait-il pas prendre un
const char * ? Ceci dit s'il la modifie ca devrait etre dit...
