Move condensed-sparse-file handling to libsquashfs

Add another helper function for getting a blocks from a condensed sparse
file, then rewrite the data writer to use that instead, using an
sqfs_file_t pointer instead of direct file i/o.

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

1 files changed, 66 insertions, 0 deletions

diff --git a/lib/sqfs/io.c b/lib/sqfs/io.c
index 4afb489..b41fc4a 100644
--- a/lib/sqfs/io.c
+++ b/lib/sqfs/io.c
@@ -37,3 +37,69 @@ int sqfs_file_create_block(sqfs_file_t *file, uint64_t offset,
 	*out = blk;
 	return 0;
 }
+
+int sqfs_file_create_block_dense(sqfs_file_t *file, uint64_t offset,
+				 size_t size, void *user, uint32_t flags,
+				 const sqfs_sparse_map_t *map,
+				 sqfs_block_t **out)
+{
+	sqfs_block_t *blk = alloc_flex(sizeof(*blk), 1, size);
+	size_t dst_start, diff, count;
+	const sqfs_sparse_map_t *it;
+	uint64_t poffset, src_start;
+	int err;
+
+	if (blk == NULL)
+		return SQFS_ERROR_ALLOC;
+
+	poffset = 0;
+
+	for (it = map; it != NULL; it = it->next) {
+		if (it->offset + it->count <= offset) {
+			poffset += it->count;
+			continue;
+		}
+
+		if (it->offset >= offset + size) {
+			poffset += it->count;
+			continue;
+		}
+
+		count = size;
+
+		if (offset + count >= it->offset + it->count)
+			count = it->offset + it->count - offset;
+
+		if (it->offset < offset) {
+			diff = offset - it->offset;
+
+			src_start = poffset + diff;
+			dst_start = 0;
+			count -= diff;
+		} else if (it->offset > offset) {
+			diff = it->offset - offset;
+
+			src_start = poffset;
+			dst_start = diff;
+		} else {
+			src_start = poffset;
+			dst_start = 0;
+		}
+
+		err = file->read_at(file, src_start,
+				    blk->data + dst_start, count);
+		if (err) {
+			free(blk);
+			return err;
+		}
+
+		poffset += it->count;
+	}
+
+	blk->user = user;
+	blk->size = size;
+	blk->flags = flags;
+
+	*out = blk;
+	return 0;
+}