io_stream_memory.cc

   1 /*
   2  * Copyright (c) 2001, Robert Collins.
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     A copy of the GNU General Public License can be found at
  10  *     http://www.gnu.org/
  11  *
  12  * Written by Robert Collins  <rbtcollins@hotmail.com>
  13  *
  14  */
  15
  16 #if 0
  17 static const char *cvsid =
  18   "\n%%% $Id$\n";
  19 #endif
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <errno.h>
  26
  27 #include "io_stream.h"
  28 #include "io_stream_memory.h"
  29
  30 /* memblock helper class */
  31 memblock::~memblock ()
  32 {
  33   if (data)
  34     delete[] data;
  35   if (next)
  36     delete next;
  37 }
  38
  39 io_stream_memory::~io_stream_memory ()
  40 {
  41   /* memblocks are self deleting. Nice of 'em eh what */
  42   destroyed = 1;
  43 }
  44
  45 /* virtuals */
  46
  47
  48 ssize_t
  49 io_stream_memory::read (void *buffer, size_t len)
  50 {
  51   if (len == 0)
  52     return 0;
  53   unsigned char *to = (unsigned char *) buffer;
  54   unsigned char *end = to + len;
  55   ssize_t count = 0;
  56   while (to < end && pos < length)
  57     {
  58       *to++ = pos_block->data[pos_block_offset++];
  59       count++;
  60       if (pos_block_offset == pos_block->len)
  61         {
  62           pos_block = pos_block->next;
  63           pos_block_offset = 0;
  64         }
  65       pos++;
  66     }
  67   return count;
  68 }
  69
  70 ssize_t
  71 io_stream_memory::write (const void *buffer, size_t len)
  72 {
  73   if (len == 0)
  74     return 0;
  75   /* talk about primitive :} */
  76   tail->next = new memblock (len);
  77   if (!tail->next->data)
  78     {
  79       delete tail->next;
  80       tail->next = 0;
  81       lasterr = ENOMEM;
  82       return -1;
  83     }
  84   tail = tail->next;
  85   memcpy (tail->data, buffer, len);
  86   pos += len;
  87   pos_block = tail;
  88   pos_block_offset = len;
  89   length += len;
  90   return len;
  91 }
  92
  93 ssize_t
  94 io_stream_memory::peek (void *buffer, size_t len)
  95 {
  96   size_t tpos = pos;
  97   size_t toff = pos_block_offset;
  98   memblock *tblock = pos_block;
  99   ssize_t tmp = read (buffer, len);
 100   pos = tpos;
 101   pos_block_offset = toff;
 102   pos_block = tblock;
 103   return tmp;
 104 }
 105
 106 int
 107 io_stream_memory::error ()
 108 {
 109   return lasterr;
 110 }