ext4_common.c

			char filename[dirent.namelen + 1];
			struct ext2fs_node *fdiro;
			int type = FILETYPE_UNKNOWN;

			status = ext4fs_read_file(diro,
						  fpos +
						  sizeof(struct ext2_dirent),
						  dirent.namelen, filename,
						  &actread);
			if (status < 0)
				return 0;

			fdiro = zalloc(sizeof(struct ext2fs_node));
			if (!fdiro)
				return 0;

			fdiro->data = diro->data;
			fdiro->ino = le32_to_cpu(dirent.inode);

			filename[dirent.namelen] = '\0';

			if (dirent.filetype != FILETYPE_UNKNOWN) {
				fdiro->inode_read = 0;

				if (dirent.filetype == FILETYPE_DIRECTORY)
					type = FILETYPE_DIRECTORY;
				else if (dirent.filetype == FILETYPE_SYMLINK)
					type = FILETYPE_SYMLINK;
				else if (dirent.filetype == FILETYPE_REG)
					type = FILETYPE_REG;
			} else {
				status = ext4fs_read_inode(diro->data,
							   le32_to_cpu
							   (dirent.inode),
							   &fdiro->inode);
				if (status == 0) {
					free(fdiro);
					return 0;
				}
				fdiro->inode_read = 1;

				if ((le16_to_cpu(fdiro->inode.mode) &
				     FILETYPE_INO_MASK) ==
				    FILETYPE_INO_DIRECTORY) {
					type = FILETYPE_DIRECTORY;
				} else if ((le16_to_cpu(fdiro->inode.mode)
					    & FILETYPE_INO_MASK) ==
					   FILETYPE_INO_SYMLINK) {
					type = FILETYPE_SYMLINK;
				} else if ((le16_to_cpu(fdiro->inode.mode)
					    & FILETYPE_INO_MASK) ==
					   FILETYPE_INO_REG) {
					type = FILETYPE_REG;
				}
			}
#ifdef DEBUG
			printf("iterate >%s<\n", filename);
#endif /* of DEBUG */
			if ((name != NULL) && (fnode != NULL)
			    && (ftype != NULL)) {
				if (strcmp(filename, name) == 0) {
					*ftype = type;
					*fnode = fdiro;
					return 1;
				}
			} else {
				if (fdiro->inode_read == 0) {
					status = ext4fs_read_inode(diro->data,
								 le32_to_cpu(
								 dirent.inode),
								 &fdiro->inode);
					if (status == 0) {
						free(fdiro);
						return 0;
					}
					fdiro->inode_read = 1;
				}
				switch (type) {
				case FILETYPE_DIRECTORY:
					printf("<DIR> ");
					break;
				case FILETYPE_SYMLINK:
					printf("<SYM> ");
					break;
				case FILETYPE_REG:
					printf("      ");
					break;
				default:
					printf("< ? > ");
					break;
				}
				printf("%10u %s\n",
				       le32_to_cpu(fdiro->inode.size),
					filename);
			}
			free(fdiro);
		}
		fpos += le16_to_cpu(dirent.direntlen);
	}
	return 0;
}

static char *ext4fs_read_symlink(struct ext2fs_node *node)
{
	char *symlink;
	struct ext2fs_node *diro = node;
	int status;
	loff_t actread;

	if (!diro->inode_read) {
		status = ext4fs_read_inode(diro->data, diro->ino, &diro->inode);
		if (status == 0)
			return NULL;
	}
	symlink = zalloc(le32_to_cpu(diro->inode.size) + 1);
	if (!symlink)
		return NULL;

	if (le32_to_cpu(diro->inode.size) < sizeof(diro->inode.b.symlink)) {
		strncpy(symlink, diro->inode.b.symlink,
			 le32_to_cpu(diro->inode.size));
	} else {
		status = ext4fs_read_file(diro, 0,
					   le32_to_cpu(diro->inode.size),
					   symlink, &actread);
		if ((status < 0) || (actread == 0)) {
			free(symlink);
			return NULL;
		}
	}
	symlink[le32_to_cpu(diro->inode.size)] = '\0';
	return symlink;
}

static int ext4fs_find_file1(const char *currpath,
			     struct ext2fs_node *currroot,
			     struct ext2fs_node **currfound, int *foundtype)
{
	char fpath[strlen(currpath) + 1];
	char *name = fpath;
	char *next;
	int status;
	int type = FILETYPE_DIRECTORY;
	struct ext2fs_node *currnode = currroot;
	struct ext2fs_node *oldnode = currroot;

	strncpy(fpath, currpath, strlen(currpath) + 1);

	/* Remove all leading slashes. */
	while (*name == '/')
		name++;

	if (!*name) {
		*currfound = currnode;
		return 1;
	}

	for (;;) {
		int found;

		/* Extract the actual part from the pathname. */
		next = strchr(name, '/');
		if (next) {
			/* Remove all leading slashes. */
			while (*next == '/')
				*(next++) = '\0';
		}

		if (type != FILETYPE_DIRECTORY) {
			ext4fs_free_node(currnode, currroot);
			return 0;
		}

		oldnode = currnode;

		/* Iterate over the directory. */
		found = ext4fs_iterate_dir(currnode, name, &currnode, &type);
		if (found == 0)
			return 0;

		if (found == -1)
			break;

		/* Read in the symlink and follow it. */
		if (type == FILETYPE_SYMLINK) {
			char *symlink;

			/* Test if the symlink does not loop. */
			if (++symlinknest == 8) {
				ext4fs_free_node(currnode, currroot);
				ext4fs_free_node(oldnode, currroot);
				return 0;
			}

			symlink = ext4fs_read_symlink(currnode);
			ext4fs_free_node(currnode, currroot);

			if (!symlink) {
				ext4fs_free_node(oldnode, currroot);
				return 0;
			}

			debug("Got symlink >%s<\n", symlink);

			if (symlink[0] == '/') {
				ext4fs_free_node(oldnode, currroot);
				oldnode = &ext4fs_root->diropen;
			}

			/* Lookup the node the symlink points to. */
			status = ext4fs_find_file1(symlink, oldnode,
						    &currnode, &type);

			free(symlink);

			if (status == 0) {
				ext4fs_free_node(oldnode, currroot);
				return 0;
			}
		}

		ext4fs_free_node(oldnode, currroot);

		/* Found the node! */
		if (!next || *next == '\0') {
			*currfound = currnode;
			*foundtype = type;
			return 1;
		}
		name = next;
	}
	return -1;
}

int ext4fs_find_file(const char *path, struct ext2fs_node *rootnode,
	struct ext2fs_node **foundnode, int expecttype)
{
	int status;
	int foundtype = FILETYPE_DIRECTORY;

	symlinknest = 0;
	if (!path)
		return 0;

	status = ext4fs_find_file1(path, rootnode, foundnode, &foundtype);
	if (status == 0)
		return 0;

	/* Check if the node that was found was of the expected type. */
	if ((expecttype == FILETYPE_REG) && (foundtype != expecttype))
		return 0;
	else if ((expecttype == FILETYPE_DIRECTORY)
		   && (foundtype != expecttype))
		return 0;

	return 1;
}

int ext4fs_open(const char *filename, loff_t *len)
{
	struct ext2fs_node *fdiro = NULL;
	int status;

	if (ext4fs_root == NULL)
		return -1;

	ext4fs_file = NULL;
	status = ext4fs_find_file(filename, &ext4fs_root->diropen, &fdiro,
				  FILETYPE_REG);
	if (status == 0)
		goto fail;

	if (!fdiro->inode_read) {
		status = ext4fs_read_inode(fdiro->data, fdiro->ino,
				&fdiro->inode);
		if (status == 0)
			goto fail;
	}
	*len = le32_to_cpu(fdiro->inode.size);
	ext4fs_file = fdiro;

	return 0;
fail:
	ext4fs_free_node(fdiro, &ext4fs_root->diropen);

	return -1;
}

int ext4fs_mount(unsigned part_length)
{
	struct ext2_data *data;
	int status;
	struct ext_filesystem *fs = get_fs();
	data = zalloc(SUPERBLOCK_SIZE);
	if (!data)
		return 0;

	/* Read the superblock. */
	status = ext4_read_superblock((char *)&data->sblock);

	if (status == 0)
		goto fail;

	/* Make sure this is an ext2 filesystem. */
	if (le16_to_cpu(data->sblock.magic) != EXT2_MAGIC)
		goto fail;

	/*
	 * The 64bit feature was enabled when metadata_csum was enabled
	 * and we do not support metadata_csum (and cannot reliably find
	 * files when it is set.  Refuse to mount.
	 */
	if (le32_to_cpu(data->sblock.feature_incompat) & EXT4_FEATURE_INCOMPAT_64BIT) {
		printf("Unsupported feature found (64bit, possibly metadata_csum), not mounting\n");
		goto fail;
	}

	if (le32_to_cpu(data->sblock.revision_level) == 0) {
		fs->inodesz = 128;
	} else {
		debug("EXT4 features COMPAT: %08x INCOMPAT: %08x RO_COMPAT: %08x\n",
		      __le32_to_cpu(data->sblock.feature_compatibility),
		      __le32_to_cpu(data->sblock.feature_incompat),
		      __le32_to_cpu(data->sblock.feature_ro_compat));

		fs->inodesz = le16_to_cpu(data->sblock.inode_size);
		fs->gdsize = le32_to_cpu(data->sblock.feature_incompat) &
			EXT4_FEATURE_INCOMPAT_64BIT ?
			le16_to_cpu(data->sblock.descriptor_size) : 32;
	}

	debug("EXT2 rev %d, inode_size %d, descriptor size %d\n",
	      le32_to_cpu(data->sblock.revision_level),
	      fs->inodesz, fs->gdsize);

	data->diropen.data = data;
	data->diropen.ino = 2;
	data->diropen.inode_read = 1;
	data->inode = &data->diropen.inode;

	status = ext4fs_read_inode(data, 2, data->inode);
	if (status == 0)
		goto fail;

	ext4fs_root = data;

	return 1;
fail:
	printf("Failed to mount ext2 filesystem...\n");
	free(data);
	ext4fs_root = NULL;

	return 0;
}