usr.bin/grep/mmfile.c

   1 /*      $NetBSD: mmfile.c,v 1.4 2007/12/06 20:33:48 cjep Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1999 James Howard and Dag-Erling Coïdan Smørgrav
   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  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  */
  29
  30 #include <sys/cdefs.h>
  31 #ifndef lint
  32 __RCSID("$NetBSD: mmfile.c,v 1.4 2007/12/06 20:33:48 cjep Exp $");
  33 #endif /* not lint */
  34
  35 #include <sys/param.h>
  36 #include <sys/mman.h>
  37 #include <sys/stat.h>
  38
  39 #include <zlib.h>
  40 #include <err.h>
  41 #include <fcntl.h>
  42 #include <stdlib.h>
  43 #include <unistd.h>
  44
  45 #include "grep.h"
  46
  47 #define MAX_MAP_LEN (SIZE_T_MAX / 64)   /* ~70M is reasonable size */
  48
  49 mmf_t *
  50 mmopen(const char *fn, const char *mode)
  51 {
  52         mmf_t *mmf;
  53         struct stat st;
  54
  55         /* XXX ignore mode for now */
  56         mode = mode;
  57
  58         mmf = grep_malloc(sizeof *mmf);
  59         if ((mmf->fd = open(fn, O_RDONLY)) == -1)
  60                 goto ouch1;
  61         if (fstat(mmf->fd, &st) == -1)
  62                 goto ouch2;
  63         if (st.st_size > (off_t)(MAX_MAP_LEN))  /* too big to mmap */
  64                 goto ouch2;
  65         if ((st.st_mode & S_IFREG) == 0)        /* only mmap regular files */
  66                 goto ouch2;
  67         mmf->len = (size_t)st.st_size;
  68         mmf->base = mmap(NULL, mmf->len, PROT_READ, MAP_PRIVATE, mmf->fd, 0);
  69         if (mmf->base == MAP_FAILED)
  70                 goto ouch2;
  71         mmf->ptr = mmf->base;
  72         mmf->end = mmf->base + mmf->len;
  73         madvise(mmf->base, mmf->len, MADV_SEQUENTIAL);
  74         return mmf;
  75
  76 ouch2:
  77         close(mmf->fd);
  78 ouch1:
  79         free(mmf);
  80         return NULL;
  81 }
  82
  83 void
  84 mmclose(mmf_t *mmf)
  85 {
  86         munmap(mmf->base, mmf->len);
  87         close(mmf->fd);
  88         free(mmf);
  89 }
  90
  91 char *
  92 mmfgetln(mmf_t *mmf, size_t *l)
  93 {
  94         static char *p;
  95
  96         if (mmf->ptr >= mmf->end)
  97                 return NULL;
  98         for (p = mmf->ptr; mmf->ptr < mmf->end; ++mmf->ptr)
  99                 if (*mmf->ptr == line_endchar)
 100                         break;
 101         *l = mmf->ptr - p;
 102         ++mmf->ptr;
 103         return p;
 104 }
 105
 106 void
 107 mmrewind(mmf_t *mmf)
 108 {
 109         mmf->ptr = mmf->base;
 110 }