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: stable/4/sys/i386/ibcs2/ibcs2_util.c 54655 1999-12-15 23:02:35Z eivind $
   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 #include <vm/vm_zone.h>
   42 
   43 const char      ibcs2_emul_path[] = "/compat/ibcs2";
   44 
   45 /*
   46  * Search an alternate path before passing pathname arguments on
   47  * to system calls. Useful for keeping a seperate 'emulation tree'.
   48  *
   49  * If cflag is set, we check if an attempt can be made to create
   50  * the named file, i.e. we check if the directory it should
   51  * be in exists.
   52  */
   53 int
   54 ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
   55         struct proc      *p;
   56         caddr_t          *sgp;          /* Pointer to stackgap memory */
   57         const char       *prefix;
   58         char             *path;
   59         char            **pbuf;
   60         int               cflag;
   61 {
   62         struct nameidata         nd;
   63         struct nameidata         ndroot;
   64         struct vattr             vat;
   65         struct vattr             vatroot;
   66         int                      error;
   67         char                    *ptr, *buf, *cp;
   68         size_t                   sz, len;
   69 
   70         buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
   71         *pbuf = path;
   72 
   73         for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
   74                 continue;
   75 
   76         sz = MAXPATHLEN - (ptr - buf);
   77 
   78         /* 
   79          * If sgp is not given then the path is already in kernel space
   80          */
   81         if (sgp == NULL)
   82                 error = copystr(path, ptr, sz, &len);
   83         else
   84                 error = copyinstr(path, ptr, sz, &len);
   85 
   86         if (error) {
   87                 free(buf, M_TEMP);
   88                 return error;
   89         }
   90 
   91         if (*ptr != '/') {
   92                 free(buf, M_TEMP);
   93                 return EINVAL;
   94         }
   95 
   96         /*
   97          * We know that there is a / somewhere in this pathname.
   98          * Search backwards for it, to find the file's parent dir
   99          * to see if it exists in the alternate tree. If it does,
  100          * and we want to create a file (cflag is set). We don't
  101          * need to worry about the root comparison in this case.
  102          */
  103 
  104         if (cflag) {
  105                 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
  106                 *cp = '\0';
  107 
  108                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
  109 
  110                 if ((error = namei(&nd)) != 0) {
  111                         free(buf, M_TEMP);
  112                         return error;
  113                 }
  114 
  115                 *cp = '/';
  116         }
  117         else {
  118                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
  119 
  120                 if ((error = namei(&nd)) != 0) {
  121                         free(buf, M_TEMP);
  122                         return error;
  123                 }
  124 
  125                 /*
  126                  * We now compare the vnode of the ibcs2_root to the one
  127                  * vnode asked. If they resolve to be the same, then we
  128                  * ignore the match so that the real root gets used.
  129                  * This avoids the problem of traversing "../.." to find the
  130                  * root directory and never finding it, because "/" resolves
  131                  * to the emulation root directory. This is expensive :-(
  132                  */
  133                 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, ibcs2_emul_path,
  134                        p);
  135 
  136                 if ((error = namei(&ndroot)) != 0) {
  137                         /* Cannot happen! */
  138                         free(buf, M_TEMP);
  139                         NDFREE(&nd, NDF_ONLY_PNBUF);
  140                         vrele(nd.ni_vp);
  141                         return error;
  142                 }
  143 
  144                 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
  145                         goto done;
  146                 }
  147 
  148                 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
  149                     != 0) {
  150                         goto done;
  151                 }
  152 
  153                 if (vat.va_fsid == vatroot.va_fsid &&
  154                     vat.va_fileid == vatroot.va_fileid) {
  155                         error = ENOENT;
  156                         goto done;
  157                 }
  158 
  159         }
  160         if (sgp == NULL)
  161                 *pbuf = buf;
  162         else {
  163                 sz = &ptr[len] - buf;
  164                 *pbuf = stackgap_alloc(sgp, sz + 1);
  165                 error = copyout(buf, *pbuf, sz);
  166                 free(buf, M_TEMP);
  167         }
  168 
  169 
  170 done:
  171         NDFREE(&nd, NDF_ONLY_PNBUF);
  172         vrele(nd.ni_vp);
  173         if (!cflag) {
  174                 NDFREE(&ndroot, NDF_ONLY_PNBUF);
  175                 vrele(ndroot.ni_vp);
  176         }
  177         return error;
  178 }

Cache object: 4f4e06e33cf8f47094df42a810ec0839


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