xdas_buf.c

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/*----------------------------------------------------------------------------
 * Copyright (c) 2006, Novell, Inc.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are 
 * met:
 * 
 *     * Redistributions of source code must retain the above copyright 
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright 
 *       notice, this list of conditions and the following disclaimer in the 
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 *     * Neither the name of the Novell nor the names of its contributors 
 *       may be used to endorse or promote products derived from this 
 *       software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
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 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
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#include "xdas_buf.h"
#include "xdas_debug.h"

#include <malloc.h>
#include <string.h>

/* set a reasonable maximum buffer size */
#define MAX_BUFFER_SIZE (8 * 64 * 1024)

xdas_buffer xdas_buffer_alloc(size_t size)
{
   xdas_buffer result;

   xdas_assert(size <= MAX_BUFFER_SIZE);
   if (size > MAX_BUFFER_SIZE)
      return 0;

   if ((result = (xdas_buffer)malloc(sizeof(*result) + size + 1)) != 0)
   {
      result->allocated = size;
      result->start = (char *)(result + 1);
      result->curpos = result->start;
      result->end = result->start + size;
   } 
   return result;
}

xdas_buffer xdas_buffer_realloc(xdas_buffer buf, size_t size)
{
   xdas_buffer result;

   xdas_assert(size <= MAX_BUFFER_SIZE);
   if (size > MAX_BUFFER_SIZE)
      return 0;

   if (buf)
   {
      size_t curoffs = buf->curpos - buf->start;

      xdas_assert(buf->curpos <= buf->end);

      if (buf->allocated >= size)
         result = buf;
      else
      {
         if ((result = (xdas_buffer)realloc(buf, sizeof(*result) + size)) != 0)
            result->allocated = size;
      }
      if (result)
      {
         result->start = (char *)(result + 1);
         result->curpos = result->start + curoffs;
         result->end = result->start + size;
      }
   }
   else
      result = xdas_buffer_alloc(size);
   return result;
}

xdas_buffer xdas_buffer_dup(xdas_buffer buf)
{
   xdas_buffer dup = 0;
   xdas_assert(!buf || buf->curpos <= buf->end);
   if (buf && (dup = xdas_buffer_alloc(buf->end - buf->start)) != 0)
      memcpy(dup->start, buf->start, buf->end - buf->start);
   return dup;
}

void xdas_buffer_free(xdas_buffer buf)
{
   xdas_assert(!buf || buf->curpos <= buf->end);
   free(buf);
}