Logo Search packages:      
Sourcecode: pax version File versions  Download package

tables.c

/*    $OpenBSD: tables.c,v 1.25 2007/09/02 15:19:08 deraadt Exp $ */
/*    $NetBSD: tables.c,v 1.4 1995/03/21 09:07:45 cgd Exp $ */

/*-
 * Copyright (c) 1992 Keith Muller.
 * Copyright (c) 1992, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Keith Muller of the University of California, San Diego.
 *
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#ifndef lint
#if 0
static const char sccsid[] = "@(#)tables.c      8.1 (Berkeley) 5/31/93";
#else
static const char rcsid[] = "$OpenBSD: tables.c,v 1.25 2007/09/02 15:19:08 deraadt Exp $";
#endif
#endif /* not lint */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include "pax.h"
#include "tables.h"
#include "extern.h"

/*
 * Routines for controlling the contents of all the different databases pax
 * keeps. Tables are dynamically created only when they are needed. The
 * goal was speed and the ability to work with HUGE archives. The databases
 * were kept simple, but do have complex rules for when the contents change.
 * As of this writing, the posix library functions were more complex than
 * needed for this application (pax databases have very short lifetimes and
 * do not survive after pax is finished). Pax is required to handle very
 * large archives. These database routines carefully combine memory usage and
 * temporary file storage in ways which will not significantly impact runtime
 * performance while allowing the largest possible archives to be handled.
 * Trying to force the fit to the posix database routines was not considered
 * time well spent.
 */

static HRDLNK **ltab = NULL;  /* hard link table for detecting hard links */
static FTM **ftab = NULL;     /* file time table for updating arch */
static NAMT **ntab = NULL;    /* interactive rename storage table */
static DEVT **dtab = NULL;    /* device/inode mapping tables */
static ATDIR **atab = NULL;   /* file tree directory time reset table */
static DIRDATA *dirp = NULL;  /* storage for setting created dir time/mode */
static size_t dirsize;        /* size of dirp table */
static long dircnt = 0;       /* entries in dir time/mode storage */
static int ffd = -1;          /* tmp file for file time table name storage */

static DEVT *chk_dev(dev_t, int);

/*
 * hard link table routines
 *
 * The hard link table tries to detect hard links to files using the device and
 * inode values. We do this when writing an archive, so we can tell the format
 * write routine that this file is a hard link to another file. The format
 * write routine then can store this file in whatever way it wants (as a hard
 * link if the format supports that like tar, or ignore this info like cpio).
 * (Actually a field in the format driver table tells us if the format wants
 * hard link info. if not, we do not waste time looking for them). We also use
 * the same table when reading an archive. In that situation, this table is
 * used by the format read routine to detect hard links from stored dev and
 * inode numbers (like cpio). This will allow pax to create a link when one
 * can be detected by the archive format.
 */

/*
 * lnk_start
 *    Creates the hard link table.
 * Return:
 *    0 if created, -1 if failure
 */

int
lnk_start(void)
{
      if (ltab != NULL)
            return(0);
      if ((ltab = (HRDLNK **)calloc(L_TAB_SZ, sizeof(HRDLNK *))) == NULL) {
            paxwarn(1, "Cannot allocate memory for hard link table");
            return(-1);
      }
      return(0);
}

/*
 * chk_lnk()
 *    Looks up entry in hard link hash table. If found, it copies the name
 *    of the file it is linked to (we already saw that file) into ln_name.
 *    lnkcnt is decremented and if goes to 1 the node is deleted from the
 *    database. (We have seen all the links to this file). If not found,
 *    we add the file to the database if it has the potential for having
 *    hard links to other files we may process (it has a link count > 1)
 * Return:
 *    if found returns 1; if not found returns 0; -1 on error
 */

int
chk_lnk(ARCHD *arcn)
{
      HRDLNK *pt;
      HRDLNK **ppt;
      u_int indx;

      if (ltab == NULL)
            return(-1);
      /*
       * ignore those nodes that cannot have hard links
       */
      if ((arcn->type == PAX_DIR) || (arcn->sb.st_nlink <= 1))
            return(0);

      /*
       * hash inode number and look for this file
       */
      indx = ((unsigned)arcn->sb.st_ino) % L_TAB_SZ;
      if ((pt = ltab[indx]) != NULL) {
            /*
             * its hash chain in not empty, walk down looking for it
             */
            ppt = &(ltab[indx]);
            while (pt != NULL) {
                  if ((pt->ino == arcn->sb.st_ino) &&
                      (pt->dev == arcn->sb.st_dev))
                        break;
                  ppt = &(pt->fow);
                  pt = pt->fow;
            }

            if (pt != NULL) {
                  /*
                   * found a link. set the node type and copy in the
                   * name of the file it is to link to. we need to
                   * handle hardlinks to regular files differently than
                   * other links.
                   */
                  arcn->ln_nlen = strlcpy(arcn->ln_name, pt->name,
                        sizeof(arcn->ln_name));
                  /* XXX truncate? */
                  if (arcn->nlen >= sizeof(arcn->name))
                        arcn->nlen = sizeof(arcn->name) - 1;
                  if (arcn->type == PAX_REG)
                        arcn->type = PAX_HRG;
                  else
                        arcn->type = PAX_HLK;

                  /*
                   * if we have found all the links to this file, remove
                   * it from the database
                   */
                  if (--pt->nlink <= 1) {
                        *ppt = pt->fow;
                        (void)free((char *)pt->name);
                        (void)free((char *)pt);
                  }
                  return(1);
            }
      }

      /*
       * we never saw this file before. It has links so we add it to the
       * front of this hash chain
       */
      if ((pt = (HRDLNK *)malloc(sizeof(HRDLNK))) != NULL) {
            if ((pt->name = strdup(arcn->name)) != NULL) {
                  pt->dev = arcn->sb.st_dev;
                  pt->ino = arcn->sb.st_ino;
                  pt->nlink = arcn->sb.st_nlink;
                  pt->fow = ltab[indx];
                  ltab[indx] = pt;
                  return(0);
            }
            (void)free((char *)pt);
      }

      paxwarn(1, "Hard link table out of memory");
      return(-1);
}

/*
 * purg_lnk
 *    remove reference for a file that we may have added to the data base as
 *    a potential source for hard links. We ended up not using the file, so
 *    we do not want to accidently point another file at it later on.
 */

void
purg_lnk(ARCHD *arcn)
{
      HRDLNK *pt;
      HRDLNK **ppt;
      u_int indx;

      if (ltab == NULL)
            return;
      /*
       * do not bother to look if it could not be in the database
       */
      if ((arcn->sb.st_nlink <= 1) || (arcn->type == PAX_DIR) ||
          (arcn->type == PAX_HLK) || (arcn->type == PAX_HRG))
            return;

      /*
       * find the hash chain for this inode value, if empty return
       */
      indx = ((unsigned)arcn->sb.st_ino) % L_TAB_SZ;
      if ((pt = ltab[indx]) == NULL)
            return;

      /*
       * walk down the list looking for the inode/dev pair, unlink and
       * free if found
       */
      ppt = &(ltab[indx]);
      while (pt != NULL) {
            if ((pt->ino == arcn->sb.st_ino) &&
                (pt->dev == arcn->sb.st_dev))
                  break;
            ppt = &(pt->fow);
            pt = pt->fow;
      }
      if (pt == NULL)
            return;

      /*
       * remove and free it
       */
      *ppt = pt->fow;
      (void)free((char *)pt->name);
      (void)free((char *)pt);
}

/*
 * lnk_end()
 *    pull apart a existing link table so we can reuse it. We do this between
 *    read and write phases of append with update. (The format may have
 *    used the link table, and we need to start with a fresh table for the
 *    write phase
 */

void
lnk_end(void)
{
      int i;
      HRDLNK *pt;
      HRDLNK *ppt;

      if (ltab == NULL)
            return;

      for (i = 0; i < L_TAB_SZ; ++i) {
            if (ltab[i] == NULL)
                  continue;
            pt = ltab[i];
            ltab[i] = NULL;

            /*
             * free up each entry on this chain
             */
            while (pt != NULL) {
                  ppt = pt;
                  pt = ppt->fow;
                  (void)free((char *)ppt->name);
                  (void)free((char *)ppt);
            }
      }
      return;
}

/*
 * modification time table routines
 *
 * The modification time table keeps track of last modification times for all
 * files stored in an archive during a write phase when -u is set. We only
 * add a file to the archive if it is newer than a file with the same name
 * already stored on the archive (if there is no other file with the same
 * name on the archive it is added). This applies to writes and appends.
 * An append with an -u must read the archive and store the modification time
 * for every file on that archive before starting the write phase. It is clear
 * that this is one HUGE database. To save memory space, the actual file names
 * are stored in a scratch file and indexed by an in-memory hash table. The
 * hash table is indexed by hashing the file path. The nodes in the table store
 * the length of the filename and the lseek offset within the scratch file
 * where the actual name is stored. Since there are never any deletions from
 * this table, fragmentation of the scratch file is never a issue. Lookups 
 * seem to not exhibit any locality at all (files in the database are rarely
 * looked up more than once...), so caching is just a waste of memory. The
 * only limitation is the amount of scratch file space available to store the
 * path names.
 */

/*
 * ftime_start()
 *    create the file time hash table and open for read/write the scratch
 *    file. (after created it is unlinked, so when we exit we leave
 *    no witnesses).
 * Return:
 *    0 if the table and file was created ok, -1 otherwise
 */

int
ftime_start(void)
{

      if (ftab != NULL)
            return(0);
      if ((ftab = (FTM **)calloc(F_TAB_SZ, sizeof(FTM *))) == NULL) {
            paxwarn(1, "Cannot allocate memory for file time table");
            return(-1);
      }

      /*
       * get random name and create temporary scratch file, unlink name
       * so it will get removed on exit
       */
      memcpy(tempbase, _TFILE_BASE, sizeof(_TFILE_BASE));
      if ((ffd = mkstemp(tempfile)) < 0) {
            syswarn(1, errno, "Unable to create temporary file: %s",
                tempfile);
            return(-1);
      }
      (void)unlink(tempfile);

      return(0);
}

/*
 * chk_ftime()
 *    looks up entry in file time hash table. If not found, the file is
 *    added to the hash table and the file named stored in the scratch file.
 *    If a file with the same name is found, the file times are compared and
 *    the most recent file time is retained. If the new file was younger (or
 *    was not in the database) the new file is selected for storage.
 * Return:
 *    0 if file should be added to the archive, 1 if it should be skipped,
 *    -1 on error
 */

int
chk_ftime(ARCHD *arcn)
{
      FTM *pt;
      int namelen;
      u_int indx;
      char ckname[PAXPATHLEN+1];

      /*
       * no info, go ahead and add to archive
       */
      if (ftab == NULL)
            return(0);

      /*
       * hash the pathname and look up in table
       */
      namelen = arcn->nlen;
      indx = st_hash(arcn->name, namelen, F_TAB_SZ);
      if ((pt = ftab[indx]) != NULL) {
            /*
             * the hash chain is not empty, walk down looking for match
             * only read up the path names if the lengths match, speeds
             * up the search a lot
             */
            while (pt != NULL) {
                  if (pt->namelen == namelen) {
                        /*
                         * potential match, have to read the name
                         * from the scratch file.
                         */
                        if (lseek(ffd,pt->seek,SEEK_SET) != pt->seek) {
                              syswarn(1, errno,
                                  "Failed ftime table seek");
                              return(-1);
                        }
                        if (read(ffd, ckname, namelen) != namelen) {
                              syswarn(1, errno,
                                  "Failed ftime table read");
                              return(-1);
                        }

                        /*
                         * if the names match, we are done
                         */
                        if (!strncmp(ckname, arcn->name, namelen))
                              break;
                  }

                  /*
                   * try the next entry on the chain
                   */
                  pt = pt->fow;
            }

            if (pt != NULL) {
                  /*
                   * found the file, compare the times, save the newer
                   */
                  if (arcn->sb.st_mtime > pt->mtime) {
                        /*
                         * file is newer
                         */
                        pt->mtime = arcn->sb.st_mtime;
                        return(0);
                  }
                  /*
                   * file is older
                   */
                  return(1);
            }
      }

      /*
       * not in table, add it
       */
      if ((pt = (FTM *)malloc(sizeof(FTM))) != NULL) {
            /*
             * add the name at the end of the scratch file, saving the
             * offset. add the file to the head of the hash chain
             */
            if ((pt->seek = lseek(ffd, (off_t)0, SEEK_END)) >= 0) {
                  if (write(ffd, arcn->name, namelen) == namelen) {
                        pt->mtime = arcn->sb.st_mtime;
                        pt->namelen = namelen;
                        pt->fow = ftab[indx];
                        ftab[indx] = pt;
                        return(0);
                  }
                  syswarn(1, errno, "Failed write to file time table");
            } else
                  syswarn(1, errno, "Failed seek on file time table");
      } else
            paxwarn(1, "File time table ran out of memory");

      if (pt != NULL)
            (void)free((char *)pt);
      return(-1);
}

/*
 * Interactive rename table routines
 *
 * The interactive rename table keeps track of the new names that the user
 * assigns to files from tty input. Since this map is unique for each file
 * we must store it in case there is a reference to the file later in archive
 * (a link). Otherwise we will be unable to find the file we know was
 * extracted. The remapping of these files is stored in a memory based hash
 * table (it is assumed since input must come from /dev/tty, it is unlikely to
 * be a very large table).
 */

/*
 * name_start()
 *    create the interactive rename table
 * Return:
 *    0 if successful, -1 otherwise
 */

int
name_start(void)
{
      if (ntab != NULL)
            return(0);
      if ((ntab = (NAMT **)calloc(N_TAB_SZ, sizeof(NAMT *))) == NULL) {
            paxwarn(1, "Cannot allocate memory for interactive rename table");
            return(-1);
      }
      return(0);
}

/*
 * add_name()
 *    add the new name to old name mapping just created by the user.
 *    If an old name mapping is found (there may be duplicate names on an
 *    archive) only the most recent is kept.
 * Return:
 *    0 if added, -1 otherwise
 */

int
add_name(char *oname, int onamelen, char *nname)
{
      NAMT *pt;
      u_int indx;

      if (ntab == NULL) {
            /*
             * should never happen
             */
            paxwarn(0, "No interactive rename table, links may fail");
            return(0);
      }

      /*
       * look to see if we have already mapped this file, if so we
       * will update it
       */
      indx = st_hash(oname, onamelen, N_TAB_SZ);
      if ((pt = ntab[indx]) != NULL) {
            /*
             * look down the has chain for the file
             */
            while ((pt != NULL) && (strcmp(oname, pt->oname) != 0))
                  pt = pt->fow;

            if (pt != NULL) {
                  /*
                   * found an old mapping, replace it with the new one
                   * the user just input (if it is different)
                   */
                  if (strcmp(nname, pt->nname) == 0)
                        return(0);

                  (void)free((char *)pt->nname);
                  if ((pt->nname = strdup(nname)) == NULL) {
                        paxwarn(1, "Cannot update rename table");
                        return(-1);
                  }
                  return(0);
            }
      }

      /*
       * this is a new mapping, add it to the table
       */
      if ((pt = (NAMT *)malloc(sizeof(NAMT))) != NULL) {
            if ((pt->oname = strdup(oname)) != NULL) {
                  if ((pt->nname = strdup(nname)) != NULL) {
                        pt->fow = ntab[indx];
                        ntab[indx] = pt;
                        return(0);
                  }
                  (void)free((char *)pt->oname);
            }
            (void)free((char *)pt);
      }
      paxwarn(1, "Interactive rename table out of memory");
      return(-1);
}

/*
 * sub_name()
 *    look up a link name to see if it points at a file that has been
 *    remapped by the user. If found, the link is adjusted to contain the
 *    new name (oname is the link to name)
 */

void
sub_name(char *oname, int *onamelen, size_t onamesize)
{
      NAMT *pt;
      u_int indx;

      if (ntab == NULL)
            return;
      /*
       * look the name up in the hash table
       */
      indx = st_hash(oname, *onamelen, N_TAB_SZ);
      if ((pt = ntab[indx]) == NULL)
            return;

      while (pt != NULL) {
            /*
             * walk down the hash chain looking for a match
             */
            if (strcmp(oname, pt->oname) == 0) {
                  /*
                   * found it, replace it with the new name
                   * and return (we know that oname has enough space)
                   */
                  *onamelen = strlcpy(oname, pt->nname, onamesize);
                  if (*onamelen >= onamesize)
                        *onamelen = onamesize - 1; /* XXX truncate? */
                  return;
            }
            pt = pt->fow;
      }

      /*
       * no match, just return
       */
      return;
}

/*
 * device/inode mapping table routines
 * (used with formats that store device and inodes fields)
 *
 * device/inode mapping tables remap the device field in a archive header. The
 * device/inode fields are used to determine when files are hard links to each
 * other. However these values have very little meaning outside of that. This
 * database is used to solve one of two different problems.
 *
 * 1) when files are appended to an archive, while the new files may have hard
 * links to each other, you cannot determine if they have hard links to any
 * file already stored on the archive from a prior run of pax. We must assume
 * that these inode/device pairs are unique only within a SINGLE run of pax
 * (which adds a set of files to an archive). So we have to make sure the
 * inode/dev pairs we add each time are always unique. We do this by observing
 * while the inode field is very dense, the use of the dev field is fairly
 * sparse. Within each run of pax, we remap any device number of a new archive
 * member that has a device number used in a prior run and already stored in a
 * file on the archive. During the read phase of the append, we store the
 * device numbers used and mark them to not be used by any file during the
 * write phase. If during write we go to use one of those old device numbers,
 * we remap it to a new value.
 *
 * 2) Often the fields in the archive header used to store these values are
 * too small to store the entire value. The result is an inode or device value
 * which can be truncated. This really can foul up an archive. With truncation
 * we end up creating links between files that are really not links (after
 * truncation the inodes are the same value). We address that by detecting
 * truncation and forcing a remap of the device field to split truncated
 * inodes away from each other. Each truncation creates a pattern of bits that
 * are removed. We use this pattern of truncated bits to partition the inodes
 * on a single device to many different devices (each one represented by the
 * truncated bit pattern). All inodes on the same device that have the same
 * truncation pattern are mapped to the same new device. Two inodes that
 * truncate to the same value clearly will always have different truncation
 * bit patterns, so they will be split from away each other. When we spot
 * device truncation we remap the device number to a non truncated value.
 * (for more info see table.h for the data structures involved).
 */

/*
 * dev_start()
 *    create the device mapping table
 * Return:
 *    0 if successful, -1 otherwise
 */

int
dev_start(void)
{
      if (dtab != NULL)
            return(0);
      if ((dtab = (DEVT **)calloc(D_TAB_SZ, sizeof(DEVT *))) == NULL) {
            paxwarn(1, "Cannot allocate memory for device mapping table");
            return(-1);
      }
      return(0);
}

/*
 * add_dev()
 *    add a device number to the table. this will force the device to be
 *    remapped to a new value if it be used during a write phase. This
 *    function is called during the read phase of an append to prohibit the
 *    use of any device number already in the archive.
 * Return:
 *    0 if added ok, -1 otherwise
 */

int
add_dev(ARCHD *arcn)
{
      if (chk_dev(arcn->sb.st_dev, 1) == NULL)
            return(-1);
      return(0);
}

/*
 * chk_dev()
 *    check for a device value in the device table. If not found and the add
 *    flag is set, it is added. This does NOT assign any mapping values, just
 *    adds the device number as one that need to be remapped. If this device
 *    is already mapped, just return with a pointer to that entry.
 * Return:
 *    pointer to the entry for this device in the device map table. Null
 *    if the add flag is not set and the device is not in the table (it is
 *    not been seen yet). If add is set and the device cannot be added, null
 *    is returned (indicates an error).
 */

static DEVT *
chk_dev(dev_t dev, int add)
{
      DEVT *pt;
      u_int indx;

      if (dtab == NULL)
            return(NULL);
      /*
       * look to see if this device is already in the table
       */
      indx = ((unsigned)dev) % D_TAB_SZ;
      if ((pt = dtab[indx]) != NULL) {
            while ((pt != NULL) && (pt->dev != dev))
                  pt = pt->fow;

            /*
             * found it, return a pointer to it
             */
            if (pt != NULL)
                  return(pt);
      }

      /*
       * not in table, we add it only if told to as this may just be a check
       * to see if a device number is being used.
       */
      if (add == 0)
            return(NULL);

      /*
       * allocate a node for this device and add it to the front of the hash
       * chain. Note we do not assign remaps values here, so the pt->list
       * list must be NULL.
       */
      if ((pt = (DEVT *)malloc(sizeof(DEVT))) == NULL) {
            paxwarn(1, "Device map table out of memory");
            return(NULL);
      }
      pt->dev = dev;
      pt->list = NULL;
      pt->fow = dtab[indx];
      dtab[indx] = pt;
      return(pt);
}
/*
 * map_dev()
 *    given an inode and device storage mask (the mask has a 1 for each bit
 *    the archive format is able to store in a header), we check for inode
 *    and device truncation and remap the device as required. Device mapping
 *    can also occur when during the read phase of append a device number was
 *    seen (and was marked as do not use during the write phase). WE ASSUME
 *    that unsigned longs are the same size or bigger than the fields used
 *    for ino_t and dev_t. If not the types will have to be changed.
 * Return:
 *    0 if all ok, -1 otherwise.
 */

int
map_dev(ARCHD *arcn, u_long dev_mask, u_long ino_mask)
{
      DEVT *pt;
      DLIST *dpt;
      static dev_t lastdev = 0;     /* next device number to try */
      int trc_ino = 0;
      int trc_dev = 0;
      ino_t trunc_bits = 0;
      ino_t nino;

      if (dtab == NULL)
            return(0);
      /*
       * check for device and inode truncation, and extract the truncated
       * bit pattern.
       */
      if ((arcn->sb.st_dev & (dev_t)dev_mask) != arcn->sb.st_dev)
            ++trc_dev;
      if ((nino = arcn->sb.st_ino & (ino_t)ino_mask) != arcn->sb.st_ino) {
            ++trc_ino;
            trunc_bits = arcn->sb.st_ino & (ino_t)(~ino_mask);
      }

      /*
       * see if this device is already being mapped, look up the device
       * then find the truncation bit pattern which applies
       */
      if ((pt = chk_dev(arcn->sb.st_dev, 0)) != NULL) {
            /*
             * this device is already marked to be remapped
             */
            for (dpt = pt->list; dpt != NULL; dpt = dpt->fow)
                  if (dpt->trunc_bits == trunc_bits)
                        break;

            if (dpt != NULL) {
                  /*
                   * we are being remapped for this device and pattern
                   * change the device number to be stored and return
                   */
                  arcn->sb.st_dev = dpt->dev;
                  arcn->sb.st_ino = nino;
                  return(0);
            }
      } else {
            /*
             * this device is not being remapped YET. if we do not have any
             * form of truncation, we do not need a remap
             */
            if (!trc_ino && !trc_dev)
                  return(0);

            /*
             * we have truncation, have to add this as a device to remap
             */
            if ((pt = chk_dev(arcn->sb.st_dev, 1)) == NULL)
                  goto bad;

            /*
             * if we just have a truncated inode, we have to make sure that
             * all future inodes that do not truncate (they have the
             * truncation pattern of all 0's) continue to map to the same
             * device number. We probably have already written inodes with
             * this device number to the archive with the truncation
             * pattern of all 0's. So we add the mapping for all 0's to the
             * same device number.
             */
            if (!trc_dev && (trunc_bits != 0)) {
                  if ((dpt = (DLIST *)malloc(sizeof(DLIST))) == NULL)
                        goto bad;
                  dpt->trunc_bits = 0;
                  dpt->dev = arcn->sb.st_dev;
                  dpt->fow = pt->list;
                  pt->list = dpt;
            }
      }

      /*
       * look for a device number not being used. We must watch for wrap
       * around on lastdev (so we do not get stuck looking forever!)
       */
      while (++lastdev > 0) {
            if (chk_dev(lastdev, 0) != NULL)
                  continue;
            /*
             * found an unused value. If we have reached truncation point
             * for this format we are hosed, so we give up. Otherwise we
             * mark it as being used.
             */
            if (((lastdev & ((dev_t)dev_mask)) != lastdev) ||
                (chk_dev(lastdev, 1) == NULL))
                  goto bad;
            break;
      }

      if ((lastdev <= 0) || ((dpt = (DLIST *)malloc(sizeof(DLIST))) == NULL))
            goto bad;

      /*
       * got a new device number, store it under this truncation pattern.
       * change the device number this file is being stored with.
       */
      dpt->trunc_bits = trunc_bits;
      dpt->dev = lastdev;
      dpt->fow = pt->list;
      pt->list = dpt;
      arcn->sb.st_dev = lastdev;
      arcn->sb.st_ino = nino;
      return(0);

    bad:
      paxwarn(1, "Unable to fix truncated inode/device field when storing %s",
          arcn->name);
      paxwarn(0, "Archive may create improper hard links when extracted");
      return(0);
}

/*
 * directory access/mod time reset table routines (for directories READ by pax)
 *
 * The pax -t flag requires that access times of archive files be the same
 * before being read by pax. For regular files, access time is restored after
 * the file has been copied. This database provides the same functionality for
 * directories read during file tree traversal. Restoring directory access time
 * is more complex than files since directories may be read several times until
 * all the descendants in their subtree are visited by fts. Directory access
 * and modification times are stored during the fts pre-order visit (done
 * before any descendants in the subtree are visited) and restored after the
 * fts post-order visit (after all the descendants have been visited). In the
 * case of premature exit from a subtree (like from the effects of -n), any
 * directory entries left in this database are reset during final cleanup
 * operations of pax. Entries are hashed by inode number for fast lookup.
 */

/*
 * atdir_start()
 *    create the directory access time database for directories READ by pax.
 * Return:
 *    0 is created ok, -1 otherwise.
 */

int
atdir_start(void)
{
      if (atab != NULL)
            return(0);
      if ((atab = (ATDIR **)calloc(A_TAB_SZ, sizeof(ATDIR *))) == NULL) {
            paxwarn(1,"Cannot allocate space for directory access time table");
            return(-1);
      }
      return(0);
}


/*
 * atdir_end()
 *    walk through the directory access time table and reset the access time
 *    of any directory who still has an entry left in the database. These
 *    entries are for directories READ by pax
 */

void
atdir_end(void)
{
      ATDIR *pt;
      int i;

      if (atab == NULL)
            return;
      /*
       * for each non-empty hash table entry reset all the directories
       * chained there.
       */
      for (i = 0; i < A_TAB_SZ; ++i) {
            if ((pt = atab[i]) == NULL)
                  continue;
            /*
             * remember to force the times, set_ftime() looks at pmtime
             * and patime, which only applies to things CREATED by pax,
             * not read by pax. Read time reset is controlled by -t.
             */
            for (; pt != NULL; pt = pt->fow)
                  set_ftime(pt->name, pt->mtime, pt->atime, 1);
      }
}

/*
 * add_atdir()
 *    add a directory to the directory access time table. Table is hashed
 *    and chained by inode number. This is for directories READ by pax
 */

void
add_atdir(char *fname, dev_t dev, ino_t ino, time_t mtime, time_t atime)
{
      ATDIR *pt;
      u_int indx;

      if (atab == NULL)
            return;

      /*
       * make sure this directory is not already in the table, if so just
       * return (the older entry always has the correct time). The only
       * way this will happen is when the same subtree can be traversed by
       * different args to pax and the -n option is aborting fts out of a
       * subtree before all the post-order visits have been made.
       */
      indx = ((unsigned)ino) % A_TAB_SZ;
      if ((pt = atab[indx]) != NULL) {
            while (pt != NULL) {
                  if ((pt->ino == ino) && (pt->dev == dev))
                        break;
                  pt = pt->fow;
            }

            /*
             * oops, already there. Leave it alone.
             */
            if (pt != NULL)
                  return;
      }

      /*
       * add it to the front of the hash chain
       */
      if ((pt = (ATDIR *)malloc(sizeof(ATDIR))) != NULL) {
            if ((pt->name = strdup(fname)) != NULL) {
                  pt->dev = dev;
                  pt->ino = ino;
                  pt->mtime = mtime;
                  pt->atime = atime;
                  pt->fow = atab[indx];
                  atab[indx] = pt;
                  return;
            }
            (void)free((char *)pt);
      }

      paxwarn(1, "Directory access time reset table ran out of memory");
      return;
}

/*
 * get_atdir()
 *    look up a directory by inode and device number to obtain the access
 *    and modification time you want to set to. If found, the modification
 *    and access time parameters are set and the entry is removed from the
 *    table (as it is no longer needed). These are for directories READ by
 *    pax
 * Return:
 *    0 if found, -1 if not found.
 */

int
get_atdir(dev_t dev, ino_t ino, time_t *mtime, time_t *atime)
{
      ATDIR *pt;
      ATDIR **ppt;
      u_int indx;

      if (atab == NULL)
            return(-1);
      /*
       * hash by inode and search the chain for an inode and device match
       */
      indx = ((unsigned)ino) % A_TAB_SZ;
      if ((pt = atab[indx]) == NULL)
            return(-1);

      ppt = &(atab[indx]);
      while (pt != NULL) {
            if ((pt->ino == ino) && (pt->dev == dev))
                  break;
            /*
             * no match, go to next one
             */
            ppt = &(pt->fow);
            pt = pt->fow;
      }

      /*
       * return if we did not find it.
       */
      if (pt == NULL)
            return(-1);

      /*
       * found it. return the times and remove the entry from the table.
       */
      *ppt = pt->fow;
      *mtime = pt->mtime;
      *atime = pt->atime;
      (void)free((char *)pt->name);
      (void)free((char *)pt);
      return(0);
}

/*
 * directory access mode and time storage routines (for directories CREATED
 * by pax).
 *
 * Pax requires that extracted directories, by default, have their access/mod
 * times and permissions set to the values specified in the archive. During the
 * actions of extracting (and creating the destination subtree during -rw copy)
 * directories extracted may be modified after being created. Even worse is
 * that these directories may have been created with file permissions which
 * prohibits any descendants of these directories from being extracted. When
 * directories are created by pax, access rights may be added to permit the
 * creation of files in their subtree. Every time pax creates a directory, the
 * times and file permissions specified by the archive are stored. After all
 * files have been extracted (or copied), these directories have their times
 * and file modes reset to the stored values. The directory info is restored in
 * reverse order as entries were added to the data file from root to leaf. To
 * restore atime properly, we must go backwards. The data file consists of
 * records with two parts, the file name followed by a DIRDATA trailer. The
 * fixed sized trailer contains the size of the name plus the off_t location in
 * the file. To restore we work backwards through the file reading the trailer
 * then the file name.
 */

/*
 * dir_start()
 *    set up the directory time and file mode storage for directories CREATED
 *    by pax.
 * Return:
 *    0 if ok, -1 otherwise
 */

int
dir_start(void)
{
      if (dirp != NULL)
            return(0);

      dirsize = DIRP_SIZE;
      if ((dirp = calloc(dirsize, sizeof(DIRDATA))) == NULL) {
            paxwarn(1, "Unable to allocate memory for directory times");
            return(-1);
      }
      return(0);
}

/*
 * add_dir()
 *    add the mode and times for a newly CREATED directory
 *    name is name of the directory, psb the stat buffer with the data in it,
 *    frc_mode is a flag that says whether to force the setting of the mode
 *    (ignoring the user set values for preserving file mode). Frc_mode is
 *    for the case where we created a file and found that the resulting
 *    directory was not writeable and the user asked for file modes to NOT
 *    be preserved. (we have to preserve what was created by default, so we
 *    have to force the setting at the end. this is stated explicitly in the
 *    pax spec)
 */

void
add_dir(char *name, struct stat *psb, int frc_mode)
{
      DIRDATA *dblk;
      char realname[MAXPATHLEN], *rp;

      if (dirp == NULL)
            return;

      if (havechd && *name != '/') {
            if ((rp = realpath(name, realname)) == NULL) {
                  paxwarn(1, "Cannot canonicalize %s", name);
                  return;
            }
            name = rp;
      }
      if (dircnt == dirsize) {
            dblk = realloc(dirp, 2 * dirsize * sizeof(DIRDATA));
            if (dblk == NULL) {
                  paxwarn(1, "Unable to store mode and times for created"
                      " directory: %s", name);
                  return;
            }
            dirp = dblk;
            dirsize *= 2;
      }
      dblk = &dirp[dircnt];
      if ((dblk->name = strdup(name)) == NULL) {
            paxwarn(1, "Unable to store mode and times for created"
                " directory: %s", name);
            return;
      }
      dblk->mode = psb->st_mode & 0xffff;
      dblk->mtime = psb->st_mtime;
      dblk->atime = psb->st_atime;
      dblk->frc_mode = frc_mode;
      ++dircnt;
}

/*
 * proc_dir()
 *    process all file modes and times stored for directories CREATED
 *    by pax
 */

void
proc_dir(void)
{
      DIRDATA *dblk;
      long cnt;

      if (dirp == NULL)
            return;
      /*
       * read backwards through the file and process each directory
       */
      cnt = dircnt;
      while (--cnt >= 0) {
            /*
             * frc_mode set, make sure we set the file modes even if
             * the user didn't ask for it (see file_subs.c for more info)
             */
            dblk = &dirp[cnt];
            if (pmode || dblk->frc_mode)
                  set_pmode(dblk->name, dblk->mode);
            if (patime || pmtime)
                  set_ftime(dblk->name, dblk->mtime, dblk->atime, 0);
            free(dblk->name);
      }

      free(dirp);
      dirp = NULL;
      dircnt = 0;
}

/*
 * database independent routines
 */

/*
 * st_hash()
 *    hashes filenames to a u_int for hashing into a table. Looks at the tail
 *    end of file, as this provides far better distribution than any other
 *    part of the name. For performance reasons we only care about the last
 *    MAXKEYLEN chars (should be at LEAST large enough to pick off the file
 *    name). Was tested on 500,000 name file tree traversal from the root
 *    and gave almost a perfectly uniform distribution of keys when used with
 *    prime sized tables (MAXKEYLEN was 128 in test). Hashes (sizeof int)
 *    chars at a time and pads with 0 for last addition.
 * Return:
 *    the hash value of the string MOD (%) the table size.
 */

u_int
st_hash(char *name, int len, int tabsz)
{
      char *pt;
      char *dest;
      char *end;
      int i;
      u_int key = 0;
      int steps;
      int res;
      u_int val;

      /*
       * only look at the tail up to MAXKEYLEN, we do not need to waste
       * time here (remember these are pathnames, the tail is what will
       * spread out the keys)
       */
      if (len > MAXKEYLEN) {
            pt = &(name[len - MAXKEYLEN]);
            len = MAXKEYLEN;
      } else
            pt = name;

      /*
       * calculate the number of u_int size steps in the string and if
       * there is a runt to deal with
       */
      steps = len/sizeof(u_int);
      res = len % sizeof(u_int);

      /*
       * add up the value of the string in unsigned integer sized pieces
       * too bad we cannot have unsigned int aligned strings, then we
       * could avoid the expensive copy.
       */
      for (i = 0; i < steps; ++i) {
            end = pt + sizeof(u_int);
            dest = (char *)&val;
            while (pt < end)
                  *dest++ = *pt++;
            key += val;
      }

      /*
       * add in the runt padded with zero to the right
       */
      if (res) {
            val = 0;
            end = pt + res;
            dest = (char *)&val;
            while (pt < end)
                  *dest++ = *pt++;
            key += val;
      }

      /*
       * return the result mod the table size
       */
      return(key % tabsz);
}

Generated by  Doxygen 1.6.0   Back to index