libcsupport/src/readlink.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  *  @file
0005  *
0006  *  @brief Read Value of a Symbolic Link
0007  *  @ingroup libcsupport
0008  */
0009
0010 /*
0011  *  COPYRIGHT (c) 1989-1999.
0012  *  On-Line Applications Research Corporation (OAR).
0013  *
0014  * Redistribution and use in source and binary forms, with or without
0015  * modification, are permitted provided that the following conditions
0016  * are met:
0017  * 1. Redistributions of source code must retain the above copyright
0018  *    notice, this list of conditions and the following disclaimer.
0019  * 2. Redistributions in binary form must reproduce the above copyright
0020  *    notice, this list of conditions and the following disclaimer in the
0021  *    documentation and/or other materials provided with the distribution.
0022  *
0023  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0024  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0025  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0026  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0027  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0028  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0029  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0030  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0031  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0032  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0033  * POSSIBILITY OF SUCH DAMAGE.
0034  */
0035
0036 #ifdef HAVE_CONFIG_H
0037 #include "config.h"
0038 #endif
0039
0040 #include <unistd.h>
0041
0042 #include <rtems/libio_.h>
0043
0044 /**
0045  *  POSIX 1003.1b - X.X.X - XXX
0046  */
0047 ssize_t readlink( const char *__restrict path, char *__restrict buf,
0048                   size_t bufsize )
0049 {
0050   ssize_t rv = 0;
0051   rtems_filesystem_eval_path_context_t ctx;
0052   int eval_flags = RTEMS_FS_FOLLOW_HARD_LINK;
0053   const rtems_filesystem_location_info_t *currentloc =
0054     rtems_filesystem_eval_path_start( &ctx, path, eval_flags );
0055   const rtems_filesystem_operations_table *ops = currentloc->mt_entry->ops;
0056   mode_t type = rtems_filesystem_location_type( currentloc );
0057
0058   if ( S_ISLNK( type ) ) {
0059     rv = (*ops->readlink_h)( currentloc, buf, bufsize );
0060   } else {
0061     rtems_filesystem_eval_path_error( &ctx, EINVAL );
0062     rv = -1;
0063   }
0064
0065   rtems_filesystem_eval_path_cleanup( &ctx );
0066
0067   return rv;
0068 }