finstext2.c

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

#include <stdio.h>
#include <string.h>
#include "finstext2.h"
#include "ext2.h"	// #defines ext2_data
#include <linux/hdreg.h>
#include <linux/ext3_fs.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#define MAJOR_VERSION	1
#define MINOR_VERSION	0

PEXT2_BOOTCODE			Ext2BootCode = (PEXT2_BOOTCODE)ext2_data;
struct ext3_super_block	Ext2SuperBlock;
struct hd_geometry		Ext2DriveGeometry;
unsigned char			Ext2ExistingBootCode[1024];

char					BlockDevice[260];
int						BlockDeviceSpecified = 0;
int						BlockDeviceFileDescriptor;

int main(int argc, char *argv[])
{
	int		Index;
	char	ch;

	// Verify that we got enough command line parameters
	if (argc < 2)
	{
		printf("finstext2 block_device [-v]\n\n");
		printf("block_device    Specifies the ext2/3 volume to install to (i.e. /dev/hda1)\n");
		printf("-v              Displays the version\n\n");
	}

	// Parse the command line parameters
	for (Index=1; Index<argc; Index++)
	{
		if (strcmp(argv[Index], "-v") == 0)
		{
			printf("FreeLoader Ext2/3 Installer v%d.%d\n", MAJOR_VERSION, MINOR_VERSION);
		}
		else
		{
			strcpy(BlockDevice, argv[Index]);
			BlockDeviceSpecified = 1;
		}
	}

	if (BlockDeviceSpecified)
	{
		BlockDeviceFileDescriptor = open(BlockDevice, O_RDWR|O_SYNC);

		if (BlockDeviceFileDescriptor == -1)
		{
			printf("Couldn't open block device %s\n", BlockDevice);
			return 1;
		}

		if (read(BlockDeviceFileDescriptor, Ext2ExistingBootCode, (size_t)1024) != (ssize_t)1024)
		{
			close(BlockDeviceFileDescriptor);
			printf("Couldn't read existing boot code from %s\n", BlockDevice);
			return 1;
		}

		for (Index=0; Index<1024; Index++)
		{
			if (Ext2ExistingBootCode[Index] != 0x00)
			{
				printf("This EXT2/3 volume has existing boot code.\n");
				printf("Do you want to overwrite it? [y/n] ");
				scanf("%c", &ch);

				if (ch == 'n' || ch == 'N')
				{
					close(BlockDeviceFileDescriptor);
					printf("Cancelled.\n");
					return 0;
				}

				break;
			}
		}

		if (read(BlockDeviceFileDescriptor, &Ext2SuperBlock, (size_t)1024) != (ssize_t)1024)
		{
			close(BlockDeviceFileDescriptor);
			printf("Couldn't read super block from %s\n", BlockDevice);
			return 1;
		}

		if (Ext2SuperBlock.s_magic != EXT3_SUPER_MAGIC)
		{
			close(BlockDeviceFileDescriptor);
			printf("Block device %s is not a EXT2/3 volume or has an invalid super block.\n", BlockDevice);
			return 1;
		}

		if (ioctl(BlockDeviceFileDescriptor, HDIO_GETGEO, &Ext2DriveGeometry) != 0)
		{
			close(BlockDeviceFileDescriptor);
			printf("Couldn't get drive geometry from block device %s\n", BlockDevice);
			return 1;
		}

		printf("Heads: %d\n", Ext2DriveGeometry.heads);
		printf("Sectors: %d\n", Ext2DriveGeometry.sectors);
		printf("Cylinders: %d\n", Ext2DriveGeometry.cylinders);
		printf("Start: %d\n", Ext2DriveGeometry.start);

		Ext2BootCode->BootDrive = 0xff;
		Ext2BootCode->BootPartition = 0x00;
		//Ext2BootCode->SectorsPerTrack = Ext2DriveGeometry.sectors;
		//Ext2BootCode->NumberOfHeads = Ext2DriveGeometry.heads;
		Ext2BootCode->Ext2VolumeStartSector = Ext2DriveGeometry.start;
		Ext2BootCode->Ext2BlockSizeInBytes = 1024 << Ext2SuperBlock.s_log_block_size;
		Ext2BootCode->Ext2BlockSize = Ext2BootCode->Ext2BlockSizeInBytes / 512;
		Ext2BootCode->Ext2PointersPerBlock = Ext2BootCode->Ext2BlockSizeInBytes / 4;
		Ext2BootCode->Ext2GroupDescPerBlock = Ext2BootCode->Ext2BlockSizeInBytes / 32;
		Ext2BootCode->Ext2FirstDataBlock = Ext2SuperBlock.s_first_data_block;
		Ext2BootCode->Ext2InodesPerGroup = Ext2SuperBlock.s_inodes_per_group;
		Ext2BootCode->Ext2InodesPerBlock = Ext2BootCode->Ext2BlockSizeInBytes / 128;

		if (lseek(BlockDeviceFileDescriptor, (off_t)0, SEEK_SET) == (off_t)-1)
		{
			close(BlockDeviceFileDescriptor);
			printf("Couldn't write boot code on %s\n", BlockDevice);
			return 1;
		}

		if (write(BlockDeviceFileDescriptor, Ext2BootCode, (size_t)1024) != (ssize_t)1024)
		{
			close(BlockDeviceFileDescriptor);
			printf("Couldn't write boot code on %s\n", BlockDevice);
			return 1;
		}

		close(BlockDeviceFileDescriptor);

		printf("Boot code written successfully!\n");
	}

	return 0;
}