Add a helper function to initialize libsquashfs objects

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

27 files changed, 72 insertions, 60 deletions

diff --git a/include/sqfs/predef.h b/include/sqfs/predef.h
index f4b544b..39da692 100644
--- a/include/sqfs/predef.h
+++ b/include/sqfs/predef.h
@@ -162,6 +162,22 @@ static SQFS_INLINE void *sqfs_copy(const void *obj)
 	return NULL;
 }
 
+/**
+ * @brief Initialize an object with default callbacks.
+ *
+ * @memberof sqfs_object_t
+ *
+ * @param obj A pointer to an uninitialized object
+ */
+static SQFS_INLINE
+void sqfs_object_init(void *obj,
+		      void (*destroy_fn)(sqfs_object_t *),
+		      sqfs_object_t *(*copy_fn)(const sqfs_object_t *))
+{
+	((sqfs_object_t *)obj)->destroy = destroy_fn;
+	((sqfs_object_t *)obj)->copy = copy_fn;
+}
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/lib/common/comp_lzo.c b/lib/common/comp_lzo.c
index 92a081c..2021d34 100644
--- a/lib/common/comp_lzo.c
+++ b/lib/common/comp_lzo.c
@@ -266,6 +266,8 @@ int lzo_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (lzo == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(lzo, lzo_destroy, lzo_create_copy);
+
 	lzo->block_size = cfg->block_size;
 	lzo->algorithm = cfg->opt.lzo.algorithm;
 	lzo->level = cfg->level;
@@ -277,8 +279,6 @@ int lzo_compressor_create(const sqfs_compressor_config_t *cfg,
 		lzo_uncomp_block : lzo_comp_block;
 	base->write_options = lzo_write_options;
 	base->read_options = lzo_read_options;
-	((sqfs_object_t *)base)->copy = lzo_create_copy;
-	((sqfs_object_t *)base)->destroy = lzo_destroy;
 
 	*out = base;
 	return 0;
diff --git a/lib/common/data_writer_ostream.c b/lib/common/data_writer_ostream.c
index 94a04f2..fbd0431 100644
--- a/lib/common/data_writer_ostream.c
+++ b/lib/common/data_writer_ostream.c
@@ -64,7 +64,6 @@ ostream_t *data_writer_ostream_create(const char *filename,
 				      int flags)
 {
 	data_writer_ostream_t *strm = calloc(1, sizeof(*strm));
-	sqfs_object_t *obj = (sqfs_object_t *)strm;
 	ostream_t *base = (ostream_t *)strm;
 	int ret;
 
@@ -73,6 +72,8 @@ ostream_t *data_writer_ostream_create(const char *filename,
 		return NULL;
 	}
 
+	sqfs_object_init(strm, stream_destroy, NULL);
+
 	ret = sqfs_block_processor_begin_file(proc, inode, NULL, flags);
 
 	if (ret != 0) {
@@ -86,6 +87,5 @@ ostream_t *data_writer_ostream_create(const char *filename,
 	base->append = stream_append;
 	base->flush = stream_flush;
 	base->get_filename = stream_get_filename;
-	obj->destroy = stream_destroy;
 	return base;
 }
diff --git a/lib/io/compress/ostream_compressor.c b/lib/io/compress/ostream_compressor.c
index 314ce6b..f63a3d2 100644
--- a/lib/io/compress/ostream_compressor.c
+++ b/lib/io/compress/ostream_compressor.c
@@ -63,7 +63,6 @@ static void comp_destroy(sqfs_object_t *obj)
 ostream_t *ostream_compressor_create(ostream_t *strm, int comp_id)
 {
 	ostream_comp_t *comp = NULL;
-	sqfs_object_t *obj;
 	ostream_t *base;
 
 	switch (comp_id) {
@@ -94,6 +93,8 @@ ostream_t *ostream_compressor_create(ostream_t *strm, int comp_id)
 	if (comp == NULL)
 		return NULL;
 
+	sqfs_object_init(comp, comp_destroy, NULL);
+
 	comp->wrapped = strm;
 	comp->inbuf_used = 0;
 
@@ -101,8 +102,5 @@ ostream_t *ostream_compressor_create(ostream_t *strm, int comp_id)
 	base->append = comp_append;
 	base->flush = comp_flush;
 	base->get_filename = comp_get_filename;
-
-	obj = (sqfs_object_t *)comp;
-	obj->destroy = comp_destroy;
 	return base;
 }
diff --git a/lib/io/uncompress/istream_compressor.c b/lib/io/uncompress/istream_compressor.c
index ab9ad8b..1c73e3a 100644
--- a/lib/io/uncompress/istream_compressor.c
+++ b/lib/io/uncompress/istream_compressor.c
@@ -25,7 +25,6 @@ static void comp_destroy(sqfs_object_t *obj)
 istream_t *istream_compressor_create(istream_t *strm, int comp_id)
 {
 	istream_comp_t *comp = NULL;
-	sqfs_object_t *obj;
 	istream_t *base;
 
 	switch (comp_id) {
@@ -56,14 +55,13 @@ istream_t *istream_compressor_create(istream_t *strm, int comp_id)
 	if (comp == NULL)
 		return NULL;
 
+	sqfs_object_init(comp, comp_destroy, NULL);
+
 	comp->wrapped = strm;
 
 	base = (istream_t *)comp;
 	base->get_filename = comp_get_filename;
 	base->buffer = comp->uncompressed;
 	base->eof = false;
-
-	obj = (sqfs_object_t *)comp;
-	obj->destroy = comp_destroy;
 	return base;
 }
diff --git a/lib/io/unix/istream.c b/lib/io/unix/istream.c
index e0b728c..f8cffad 100644
--- a/lib/io/unix/istream.c
+++ b/lib/io/unix/istream.c
@@ -65,7 +65,6 @@ static void file_destroy(sqfs_object_t *obj)
 istream_t *istream_open_file(const char *path)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	istream_t *strm = (istream_t *)file;
 
 	if (file == NULL) {
@@ -73,6 +72,8 @@ istream_t *istream_open_file(const char *path)
 		return NULL;
 	}
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	file->path = strdup(path);
 	if (file->path == NULL) {
 		perror(path);
@@ -88,7 +89,6 @@ istream_t *istream_open_file(const char *path)
 	strm->buffer = file->buffer;
 	strm->precache = file_precache;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail_path:
 	free(file->path);
@@ -100,12 +100,13 @@ fail_free:
 istream_t *istream_open_stdin(void)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	istream_t *strm = (istream_t *)file;
 
 	if (file == NULL)
 		goto fail;
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	file->path = strdup("stdin");
 	if (file->path == NULL)
 		goto fail;
@@ -114,7 +115,6 @@ istream_t *istream_open_stdin(void)
 	strm->buffer = file->buffer;
 	strm->precache = file_precache;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail:
 	perror("creating file wrapper for stdin");
diff --git a/lib/io/unix/ostream.c b/lib/io/unix/ostream.c
index 17f1998..6ed18e6 100644
--- a/lib/io/unix/ostream.c
+++ b/lib/io/unix/ostream.c
@@ -107,7 +107,6 @@ static const char *file_get_filename(ostream_t *strm)
 ostream_t *ostream_open_file(const char *path, int flags)
 {
 	file_ostream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	ostream_t *strm = (ostream_t *)file;
 
 	if (file == NULL) {
@@ -115,6 +114,8 @@ ostream_t *ostream_open_file(const char *path, int flags)
 		return NULL;
 	}
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	file->path = strdup(path);
 	if (file->path == NULL) {
 		perror(path);
@@ -138,7 +139,6 @@ ostream_t *ostream_open_file(const char *path, int flags)
 	strm->append = file_append;
 	strm->flush = file_flush;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail_path:
 	free(file->path);
@@ -150,7 +150,6 @@ fail_free:
 ostream_t *ostream_open_stdout(void)
 {
 	file_ostream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	ostream_t *strm = (ostream_t *)file;
 
 	if (file == NULL)
@@ -164,7 +163,6 @@ ostream_t *ostream_open_stdout(void)
 	strm->append = file_append;
 	strm->flush = file_flush;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail:
 	perror("creating file wrapper for stdout");
diff --git a/lib/io/win32/istream.c b/lib/io/win32/istream.c
index b591584..be3d829 100644
--- a/lib/io/win32/istream.c
+++ b/lib/io/win32/istream.c
@@ -77,7 +77,6 @@ static void file_destroy(sqfs_object_t *obj)
 istream_t *istream_open_file(const char *path)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	istream_t *strm = (istream_t *)file;
 	WCHAR *wpath = NULL;
 
@@ -86,6 +85,8 @@ istream_t *istream_open_file(const char *path)
 		return NULL;
 	}
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	wpath = path_to_windows(path);
 	if (wpath == NULL)
 		goto fail_free;
@@ -109,7 +110,6 @@ istream_t *istream_open_file(const char *path)
 	strm->buffer = file->buffer;
 	strm->precache = file_precache;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail_path:
 	free(file->path);
@@ -122,7 +122,6 @@ fail_free:
 istream_t *istream_open_stdin(void)
 {
 	file_istream_t *file = calloc(1, sizeof(*file));
-	sqfs_object_t *obj = (sqfs_object_t *)file;
 	istream_t *strm = (istream_t *)file;
 
 	if (file == NULL) {
@@ -130,9 +129,10 @@ istream_t *istream_open_stdin(void)
 		return NULL;
 	}
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	strm->buffer = file->buffer;
 	strm->precache = file_precache;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 }
diff --git a/lib/io/win32/ostream.c b/lib/io/win32/ostream.c
index 2bd78c8..0fe04f3 100644
--- a/lib/io/win32/ostream.c
+++ b/lib/io/win32/ostream.c
@@ -135,6 +135,8 @@ ostream_t *ostream_open_file(const char *path, int flags)
 		return NULL;
 	}
 
+	sqfs_object_init(file, file_destroy, NULL);
+
 	wpath = path_to_windows(path);
 	if (wpath == NULL)
 		goto fail_free;
@@ -169,7 +171,6 @@ ostream_t *ostream_open_file(const char *path, int flags)
 	strm->append = file_append;
 	strm->flush = file_flush;
 	strm->get_filename = file_get_filename;
-	obj->destroy = file_destroy;
 	return strm;
 fail_path:
 	free(file->path);
@@ -189,9 +190,10 @@ ostream_t *ostream_open_stdout(void)
 		return NULL;
 	}
 
+	sqfs_object_init(strm, stdout_destroy, NULL);
+
 	strm->append = stdout_append;
 	strm->flush = stdout_flush;
 	strm->get_filename = stdout_get_filename;
-	obj->destroy = stdout_destroy;
 	return strm;
 }
diff --git a/lib/sqfs/block_processor/block_processor.c b/lib/sqfs/block_processor/block_processor.c
index 97b8958..e223718 100644
--- a/lib/sqfs/block_processor/block_processor.c
+++ b/lib/sqfs/block_processor/block_processor.c
@@ -268,6 +268,8 @@ int sqfs_block_processor_create_ex(const sqfs_block_processor_desc_t *desc,
 	if (proc == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(proc, block_processor_destroy, NULL);
+
 	proc->max_backlog = desc->max_backlog;
 	proc->max_block_size = desc->max_block_size;
 	proc->frag_tbl = desc->tbl;
@@ -275,7 +277,6 @@ int sqfs_block_processor_create_ex(const sqfs_block_processor_desc_t *desc,
 	proc->file = desc->file;
 	proc->uncmp = desc->uncmp;
 	proc->stats.size = sizeof(proc->stats);
-	((sqfs_object_t *)proc)->destroy = block_processor_destroy;
 
 	/* we need at least one current data block + one fragment block */
 	if (proc->max_backlog < 3)
diff --git a/lib/sqfs/block_writer.c b/lib/sqfs/block_writer.c
index 7302736..1612986 100644
--- a/lib/sqfs/block_writer.c
+++ b/lib/sqfs/block_writer.c
@@ -219,9 +219,10 @@ sqfs_block_writer_t *sqfs_block_writer_create(sqfs_file_t *file,
 	if (wr == NULL)
 		return NULL;
 
+	sqfs_object_init(wr, block_writer_destroy, NULL);
+
 	((sqfs_block_writer_t *)wr)->write_data_block = write_data_block;
 	((sqfs_block_writer_t *)wr)->get_block_count = get_block_count;
-	((sqfs_object_t *)wr)->destroy = block_writer_destroy;
 	wr->flags = flags;
 	wr->file = file;
 	wr->devblksz = devblksz;
diff --git a/lib/sqfs/comp/gzip.c b/lib/sqfs/comp/gzip.c
index 39d4227..beacfb8 100644
--- a/lib/sqfs/comp/gzip.c
+++ b/lib/sqfs/comp/gzip.c
@@ -277,6 +277,8 @@ int gzip_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (gzip == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(gzip, gzip_destroy, gzip_create_copy);
+
 	gzip->opt.level = cfg->level;
 	gzip->opt.window = cfg->opt.gzip.window_size;
 	gzip->opt.strategies = cfg->flags & SQFS_COMP_FLAG_GZIP_ALL;
@@ -286,8 +288,6 @@ int gzip_compressor_create(const sqfs_compressor_config_t *cfg,
 	base->do_block = gzip_do_block;
 	base->write_options = gzip_write_options;
 	base->read_options = gzip_read_options;
-	((sqfs_object_t *)base)->copy = gzip_create_copy;
-	((sqfs_object_t *)base)->destroy = gzip_destroy;
 
 	if (gzip->compress) {
 		ret = deflateInit2(&gzip->strm, cfg->level,
diff --git a/lib/sqfs/comp/lz4.c b/lib/sqfs/comp/lz4.c
index 152ae75..77f4a6e 100644
--- a/lib/sqfs/comp/lz4.c
+++ b/lib/sqfs/comp/lz4.c
@@ -156,6 +156,8 @@ int lz4_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (lz4 == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(lz4, lz4_destroy, lz4_create_copy);
+
 	lz4->high_compression = (cfg->flags & SQFS_COMP_FLAG_LZ4_HC) != 0;
 	lz4->block_size = cfg->block_size;
 
@@ -164,8 +166,6 @@ int lz4_compressor_create(const sqfs_compressor_config_t *cfg,
 		lz4_uncomp_block : lz4_comp_block;
 	base->write_options = lz4_write_options;
 	base->read_options = lz4_read_options;
-	((sqfs_object_t *)base)->copy = lz4_create_copy;
-	((sqfs_object_t *)base)->destroy = lz4_destroy;
 
 	*out = base;
 	return 0;
diff --git a/lib/sqfs/comp/lzma.c b/lib/sqfs/comp/lzma.c
index 01e6042..5456603 100644
--- a/lib/sqfs/comp/lzma.c
+++ b/lib/sqfs/comp/lzma.c
@@ -260,6 +260,8 @@ int lzma_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (lzma == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(lzma, lzma_destroy, lzma_create_copy);
+
 	lzma->block_size = cfg->block_size;
 	lzma->flags = cfg->flags;
 	lzma->level = cfg->level;
@@ -273,8 +275,6 @@ int lzma_compressor_create(const sqfs_compressor_config_t *cfg,
 		lzma_uncomp_block : lzma_comp_block;
 	base->write_options = lzma_write_options;
 	base->read_options = lzma_read_options;
-	((sqfs_object_t *)base)->copy = lzma_create_copy;
-	((sqfs_object_t *)base)->destroy = lzma_destroy;
 
 	*out = base;
 	return 0;
diff --git a/lib/sqfs/comp/xz.c b/lib/sqfs/comp/xz.c
index 3fb27b2..13545ed 100644
--- a/lib/sqfs/comp/xz.c
+++ b/lib/sqfs/comp/xz.c
@@ -304,6 +304,8 @@ int xz_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (xz == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(xz, xz_destroy, xz_create_copy);
+
 	xz->flags = cfg->flags;
 	xz->dict_size = cfg->opt.xz.dict_size;
 	xz->block_size = cfg->block_size;
@@ -316,8 +318,6 @@ int xz_compressor_create(const sqfs_compressor_config_t *cfg,
 		xz_uncomp_block : xz_comp_block;
 	base->write_options = xz_write_options;
 	base->read_options = xz_read_options;
-	((sqfs_object_t *)base)->copy = xz_create_copy;
-	((sqfs_object_t *)base)->destroy = xz_destroy;
 
 	*out = base;
 	return 0;
diff --git a/lib/sqfs/comp/zstd.c b/lib/sqfs/comp/zstd.c
index af5bd84..a6d7975 100644
--- a/lib/sqfs/comp/zstd.c
+++ b/lib/sqfs/comp/zstd.c
@@ -151,6 +151,8 @@ int zstd_compressor_create(const sqfs_compressor_config_t *cfg,
 	if (zstd == NULL)
 		return SQFS_ERROR_ALLOC;
 
+	sqfs_object_init(zstd, zstd_destroy, zstd_create_copy);
+
 	zstd->block_size = cfg->block_size;
 	zstd->level = cfg->level;
 	zstd->zctx = ZSTD_createCCtx();
@@ -164,8 +166,6 @@ int zstd_compressor_create(const sqfs_compressor_config_t *cfg,
 		zstd_uncomp_block : zstd_comp_block;
 	base->write_options = zstd_write_options;
 	base->read_options = zstd_read_options;
-	((sqfs_object_t *)base)->copy = zstd_create_copy;
-	((sqfs_object_t *)base)->destroy = zstd_destroy;
 
 	*out = base;
 	return 0;
diff --git a/lib/sqfs/data_reader.c b/lib/sqfs/data_reader.c
index 1033db9..c3fc1b9 100644
--- a/lib/sqfs/data_reader.c
+++ b/lib/sqfs/data_reader.c
@@ -196,14 +196,14 @@ sqfs_data_reader_t *sqfs_data_reader_create(sqfs_file_t *file,
 	if (data == NULL)
 		return NULL;
 
+	sqfs_object_init(data, data_reader_destroy, data_reader_copy);
+
 	data->frag_tbl = sqfs_frag_table_create(0);
 	if (data->frag_tbl == NULL) {
 		free(data);
 		return NULL;
 	}
 
-	((sqfs_object_t *)data)->destroy = data_reader_destroy;
-	((sqfs_object_t *)data)->copy = data_reader_copy;
 	data->file = file;
 	data->block_size = block_size;
 	data->cmp = cmp;
diff --git a/lib/sqfs/dir_reader/dir_reader.c b/lib/sqfs/dir_reader/dir_reader.c
index 68cebd3..38700df 100644
--- a/lib/sqfs/dir_reader/dir_reader.c
+++ b/lib/sqfs/dir_reader/dir_reader.c
@@ -122,6 +122,8 @@ sqfs_dir_reader_t *sqfs_dir_reader_create(const sqfs_super_t *super,
 	if (rd == NULL)
 		return NULL;
 
+	sqfs_object_init(rd, dir_reader_destroy, dir_reader_copy);
+
 	if (flags & SQFS_DIR_READER_DOT_ENTRIES) {
 		ret = rbtree_init(&rd->dcache, sizeof(sqfs_u32),
 				  sizeof(sqfs_u64), dcache_key_compare);
@@ -150,8 +152,6 @@ sqfs_dir_reader_t *sqfs_dir_reader_create(const sqfs_super_t *super,
 	if (rd->meta_dir == NULL)
 		goto fail_mdir;
 
-	((sqfs_object_t *)rd)->destroy = dir_reader_destroy;
-	((sqfs_object_t *)rd)->copy = dir_reader_copy;
 	rd->super = super;
 	rd->flags = flags;
 	rd->state = DIR_STATE_NONE;
diff --git a/lib/sqfs/dir_writer.c b/lib/sqfs/dir_writer.c
index ce63a1e..f56e0a7 100644
--- a/lib/sqfs/dir_writer.c
+++ b/lib/sqfs/dir_writer.c
@@ -147,6 +147,8 @@ sqfs_dir_writer_t *sqfs_dir_writer_create(sqfs_meta_writer_t *dm,
 	if (writer == NULL)
 		return NULL;
 
+	sqfs_object_init(writer, dir_writer_destroy, NULL);
+
 	if (flags & SQFS_DIR_WRITER_CREATE_EXPORT_TABLE) {
 		if (array_init(&writer->export_tbl, sizeof(sqfs_u64), 512)) {
 			free(writer);
@@ -157,7 +159,6 @@ sqfs_dir_writer_t *sqfs_dir_writer_create(sqfs_meta_writer_t *dm,
 		       writer->export_tbl.size * writer->export_tbl.count);
 	}
 
-	((sqfs_object_t *)writer)->destroy = dir_writer_destroy;
 	writer->dm = dm;
 	return writer;
 }
diff --git a/lib/sqfs/frag_table.c b/lib/sqfs/frag_table.c
index 71627df..151df28 100644
--- a/lib/sqfs/frag_table.c
+++ b/lib/sqfs/frag_table.c
@@ -59,9 +59,9 @@ sqfs_frag_table_t *sqfs_frag_table_create(sqfs_u32 flags)
 	if (tbl == NULL)
 		return NULL;
 
+	sqfs_object_init(tbl, frag_table_destroy, frag_table_copy);
+
 	array_init(&tbl->table, sizeof(sqfs_fragment_t), 0);
-	((sqfs_object_t *)tbl)->copy = frag_table_copy;
-	((sqfs_object_t *)tbl)->destroy = frag_table_destroy;
 	return tbl;
 }
 
diff --git a/lib/sqfs/id_table.c b/lib/sqfs/id_table.c
index cebf64b..ec3fdfe 100644
--- a/lib/sqfs/id_table.c
+++ b/lib/sqfs/id_table.c
@@ -58,9 +58,7 @@ sqfs_id_table_t *sqfs_id_table_create(sqfs_u32 flags)
 
 	if (tbl != NULL) {
 		array_init(&tbl->ids, sizeof(sqfs_u32), 0);
-
-		((sqfs_object_t *)tbl)->destroy = id_table_destroy;
-		((sqfs_object_t *)tbl)->copy = id_table_copy;
+		sqfs_object_init(tbl, id_table_destroy, id_table_copy);
 	}
 
 	return tbl;
diff --git a/lib/sqfs/meta_reader.c b/lib/sqfs/meta_reader.c
index cddcda6..1b48fb8 100644
--- a/lib/sqfs/meta_reader.c
+++ b/lib/sqfs/meta_reader.c
@@ -74,8 +74,8 @@ sqfs_meta_reader_t *sqfs_meta_reader_create(sqfs_file_t *file,
 	if (m == NULL)
 		return NULL;
 
-	((sqfs_object_t *)m)->copy = meta_reader_copy;
-	((sqfs_object_t *)m)->destroy = meta_reader_destroy;
+	sqfs_object_init(m, meta_reader_destroy, meta_reader_copy);
+
 	m->block_offset = 0xFFFFFFFFFFFFFFFFUL;
 	m->start = start;
 	m->limit = limit;
diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
index 2314e06..5b8898b 100644
--- a/lib/sqfs/meta_writer.c
+++ b/lib/sqfs/meta_writer.c
@@ -87,7 +87,8 @@ 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;
+	sqfs_object_init(m, meta_writer_destroy, NULL);
+
 	m->cmp = cmp;
 	m->file = file;
 	m->flags = flags;
diff --git a/lib/sqfs/unix/io_file.c b/lib/sqfs/unix/io_file.c
index d4c1232..e1fb9db 100644
--- a/lib/sqfs/unix/io_file.c
+++ b/lib/sqfs/unix/io_file.c
@@ -154,6 +154,8 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 	if (file == NULL)
 		return NULL;
 
+	sqfs_object_init(file, stdio_destroy, stdio_copy);
+
 	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
 		file->readonly = true;
 		open_mode = O_RDONLY;
@@ -190,7 +192,5 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 	base->write_at = stdio_write_at;
 	base->get_size = stdio_get_size;
 	base->truncate = stdio_truncate;
-	((sqfs_object_t *)base)->copy = stdio_copy;
-	((sqfs_object_t *)base)->destroy = stdio_destroy;
 	return base;
 }
diff --git a/lib/sqfs/win32/io_file.c b/lib/sqfs/win32/io_file.c
index cfef296..548a246 100644
--- a/lib/sqfs/win32/io_file.c
+++ b/lib/sqfs/win32/io_file.c
@@ -187,6 +187,8 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 		return NULL;
 	}
 
+	sqfs_object_init(file, stdio_destroy, stdio_copy);
+
 	if (flags & SQFS_FILE_OPEN_READ_ONLY) {
 		file->readonly = true;
 		access_flags = GENERIC_READ;
@@ -231,7 +233,5 @@ sqfs_file_t *sqfs_open_file(const char *filename, sqfs_u32 flags)
 	base->write_at = stdio_write_at;
 	base->get_size = stdio_get_size;
 	base->truncate = stdio_truncate;
-	((sqfs_object_t *)base)->destroy = stdio_destroy;
-	((sqfs_object_t *)base)->copy = stdio_copy;
 	return base;
 }
diff --git a/lib/sqfs/xattr/xattr_reader.c b/lib/sqfs/xattr/xattr_reader.c
index a55ad2f..313da88 100644
--- a/lib/sqfs/xattr/xattr_reader.c
+++ b/lib/sqfs/xattr/xattr_reader.c
@@ -347,7 +347,6 @@ sqfs_xattr_reader_t *sqfs_xattr_reader_create(sqfs_u32 flags)
 	if (xr == NULL)
 		return NULL;
 
-	((sqfs_object_t *)xr)->copy = xattr_reader_copy;
-	((sqfs_object_t *)xr)->destroy = xattr_reader_destroy;
+	sqfs_object_init(xr, xattr_reader_destroy, xattr_reader_copy);
 	return xr;
 }
diff --git a/lib/sqfs/xattr/xattr_writer.c b/lib/sqfs/xattr/xattr_writer.c
index c49aaf1..39e1b05 100644
--- a/lib/sqfs/xattr/xattr_writer.c
+++ b/lib/sqfs/xattr/xattr_writer.c
@@ -95,6 +95,8 @@ sqfs_xattr_writer_t *sqfs_xattr_writer_create(sqfs_u32 flags)
 	if (xwr == NULL)
 		return NULL;
 
+	sqfs_object_init(xwr, xattr_writer_destroy, xattr_writer_copy);
+
 	if (str_table_init(&xwr->keys))
 		goto fail_keys;
 
@@ -112,9 +114,6 @@ sqfs_xattr_writer_t *sqfs_xattr_writer_create(sqfs_u32 flags)
 	}
 
 	xwr->kv_block_tree.key_context = xwr;
-
-	((sqfs_object_t *)xwr)->copy = xattr_writer_copy;
-	((sqfs_object_t *)xwr)->destroy = xattr_writer_destroy;
 	return xwr;
 fail_tree:
 	array_cleanup(&xwr->kv_pairs);