kernel/syscall/symlink.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
  24  */
  25
  26 /*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
  27 /*        All Rights Reserved   */
  28
  29 /*
  30  * Portions of this source code were derived from Berkeley 4.3 BSD
  31  * under license from the Regents of the University of California.
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/isa_defs.h>
  36 #include <sys/types.h>
  37 #include <sys/sysmacros.h>
  38 #include <sys/systm.h>
  39 #include <sys/errno.h>
  40 #include <sys/pathname.h>
  41 #include <sys/vfs.h>
  42 #include <sys/vnode.h>
  43 #include <sys/file.h>
  44 #include <sys/fcntl.h>
  45 #include <sys/proc.h>
  46 #include <sys/uio.h>
  47 #include <sys/debug.h>
  48 #include <sys/fs_subr.h>
  49
  50 /*
  51  * Create a symbolic link.  Similar to link or rename except target
  52  * name is passed as string argument, not converted to vnode reference.
  53  */
  54 int
  55 symlinkat(char *target, int dfd, char *linkname)
  56 {
  57         vnode_t *startvp;
  58         vnode_t *dvp;
  59         struct vattr vattr;
  60         struct pathname lpn;
  61         char *tbuf;
  62         size_t tlen;
  63         int error;
  64         int estale_retry = 0;
  65
  66         if (linkname == NULL)
  67                 return (set_errno(EFAULT));
  68         if ((error = fgetstartvp(dfd, linkname, &startvp)) != 0)
  69                 return (set_errno(error));
  70
  71 top:
  72         if (error = pn_get(linkname, UIO_USERSPACE, &lpn))
  73                 goto out;
  74         if (error = lookuppnat(&lpn, NULL, NO_FOLLOW, &dvp, NULLVPP, startvp)) {
  75                 pn_free(&lpn);
  76                 if (error == ESTALE && fs_need_estale_retry(estale_retry++))
  77                         goto top;
  78                 goto out;
  79         }
  80         if (vn_is_readonly(dvp))
  81                 error = EROFS;
  82         else if (pn_fixslash(&lpn))
  83                 error = ENOTDIR;
  84         else {
  85                 tbuf = kmem_alloc(MAXPATHLEN, KM_SLEEP);
  86                 if ((error = copyinstr(target, tbuf, MAXPATHLEN, &tlen)) == 0) {
  87                         vattr.va_type = VLNK;
  88                         vattr.va_mode = 0777;
  89                         vattr.va_mask = VATTR_TYPE|VATTR_MODE;
  90                         error = fop_symlink(dvp, lpn.pn_path, &vattr,
  91                             tbuf, CRED(), NULL, 0);
  92                 }
  93                 kmem_free(tbuf, MAXPATHLEN);
  94         }
  95         pn_free(&lpn);
  96         VN_RELE(dvp);
  97         if (error == ESTALE && fs_need_estale_retry(estale_retry++))
  98                 goto top;
  99 out:
 100         if (startvp != NULL)
 101                 VN_RELE(startvp);
 102         if (error)
 103                 return (set_errno(error));
 104         return (0);
 105 }