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  */
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/namei.h>
   35 #include <sys/malloc.h>
   36 #include <sys/vnode.h>
   37 
   38 #include <i386/ibcs2/ibcs2_util.h>
   39 
   40 const char      ibcs2_emul_path[] = "/compat/ibcs2";
   41 
   42 /*
   43  * Search an alternate path before passing pathname arguments on
   44  * to system calls. Useful for keeping a seperate 'emulation tree'.
   45  *
   46  * If cflag is set, we check if an attempt can be made to create
   47  * the named file, i.e. we check if the directory it should
   48  * be in exists.
   49  */
   50 int
   51 ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
   52         struct proc      *p;
   53         caddr_t          *sgp;          /* Pointer to stackgap memory */
   54         const char       *prefix;
   55         char             *path;
   56         char            **pbuf;
   57         int               cflag;
   58 {
   59         struct nameidata         nd;
   60         struct nameidata         ndroot;
   61         struct vattr             vat;
   62         struct vattr             vatroot;
   63         int                      error;
   64         char                    *ptr, *buf, *cp;
   65         size_t                   sz, len;
   66 
   67         buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
   68         *pbuf = path;
   69 
   70         for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
   71                 continue;
   72 
   73         sz = MAXPATHLEN - (ptr - buf);
   74 
   75         /* 
   76          * If sgp is not given then the path is already in kernel space
   77          */
   78         if (sgp == NULL)
   79                 error = copystr(path, ptr, sz, &len);
   80         else
   81                 error = copyinstr(path, ptr, sz, &len);
   82 
   83         if (error) {
   84                 free(buf, M_TEMP);
   85                 return error;
   86         }
   87 
   88         if (*ptr != '/') {
   89                 free(buf, M_TEMP);
   90                 return EINVAL;
   91         }
   92 
   93         /*
   94          * We know that there is a / somewhere in this pathname.
   95          * Search backwards for it, to find the file's parent dir
   96          * to see if it exists in the alternate tree. If it does,
   97          * and we want to create a file (cflag is set). We don't
   98          * need to worry about the root comparison in this case.
   99          */
  100 
  101         if (cflag) {
  102                 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
  103                 *cp = '\0';
  104 
  105                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
  106 
  107                 if ((error = namei(&nd)) != 0) {
  108                         free(buf, M_TEMP);
  109                         return error;
  110                 }
  111 
  112                 *cp = '/';
  113         }
  114         else {
  115                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
  116 
  117                 if ((error = namei(&nd)) != 0) {
  118                         free(buf, M_TEMP);
  119                         return error;
  120                 }
  121 
  122                 /*
  123                  * We now compare the vnode of the ibcs2_root to the one
  124                  * vnode asked. If they resolve to be the same, then we
  125                  * ignore the match so that the real root gets used.
  126                  * This avoids the problem of traversing "../.." to find the
  127                  * root directory and never finding it, because "/" resolves
  128                  * to the emulation root directory. This is expensive :-(
  129                  */
  130                 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, ibcs2_emul_path,
  131                        p);
  132 
  133                 if ((error = namei(&ndroot)) != 0) {
  134                         /* Cannot happen! */
  135                         free(buf, M_TEMP);
  136                         vrele(nd.ni_vp);
  137                         return error;
  138                 }
  139 
  140                 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
  141                         goto done;
  142                 }
  143 
  144                 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
  145                     != 0) {
  146                         goto done;
  147                 }
  148 
  149                 if (vat.va_fsid == vatroot.va_fsid &&
  150                     vat.va_fileid == vatroot.va_fileid) {
  151                         error = ENOENT;
  152                         goto done;
  153                 }
  154 
  155         }
  156         if (sgp == NULL)
  157                 *pbuf = buf;
  158         else {
  159                 sz = &ptr[len] - buf;
  160                 *pbuf = stackgap_alloc(sgp, sz + 1);
  161                 error = copyout(buf, *pbuf, sz);
  162                 free(buf, M_TEMP);
  163         }
  164 
  165 
  166 done:
  167         vrele(nd.ni_vp);
  168         if (!cflag)
  169                 vrele(ndroot.ni_vp);
  170         return error;
  171 }

Cache object: 0b51e1f2453670cf3fa0c5311092da51


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