unsquashfs: restore fstree from image

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 138 insertions, 0 deletions

diff --git a/unpack/read_fstree.c b/unpack/read_fstree.c
new file mode 100644
index 0000000..a6903b0
--- /dev/null
+++ b/unpack/read_fstree.c
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "unsquashfs.h"
+
+
+static int fill_dir(meta_reader_t *ir, meta_reader_t *dr, tree_node_t *root,
+		    sqfs_super_t *super, id_table_t *idtbl)
+{
+	sqfs_inode_generic_t *inode;
+	sqfs_dir_header_t hdr;
+	sqfs_dir_entry_t *ent;
+	uint64_t block_start;
+	size_t size, diff;
+	tree_node_t *n;
+	uint32_t i;
+
+	block_start = root->data.dir->start_block;
+	block_start += super->directory_table_start;
+
+	if (meta_reader_seek(dr, block_start, root->data.dir->block_offset))
+		return -1;
+
+	size = root->data.dir->size;
+
+	while (size != 0) {
+		if (meta_reader_read_dir_header(dr, &hdr))
+			return -1;
+
+		size -= sizeof(hdr) > size ? size : sizeof(hdr);
+
+		for (i = 0; i <= hdr.count; ++i) {
+			ent = meta_reader_read_dir_ent(dr);
+			if (ent == NULL)
+				return -1;
+
+			diff = sizeof(*ent) + strlen((char *)ent->name);
+			size -= diff > size ? size : diff;
+
+			inode = meta_reader_read_inode(ir, super,
+						       hdr.start_block,
+						       ent->offset);
+			if (inode == NULL) {
+				free(ent);
+				return -1;
+			}
+
+			n = tree_node_from_inode(inode, idtbl,
+						 (char *)ent->name,
+						 super->block_size);
+			free(ent);
+			free(inode);
+
+			if (n == NULL)
+				return -1;
+
+			n->parent = root;
+			n->next = root->data.dir->children;
+			root->data.dir->children = n;
+		}
+	}
+
+	for (n = root->data.dir->children; n != NULL; n = n->next) {
+		if (S_ISDIR(n->mode)) {
+			if (fill_dir(ir, dr, n, super, idtbl))
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+int read_fstree(fstree_t *out, int fd, sqfs_super_t *super, compressor_t *cmp)
+{
+	sqfs_inode_generic_t *root;
+	meta_reader_t *ir, *dr;
+	uint64_t block_start;
+	id_table_t idtbl;
+	int status = -1;
+	size_t offset;
+
+	ir = meta_reader_create(fd, cmp);
+	if (ir == NULL)
+		return -1;
+
+	dr = meta_reader_create(fd, cmp);
+	if (dr == NULL)
+		goto out_ir;
+
+	if (id_table_init(&idtbl))
+		goto out_dr;
+
+	if (id_table_read(&idtbl, fd, super, cmp))
+		goto out_id;
+
+	block_start = super->root_inode_ref >> 16;
+	offset = super->root_inode_ref & 0xFFFF;
+	root = meta_reader_read_inode(ir, super, block_start, offset);
+	if (root == NULL)
+		goto out_id;
+
+	if (root->base.type != SQFS_INODE_DIR &&
+	    root->base.type != SQFS_INODE_EXT_DIR) {
+		free(root);
+		fputs("File system root inode is not a directory inode!\n",
+		      stderr);
+		goto out_id;
+	}
+
+	memset(out, 0, sizeof(*out));
+	out->block_size = super->block_size;
+	out->default_uid = 0;
+	out->default_gid = 0;
+	out->default_mode = 0755;
+	out->default_mtime = super->modification_time;
+
+	out->root = tree_node_from_inode(root, &idtbl, "", super->block_size);
+	free(root);
+	root = NULL;
+
+	if (out->root == NULL)
+		goto out_id;
+
+	if (fill_dir(ir, dr, out->root, super, &idtbl))
+		goto fail_fs;
+
+	fstree_sort(out);
+
+	status = 0;
+out_id:
+	id_table_cleanup(&idtbl);
+out_dr:
+	meta_reader_destroy(dr);
+out_ir:
+	meta_reader_destroy(ir);
+	return status;
+fail_fs:
+	fstree_cleanup(out);
+	goto out_id;
+}