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rec_open.c

/*-
 * Copyright (c) 1990, 1993, 1994
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Olson.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the University of
 *    California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)rec_open.c    8.12 (Berkeley) 11/18/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#ifdef RECNO_USE_MMAP
#include <sys/mman.h>
#endif
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <unistd.h>

#include <db.h>
#include "recno.h"

DB *
__rec_open(fname, flags, mode, openinfo, dflags)
      const char *fname;
      int flags, mode, dflags;
      const RECNOINFO *openinfo;
{
      BTREE *t;
      BTREEINFO btopeninfo;
      DB *dbp;
      PAGE *h;
      struct stat sb;
      int rfd, sverrno;

      /* Open the user's file -- if this fails, we're done. */
      if (fname != NULL && (rfd = open(fname, flags, mode)) < 0)
            return (NULL);

      /* Create a btree in memory (backed by disk). */
      dbp = NULL;
      if (openinfo) {
            if (openinfo->flags & ~(R_FIXEDLEN | R_NOKEY | R_SNAPSHOT))
                  goto einval;
            btopeninfo.flags = 0;
            btopeninfo.cachesize = openinfo->cachesize;
            btopeninfo.maxkeypage = 0;
            btopeninfo.minkeypage = 0;
            btopeninfo.psize = openinfo->psize;
            btopeninfo.compare = NULL;
            btopeninfo.prefix = NULL;
            btopeninfo.lorder = openinfo->lorder;
            dbp = __bt_open(openinfo->bfname,
                O_RDWR, S_IRUSR | S_IWUSR, &btopeninfo, dflags);
      } else
            dbp = __bt_open(NULL, O_RDWR, S_IRUSR | S_IWUSR, NULL, dflags);
      if (dbp == NULL)
            goto err;

      /*
       * Some fields in the tree structure are recno specific.  Fill them
       * in and make the btree structure look like a recno structure.  We
       * don't change the bt_ovflsize value, it's close enough and slightly
       * bigger.
       */
      t = dbp->internal;
      if (openinfo) {
            if (openinfo->flags & R_FIXEDLEN) {
                  F_SET(t, R_FIXLEN);
                  t->bt_reclen = openinfo->reclen;
                  if (t->bt_reclen == 0)
                        goto einval;
            }
            t->bt_bval = openinfo->bval;
      } else
            t->bt_bval = '\n';

      F_SET(t, R_RECNO);
      if (fname == NULL)
            F_SET(t, R_EOF | R_INMEM);
      else
            t->bt_rfd = rfd;

      if (fname != NULL) {
            /*
             * In 4.4BSD, stat(2) returns true for ISSOCK on pipes.
             * Unfortunately, that's not portable, so we use lseek
             * and check the errno values.
             */
            errno = 0;
            if (lseek(rfd, (off_t)0, SEEK_CUR) == -1 && errno == ESPIPE) {
                  switch (flags & O_ACCMODE) {
                  case O_RDONLY:
                        F_SET(t, R_RDONLY);
                        break;
                  default:
                        goto einval;
                  }
slow:             if ((t->bt_rfp = fdopen(rfd, "r")) == NULL)
                        goto err;
                  F_SET(t, R_CLOSEFP);
                  t->bt_irec =
                      F_ISSET(t, R_FIXLEN) ? __rec_fpipe : __rec_vpipe;
            } else {
                  switch (flags & O_ACCMODE) {
                  case O_RDONLY:
                        F_SET(t, R_RDONLY);
                        break;
                  case O_RDWR:
                        break;
                  default:
                        goto einval;
                  }

                  if (fstat(rfd, &sb))
                        goto err;
                  /*
                   * Kluge -- we'd like to test to see if the file is too
                   * big to mmap.  Since, we don't know what size or type
                   * off_t's or size_t's are, what the largest unsigned
                   * integral type is, or what random insanity the local
                   * C compiler will perpetrate, doing the comparison in
                   * a portable way is flatly impossible.  Hope that mmap
                   * fails if the file is too large.
                   */
                  if (sb.st_size == 0)
                        F_SET(t, R_EOF);
                  else {
#ifdef RECNO_USE_MMAP
                        /*
                         * XXX
                         * Mmap doesn't work correctly on many current
                         * systems.  In particular, it can fail subtly,
                         * with cache coherency problems.  Don't use it
                         * for now.
                         */
                        t->bt_msize = sb.st_size;
                        if ((t->bt_smap = mmap(NULL, t->bt_msize,
                            PROT_READ, MAP_PRIVATE, rfd,
                            (off_t)0)) == (caddr_t)-1)
                              goto slow;
                        t->bt_cmap = t->bt_smap;
                        t->bt_emap = t->bt_smap + sb.st_size;
                        t->bt_irec = F_ISSET(t, R_FIXLEN) ?
                            __rec_fmap : __rec_vmap;
                        F_SET(t, R_MEMMAPPED);
#else
                        goto slow;
#endif
                  }
            }
      }

      /* Use the recno routines. */
      dbp->close = __rec_close;
      dbp->del = __rec_delete;
      dbp->fd = __rec_fd;
      dbp->get = __rec_get;
      dbp->put = __rec_put;
      dbp->seq = __rec_seq;
      dbp->sync = __rec_sync;

      /* If the root page was created, reset the flags. */
      if ((h = mpool_get(t->bt_mp, P_ROOT, 0)) == NULL)
            goto err;
      if ((h->flags & P_TYPE) == P_BLEAF) {
            F_CLR(h, P_TYPE);
            F_SET(h, P_RLEAF);
            mpool_put(t->bt_mp, h, MPOOL_DIRTY);
      } else
            mpool_put(t->bt_mp, h, 0);

      if (openinfo && openinfo->flags & R_SNAPSHOT &&
          !F_ISSET(t, R_EOF | R_INMEM) &&
          t->bt_irec(t, MAX_REC_NUMBER) == RET_ERROR)
                goto err;
      return (dbp);

einval:     errno = EINVAL;
err:  sverrno = errno;
      if (dbp != NULL)
            (void)__bt_close(dbp);
      if (fname != NULL)
            (void)close(rfd);
      errno = sverrno;
      return (NULL);
}

int
__rec_fd(dbp)
      const DB *dbp;
{
      BTREE *t;

      t = dbp->internal;

      /* Toss any page pinned across calls. */
      if (t->bt_pinned != NULL) {
            mpool_put(t->bt_mp, t->bt_pinned, 0);
            t->bt_pinned = NULL;
      }

      /* In-memory database can't have a file descriptor. */
      if (F_ISSET(t, R_INMEM)) {
            errno = ENOENT;
            return (-1);
      }
      return (t->bt_rfd);
}

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