ACCESS(2-BSD)       RISC/os Reference Manual        ACCESS(2-BSD)



NAME
     access - determine accessibility of file

SYNOPSIS
     #include <sys/file.h>

     #define ROK    4/* test for read permission */
     #define WOK    2/* test for write permission */
     #define XOK    1/* test for execute (search) permission */
     #define FOK    0/* test for presence of file */

     accessible = access(path, mode)
     int accessible;
     char *path;
     int mode;

DESCRIPTION
     access checks the given file path for accessibility accord-
     ing to mode, which is an inclusive or of the bits R_OK, W_OK
     and X_OK. Specifying mode as F_OK (i.e., 0) tests whether
     the directories leading to the file can be searched and the
     file exists.

     The real user ID and the group access list (including the
     real group ID) are used in verifying permission, so this
     call is useful to set-UID programs.

     Notice that only access bits are checked.  A directory may
     be indicated as writable by access, but an attempt to open
     it for writing will fail (although files may be created
     there); a file may look executable, but execve will fail
     unless it is in proper format.

RETURN VALUE
     If path cannot be found or if any of the desired access
     modes would not be granted, then a -1 value is returned;
     otherwise a 0 value is returned.

ERRORS
     Access to the file is denied if one or more of the following
     are true:

     [ENOTDIR]                A component of the path prefix is
                              not a directory.

     [EINVAL]                 The pathname contains a character
                              with the high-order bit set.

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




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ACCESS(2-BSD)       RISC/os Reference Manual        ACCESS(2-BSD)



     [ENOENT]                 The named file does not exist.

     [EACCES]                 Search permission is denied for a
                              component of the path prefix.

     [ELOOP]                  Too many symbolic links were
                              encountered in translating the
                              pathname.

     [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.

     [EACCES]                 Permission bits of the file mode do
                              not permit the requested access, or
                              search permission is denied on a
                              component of the path prefix.  The
                              owner of a file has permission
                              checked with respect to the
                              ``owner'' read, write, and execute
                              mode bits, members of the file's
                              group other than the owner have
                              permission checked with respect to
                              the ``group'' mode bits, and all
                              others have permissions checked
                              with respect to the ``other'' mode
                              bits.

     [EFAULT]                 path points outside the process's
                              allocated address space.

     [EIO]                    An I/O error occurred while reading
                              from or writing to the file system.

SEE ALSO
     chmod(2), stat(2)
















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