UtilBuffer.hpp

/*
   Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

#ifndef __BUFFER_HPP_INCLUDED__
#define __BUFFER_HPP_INCLUDED__

#include <ndb_global.h>

/* This class represents a buffer of binary data, where you can append
 * data at the end, and later read the entire bunch.
 * It will take care of the hairy details of realloc()ing the space
 * for you
 */
class UtilBuffer {
public:
  UtilBuffer() { data = NULL; len = 0; alloc_size = 0; };
  ~UtilBuffer() { if(data) free(data); data = NULL; len = 0; alloc_size = 0; };


  int reallocate(size_t newsize) {
    if(newsize < len) {
      errno = EINVAL;
      return -1;
    }
    void *newdata;
    if((newdata = realloc(data, newsize)) == NULL) {
      errno = ENOMEM;
      return -1;
    }
    alloc_size = newsize;
    data = newdata;
    return 0;
  };

  int grow(size_t l) {
    if(l > alloc_size)
      return reallocate(l);
    return 0;
  };

  int append(const void *d, size_t l) {
    int ret;
    ret = grow(len+l);
    if(ret != 0)
      return ret;
      
    memcpy((char *)data+len, d, l);
    len+=l;

    return 0;
  };

  void * append(size_t l){
    if(grow(len+l) != 0)
      return 0;

    void * ret = (char*)data+len;
    len += l;
    return ret;
  }
  
  int assign(const void * d, size_t l) {
    /* Free the old data only after copying, in case d==data. */
    void *old_data= data;
    data = NULL;
    len = 0;
    alloc_size = 0;
    int ret= append(d, l);
    if (old_data)
      free(old_data);
    return ret;
  }

  void clear() {
    len = 0;
  }

  int length() const { assert(Uint64(len) == Uint32(len)); return (int)len; }

  void *get_data() const { return data; }

  bool empty () const { return len == 0; }

  bool equal(const UtilBuffer &cmp) const {
    if(len==0 && cmp.len==0)
      return true;
    else if(len!=cmp.len)
      return false;
    else
      return (memcmp(get_data(), cmp.get_data(), len) == 0);
  }

  int assign(const UtilBuffer& buf) {
    int ret = 0;
    if(this != &buf) {
      ret = assign(buf.get_data(), buf.length());
    }
    return ret;
  }
private:
  void *data;          /* Pointer to data storage */
  size_t len;          /* Size of the stored data */
  size_t alloc_size;   /* Size of the allocated space,
                        *  i.e. len can grow to this size */
};

#endif /* !__BUFFER_HPP_INCLUDED__ */