--- /dev/null
+/**
+ * \file fsw_ext4.c
+ * ext4 file system driver code.
+ */
+
+/*-
+ * Copyright (c) 2012 Stefan Agner
+ * Portions Copyright (c) 2006 Christoph Pfisterer
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#include "fsw_ext4.h"
+
+
+// functions
+
+static fsw_status_t fsw_ext4_volume_mount(struct fsw_ext4_volume *vol);
+static void fsw_ext4_volume_free(struct fsw_ext4_volume *vol);
+static fsw_status_t fsw_ext4_volume_stat(struct fsw_ext4_volume *vol, struct fsw_volume_stat *sb);
+
+static fsw_status_t fsw_ext4_dnode_fill(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno);
+static void fsw_ext4_dnode_free(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno);
+static fsw_status_t fsw_ext4_dnode_stat(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_dnode_stat *sb);
+static fsw_status_t fsw_ext4_get_extent(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_extent *extent);
+
+static fsw_status_t fsw_ext4_dir_lookup(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_string *lookup_name, struct fsw_ext4_dnode **child_dno);
+static fsw_status_t fsw_ext4_dir_read(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_shandle *shand, struct fsw_ext4_dnode **child_dno);
+static fsw_status_t fsw_ext4_read_dentry(struct fsw_shandle *shand, struct ext4_dir_entry *entry);
+
+static fsw_status_t fsw_ext4_readlink(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_string *link);
+
+//
+// Dispatch Table
+//
+
+struct fsw_fstype_table FSW_FSTYPE_TABLE_NAME(ext4) = {
+ { FSW_STRING_TYPE_ISO88591, 4, 4, "ext4" },
+ sizeof(struct fsw_ext4_volume),
+ sizeof(struct fsw_ext4_dnode),
+
+ fsw_ext4_volume_mount,
+ fsw_ext4_volume_free,
+ fsw_ext4_volume_stat,
+ fsw_ext4_dnode_fill,
+ fsw_ext4_dnode_free,
+ fsw_ext4_dnode_stat,
+ fsw_ext4_get_extent,
+ fsw_ext4_dir_lookup,
+ fsw_ext4_dir_read,
+ fsw_ext4_readlink,
+};
+
+/**
+ * Mount an ext4 volume. Reads the superblock and constructs the
+ * root directory dnode.
+ */
+
+static fsw_status_t fsw_ext4_volume_mount(struct fsw_ext4_volume *vol)
+{
+ fsw_status_t status;
+ void *buffer;
+ fsw_u32 blocksize;
+ fsw_u32 groupcnt, groupno, gdesc_per_block, gdesc_bno, gdesc_index;
+ struct ext4_group_desc *gdesc;
+ int i;
+ struct fsw_string s;
+
+ // allocate memory to keep the superblock around
+ status = fsw_alloc(sizeof(struct ext4_super_block), &vol->sb);
+ if (status)
+ return status;
+
+ // read the superblock into its buffer
+ fsw_set_blocksize(vol, EXT4_SUPERBLOCK_BLOCKSIZE, EXT4_SUPERBLOCK_BLOCKSIZE);
+ status = fsw_block_get(vol, EXT4_SUPERBLOCK_BLOCKNO, 0, &buffer);
+ if (status)
+ return status;
+ fsw_memcpy(vol->sb, buffer, sizeof(struct ext4_super_block));
+ fsw_block_release(vol, EXT4_SUPERBLOCK_BLOCKNO, buffer);
+
+ // check the superblock
+ if (vol->sb->s_magic != EXT4_SUPER_MAGIC)
+ return FSW_UNSUPPORTED;
+ if (vol->sb->s_rev_level != EXT4_GOOD_OLD_REV &&
+ vol->sb->s_rev_level != EXT4_DYNAMIC_REV)
+ return FSW_UNSUPPORTED;
+
+ FSW_MSG_DEBUG((FSW_MSGSTR("fsw_ext4_volume_mount: Incompat flag %x\n"), vol->sb->s_feature_incompat));
+
+ if (vol->sb->s_rev_level == EXT4_DYNAMIC_REV &&
+ (vol->sb->s_feature_incompat & ~(EXT4_FEATURE_INCOMPAT_FILETYPE | EXT4_FEATURE_INCOMPAT_RECOVER)))
+ return FSW_UNSUPPORTED;
+
+
+ if (vol->sb->s_rev_level == EXT4_DYNAMIC_REV &&
+ (vol->sb->s_feature_incompat & EXT4_FEATURE_INCOMPAT_RECOVER))
+ {
+ FSW_MSG_DEBUG((FSW_MSGSTR("fsw_ext4_volume_mount: This ext3 file system needs recovery\n")));
+ // Print(L"Ext4 WARNING: This file system needs recovery, trying to use it anyway.\n");
+ }
+
+ // set real blocksize
+ blocksize = EXT4_BLOCK_SIZE(vol->sb);
+ fsw_set_blocksize(vol, blocksize, blocksize);
+
+ // get other info from superblock
+ vol->ind_bcnt = EXT4_ADDR_PER_BLOCK(vol->sb);
+ vol->dind_bcnt = vol->ind_bcnt * vol->ind_bcnt;
+ vol->inode_size = EXT4_INODE_SIZE(vol->sb);
+
+ for (i = 0; i < 16; i++)
+ if (vol->sb->s_volume_name[i] == 0)
+ break;
+ s.type = FSW_STRING_TYPE_ISO88591;
+ s.size = s.len = i;
+ s.data = vol->sb->s_volume_name;
+ status = fsw_strdup_coerce(&vol->g.label, vol->g.host_string_type, &s);
+ if (status)
+ return status;
+
+ // read the group descriptors to get inode table offsets
+ groupcnt = ((vol->sb->s_inodes_count - 2) / vol->sb->s_inodes_per_group) + 1;
+ gdesc_per_block = (vol->g.phys_blocksize / sizeof(struct ext4_group_desc));
+
+ status = fsw_alloc(sizeof(fsw_u32) * groupcnt, &vol->inotab_bno);
+ if (status)
+ return status;
+ for (groupno = 0; groupno < groupcnt; groupno++) {
+ // get the block group descriptor
+ gdesc_bno = (vol->sb->s_first_data_block + 1) + groupno / gdesc_per_block;
+ gdesc_index = groupno % gdesc_per_block;
+ status = fsw_block_get(vol, gdesc_bno, 1, (void **)&buffer);
+ if (status)
+ return status;
+ gdesc = ((struct ext4_group_desc *)(buffer)) + gdesc_index;
+ vol->inotab_bno[groupno] = gdesc->bg_inode_table_lo;
+ fsw_block_release(vol, gdesc_bno, buffer);
+ }
+
+ // setup the root dnode
+ status = fsw_dnode_create_root(vol, EXT4_ROOT_INO, &vol->g.root);
+ if (status)
+ return status;
+
+ FSW_MSG_DEBUG((FSW_MSGSTR("fsw_ext4_volume_mount: success, blocksize %d\n"), blocksize));
+
+ return FSW_SUCCESS;
+}
+
+/**
+ * Free the volume data structure. Called by the core after an unmount or after
+ * an unsuccessful mount to release the memory used by the file system type specific
+ * part of the volume structure.
+ */
+
+static void fsw_ext4_volume_free(struct fsw_ext4_volume *vol)
+{
+ if (vol->sb)
+ fsw_free(vol->sb);
+ if (vol->inotab_bno)
+ fsw_free(vol->inotab_bno);
+}
+
+/**
+ * Get in-depth information on a volume.
+ */
+
+static fsw_status_t fsw_ext4_volume_stat(struct fsw_ext4_volume *vol, struct fsw_volume_stat *sb)
+{
+ sb->total_bytes = (fsw_u64)vol->sb->s_blocks_count_lo * vol->g.log_blocksize;
+ sb->free_bytes = (fsw_u64)vol->sb->s_free_blocks_count_lo * vol->g.log_blocksize;
+ return FSW_SUCCESS;
+}
+
+/**
+ * Get full information on a dnode from disk. This function is called by the core
+ * whenever it needs to access fields in the dnode structure that may not
+ * be filled immediately upon creation of the dnode. In the case of ext4, we
+ * delay fetching of the inode structure until dnode_fill is called. The size and
+ * type fields are invalid until this function has been called.
+ */
+
+static fsw_status_t fsw_ext4_dnode_fill(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno)
+{
+ fsw_status_t status;
+ fsw_u32 groupno, ino_in_group, ino_bno, ino_index;
+ fsw_u8 *buffer;
+
+ if (dno->raw)
+ return FSW_SUCCESS;
+
+ FSW_MSG_DEBUG((FSW_MSGSTR("fsw_ext4_dnode_fill: inode %d\n"), dno->g.dnode_id));
+
+ // read the inode block
+ groupno = (dno->g.dnode_id - 1) / vol->sb->s_inodes_per_group;
+ ino_in_group = (dno->g.dnode_id - 1) % vol->sb->s_inodes_per_group;
+ ino_bno = vol->inotab_bno[groupno] +
+ ino_in_group / (vol->g.phys_blocksize / vol->inode_size);
+ ino_index = ino_in_group % (vol->g.phys_blocksize / vol->inode_size);
+ status = fsw_block_get(vol, ino_bno, 2, (void **)&buffer);
+ if (status)
+ return status;
+
+ // keep our inode around
+ status = fsw_memdup((void **)&dno->raw, buffer + ino_index * vol->inode_size, vol->inode_size);
+ fsw_block_release(vol, ino_bno, buffer);
+ if (status)
+ return status;
+
+ // get info from the inode
+ dno->g.size = dno->raw->i_size_lo; // TODO: check docs for 64-bit sized files
+
+ if (S_ISREG(dno->raw->i_mode))
+ dno->g.type = FSW_DNODE_TYPE_FILE;
+ else if (S_ISDIR(dno->raw->i_mode))
+ dno->g.type = FSW_DNODE_TYPE_DIR;
+ else if (S_ISLNK(dno->raw->i_mode))
+ dno->g.type = FSW_DNODE_TYPE_SYMLINK;
+ else
+ dno->g.type = FSW_DNODE_TYPE_SPECIAL;
+
+ return FSW_SUCCESS;
+}
+
+/**
+ * Free the dnode data structure. Called by the core when deallocating a dnode
+ * structure to release the memory used by the file system type specific part
+ * of the dnode structure.
+ */
+
+static void fsw_ext4_dnode_free(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno)
+{
+ if (dno->raw)
+ fsw_free(dno->raw);
+}
+
+/**
+ * Get in-depth information on a dnode. The core makes sure that fsw_ext4_dnode_fill
+ * has been called on the dnode before this function is called. Note that some
+ * data is not directly stored into the structure, but passed to a host-specific
+ * callback that converts it to the host-specific format.
+ */
+
+static fsw_status_t fsw_ext4_dnode_stat(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_dnode_stat *sb)
+{
+ sb->used_bytes = dno->raw->i_blocks_lo * EXT4_BLOCK_SIZE(vol->sb); // very, very strange...
+ sb->store_time_posix(sb, FSW_DNODE_STAT_CTIME, dno->raw->i_ctime);
+ sb->store_time_posix(sb, FSW_DNODE_STAT_ATIME, dno->raw->i_atime);
+ sb->store_time_posix(sb, FSW_DNODE_STAT_MTIME, dno->raw->i_mtime);
+ sb->store_attr_posix(sb, dno->raw->i_mode);
+
+ return FSW_SUCCESS;
+}
+
+/**
+ * Retrieve file data mapping information. This function is called by the core when
+ * fsw_shandle_read needs to know where on the disk the required piece of the file's
+ * data can be found. The core makes sure that fsw_ext4_dnode_fill has been called
+ * on the dnode before. Our task here is to get the physical disk block number for
+ * the requested logical block number.
+ *
+ * TODO...
+ * The ext2 file system does not use extents, but stores a list of block numbers
+ * using the usual direct, indirect, double-indirect, triple-indirect scheme. To
+ * optimize access, this function checks if the following file blocks are mapped
+ * to consecutive disk blocks and returns a combined extent if possible.
+ */
+
+static fsw_status_t fsw_ext4_get_extent(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_extent *extent)
+{
+ fsw_status_t status;
+ fsw_u32 bno, release_bno, buf_bcnt, file_bcnt;
+ fsw_u32 *buffer;
+ int path[5], i;
+
+ // Preconditions: The caller has checked that the requested logical block
+ // is within the file's size. The dnode has complete information, i.e.
+ // fsw_ext4_dnode_read_info was called successfully on it.
+
+ extent->type = FSW_EXTENT_TYPE_PHYSBLOCK;
+ extent->log_count = 1;
+ bno = extent->log_start;
+
+ // try direct block pointers in the inode
+ if (bno < EXT4_NDIR_BLOCKS) {
+ path[0] = bno;
+ path[1] = -1;
+ } else {
+ bno -= EXT4_NDIR_BLOCKS;
+
+ // try indirect block
+ if (bno < vol->ind_bcnt) {
+ path[0] = EXT4_IND_BLOCK;
+ path[1] = bno;
+ path[2] = -1;
+ } else {
+ bno -= vol->ind_bcnt;
+
+ // try double-indirect block
+ if (bno < vol->dind_bcnt) {
+ path[0] = EXT4_DIND_BLOCK;
+ path[1] = bno / vol->ind_bcnt;
+ path[2] = bno % vol->ind_bcnt;
+ path[3] = -1;
+ } else {
+ bno -= vol->dind_bcnt;
+
+ // use the triple-indirect block
+ path[0] = EXT4_TIND_BLOCK;
+ path[1] = bno / vol->dind_bcnt;
+ path[2] = (bno / vol->ind_bcnt) % vol->ind_bcnt;
+ path[3] = bno % vol->ind_bcnt;
+ path[4] = -1;
+ }
+ }
+ }
+
+ // follow the indirection path
+ buffer = dno->raw->i_block;
+ buf_bcnt = EXT4_NDIR_BLOCKS;
+ release_bno = 0;
+ for (i = 0; ; i++) {
+ bno = buffer[path[i]];
+ if (bno == 0) {
+ extent->type = FSW_EXTENT_TYPE_SPARSE;
+ if (release_bno)
+ fsw_block_release(vol, release_bno, buffer);
+ return FSW_SUCCESS;
+ }
+ if (path[i+1] < 0)
+ break;
+
+ if (release_bno)
+ fsw_block_release(vol, release_bno, buffer);
+ status = fsw_block_get(vol, bno, 1, (void **)&buffer);
+ if (status)
+ return status;
+ release_bno = bno;
+ buf_bcnt = vol->ind_bcnt;
+ }
+ extent->phys_start = bno;
+
+ // check if the following blocks can be aggregated into one extent
+ file_bcnt = (fsw_u32)((dno->g.size + vol->g.log_blocksize - 1) & (vol->g.log_blocksize - 1));
+ while (path[i] + extent->log_count < buf_bcnt && // indirect block has more block pointers
+ extent->log_start + extent->log_count < file_bcnt) { // file has more blocks
+ if (buffer[path[i] + extent->log_count] == buffer[path[i] + extent->log_count - 1] + 1)
+ extent->log_count++;
+ else
+ break;
+ }
+
+ if (release_bno)
+ fsw_block_release(vol, release_bno, buffer);
+ return FSW_SUCCESS;
+}
+
+/**
+ * Lookup a directory's child dnode by name. This function is called on a directory
+ * to retrieve the directory entry with the given name. A dnode is constructed for
+ * this entry and returned. The core makes sure that fsw_ext4_dnode_fill has been called
+ * and the dnode is actually a directory.
+ */
+
+static fsw_status_t fsw_ext4_dir_lookup(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_string *lookup_name, struct fsw_ext4_dnode **child_dno_out)
+{
+ fsw_status_t status;
+ struct fsw_shandle shand;
+ fsw_u32 child_ino;
+ struct ext4_dir_entry entry;
+ struct fsw_string entry_name;
+
+ // Preconditions: The caller has checked that dno is a directory node.
+
+ entry_name.type = FSW_STRING_TYPE_ISO88591;
+
+ // setup handle to read the directory
+ status = fsw_shandle_open(dno, &shand);
+ if (status)
+ return status;
+
+ // scan the directory for the file
+ child_ino = 0;
+ while (child_ino == 0) {
+ // read next entry
+ status = fsw_ext4_read_dentry(&shand, &entry);
+ if (status)
+ goto errorexit;
+ if (entry.inode == 0) {
+ // end of directory reached
+ status = FSW_NOT_FOUND;
+ goto errorexit;
+ }
+
+ // compare name
+ entry_name.len = entry_name.size = entry.name_len;
+ entry_name.data = entry.name;
+ if (fsw_streq(lookup_name, &entry_name)) {
+ child_ino = entry.inode;
+ break;
+ }
+ }
+
+ // setup a dnode for the child item
+ status = fsw_dnode_create(dno, child_ino, FSW_DNODE_TYPE_UNKNOWN, &entry_name, child_dno_out);
+
+errorexit:
+ fsw_shandle_close(&shand);
+ return status;
+}
+
+/**
+ * Get the next directory entry when reading a directory. This function is called during
+ * directory iteration to retrieve the next directory entry. A dnode is constructed for
+ * the entry and returned. The core makes sure that fsw_ext4_dnode_fill has been called
+ * and the dnode is actually a directory. The shandle provided by the caller is used to
+ * record the position in the directory between calls.
+ */
+
+static fsw_status_t fsw_ext4_dir_read(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_shandle *shand, struct fsw_ext4_dnode **child_dno_out)
+{
+ fsw_status_t status;
+ struct ext4_dir_entry entry;
+ struct fsw_string entry_name;
+
+ // Preconditions: The caller has checked that dno is a directory node. The caller
+ // has opened a storage handle to the directory's storage and keeps it around between
+ // calls.
+
+ while (1) {
+ // read next entry
+ status = fsw_ext4_read_dentry(shand, &entry);
+ if (status)
+ return status;
+ if (entry.inode == 0) // end of directory
+ return FSW_NOT_FOUND;
+
+ // skip . and ..
+ if ((entry.name_len == 1 && entry.name[0] == '.') ||
+ (entry.name_len == 2 && entry.name[0] == '.' && entry.name[1] == '.'))
+ continue;
+ break;
+ }
+
+ // setup name
+ entry_name.type = FSW_STRING_TYPE_ISO88591;
+ entry_name.len = entry_name.size = entry.name_len;
+ entry_name.data = entry.name;
+
+ // setup a dnode for the child item
+ status = fsw_dnode_create(dno, entry.inode, FSW_DNODE_TYPE_UNKNOWN, &entry_name, child_dno_out);
+
+ return status;
+}
+
+/**
+ * Read a directory entry from the directory's raw data. This internal function is used
+ * to read a raw ext2 directory entry into memory. The shandle's position pointer is adjusted
+ * to point to the next entry.
+ */
+
+static fsw_status_t fsw_ext4_read_dentry(struct fsw_shandle *shand, struct ext4_dir_entry *entry)
+{
+ fsw_status_t status;
+ fsw_u32 buffer_size;
+
+ while (1) {
+ // read dir_entry header (fixed length)
+ buffer_size = 8;
+ status = fsw_shandle_read(shand, &buffer_size, entry);
+ if (status)
+ return status;
+
+ if (buffer_size < 8 || entry->rec_len == 0) {
+ // end of directory reached
+ entry->inode = 0;
+ return FSW_SUCCESS;
+ }
+ if (entry->rec_len < 8)
+ return FSW_VOLUME_CORRUPTED;
+ if (entry->inode != 0) {
+ // this entry is used
+ if (entry->rec_len < 8 + entry->name_len)
+ return FSW_VOLUME_CORRUPTED;
+ break;
+ }
+
+ // valid, but unused entry, skip it
+ shand->pos += entry->rec_len - 8;
+ }
+
+ // read file name (variable length)
+ buffer_size = entry->name_len;
+ status = fsw_shandle_read(shand, &buffer_size, entry->name);
+ if (status)
+ return status;
+ if (buffer_size < entry->name_len)
+ return FSW_VOLUME_CORRUPTED;
+
+ // skip any remaining padding
+ shand->pos += entry->rec_len - (8 + entry->name_len);
+
+ return FSW_SUCCESS;
+}
+
+/**
+ * Get the target path of a symbolic link. This function is called when a symbolic
+ * link needs to be resolved. The core makes sure that the fsw_ext4_dnode_fill has been
+ * called on the dnode and that it really is a symlink.
+ *
+ * For ext4, the target path can be stored inline in the inode structure (in the space
+ * otherwise occupied by the block pointers) or in the inode's data. There is no flag
+ * indicating this, only the number of blocks entry (i_blocks) can be used as an
+ * indication. The check used here comes from the Linux kernel.
+ */
+
+static fsw_status_t fsw_ext4_readlink(struct fsw_ext4_volume *vol, struct fsw_ext4_dnode *dno,
+ struct fsw_string *link_target)
+{
+ fsw_status_t status;
+ int ea_blocks;
+ struct fsw_string s;
+
+ if (dno->g.size > FSW_PATH_MAX)
+ return FSW_VOLUME_CORRUPTED;
+
+ /* Linux kernels ext4_inode_is_fast_symlink... */
+ ea_blocks = dno->raw->i_file_acl_lo ? (vol->g.log_blocksize >> 9) : 0;
+
+ if (dno->raw->i_blocks_lo - ea_blocks == 0) {
+ // "fast" symlink, path is stored inside the inode
+ s.type = FSW_STRING_TYPE_ISO88591;
+ s.size = s.len = (int)dno->g.size;
+ s.data = dno->raw->i_block;
+ status = fsw_strdup_coerce(link_target, vol->g.host_string_type, &s);
+ } else {
+ // "slow" symlink, path is stored in normal inode data
+ status = fsw_dnode_readlink_data(dno, link_target);
+ }
+
+ return status;
+}
+
+// EOF