Implement a more explicit object system

Make every dynamically allocated, opaque data structure inherit from
a common sqfs_object_t structure with common entry points (e.g. destroy).

This removes tons of public API functions and replaces them with a
simple sqfs_destroy instead. If semantics of the (until now implicit)
object system need to be extended, it can be much more conveniantely
done this way.

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

1 files changed, 17 insertions, 13 deletions

diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
index acb2235..46a67cd 100644
--- a/lib/sqfs/meta_writer.c
+++ b/lib/sqfs/meta_writer.c
@@ -25,6 +25,8 @@ typedef struct meta_block_t {
 } meta_block_t;
 
 struct sqfs_meta_writer_t {
+	sqfs_object_t base;
+
 	/* A byte offset into the uncompressed data of the current block */
 	size_t offset;
 
@@ -53,6 +55,20 @@ static int write_block(sqfs_file_t *file, meta_block_t *outblk)
 	return file->write_at(file, off, outblk->data, count + 2);
 }
 
+static void meta_writer_destroy(sqfs_object_t *obj)
+{
+	sqfs_meta_writer_t *m = (sqfs_meta_writer_t *)obj;
+	meta_block_t *blk;
+
+	while (m->list != NULL) {
+		blk = m->list;
+		m->list = blk->next;
+		free(blk);
+	}
+
+	free(m);
+}
+
 sqfs_meta_writer_t *sqfs_meta_writer_create(sqfs_file_t *file,
 					    sqfs_compressor_t *cmp,
 					    sqfs_u32 flags)
@@ -66,25 +82,13 @@ sqfs_meta_writer_t *sqfs_meta_writer_create(sqfs_file_t *file,
 	if (m == NULL)
 		return NULL;
 
+	((sqfs_object_t *)m)->destroy = meta_writer_destroy;
 	m->cmp = cmp;
 	m->file = file;
 	m->flags = flags;
 	return m;
 }
 
-void sqfs_meta_writer_destroy(sqfs_meta_writer_t *m)
-{
-	meta_block_t *blk;
-
-	while (m->list != NULL) {
-		blk = m->list;
-		m->list = blk->next;
-		free(blk);
-	}
-
-	free(m);
-}
-
 int sqfs_meta_writer_flush(sqfs_meta_writer_t *m)
 {
 	meta_block_t *outblk;