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 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <unistd.h>
  20 #include <errno.h>
  21
  22 #include "io_stream.h"
  23 #include "io_stream_memory.h"
  24
  25 /* memblock helper class */
  26 memblock::~memblock ()
  27 {
  28   if (data)
  29     delete[] data;
  30   if (next)
  31     delete next;
  32 }
  33
  34 io_stream_memory::~io_stream_memory ()
  35 {
  36   /* memblocks are self deleting. Nice of 'em eh what */
  37 }
  38
  39 /* virtuals */
  40
  41
  42 ssize_t
  43 io_stream_memory::read (void *buffer, size_t len)
  44 {
  45   if (len == 0)
  46     return 0;
  47   unsigned char *to = (unsigned char *) buffer;
  48   unsigned char *end = to + len;
  49   ssize_t count = 0;
  50   while (to < end && pos < (off_t) length)
  51     {
  52       *to++ = pos_block->data[pos_block_offset++];
  53       count++;
  54       if (pos_block_offset == pos_block->len)
  55         {
  56           pos_block = pos_block->next;
  57           pos_block_offset = 0;
  58         }
  59       pos++;
  60     }
  61   return count;
  62 }
  63
  64 ssize_t
  65 io_stream_memory::write (const void *buffer, size_t len)
  66 {
  67   if (len == 0)
  68     return 0;
  69   /* talk about primitive :} */
  70   tail->next = new memblock (len);
  71   if (!tail->next->data)
  72     {
  73       delete tail->next;
  74       tail->next = 0;
  75       lasterr = ENOMEM;
  76       return -1;
  77     }
  78   tail = tail->next;
  79   memcpy (tail->data, buffer, len);
  80   pos += len;
  81   pos_block = tail;
  82   pos_block_offset = len;
  83   length += len;
  84   return len;
  85 }
  86
  87 ssize_t
  88 io_stream_memory::peek (void *buffer, size_t len)
  89 {
  90   size_t tpos = pos;
  91   size_t toff = pos_block_offset;
  92   memblock *tblock = pos_block;
  93   ssize_t tmp = read (buffer, len);
  94   pos = tpos;
  95   pos_block_offset = toff;
  96   pos_block = tblock;
  97   return tmp;
  98 }
  99
 100 int
 101 io_stream_memory::error ()
 102 {
 103   return lasterr;
 104 }