ladybird/VirtualFileSystem/FileBackedDiskDevice.cpp
Andreas Kling 9cd0a34b5c BlockDevice -> DiskDevice.
BlockDevice was the wrong name for this abstraction, since a block device
is a type of file in a unix system, and we should use that name for that
concept in the fs implementation.
2018-10-16 11:21:49 +02:00

82 lines
2.2 KiB
C++

#define _FILE_OFFSET_BITS 64
#include "FileBackedDiskDevice.h"
#include <cstring>
#include <sys/stat.h>
//#define FBBD_DEBUG
#define IGNORE_FILE_LENGTH // Useful for e.g /dev/hda2
RetainPtr<FileBackedDiskDevice> FileBackedDiskDevice::create(String&& imagePath, unsigned blockSize)
{
return adopt(*new FileBackedDiskDevice(std::move(imagePath), blockSize));
}
FileBackedDiskDevice::FileBackedDiskDevice(String&& imagePath, unsigned blockSize)
: m_imagePath(std::move(imagePath))
, m_blockSize(blockSize)
{
struct stat st;
int result = stat(m_imagePath.characters(), &st);
ASSERT(result != -1);
m_fileLength = st.st_size;
m_file = fopen(m_imagePath.characters(), "r+");
}
FileBackedDiskDevice::~FileBackedDiskDevice()
{
}
unsigned FileBackedDiskDevice::blockSize() const
{
return m_blockSize;
}
bool FileBackedDiskDevice::readBlock(unsigned index, byte* out) const
{
qword offset = index * m_blockSize;
return read(offset, blockSize(), out);
}
bool FileBackedDiskDevice::writeBlock(unsigned index, const byte* data)
{
qword offset = index * m_blockSize;
return write(offset, blockSize(), data);
}
bool FileBackedDiskDevice::read(qword offset, unsigned length, byte* out) const
{
#ifndef IGNORE_FILE_LENGTH
if (offset + length >= m_fileLength)
return false;
#endif
#ifdef FBBD_DEBUG
printf("[FileBackedDiskDevice] Read device @ offset %llx, length %u\n", offset, length);
#endif
fseeko(m_file, offset, SEEK_SET);
unsigned nread = fread(out, sizeof(byte), length, m_file);
ASSERT(nread == length);
return true;
}
bool FileBackedDiskDevice::write(qword offset, unsigned length, const byte* data)
{
#ifndef IGNORE_FILE_LENGTH
if (offset + length >= m_fileLength)
return false;
#endif
#ifdef FBBD_DEBUG
printf("[FileBackedDiskDevice] Write device @ offset %llx, length %u\n", offset, length);
#endif
fseeko(m_file, offset, SEEK_SET);
// size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
unsigned nwritten = fwrite(data, sizeof(byte), length, m_file);
ASSERT(nwritten == length);
return true;
}
const char* FileBackedDiskDevice::className() const
{
return "FileBackedDiskDevice";
}