The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/i386/ibcs2/ibcs2_util.c

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    1 /*
    2  * Copyright (c) 1994 Christos Zoulas
    3  * Copyright (c) 1995 Frank van der Linden
    4  * Copyright (c) 1995 Scott Bartram
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. The name of the author may not be used to endorse or promote products
   16  *    derived from this software without specific prior written permission
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   28  *
   29  *      from: svr4_util.c,v 1.5 1995/01/22 23:44:50 christos Exp
   30  * $FreeBSD: releng/5.0/sys/i386/ibcs2/ibcs2_util.c 91406 2002-02-27 18:32:23Z jhb $
   31  */
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/namei.h>
   36 #include <sys/malloc.h>
   37 #include <sys/vnode.h>
   38 
   39 #include <i386/ibcs2/ibcs2_util.h>
   40 
   41 
   42 const char      ibcs2_emul_path[] = "/compat/ibcs2";
   43 
   44 /*
   45  * Search an alternate path before passing pathname arguments on
   46  * to system calls. Useful for keeping a separate 'emulation tree'.
   47  *
   48  * If cflag is set, we check if an attempt can be made to create
   49  * the named file, i.e. we check if the directory it should
   50  * be in exists.
   51  */
   52 int
   53 ibcs2_emul_find(td, sgp, prefix, path, pbuf, cflag)
   54         struct thread    *td;
   55         caddr_t          *sgp;          /* Pointer to stackgap memory */
   56         const char       *prefix;
   57         char             *path;
   58         char            **pbuf;
   59         int               cflag;
   60 {
   61         struct nameidata         nd;
   62         struct nameidata         ndroot;
   63         struct vattr             vat;
   64         struct vattr             vatroot;
   65         int                      error;
   66         char                    *ptr, *buf, *cp;
   67         size_t                   sz, len;
   68 
   69         buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
   70         *pbuf = path;
   71 
   72         for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
   73                 continue;
   74 
   75         sz = MAXPATHLEN - (ptr - buf);
   76 
   77         /* 
   78          * If sgp is not given then the path is already in kernel space
   79          */
   80         if (sgp == NULL)
   81                 error = copystr(path, ptr, sz, &len);
   82         else
   83                 error = copyinstr(path, ptr, sz, &len);
   84 
   85         if (error) {
   86                 free(buf, M_TEMP);
   87                 return error;
   88         }
   89 
   90         if (*ptr != '/') {
   91                 free(buf, M_TEMP);
   92                 return EINVAL;
   93         }
   94 
   95         /*
   96          * We know that there is a / somewhere in this pathname.
   97          * Search backwards for it, to find the file's parent dir
   98          * to see if it exists in the alternate tree. If it does,
   99          * and we want to create a file (cflag is set). We don't
  100          * need to worry about the root comparison in this case.
  101          */
  102 
  103         if (cflag) {
  104                 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
  105                 *cp = '\0';
  106 
  107                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
  108 
  109                 if ((error = namei(&nd)) != 0) {
  110                         free(buf, M_TEMP);
  111                         return error;
  112                 }
  113 
  114                 *cp = '/';
  115         }
  116         else {
  117                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
  118 
  119                 if ((error = namei(&nd)) != 0) {
  120                         free(buf, M_TEMP);
  121                         return error;
  122                 }
  123 
  124                 /*
  125                  * We now compare the vnode of the ibcs2_root to the one
  126                  * vnode asked. If they resolve to be the same, then we
  127                  * ignore the match so that the real root gets used.
  128                  * This avoids the problem of traversing "../.." to find the
  129                  * root directory and never finding it, because "/" resolves
  130                  * to the emulation root directory. This is expensive :-(
  131                  */
  132                 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, ibcs2_emul_path,
  133                        td);
  134 
  135                 if ((error = namei(&ndroot)) != 0) {
  136                         /* Cannot happen! */
  137                         free(buf, M_TEMP);
  138                         NDFREE(&nd, NDF_ONLY_PNBUF);
  139                         vrele(nd.ni_vp);
  140                         return error;
  141                 }
  142 
  143                 if ((error = VOP_GETATTR(nd.ni_vp, &vat, td->td_ucred, td)) != 0) {
  144                         goto done;
  145                 }
  146 
  147                 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, td->td_ucred, td))
  148                     != 0) {
  149                         goto done;
  150                 }
  151 
  152                 if (vat.va_fsid == vatroot.va_fsid &&
  153                     vat.va_fileid == vatroot.va_fileid) {
  154                         error = ENOENT;
  155                         goto done;
  156                 }
  157 
  158         }
  159         if (sgp == NULL)
  160                 *pbuf = buf;
  161         else {
  162                 sz = &ptr[len] - buf;
  163                 *pbuf = stackgap_alloc(sgp, sz + 1);
  164                 error = copyout(buf, *pbuf, sz);
  165                 free(buf, M_TEMP);
  166         }
  167 
  168 
  169 done:
  170         NDFREE(&nd, NDF_ONLY_PNBUF);
  171         vrele(nd.ni_vp);
  172         if (!cflag) {
  173                 NDFREE(&ndroot, NDF_ONLY_PNBUF);
  174                 vrele(ndroot.ni_vp);
  175         }
  176         return error;
  177 }

Cache object: d5e01b4a1907fcfab8870c8b3fcea351


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