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 }
  43
  44 /* virtuals */
  45
  46
  47 ssize_t
  48 io_stream_memory::read (void *buffer, size_t len)
  49 {
  50   if (len == 0)
  51     return 0;
  52   unsigned char *to = (unsigned char *) buffer;
  53   unsigned char *end = to + len;
  54   ssize_t count = 0;
  55   while (to < end && pos < length)
  56     {
  57       *to++ = pos_block->data[pos_block_offset++];
  58       count++;
  59       if (pos_block_offset == pos_block->len)
  60         {
  61           pos_block = pos_block->next;
  62           pos_block_offset = 0;
  63         }
  64       pos++;
  65     }
  66   return count;
  67 }
  68
  69 ssize_t
  70 io_stream_memory::write (const void *buffer, size_t len)
  71 {
  72   if (len == 0)
  73     return 0;
  74   /* talk about primitive :} */
  75   tail->next = new memblock (len);
  76   if (!tail->next->data)
  77     {
  78       delete tail->next;
  79       tail->next = 0;
  80       lasterr = ENOMEM;
  81       return -1;
  82     }
  83   tail = tail->next;
  84   memcpy (tail->data, buffer, len);
  85   pos += len;
  86   pos_block = tail;
  87   pos_block_offset = len;
  88   length += len;
  89   return len;
  90 }
  91
  92 ssize_t
  93 io_stream_memory::peek (void *buffer, size_t len)
  94 {
  95   size_t tpos = pos;
  96   size_t toff = pos_block_offset;
  97   memblock *tblock = pos_block;
  98   ssize_t tmp = read (buffer, len);
  99   pos = tpos;
 100   pos_block_offset = toff;
 101   pos_block = tblock;
 102   return tmp;
 103 }
 104
 105 int
 106 io_stream_memory::error ()
 107 {
 108   return lasterr;
 109 }