gctf2023/pwn/flipper/dist/common/source/fs/minixfs/MinixStorageManager.cpp

#include "MinixStorageManager.h"
#include "MinixFSSuperblock.h"
#include <assert.h>
#include "kprintf.h"

MinixStorageManager::MinixStorageManager(char *bm_buffer, uint16 num_inode_bm_blocks, uint16 num_zone_bm_blocks,
                                         uint16 num_inodes, uint16 num_zones) :
    StorageManager(num_inodes, num_zones)
{
  debug(M_STORAGE_MANAGER,
        "Constructor: num_inodes:%d\tnum_inode_bm_blocks:%d\tnum_zones:%d\tnum_zone_bm_blocks:%d\t\n", num_inodes,
        num_inode_bm_blocks, num_zones, num_zone_bm_blocks);

  num_inode_bm_blocks_ = num_inode_bm_blocks;
  num_zone_bm_blocks_ = num_zone_bm_blocks;

  uint32 i_byte = 0;
  for (; i_byte < num_inodes / 8; i_byte++)
  {
    inode_bitmap_.setByte(i_byte, bm_buffer[i_byte]);
  }
  for (uint32 i_bit = 0; i_bit < num_inodes % 8; i_bit++)
  {
    uint8 byte = bm_buffer[i_byte];
    if ((byte >> i_bit) & 0x01)
      inode_bitmap_.setBit(i_byte * 8 + i_bit);
  }
  //read zone bitmap
  uint32 z_byte = num_inode_bm_blocks * BLOCK_SIZE;
  uint32 z_bm_byte = 0;
  for (; z_bm_byte < num_zones / 8; z_byte++, z_bm_byte++)
  {
    zone_bitmap_.setByte(z_bm_byte, bm_buffer[z_byte]);
  }
  for (uint32 z_bit = 0; z_bit < num_zones % 8; z_bit++)
  {
    uint8 byte = bm_buffer[z_byte];
    if ((byte >> z_bit) & 0x01)
      zone_bitmap_.setBit(z_bm_byte * 8 + z_bit);
  }
  curr_inode_pos_ = 0;
  curr_zone_pos_ = 0;
}

MinixStorageManager::~MinixStorageManager()
{
  debug(M_STORAGE_MANAGER, "Destructor: destroyed\n");
}

bool MinixStorageManager::isInodeSet(size_t index)
{
  assert(index < inode_bitmap_.getSize() && "MinixStorageManager::isInodeSet called with bad index number");
  return inode_bitmap_.getBit(index);
}

uint32 MinixStorageManager::getNumUsedInodes()
{
  return inode_bitmap_.getNumBitsSet();
}

size_t MinixStorageManager::allocZone()
{
  size_t pos = curr_zone_pos_ + 1;
  for (; pos != curr_zone_pos_; ++pos)
  {
    if (pos >= zone_bitmap_.getSize())
    {
      pos = 0;
      if(pos == curr_zone_pos_) // Increment happens before check in for loop, which would lead to an infinite loop when curr_zone_pos_ = 0
      {
              break;
      }
    }
    if (!zone_bitmap_.getBit(pos))
    {
      zone_bitmap_.setBit(pos);
      curr_zone_pos_ = pos;
      debug(M_STORAGE_MANAGER, "acquireZone: Zone %zu acquired\n", pos);
      return pos;
    }
  }
  debug(M_STORAGE_MANAGER, "acquireZone: NO FREE ZONE FOUND!\n");
  assert(false); // full memory should have been checked.
  return 0;
}

size_t MinixStorageManager::allocInode()
{
  size_t pos = curr_inode_pos_ + 1;
  for (; pos != curr_inode_pos_; pos++)
  {
    if (pos >= inode_bitmap_.getSize())
      pos = 0;
    if (!inode_bitmap_.getBit(pos))
    {
      inode_bitmap_.setBit(pos);
      curr_inode_pos_ = pos;
      debug(M_STORAGE_MANAGER, "acquireInode: Inode %zu acquired\n", pos);
      return pos;
    }
  }
  kprintfd("acquireInode: NO FREE INODE FOUND!\n");
  assert(false); // full memory should have been checked.
  return 0;
}

void MinixStorageManager::freeZone(size_t index)
{
  zone_bitmap_.unsetBit(index);
  debug(M_STORAGE_MANAGER, "freeZone: Zone %zu freed\n", index);
}

void MinixStorageManager::freeInode(size_t index)
{
  inode_bitmap_.unsetBit(index);
  debug(M_STORAGE_MANAGER, "freeInode: Inode %zu freed\n", index);
}

void MinixStorageManager::flush(MinixFSSuperblock *superblock)
{
  debug(M_STORAGE_MANAGER, "flush: starting flushing\n");
  char* bm_buffer = new char[(num_inode_bm_blocks_ + num_zone_bm_blocks_) * BLOCK_SIZE];
  uint32 num_inodes = inode_bitmap_.getSize();
  uint32 i_byte = 0;
  for (; i_byte < num_inodes / 8; i_byte++)
  {
    bm_buffer[i_byte] = inode_bitmap_.getByte(i_byte);
  }
  uint8 byte = 0;
  for (uint32 i_bit = 0; i_bit < 8; i_bit++)
  {
    if (i_bit < num_inodes % 8)
    {
      if (inode_bitmap_.getBit(i_byte * 8 + i_bit))
      {
        byte &= 0x01 << i_bit;
      }
    }
    else
      byte &= 0x01 << i_bit;
  }
  bm_buffer[i_byte] = byte;
  ++i_byte;
  for (; i_byte < num_inode_bm_blocks_ * BLOCK_SIZE; i_byte++)
  {
    bm_buffer[i_byte] = 0xff;
  }

  uint32 num_zones = zone_bitmap_.getSize();
  uint32 z_byte = 0;
  for (; z_byte < num_zones / 8; z_byte++, i_byte++)
  {
    bm_buffer[i_byte] = zone_bitmap_.getByte(z_byte);
  }
  byte = 0;
  for (uint32 z_bit = 0; z_bit < 8; z_bit++)
  {
    if (z_bit < num_zones % 8)
    {
      if (zone_bitmap_.getBit(z_byte * 8 + z_bit))
      {
        byte &= 0x01 << z_bit;
      }
    }
    else
      byte &= 0x01 << z_bit;
  }
  bm_buffer[i_byte] = byte;
  ++z_byte;
  ++i_byte;
  for (; z_byte < num_zone_bm_blocks_ * BLOCK_SIZE; z_byte++, i_byte++)
  {
    bm_buffer[i_byte] = 0xff;
  }
  superblock->writeBlocks(2, num_inode_bm_blocks_ + num_zone_bm_blocks_, bm_buffer);
  delete[] bm_buffer;
  debug(M_STORAGE_MANAGER, "flush: flushing finished\n");
}

void MinixStorageManager::printBitmap()
{
  inode_bitmap_.bmprint();
  zone_bitmap_.bmprint();
}