com32/lib/syslinux/floadfile.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2005-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * floadfile.c
  30  *
  31  * Read the contents of a data file into a malloc'd buffer
  32  */
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <unistd.h>
  37 #include <string.h>
  38 #include <fcntl.h>
  39 #include <sys/stat.h>
  40
  41 #include <syslinux/loadfile.h>
  42
  43 #define INCREMENTAL_CHUNK 1024*1024
  44
  45 int floadfile(FILE * f, void **ptr, size_t * len, const void *prefix,
  46               size_t prefix_len)
  47 {
  48     struct stat st;
  49     void *data, *dp;
  50     size_t alen, clen, rlen, xlen;
  51
  52     clen = alen = 0;
  53     data = NULL;
  54
  55     if (fstat(fileno(f), &st))
  56         goto err;
  57
  58     if (!S_ISREG(st.st_mode)) {
  59         /* Not a regular file, we can't assume we know the file size */
  60         if (prefix_len) {
  61             clen = alen = prefix_len;
  62             data = malloc(prefix_len);
  63             if (!data)
  64                 goto err;
  65
  66             memcpy(data, prefix, prefix_len);
  67         }
  68
  69         do {
  70             alen += INCREMENTAL_CHUNK;
  71             dp = realloc(data, alen);
  72             if (!dp)
  73                 goto err;
  74             data = dp;
  75
  76             rlen = fread((char *)data + clen, 1, alen - clen, f);
  77             clen += rlen;
  78         } while (clen == alen);
  79
  80         *len = clen;
  81         xlen = (clen + LOADFILE_ZERO_PAD - 1) & ~(LOADFILE_ZERO_PAD - 1);
  82         dp = realloc(data, xlen);
  83         if (dp)
  84             data = dp;
  85         *ptr = data;
  86     } else {
  87         *len = clen = st.st_size + prefix_len - ftell(f);
  88         xlen = (clen + LOADFILE_ZERO_PAD - 1) & ~(LOADFILE_ZERO_PAD - 1);
  89
  90         *ptr = data = malloc(xlen);
  91         if (!data)
  92             return -1;
  93
  94         memcpy(data, prefix, prefix_len);
  95
  96         if ((off_t) fread((char *)data + prefix_len, 1, clen - prefix_len, f)
  97             != clen - prefix_len)
  98             goto err;
  99     }
 100
 101     memset((char *)data + clen, 0, xlen - clen);
 102     return 0;
 103
 104 err:
 105     if (data)
 106         free(data);
 107     return -1;
 108 }