ext4-realloc-inodes/patch.c

#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE

#include <unistd.h>
#include <fcntl.h>
#include "patch.h"

errcode_t retry_read(int fd, ssize_t size, void *buf)
{
	ssize_t r, done = 0;
	while (done < size)
	{
		r = read(fd, buf+done, size-done);
		if (r < 0 && errno != EAGAIN)
			break;
		done += r;
	}
	if (done < size)
		return errno;
	return 0;
}

errcode_t retry_write(int fd, ssize_t size, void *buf)
{
	ssize_t r, done = 0;
	while (done < size)
	{
		r = write(fd, buf+done, size-done);
		if (r < 0 && errno != EAGAIN)
			break;
		done += r;
	}
	if (done < size)
		return errno;
	return 0;
}

errcode_t retry_read_at(int fd, unsigned long long offset, ssize_t size, void *buf)
{
	if ((unsigned)ext2fs_llseek(fd, offset, SEEK_SET) != offset)
		return errno ? errno : EXT2_ET_LLSEEK_FAILED;
	return retry_read(fd, size, buf);
}

errcode_t retry_write_at(int fd, unsigned long long offset, ssize_t size, void *buf)
{
	if ((unsigned)ext2fs_llseek(fd, offset, SEEK_SET) != offset)
		return errno ? errno : EXT2_ET_LLSEEK_FAILED;
	return retry_write(fd, size, buf);
}

errcode_t ext2fs_patch_read_bmap(struct ext2fs_patch_file *data)
{
	errcode_t retval = 0;
	int bufsize = 65536;
	blk64_t i, r;
	void *buf = malloc(bufsize);
	if (!buf)
		return ENOMEM;
	ext2fs_llseek(data->patch_fd, data->size*data->block_size, SEEK_SET);
	for (i = 0; i < data->size/8; )
	{
		r = bufsize;
		if (data->size/8 - i < r)
			r = data->size/8 - i;
		retval = retry_read(data->patch_fd, r, buf);
		if (retval)
			goto out;
		ext2fs_set_generic_bmap_range(data->bmap, i*8, r*8, buf);
		i += r;
	}
out:
	free(buf);
	return retval;
}

errcode_t ext2fs_patch_write_bmap(struct ext2fs_patch_file *data)
{
	errcode_t retval = 0;
	int bufsize = 65536;
	blk64_t i, r;
	void *buf = malloc(bufsize);
	if (!buf)
		return ENOMEM;
	ext2fs_llseek(data->patch_fd, data->size*data->block_size, SEEK_SET);
	for (i = 0; i < data->size/8; )
	{
		r = bufsize;
		if (data->size/8 - i < r)
			r = data->size/8 - i;
		ext2fs_get_generic_bmap_range(data->bmap, i*8, r*8, buf);
		retval = retry_write(data->patch_fd, r, buf);
		if (retval)
			goto out;
		i += r;
	}
	write(data->patch_fd, &data->block_size, sizeof(__u32));
	write(data->patch_fd, &data->size, sizeof(blk64_t));
out:
	free(buf);
	return 0;
}

errcode_t ext2fs_patch_open(struct ext2fs_patch_file *data, char *patch_file)
{
	errcode_t retval = 0;
	ext2_loff_t size;
	data->block_size = 0;
	data->size = 0;
	data->bmap = NULL;
	data->patch_file = strdup(patch_file);
	data->patch_fd = open(data->patch_file, O_CREAT|O_RDWR, 0666);
	if (data->patch_fd < 0)
		return errno;
	size = ext2fs_llseek(data->patch_fd, 0, SEEK_END);
	if (size < 0)
		return errno;
	if (size > 0)
	{
		size = ext2fs_llseek(data->patch_fd, size-sizeof(__u32)-sizeof(blk64_t), SEEK_SET);
		read(data->patch_fd, &data->block_size, sizeof(__u32));
		read(data->patch_fd, &data->size, sizeof(blk64_t));
		retval = ext2fs_make_generic_bitmap(EXT2_ET_MAGIC_BLOCK_BITMAP, NULL,
			0, data->size, data->size, "overwritten blocks", 0, &data->bmap);
		if (retval)
			return retval;
		retval = ext2fs_patch_read_bmap(data);
	}
	return 0;
}

errcode_t ext2fs_patch_close(struct ext2fs_patch_file *data)
{
	if (data)
	{
		if (data->bmap)
		{
			if (data->patch_fd >= 0)
				ext2fs_patch_write_bmap(data);
			ext2fs_free_generic_bmap(data->bmap);
			data->bmap = NULL;
		}
		if (data->patch_fd >= 0)
		{
			close(data->patch_fd);
			data->patch_fd = -1;
		}
		if (data->patch_file)
		{
			free(data->patch_file);
			data->patch_file = NULL;
		}
	}
	return 0;
}

errcode_t ext2fs_patch_init_bmap(struct ext2fs_patch_file *data, io_channel channel)
{
	errcode_t retval = 0;
	if (!data->bmap)
	{
		if (channel)
		{
			data->block_size = channel->block_size;
			retval = ext2fs_get_device_size2(channel->name, data->block_size, &data->size);
			if (retval)
				return retval;
		}
		else if (!data->block_size || !data->size)
			return EINVAL;
		retval = ext2fs_make_generic_bitmap(EXT2_ET_MAGIC_BLOCK_BITMAP, NULL,
			0, data->size, data->size, "overwritten blocks", 0, &data->bmap);
	}
	return retval;
}