/////////////////////////////////////////////////////////////////////////
// $Id: vmware4.cc,v 1.4 2009-02-07 21:05:31 sshwarts Exp $
/////////////////////////////////////////////////////////////////////////

/*
 * This file provides support for VMWare's virtual disk image
 * format version 4 and above.
 *
 * Author: Sharvil Nanavati
 * Contact: snrrrub@gmail.com
 *
 * Copyright (C) 2006 Sharvil Nanavati.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA B 02110-1301 USA
 */

// Define BX_PLUGGABLE in files that can be compiled into plugins.  For
// platforms that require a special tag on exported symbols, BX_PLUGGABLE
// is used to know when we are exporting symbols and when we are importing.
#define BX_PLUGGABLE

#define NO_DEVICE_INCLUDES

#include "iodev.h"
#include "hdimage.h"
#include "vmware4.h"

#define LOG_THIS bx_devices.pluginHardDrive->
const off_t vmware4_image_t::INVALID_OFFSET = (off_t)-1;
const int vmware4_image_t::SECTOR_SIZE = 512;

vmware4_image_t::vmware4_image_t()
    : file_descriptor(-1),
      tlb(0),
      tlb_offset(INVALID_OFFSET),
      current_offset(INVALID_OFFSET),
      is_dirty(false)
{
}

vmware4_image_t::~vmware4_image_t()
{
    close();
}

int vmware4_image_t::open(const char * pathname)
{
    close();

    int flags = O_RDWR;
#ifdef O_BINARY
    flags |= O_BINARY;
#endif

    file_descriptor = ::open(pathname, flags);

    if(!is_open())
        return -1;

    if(!read_header())
        BX_PANIC(("unable to read vmware4 virtual disk header from file '%s'", pathname));

    tlb = new Bit8u[(unsigned)header.tlb_size_sectors * SECTOR_SIZE];
    if(tlb == 0)
        BX_PANIC(("unable to allocate " FMT_LL "d bytes for vmware4 image's tlb", header.tlb_size_sectors * SECTOR_SIZE));

    tlb_offset = INVALID_OFFSET;
    current_offset = 0;
    is_dirty = false;

    hd_size = header.total_sectors * SECTOR_SIZE;
    cylinders = (unsigned)hd_size / (16 * 63);
    heads = 16;
    sectors = 63;

    BX_DEBUG(("VMware 4 disk geometry:"));
    BX_DEBUG(("   .size      = " FMT_LL "d", hd_size));
    BX_DEBUG(("   .cylinders = %d", cylinders));
    BX_DEBUG(("   .heads     = %d", heads));
    BX_DEBUG(("   .sectors   = %d", sectors));

    return 1;
}

void vmware4_image_t::close()
{
    if(file_descriptor == -1)
        return;

    flush();
    delete [] tlb; tlb = 0;

    ::close(file_descriptor);
    file_descriptor = -1;
}

Bit64s vmware4_image_t::lseek(Bit64s offset, int whence)
{
    switch(whence)
    {
        case SEEK_SET:
            current_offset = (off_t)offset;
            return current_offset;
        case SEEK_CUR:
            current_offset += (off_t)offset;
            return current_offset;
        case SEEK_END:
            current_offset = header.total_sectors * SECTOR_SIZE + (off_t)offset;
            return current_offset;
        default:
            BX_DEBUG(("unknown 'whence' value (%d) when trying to seek vmware4 image", whence));
            return INVALID_OFFSET;
    }
}

ssize_t vmware4_image_t::read(void * buf, size_t count)
{
    ssize_t total = 0;
    while(count > 0)
    {
        off_t readable = perform_seek();
        if(readable == INVALID_OFFSET)
        {
            BX_DEBUG(("vmware4 disk image read failed on %d bytes at " FMT_LL "d", count, current_offset));
            return -1;
        }

        off_t copysize = (count > readable) ? readable : count;
        memcpy(buf, tlb + current_offset - tlb_offset, (size_t)copysize);

        current_offset += copysize;
        total += (long)copysize;
        count -= (size_t)copysize;
    }
    return total;
}

ssize_t vmware4_image_t::write(const void * buf, size_t count)
{
    ssize_t total = 0;
    while(count > 0)
    {
        off_t writable = perform_seek();
        if(writable == INVALID_OFFSET)
        {
            BX_DEBUG(("vmware4 disk image write failed on %d bytes at " FMT_LL "d", count, current_offset));
            return -1;
        }

        off_t writesize = (count > writable) ? writable : count;
        memcpy(tlb + current_offset - tlb_offset, buf, (size_t)writesize);

        current_offset += writesize;
        total += (long)writesize;
        count -= (size_t)writesize;
        is_dirty = true;
    }
    return total;
}

bool vmware4_image_t::is_open() const
{
    return (file_descriptor != -1);
}

bool vmware4_image_t::is_valid_header() const
{
    if(header.id[0] != 'K' || header.id[1] != 'D' || header.id[2] != 'M' ||
       header.id[3] != 'V')
    {
        BX_DEBUG(("not a vmware4 image"));
        return false;
    }

    if(header.version != 1)
    {
        BX_DEBUG(("unsupported vmware4 image version"));
        return false;
    }

    return true;
}

bool vmware4_image_t::read_header()
{
    if(!is_open())
        BX_PANIC(("attempt to read vmware4 header from a closed file"));

    if(::read(file_descriptor, &header, sizeof(VM4_Header)) != sizeof(VM4_Header))
        return false;

    header.version = dtoh32(header.version);
    header.flags = dtoh32(header.flags);
    header.total_sectors = dtoh64(header.total_sectors);
    header.tlb_size_sectors = dtoh64(header.tlb_size_sectors);
    header.description_offset_sectors = dtoh64(header.description_offset_sectors);
    header.description_size_sectors = dtoh64(header.description_size_sectors);
    header.slb_count = dtoh32(header.slb_count);
    header.flb_offset_sectors = dtoh64(header.flb_offset_sectors);
    header.flb_copy_offset_sectors = dtoh64(header.flb_copy_offset_sectors);
    header.tlb_offset_sectors = dtoh64(header.tlb_offset_sectors);

    if(!is_valid_header())
        BX_PANIC(("invalid vmware4 virtual disk image"));

    BX_DEBUG(("VM4_Header (size=%d)", sizeof(VM4_Header)));
    BX_DEBUG(("   .version                    = %d", header.version));
    BX_DEBUG(("   .flags                      = %d", header.flags));
    BX_DEBUG(("   .total_sectors              = " FMT_LL "d", header.total_sectors));
    BX_DEBUG(("   .tlb_size_sectors           = " FMT_LL "d", header.tlb_size_sectors));
    BX_DEBUG(("   .description_offset_sectors = " FMT_LL "d", header.description_offset_sectors));
    BX_DEBUG(("   .description_size_sectors   = " FMT_LL "d", header.description_size_sectors));
    BX_DEBUG(("   .slb_count                  = %d", header.slb_count));
    BX_DEBUG(("   .flb_offset_sectors         = " FMT_LL "d", header.flb_offset_sectors));
    BX_DEBUG(("   .flb_copy_offset_sectors    = " FMT_LL "d", header.flb_copy_offset_sectors));
    BX_DEBUG(("   .tlb_offset_sectors         = " FMT_LL "d", header.tlb_offset_sectors));

    return true;
}

//
// Returns the number of bytes that can be read from the current offset before needing
// to perform another seek.
//
off_t vmware4_image_t::perform_seek()
{
    if(current_offset == INVALID_OFFSET)
    {
        BX_DEBUG(("invalid offset specified in vmware4 seek"));
        return INVALID_OFFSET;
    }

    //
    // The currently loaded tlb can service the request.
    //
    if(tlb_offset / (header.tlb_size_sectors * SECTOR_SIZE) == current_offset / (header.tlb_size_sectors * SECTOR_SIZE))
        return (header.tlb_size_sectors * SECTOR_SIZE) - (current_offset - tlb_offset);

    flush();

    Bit64u index = current_offset / (header.tlb_size_sectors * SECTOR_SIZE);
    Bit32u slb_index = (Bit32u)(index % header.slb_count);
    Bit32u flb_index = (Bit32u)(index / header.slb_count);

    Bit32u slb_sector = read_block_index(header.flb_offset_sectors, flb_index);
    Bit32u slb_copy_sector = read_block_index(header.flb_copy_offset_sectors, flb_index);

    if(slb_sector == 0 && slb_copy_sector == 0)
    {
        BX_DEBUG(("loaded vmware4 disk image requires un-implemented feature"));
        return INVALID_OFFSET;
    }
    if(slb_sector == 0)
        slb_sector = slb_copy_sector;

    Bit32u tlb_sector = read_block_index(slb_sector, slb_index);
    tlb_offset = index * header.tlb_size_sectors * SECTOR_SIZE;
    if(tlb_sector == 0)
    {
        //
        // Allocate a new tlb
        //
        memset(tlb, 0, (size_t)header.tlb_size_sectors * SECTOR_SIZE);

        //
        // Instead of doing a write to increase the file size, we could use
        // ftruncate but it is not portable.
        //
        off_t eof = ((::lseek(file_descriptor, 0, SEEK_END) + SECTOR_SIZE - 1) / SECTOR_SIZE) * SECTOR_SIZE;
        ::write(file_descriptor, tlb, (unsigned)header.tlb_size_sectors * SECTOR_SIZE);
        tlb_sector = (Bit32u)eof / SECTOR_SIZE;

        write_block_index(slb_sector, slb_index, tlb_sector);
        write_block_index(slb_copy_sector, slb_index, tlb_sector);

        ::lseek(file_descriptor, eof, SEEK_SET);
    }
    else
    {
        ::lseek(file_descriptor, tlb_sector * SECTOR_SIZE, SEEK_SET);
        ::read(file_descriptor, tlb, (unsigned)header.tlb_size_sectors * SECTOR_SIZE);
        ::lseek(file_descriptor, tlb_sector * SECTOR_SIZE, SEEK_SET);
    }

    return (header.tlb_size_sectors * SECTOR_SIZE) - (current_offset - tlb_offset);
}

void vmware4_image_t::flush()
{
    if(!is_dirty)
        return;

    //
    // Write dirty sectors to disk first. Assume that the file is already at the
    // position for the current tlb.
    //
    ::write(file_descriptor, tlb, (unsigned)header.tlb_size_sectors * SECTOR_SIZE);
    is_dirty = false;
}

Bit32u vmware4_image_t::read_block_index(Bit64u sector, Bit32u index)
{
    Bit32u ret;

    ::lseek(file_descriptor, sector * SECTOR_SIZE + index * sizeof(Bit32u), SEEK_SET);
    ::read(file_descriptor, &ret, sizeof(Bit32u));

    return dtoh32(ret);
}

void vmware4_image_t::write_block_index(Bit64u sector, Bit32u index, Bit32u block_sector)
{
    block_sector = htod32(block_sector);

    ::lseek(file_descriptor, sector * SECTOR_SIZE + index * sizeof(Bit32u), SEEK_SET);
    ::write(file_descriptor, &block_sector, sizeof(Bit32u));
}