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

     /*-
      * Copyright (c) 1994 Christos Zoulas
      * Copyright (c) 1995 Frank van der Linden
      * Copyright (c) 1995 Scott Bartram
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     *      from: svr4_util.c,v 1.5 1995/01/22 23:44:50 christos Exp
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/5.4/sys/compat/linux/linux_util.c 141016 2005-01-30 01:00:13Z imp $");
    
    #include <sys/param.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/namei.h>
    #include <sys/proc.h>
    #include <sys/systm.h>
    #include <sys/vnode.h>
    
    #include <machine/stdarg.h>
    
    #include <compat/linux/linux_util.h>
    
    const char      linux_emul_path[] = "/compat/linux";
    
    /*
     * Search an alternate path before passing pathname arguments on
     * to system calls. Useful for keeping a separate 'emulation tree'.
     *
     * If cflag is set, we check if an attempt can be made to create
     * the named file, i.e. we check if the directory it should
     * be in exists.
     */
    int
    linux_emul_find(td, sgp, path, pbuf, cflag)
            struct thread    *td;
            caddr_t          *sgp;          /* Pointer to stackgap memory */
            char             *path;
            char            **pbuf;
            int               cflag;
    {
            char *newpath;
            size_t sz;
            int error;
    
            error = linux_emul_convpath(td, path, (sgp == NULL) ? UIO_SYSSPACE :
                UIO_USERSPACE, &newpath, cflag);
            if (newpath == NULL)
                    return (error);
    
            if (sgp == NULL) {
                    *pbuf = newpath;
                    return (error);
            }
    
            sz = strlen(newpath);
            *pbuf = stackgap_alloc(sgp, sz + 1);
            if (*pbuf != NULL)
                    error = copyout(newpath, *pbuf, sz + 1);
            else
                    error = ENAMETOOLONG;
            free(newpath, M_TEMP);
    
            return (error);
    }
    
    int
    linux_emul_convpath(td, path, pathseg, pbuf, cflag)
            struct thread    *td;
            char             *path;
            enum uio_seg      pathseg;
            char            **pbuf;
            int               cflag;
    {
            struct nameidata         nd;
           struct nameidata         ndroot;
           int                      error;
           const char              *prefix;
           char                    *ptr, *buf, *cp;
           size_t                   len, sz;
   
           GIANT_REQUIRED;
   
           buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
           *pbuf = buf;
   
           prefix = linux_emul_path;
           for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
                   continue;
           sz = MAXPATHLEN - (ptr - buf);
   
           if (pathseg == UIO_SYSSPACE)
                   error = copystr(path, ptr, sz, &len);
           else
                   error = copyinstr(path, ptr, sz, &len);
   
           if (error) {
                   *pbuf = NULL;
                   free(buf, M_TEMP);
                   return error;
           }
   
           if (*ptr != '/') {
                   error = EINVAL;
                   goto keeporig;
           }
   
           /*
            * We know that there is a / somewhere in this pathname.
            * Search backwards for it, to find the file's parent dir
            * to see if it exists in the alternate tree. If it does,
            * and we want to create a file (cflag is set). We don't
            * need to worry about the root comparison in this case.
            */
   
           if (cflag) {
                   for (cp = &ptr[len] - 1; *cp != '/'; cp--);
                   *cp = '\0';
   
                   NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
                   error = namei(&nd);
                   *cp = '/';
                   if (error != 0)
                           goto keeporig;
           }
           else {
                   NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
   
                   if ((error = namei(&nd)) != 0)
                           goto keeporig;
   
                   /*
                    * We now compare the vnode of the linux_root to the one
                    * vnode asked. If they resolve to be the same, then we
                    * ignore the match so that the real root gets used.
                    * This avoids the problem of traversing "../.." to find the
                    * root directory and never finding it, because "/" resolves
                    * to the emulation root directory. This is expensive :-(
                    */
                   NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
                          td);
   
                   if ((error = namei(&ndroot)) != 0) {
                           /* Cannot happen! */
                           NDFREE(&nd, NDF_ONLY_PNBUF);
                           vrele(nd.ni_vp);
                           goto keeporig;
                   }
   
                   if (nd.ni_vp == ndroot.ni_vp) {
                           error = ENOENT;
                           goto bad;
                   }
   
           }
   
           NDFREE(&nd, NDF_ONLY_PNBUF);
           vrele(nd.ni_vp);
           if (!cflag) {
                   NDFREE(&ndroot, NDF_ONLY_PNBUF);
                   vrele(ndroot.ni_vp);
           }
           return error;
   
   bad:
           NDFREE(&ndroot, NDF_ONLY_PNBUF);
           vrele(ndroot.ni_vp);
           NDFREE(&nd, NDF_ONLY_PNBUF);
           vrele(nd.ni_vp);
   keeporig:
           /* Keep the original path; copy it back to the start of the buffer. */
           bcopy(ptr, buf, len);
           return error;
   }
   
   void
   linux_msg(const struct thread *td, const char *fmt, ...)
   {
           va_list ap;
           struct proc *p;
   
           p = td->td_proc;
           printf("linux: pid %d (%s): ", (int)p->p_pid, p->p_comm);
           va_start(ap, fmt);
           vprintf(fmt, ap);
           va_end(ap);
           printf("\n");
   }

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