errcode_t ext2fs_mmp_read(ext2_filsys fs, blk64_t mmp_blk, void *buf)
{
struct mmp_struct *mmp_cmp;
errcode_t retval = 0;
if ((mmp_blk <= fs->super->s_first_data_block) ||
(mmp_blk >= fs->super->s_blocks_count))
return EXT2_ET_MMP_BAD_BLOCK;
/* ext2fs_open() reserves fd0,1,2 to avoid stdio collision, so checking
* mmp_fd <= 0 is OK to validate that the fd is valid. This opens its
* own fd to read the MMP block to ensure that it is using O_DIRECT,
* regardless of how the io_manager is doing reads, to avoid caching of
* the MMP block by the io_manager or the VM. It needs to be fresh. */
if (fs->mmp_fd <= 0) {
/*
fs->mmp_fd = open(fs->device_name, O_RDWR | O_DIRECT);
if (fs->mmp_fd < 0) {
retval = EXT2_ET_MMP_OPEN_DIRECT;
goto out;
}
*/
}
if (fs->mmp_cmp == NULL) {
int align = ext2fs_get_dio_alignment(fs->mmp_fd);
retval = ext2fs_get_memalign(fs->blocksize, align,
&fs->mmp_cmp);
if (retval)
return retval;
}
if (ext2fs_llseek(fs->mmp_fd, mmp_blk * fs->blocksize, SEEK_SET) !=
mmp_blk * fs->blocksize) {
retval = EXT2_ET_LLSEEK_FAILED;
goto out;
}
if (read(fs->mmp_fd, fs->mmp_cmp, fs->blocksize) != fs->blocksize) {
retval = EXT2_ET_SHORT_READ;
goto out;
}
mmp_cmp = fs->mmp_cmp;
#ifdef WORDS_BIGENDIAN
ext2fs_swap_mmp(mmp_cmp);
#endif
if (buf != NULL && buf != fs->mmp_cmp)
memcpy(buf, fs->mmp_cmp, fs->blocksize);
if (mmp_cmp->mmp_magic != EXT4_MMP_MAGIC) {
retval = EXT2_ET_MMP_MAGIC_INVALID;
goto out;
}
out:
return retval;
}
int main(int argc, char **argv)
{
int lsectsize, psectsize;
int retval;
int fd;
if (argc < 2) {
fprintf(stderr, "Usage: %s device\n", argv[0]);
exit(1);
}
retval = ext2fs_get_device_sectsize(argv[1], &lsectsize);
if (retval) {
com_err(argv[0], retval,
"while calling ext2fs_get_device_sectsize");
exit(1);
}
retval = ext2fs_get_device_phys_sectsize(argv[1], &psectsize);
if (retval) {
com_err(argv[0], retval,
"while calling ext2fs_get_device_phys_sectsize");
exit(1);
}
printf("Device %s has logical/physical sector size of %d/%d.\n",
argv[1], lsectsize, psectsize);
fd = open(argv[1], O_RDONLY);
if (fd < 0) {
perror("open");
exit(1);
}
printf("The device's DIO alignment is %d\n",
ext2fs_get_dio_alignment(fd));
close(fd);
exit(0);
}
static errcode_t unix_open(const char *name, int flags, io_channel *channel)
{
io_channel io = NULL;
struct unix_private_data *data = NULL;
errcode_t retval;
int open_flags, zeroes = 0;
int f_nocache = 0;
ext2fs_struct_stat st;
#ifdef __linux__
struct utsname ut;
#endif
if (name == 0)
return EXT2_ET_BAD_DEVICE_NAME;
retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
if (retval)
goto cleanup;
memset(io, 0, sizeof(struct struct_io_channel));
io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
if (retval)
goto cleanup;
io->manager = unix_io_manager;
retval = ext2fs_get_mem(strlen(name)+1, &io->name);
if (retval)
goto cleanup;
strcpy(io->name, name);
io->private_data = data;
io->block_size = 1024;
io->read_error = 0;
io->write_error = 0;
io->refcount = 1;
memset(data, 0, sizeof(struct unix_private_data));
data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
data->io_stats.num_fields = 2;
open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
if (flags & IO_FLAG_EXCLUSIVE)
open_flags |= O_EXCL;
#if defined(O_DIRECT)
if (flags & IO_FLAG_DIRECT_IO) {
open_flags |= O_DIRECT;
io->align = ext2fs_get_dio_alignment(data->dev);
}
#elif defined(F_NOCACHE)
if (flags & IO_FLAG_DIRECT_IO) {
f_nocache = F_NOCACHE;
io->align = 4096;
}
#endif
data->flags = flags;
data->dev = ext2fs_open_file(io->name, open_flags, 0);
if (data->dev < 0) {
retval = errno;
goto cleanup;
}
if (f_nocache) {
if (fcntl(data->dev, f_nocache, 1) < 0) {
retval = errno;
goto cleanup;
}
}
/*
* If the device is really a block device, then set the
* appropriate flag, otherwise we can set DISCARD_ZEROES flag
* because we are going to use punch hole instead of discard
* and if it succeed, subsequent read from sparse area returns
* zero.
*/
if (ext2fs_stat(io->name, &st) == 0) {
if (S_ISBLK(st.st_mode))
io->flags |= CHANNEL_FLAGS_BLOCK_DEVICE;
else
io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
}
#ifdef BLKDISCARDZEROES
ioctl(data->dev, BLKDISCARDZEROES, &zeroes);
if (zeroes)
io->flags |= CHANNEL_FLAGS_DISCARD_ZEROES;
#endif
#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
/*
* Some operating systems require that the buffers be aligned,
* regardless of O_DIRECT
*/
if (!io->align)
io->align = 512;
#endif
if ((retval = alloc_cache(io, data)))
goto cleanup;
#ifdef BLKROGET
if (flags & IO_FLAG_RW) {
int error;
int readonly = 0;
/* Is the block device actually writable? */
error = ioctl(data->dev, BLKROGET, &readonly);
if (!error && readonly) {
close(data->dev);
retval = EPERM;
goto cleanup;
}
}
#endif
#ifdef __linux__
#undef RLIM_INFINITY
#if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
#define RLIM_INFINITY ((unsigned long)(~0UL>>1))
#else
#define RLIM_INFINITY (~0UL)
#endif
/*
* Work around a bug in 2.4.10-2.4.18 kernels where writes to
* block devices are wrongly getting hit by the filesize
* limit. This workaround isn't perfect, since it won't work
* if glibc wasn't built against 2.2 header files. (Sigh.)
*
*/
if ((flags & IO_FLAG_RW) &&
(uname(&ut) == 0) &&
((ut.release[0] == '2') && (ut.release[1] == '.') &&
(ut.release[2] == '4') && (ut.release[3] == '.') &&
(ut.release[4] == '1') && (ut.release[5] >= '0') &&
(ut.release[5] < '8')) &&
(ext2fs_stat(io->name, &st) == 0) &&
(S_ISBLK(st.st_mode))) {
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
setrlimit(RLIMIT_FSIZE, &rlim);
getrlimit(RLIMIT_FSIZE, &rlim);
if (((unsigned long) rlim.rlim_cur) <
((unsigned long) rlim.rlim_max)) {
rlim.rlim_cur = rlim.rlim_max;
setrlimit(RLIMIT_FSIZE, &rlim);
}
}
#endif
*channel = io;
return 0;
cleanup:
if (data) {
free_cache(data);
ext2fs_free_mem(&data);
}
if (io)
ext2fs_free_mem(&io);
return retval;
}
errcode_t ext2fs_dup_handle(ext2_filsys src, ext2_filsys *dest)
{
ext2_filsys fs;
errcode_t retval;
EXT2_CHECK_MAGIC(src, EXT2_ET_MAGIC_EXT2FS_FILSYS);
retval = ext2fs_get_mem(sizeof(struct struct_ext2_filsys), &fs);
if (retval)
return retval;
*fs = *src;
fs->device_name = 0;
fs->super = 0;
fs->orig_super = 0;
fs->group_desc = 0;
fs->inode_map = 0;
fs->block_map = 0;
fs->badblocks = 0;
fs->dblist = 0;
fs->mmp_buf = 0;
fs->mmp_cmp = 0;
fs->mmp_fd = -1;
io_channel_bumpcount(fs->io);
if (fs->icache)
fs->icache->refcount++;
retval = ext2fs_get_mem(strlen(src->device_name)+1, &fs->device_name);
if (retval)
goto errout;
strcpy(fs->device_name, src->device_name);
retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->super);
if (retval)
goto errout;
memcpy(fs->super, src->super, SUPERBLOCK_SIZE);
retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &fs->orig_super);
if (retval)
goto errout;
memcpy(fs->orig_super, src->orig_super, SUPERBLOCK_SIZE);
retval = ext2fs_get_array(fs->desc_blocks, fs->blocksize,
&fs->group_desc);
if (retval)
goto errout;
memcpy(fs->group_desc, src->group_desc,
(size_t) fs->desc_blocks * fs->blocksize);
if (src->inode_map) {
retval = ext2fs_copy_bitmap(src->inode_map, &fs->inode_map);
if (retval)
goto errout;
}
if (src->block_map) {
retval = ext2fs_copy_bitmap(src->block_map, &fs->block_map);
if (retval)
goto errout;
}
if (src->badblocks) {
retval = ext2fs_badblocks_copy(src->badblocks, &fs->badblocks);
if (retval)
goto errout;
}
if (src->dblist) {
retval = ext2fs_copy_dblist(src->dblist, &fs->dblist);
if (retval)
goto errout;
}
if (src->mmp_buf) {
retval = ext2fs_get_mem(src->blocksize, &fs->mmp_buf);
if (retval)
goto errout;
memcpy(fs->mmp_buf, src->mmp_buf, src->blocksize);
}
if (src->mmp_fd >= 0) {
fs->mmp_fd = dup(src->mmp_fd);
if (fs->mmp_fd < 0) {
retval = EXT2_ET_MMP_OPEN_DIRECT;
goto errout;
}
}
if (src->mmp_cmp) {
int align = ext2fs_get_dio_alignment(src->mmp_fd);
retval = ext2fs_get_memalign(src->blocksize, align,
&fs->mmp_cmp);
if (retval)
goto errout;
memcpy(fs->mmp_cmp, src->mmp_cmp, src->blocksize);
}
*dest = fs;
return 0;
errout:
ext2fs_free(fs);
return retval;
}
