linux_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/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/5.2/sys/compat/linux/linux_util.c 116173 2003-06-10 21:29:12Z obrien $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/namei.h>
   38 #include <sys/proc.h>
   39 #include <sys/malloc.h>
   40 #include <sys/vnode.h>
   41 
   42 #include <machine/stdarg.h>
   43 
   44 #include <compat/linux/linux_util.h>
   45 
   46 const char      linux_emul_path[] = "/compat/linux";
   47 
   48 /*
   49  * Search an alternate path before passing pathname arguments on
   50  * to system calls. Useful for keeping a separate 'emulation tree'.
   51  *
   52  * If cflag is set, we check if an attempt can be made to create
   53  * the named file, i.e. we check if the directory it should
   54  * be in exists.
   55  */
   56 int
   57 linux_emul_find(td, sgp, path, pbuf, cflag)
   58         struct thread    *td;
   59         caddr_t          *sgp;          /* Pointer to stackgap memory */
   60         char             *path;
   61         char            **pbuf;
   62         int               cflag;
   63 {
   64         char *newpath;
   65         size_t sz;
   66         int error;
   67 
   68         error = linux_emul_convpath(td, path, (sgp == NULL) ? UIO_SYSSPACE :
   69             UIO_USERSPACE, &newpath, cflag);
   70         if (newpath == NULL)
   71                 return (error);
   72 
   73         if (sgp == NULL) {
   74                 *pbuf = newpath;
   75                 return (error);
   76         }
   77 
   78         sz = strlen(newpath);
   79         *pbuf = stackgap_alloc(sgp, sz + 1);
   80         if (*pbuf != NULL)
   81                 error = copyout(newpath, *pbuf, sz + 1);
   82         else
   83                 error = ENAMETOOLONG;
   84         free(newpath, M_TEMP);
   85 
   86         return (error);
   87 }
   88 
   89 int
   90 linux_emul_convpath(td, path, pathseg, pbuf, cflag)
   91         struct thread    *td;
   92         char             *path;
   93         enum uio_seg      pathseg;
   94         char            **pbuf;
   95         int               cflag;
   96 {
   97         struct nameidata         nd;
   98         struct nameidata         ndroot;
   99         struct vattr             vat;
  100         struct vattr             vatroot;
  101         int                      error;
  102         const char              *prefix;
  103         char                    *ptr, *buf, *cp;
  104         size_t                   len, sz;
  105 
  106         buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
  107         *pbuf = buf;
  108 
  109         prefix = linux_emul_path;
  110         for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
  111                 continue;
  112         sz = MAXPATHLEN - (ptr - buf);
  113 
  114         if (pathseg == UIO_SYSSPACE)
  115                 error = copystr(path, ptr, sz, &len);
  116         else
  117                 error = copyinstr(path, ptr, sz, &len);
  118 
  119         if (error) {
  120                 *pbuf = NULL;
  121                 free(buf, M_TEMP);
  122                 return error;
  123         }
  124 
  125         if (*ptr != '/') {
  126                 error = EINVAL;
  127                 goto keeporig;
  128         }
  129 
  130         /*
  131          * We know that there is a / somewhere in this pathname.
  132          * Search backwards for it, to find the file's parent dir
  133          * to see if it exists in the alternate tree. If it does,
  134          * and we want to create a file (cflag is set). We don't
  135          * need to worry about the root comparison in this case.
  136          */
  137 
  138         if (cflag) {
  139                 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
  140                 *cp = '\0';
  141 
  142                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
  143                 error = namei(&nd);
  144                 *cp = '/';
  145                 if (error != 0)
  146                         goto keeporig;
  147         }
  148         else {
  149                 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
  150 
  151                 if ((error = namei(&nd)) != 0)
  152                         goto keeporig;
  153 
  154                 /*
  155                  * We now compare the vnode of the linux_root to the one
  156                  * vnode asked. If they resolve to be the same, then we
  157                  * ignore the match so that the real root gets used.
  158                  * This avoids the problem of traversing "../.." to find the
  159                  * root directory and never finding it, because "/" resolves
  160                  * to the emulation root directory. This is expensive :-(
  161                  */
  162                 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
  163                        td);
  164 
  165                 if ((error = namei(&ndroot)) != 0) {
  166                         /* Cannot happen! */
  167                         NDFREE(&nd, NDF_ONLY_PNBUF);
  168                         vrele(nd.ni_vp);
  169                         goto keeporig;
  170                 }
  171 
  172                 if ((error = VOP_GETATTR(nd.ni_vp, &vat, td->td_ucred, td)) != 0) {
  173                         goto bad;
  174                 }
  175 
  176                 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, td->td_ucred, td))
  177                     != 0) {
  178                         goto bad;
  179                 }
  180 
  181                 if (vat.va_fsid == vatroot.va_fsid &&
  182                     vat.va_fileid == vatroot.va_fileid) {
  183                         error = ENOENT;
  184                         goto bad;
  185                 }
  186 
  187         }
  188 
  189         NDFREE(&nd, NDF_ONLY_PNBUF);
  190         vrele(nd.ni_vp);
  191         if (!cflag) {
  192                 NDFREE(&ndroot, NDF_ONLY_PNBUF);
  193                 vrele(ndroot.ni_vp);
  194         }
  195         return error;
  196 
  197 bad:
  198         NDFREE(&ndroot, NDF_ONLY_PNBUF);
  199         vrele(ndroot.ni_vp);
  200         NDFREE(&nd, NDF_ONLY_PNBUF);
  201         vrele(nd.ni_vp);
  202 keeporig:
  203         /* Keep the original path; copy it back to the start of the buffer. */
  204         bcopy(ptr, buf, len);
  205         return error;
  206 }
  207 
  208 void
  209 linux_msg(const struct thread *td, const char *fmt, ...)
  210 {
  211         va_list ap;
  212         struct proc *p;
  213 
  214         p = td->td_proc;
  215         printf("linux: pid %d (%s): ", (int)p->p_pid, p->p_comm);
  216         va_start(ap, fmt);
  217         vprintf(fmt, ap);
  218         va_end(ap);
  219         printf("\n");
  220 }

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FreeBSD/Linux Kernel Cross Reference sys/compat/linux/linux_util.c

FreeBSD/Linux Kernel Cross Reference
sys/compat/linux/linux_util.c