commands/grep/mmfile.c

   1 #ifndef __minix
   2 /*      $OpenBSD: mmfile.c,v 1.11 2006/09/19 05:52:23 otto Exp $        */
   3
   4 /*-
   5  * Copyright (c) 1999 James Howard and Dag-Erling Coïdan Smørgrav
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #include <sys/param.h>
  31 #include <sys/mman.h>
  32 #include <sys/stat.h>
  33
  34 #include <err.h>
  35 #include <fcntl.h>
  36 #include <stdlib.h>
  37 #include <unistd.h>
  38
  39 #include "grep.h"
  40
  41 #define MAX_MAP_LEN 1048576
  42
  43 mmf_t *
  44 mmopen(char *fn, char *mode)
  45 {
  46         mmf_t *mmf;
  47         struct stat st;
  48
  49         /* XXX ignore mode for now */
  50         mode = mode;
  51
  52         mmf = grep_malloc(sizeof *mmf);
  53         if ((mmf->fd = open(fn, O_RDONLY)) == -1)
  54                 goto ouch1;
  55         if (fstat(mmf->fd, &st) == -1)
  56                 goto ouch2;
  57         if (st.st_size > SIZE_T_MAX) /* too big to mmap */
  58                 goto ouch2;
  59         if (!S_ISREG(st.st_mode)) /* only mmap regular files */
  60                 goto ouch2;
  61         mmf->len = (size_t)st.st_size;
  62         mmf->base = mmap(NULL, mmf->len, PROT_READ, MAP_PRIVATE, mmf->fd, (off_t)0);
  63         if (mmf->base == MAP_FAILED)
  64                 goto ouch2;
  65         mmf->ptr = mmf->base;
  66         mmf->end = mmf->base + mmf->len;
  67 #ifndef __minix
  68         madvise(mmf->base, mmf->len, MADV_SEQUENTIAL);
  69 #endif
  70         return mmf;
  71
  72 ouch2:
  73         close(mmf->fd);
  74 ouch1:
  75         free(mmf);
  76         return NULL;
  77 }
  78
  79 void
  80 mmclose(mmf_t *mmf)
  81 {
  82         munmap(mmf->base, mmf->len);
  83         close(mmf->fd);
  84         free(mmf);
  85 }
  86
  87 char *
  88 mmfgetln(mmf_t *mmf, size_t *l)
  89 {
  90         static char *p;
  91         char *start = mmf->ptr;          /* Remove speed bump */
  92         char *end = mmf->end;            /* Remove speed bump */
  93
  94         if (start >= end)
  95                 return NULL;
  96         for (p = mmf->ptr; mmf->ptr < mmf->end; ++mmf->ptr)
  97                 if (*mmf->ptr == '\n')
  98                         break;
  99
 100         *l = mmf->ptr - p;
 101         ++mmf->ptr;
 102         return p;
 103 }
 104 #endif