usr/src/lib/libast/common/comp/readlink.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23
  24 #include <ast.h>
  25
  26 #if _lib_readlink
  27
  28 NoN(readlink)
  29
  30 #else
  31
  32 #include "fakelink.h"
  33
  34 #include <error.h>
  35
  36 #ifndef ENOSYS
  37 #define ENOSYS  EINVAL
  38 #endif
  39
  40 int
  41 readlink(const char* path, char* buf, int siz)
  42 {
  43         int     fd;
  44         int     n;
  45
  46         if (siz > sizeof(FAKELINK_MAGIC))
  47         {
  48                 if ((fd = open(path, O_RDONLY)) < 0)
  49                         return -1;
  50                 if (read(fd, buf, sizeof(FAKELINK_MAGIC)) == sizeof(FAKELINK_MAGIC) && !strcmp(buf, FAKELINK_MAGIC) && (n = read(fd, buf, siz)) > 0 && !buf[n - 1])
  51                 {
  52                         close(fd);
  53                         return n;
  54                 }
  55                 close(fd);
  56         }
  57         errno = ENOSYS;
  58         return -1;
  59 }
  60
  61 #endif