minix/usr.bin/grep/mmfile.c

   1 /*      $OpenBSD: mmfile.c,v 1.14 2011/07/17 12:17:10 aschrijver 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 #include <sys/param.h>
  30 #include <sys/mman.h>
  31 #include <sys/stat.h>
  32
  33 #include <err.h>
  34 #include <fcntl.h>
  35 #include <stdlib.h>
  36 #include <unistd.h>
  37
  38 #include "grep.h"
  39
  40 #ifndef SMALL
  41
  42 #define MAX_MAP_LEN 1048576
  43
  44 mmf_t *
  45 mmopen(const char *fn, const char *mode)
  46 {
  47         mmf_t *mmf;
  48         struct stat st;
  49
  50 #ifndef __minix
  51         /* XXX ignore mode for now */
  52         mode = mode;
  53 #endif /* !__minix */
  54
  55         mmf = grep_malloc(sizeof *mmf);
  56         if ((mmf->fd = open(fn, O_RDONLY)) == -1)
  57                 goto ouch1;
  58         if (fstat(mmf->fd, &st) == -1)
  59                 goto ouch2;
  60         if (st.st_size > SIZE_T_MAX) /* too big to mmap */
  61                 goto ouch2;
  62         if (!S_ISREG(st.st_mode)) /* only mmap regular files */
  63                 goto ouch2;
  64         mmf->len = (size_t)st.st_size;
  65         mmf->base = mmap(NULL, mmf->len, PROT_READ, MAP_PRIVATE, mmf->fd, (off_t)0);
  66         if (mmf->base == MAP_FAILED)
  67                 goto ouch2;
  68         mmf->ptr = mmf->base;
  69         mmf->end = mmf->base + mmf->len;
  70 #ifndef __minix
  71         madvise(mmf->base, mmf->len, MADV_SEQUENTIAL);
  72 #endif /* !__minix */
  73         return mmf;
  74
  75 ouch2:
  76         close(mmf->fd);
  77 ouch1:
  78         free(mmf);
  79         return NULL;
  80 }
  81
  82 void
  83 mmclose(mmf_t *mmf)
  84 {
  85         munmap(mmf->base, mmf->len);
  86         close(mmf->fd);
  87         free(mmf);
  88 }
  89
  90 char *
  91 mmfgetln(mmf_t *mmf, size_t *l)
  92 {
  93         static char *p;
  94
  95         if (mmf->ptr >= mmf->end)
  96                 return NULL;
  97         for (p = mmf->ptr; mmf->ptr < mmf->end; ++mmf->ptr)
  98                 if (*mmf->ptr == '\n')
  99                     break;
 100
 101         *l = mmf->ptr - p;
 102         ++mmf->ptr;
 103         return p;
 104 }
 105
 106 #endif