upx/src/mem.cpp

/* mem.cpp --

   This file is part of the UPX executable compressor.

   Copyright (C) 1996-2003 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996-2003 Laszlo Molnar
   All Rights Reserved.

   UPX and the UCL library are free software; you can redistribute them
   and/or modify them under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   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; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer              Laszlo Molnar
   <mfx@users.sourceforge.net>          <ml1050@users.sourceforge.net>
 */


#include "conf.h"
#include "mem.h"


/*************************************************************************
//
**************************************************************************/

MemBuffer::MemBuffer(unsigned size) :
    ptr(NULL), psize(0)
{
    if (size > 0)
        alloc(size);
}


MemBuffer::~MemBuffer()
{
    this->dealloc();
}

void MemBuffer::dealloc()
{
    if (ptr)
    {
        checkState();
        ::free(ptr - 8);
    }
    ptr = NULL;
    psize = 0;
}


void MemBuffer::allocForCompression(unsigned uncompressed_size, unsigned extra)
{
    assert((int)uncompressed_size > 0);
    assert((int)extra >= 0);
    alloc(uncompressed_size + uncompressed_size/8 + 256 + extra);
}


void MemBuffer::allocForUncompression(unsigned uncompressed_size, unsigned extra)
{
    assert((int)uncompressed_size > 0);
    assert((int)extra >= 0);
    // note: 3 bytes are allowed overrun for the asm_fast decompressors
//    alloc(uncompressed_size + 3 + 512 + extra); // 512 safety bytes
    alloc(uncompressed_size + 3 + extra);
}


/*************************************************************************
//
**************************************************************************/

#define MAGIC1(p)       ((unsigned)(p) ^ 0xfefdbeeb)
#define MAGIC2(p)       ((unsigned)(p) ^ 0xfefdbeeb ^ 0x80024001)

unsigned MemBuffer::global_alloc_counter = 0;


void MemBuffer::checkState() const
{
    if (!ptr)
        throwInternalError("block not allocated");
    if (get_be32(ptr - 4) != MAGIC1(ptr))
        throwInternalError("memory clobbered before allocated block 1");
    if (get_be32(ptr - 8) != psize)
        throwInternalError("memory clobbered before allocated block 2");
    if (get_be32(ptr + psize) != MAGIC2(ptr))
        throwInternalError("memory clobbered past end of allocated block");
}


void MemBuffer::alloc(unsigned size)
{
    // NOTE: we don't automaticlly free a used buffer
    assert(ptr == NULL);
    assert(psize == 0);
    //
    assert((int)size > 0);
    unsigned total = 4 + 4 + size + 4 + 4;
    assert((int)total > 0);
    unsigned char *p = (unsigned char *) malloc(total);
    if (!p)
    {
        //throw bad_alloc();
        throwCantPack("out of memory");
        //exit(1);
    }
    ptr = p + 8;
    psize = size;
    // store magic state
    set_be32(ptr - 8, psize);
    set_be32(ptr - 4, MAGIC1(ptr));
    set_be32(ptr + psize, MAGIC2(ptr));
    set_be32(ptr + psize + 4, global_alloc_counter++);
}


/*
vi:ts=4:et
*/