libsqfs: externalize the dir reader state

Instead of holding the state internally, move it outside and let the
user pass it in. This allows processing multiple directories and going
back and forth between them, while also simplifying the dir reader
internals.

The sqfs_dir_reader_get_inode function can also be made more generic
to accept a reference instead of being fully state dependent.

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

1 files changed, 24 insertions, 32 deletions

diff --git a/lib/sqfs/src/dir_reader.c b/lib/sqfs/src/dir_reader.c
index c904f35..2b6d0e8 100644
--- a/lib/sqfs/src/dir_reader.c
+++ b/lib/sqfs/src/dir_reader.c
@@ -36,8 +36,6 @@ struct sqfs_dir_reader_t {
 	sqfs_u32 flags;
 
 	rbtree_t dcache;
-
-	sqfs_dir_reader_state_t state;
 };
 
 static int dcache_key_compare(const void *ctx, const void *l, const void *r)
@@ -189,6 +187,7 @@ fail_dcache:
 
 int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
 			     const sqfs_inode_generic_t *inode,
+			     sqfs_dir_reader_state_t *state,
 			     sqfs_u32 flags)
 {
 	sqfs_u32 parent;
@@ -197,7 +196,9 @@ int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
 	if (flags & (~SQFS_DIR_OPEN_ALL_FLAGS))
 		return SQFS_ERROR_UNSUPPORTED;
 
-	ret = sqfs_readdir_state_init(&rd->state.cursor, &rd->super, inode);
+	memset(state, 0, sizeof(*state));
+
+	ret = sqfs_readdir_state_init(&state->cursor, &rd->super, inode);
 	if (ret)
 		return ret;
 
@@ -209,21 +210,21 @@ int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
 			parent = inode->data.dir.parent_inode;
 		}
 
-		if (dcache_find(rd, inode->base.inode_number, &rd->state.cur_ref))
+		if (dcache_find(rd, inode->base.inode_number, &state->cur_ref))
 			return SQFS_ERROR_NO_ENTRY;
 
-		if (rd->state.cur_ref == rd->super.root_inode_ref) {
-			rd->state.parent_ref = rd->state.cur_ref;
-		} else if (dcache_find(rd, parent, &rd->state.parent_ref)) {
+		if (state->cur_ref == rd->super.root_inode_ref) {
+			state->parent_ref = state->cur_ref;
+		} else if (dcache_find(rd, parent, &state->parent_ref)) {
 			return SQFS_ERROR_NO_ENTRY;
 		}
 
-		rd->state.state = DIR_STATE_OPENED;
+		state->state = DIR_STATE_OPENED;
 	} else {
-		rd->state.state = DIR_STATE_ENTRIES;
+		state->state = DIR_STATE_ENTRIES;
 	}
 
-	rd->state.start_state = rd->state.state;
+	state->start_state = state->state;
 	return 0;
 }
 
@@ -245,23 +246,24 @@ static int mk_dummy_entry(const char *str, sqfs_dir_node_t **out)
 	return 0;
 }
 
-int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_node_t **out)
+int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_reader_state_t *state,
+			 sqfs_dir_node_t **out)
 {
 	int err;
 
-	switch (rd->state.state) {
+	switch (state->state) {
 	case DIR_STATE_OPENED:
 		err = mk_dummy_entry(".", out);
 		if (err == 0) {
-			rd->state.state = DIR_STATE_DOT;
-			rd->state.ent_ref = rd->state.cur_ref;
+			state->state = DIR_STATE_DOT;
+			state->ent_ref = state->cur_ref;
 		}
 		return err;
 	case DIR_STATE_DOT:
 		err = mk_dummy_entry("..", out);
 		if (err == 0) {
-			rd->state.state = DIR_STATE_ENTRIES;
-			rd->state.ent_ref = rd->state.parent_ref;
+			state->state = DIR_STATE_ENTRIES;
+			state->ent_ref = state->parent_ref;
 		}
 		return err;
 	case DIR_STATE_ENTRIES:
@@ -270,35 +272,25 @@ int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_node_t **out)
 		return SQFS_ERROR_SEQUENCE;
 	}
 
-	return sqfs_meta_reader_readdir(rd->meta_dir, &rd->state.cursor,
-					out, NULL, &rd->state.ent_ref);
+	return sqfs_meta_reader_readdir(rd->meta_dir, &state->cursor,
+					out, NULL, &state->ent_ref);
 }
 
-int sqfs_dir_reader_get_inode(sqfs_dir_reader_t *rd,
+int sqfs_dir_reader_get_inode(sqfs_dir_reader_t *rd, sqfs_u64 ref,
 			      sqfs_inode_generic_t **inode)
 {
 	int ret;
 
 	ret = sqfs_meta_reader_read_inode(rd->meta_inode, &rd->super,
-					  rd->state.ent_ref >> 16,
-					  rd->state.ent_ref & 0x0FFFF, inode);
+					  ref >> 16, ref & 0x0FFFF, inode);
 	if (ret != 0)
 		return ret;
 
-	return dcache_add(rd, *inode, rd->state.ent_ref);
+	return dcache_add(rd, *inode, ref);
 }
 
 int sqfs_dir_reader_get_root_inode(sqfs_dir_reader_t *rd,
 				   sqfs_inode_generic_t **inode)
 {
-	sqfs_u64 block_start = rd->super.root_inode_ref >> 16;
-	sqfs_u16 offset = rd->super.root_inode_ref & 0xFFFF;
-	int ret;
-
-	ret = sqfs_meta_reader_read_inode(rd->meta_inode, &rd->super,
-					  block_start, offset, inode);
-	if (ret != 0)
-		return ret;
-
-	return dcache_add(rd, *inode, rd->super.root_inode_ref);
+	return sqfs_dir_reader_get_inode(rd, rd->super.root_inode_ref, inode);
 }