libsparse: add function to resparse a file and a utility to use it
Add sparse_file_repsarse, which splits chunks in an existing sparse
file such that the maximum size of a chunk, plus a header and footer,
is smaller than the given size. This will allow multiple smaller
sparse files to result in the same data as a large sparse file.
Change-Id: I177abdb958a23d5afd394ff265c5b0c6a3ff22fa
diff --git a/libsparse/backed_block.c b/libsparse/backed_block.c
index 629fc28..dfb217b 100644
--- a/libsparse/backed_block.c
+++ b/libsparse/backed_block.c
@@ -141,6 +141,52 @@
free(bbl);
}
+void backed_block_list_move(struct backed_block_list *from,
+ struct backed_block_list *to, struct backed_block *start,
+ struct backed_block *end)
+{
+ struct backed_block *bb;
+
+ if (start == NULL) {
+ start = from->data_blocks;
+ }
+
+ if (!end) {
+ for (end = start; end && end->next; end = end->next)
+ ;
+ }
+
+ if (start == NULL || end == NULL) {
+ return;
+ }
+
+ from->last_used = NULL;
+ to->last_used = NULL;
+ if (from->data_blocks == start) {
+ from->data_blocks = end->next;
+ } else {
+ for (bb = from->data_blocks; bb; bb = bb->next) {
+ if (bb->next == start) {
+ bb->next = end->next;
+ break;
+ }
+ }
+ }
+
+ if (!to->data_blocks) {
+ to->data_blocks = start;
+ end->next = NULL;
+ } else {
+ for (bb = to->data_blocks; bb; bb = bb->next) {
+ if (!bb->next || bb->next->block > start->block) {
+ end->next = bb->next;
+ bb->next = start;
+ break;
+ }
+ }
+ }
+}
+
/* may free b */
static int merge_bb(struct backed_block_list *bbl,
struct backed_block *a, struct backed_block *b)
@@ -311,3 +357,44 @@
return queue_bb(bbl, bb);
}
+
+int backed_block_split(struct backed_block_list *bbl, struct backed_block *bb,
+ unsigned int max_len)
+{
+ struct backed_block *new_bb;
+
+ max_len = ALIGN_DOWN(max_len, bbl->block_size);
+
+ if (bb->len <= max_len) {
+ return 0;
+ }
+
+ new_bb = malloc(sizeof(struct backed_block));
+ if (bb == NULL) {
+ return -ENOMEM;
+ }
+
+ *new_bb = *bb;
+
+ new_bb->len = bb->len - max_len;
+ new_bb->block = bb->block + max_len / bbl->block_size;
+ new_bb->next = bb->next;
+ bb->next = new_bb;
+ bb->len = max_len;
+
+ switch (bb->type) {
+ case BACKED_BLOCK_DATA:
+ new_bb->data.data = (char *)bb->data.data + max_len;
+ break;
+ case BACKED_BLOCK_FILE:
+ new_bb->file.offset += max_len;
+ break;
+ case BACKED_BLOCK_FD:
+ new_bb->fd.offset += max_len;
+ break;
+ case BACKED_BLOCK_FILL:
+ break;
+ }
+
+ return 0;
+}