1 files changed, 400 insertions, 0 deletions

diff --git a/libsparse/backed_block.c b/libsparse/backed_block.c
new file mode 100644
index 0000000..dfb217b
--- /dev/null
+++ b/libsparse/backed_block.c
@@ -0,0 +1,400 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "backed_block.h"
+#include "sparse_defs.h"
+
+struct backed_block {
+	unsigned int block;
+	unsigned int len;
+	enum backed_block_type type;
+	union {
+		struct {
+			void *data;
+		} data;
+		struct {
+			char *filename;
+			int64_t offset;
+		} file;
+		struct {
+			int fd;
+			int64_t offset;
+		} fd;
+		struct {
+			uint32_t val;
+		} fill;
+	};
+	struct backed_block *next;
+};
+
+struct backed_block_list {
+	struct backed_block *data_blocks;
+	struct backed_block *last_used;
+	unsigned int block_size;
+};
+
+struct backed_block *backed_block_iter_new(struct backed_block_list *bbl)
+{
+	return bbl->data_blocks;
+}
+
+struct backed_block *backed_block_iter_next(struct backed_block *bb)
+{
+	return bb->next;
+}
+
+unsigned int backed_block_len(struct backed_block *bb)
+{
+	return bb->len;
+}
+
+unsigned int backed_block_block(struct backed_block *bb)
+{
+	return bb->block;
+}
+
+void *backed_block_data(struct backed_block *bb)
+{
+	assert(bb->type == BACKED_BLOCK_DATA);
+	return bb->data.data;
+}
+
+const char *backed_block_filename(struct backed_block *bb)
+{
+	assert(bb->type == BACKED_BLOCK_FILE);
+	return bb->file.filename;
+}
+
+int backed_block_fd(struct backed_block *bb)
+{
+	assert(bb->type == BACKED_BLOCK_FD);
+	return bb->fd.fd;
+}
+
+int64_t backed_block_file_offset(struct backed_block *bb)
+{
+	assert(bb->type == BACKED_BLOCK_FILE || bb->type == BACKED_BLOCK_FD);
+	if (bb->type == BACKED_BLOCK_FILE) {
+		return bb->file.offset;
+	} else { /* bb->type == BACKED_BLOCK_FD */
+		return bb->fd.offset;
+	}
+}
+
+uint32_t backed_block_fill_val(struct backed_block *bb)
+{
+	assert(bb->type == BACKED_BLOCK_FILL);
+	return bb->fill.val;
+}
+
+enum backed_block_type backed_block_type(struct backed_block *bb)
+{
+	return bb->type;
+}
+
+void backed_block_destroy(struct backed_block *bb)
+{
+	if (bb->type == BACKED_BLOCK_FILE) {
+		free(bb->file.filename);
+	}
+
+	free(bb);
+}
+
+struct backed_block_list *backed_block_list_new(unsigned int block_size)
+{
+	struct backed_block_list *b = calloc(sizeof(struct backed_block_list), 1);
+	b->block_size = block_size;
+	return b;
+}
+
+void backed_block_list_destroy(struct backed_block_list *bbl)
+{
+	if (bbl->data_blocks) {
+		struct backed_block *bb = bbl->data_blocks;
+		while (bb) {
+			struct backed_block *next = bb->next;
+			backed_block_destroy(bb);
+			bb = next;
+		}
+	}
+
+	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)
+{
+	unsigned int block_len;
+
+	/* Block doesn't exist (possible if one block is the last block) */
+	if (!a || !b) {
+		return -EINVAL;
+	}
+
+	assert(a->block < b->block);
+
+	/* Blocks are of different types */
+	if (a->type != b->type) {
+		return -EINVAL;
+	}
+
+	/* Blocks are not adjacent */
+	block_len = a->len / bbl->block_size; /* rounds down */
+	if (a->block + block_len != b->block) {
+		return -EINVAL;
+	}
+
+	switch (a->type) {
+	case BACKED_BLOCK_DATA:
+		/* Don't support merging data for now */
+		return -EINVAL;
+	case BACKED_BLOCK_FILL:
+		if (a->fill.val != b->fill.val) {
+			return -EINVAL;
+		}
+		break;
+	case BACKED_BLOCK_FILE:
+		if (a->file.filename != b->file.filename ||
+				a->file.offset + a->len != b->file.offset) {
+			return -EINVAL;
+		}
+		break;
+	case BACKED_BLOCK_FD:
+		if (a->fd.fd != b->fd.fd ||
+				a->fd.offset + a->len != b->fd.offset) {
+			return -EINVAL;
+		}
+		break;
+	}
+
+	/* Blocks are compatible and adjacent, with a before b.  Merge b into a,
+	 * and free b */
+	a->len += b->len;
+	a->next = b->next;
+
+	backed_block_destroy(b);
+
+	return 0;
+}
+
+static int queue_bb(struct backed_block_list *bbl, struct backed_block *new_bb)
+{
+	struct backed_block *bb;
+
+	if (bbl->data_blocks == NULL) {
+		bbl->data_blocks = new_bb;
+		return 0;
+	}
+
+	if (bbl->data_blocks->block > new_bb->block) {
+		new_bb->next = bbl->data_blocks;
+		bbl->data_blocks = new_bb;
+		return 0;
+	}
+
+	/* Optimization: blocks are mostly queued in sequence, so save the
+	   pointer to the last bb that was added, and start searching from
+	   there if the next block number is higher */
+	if (bbl->last_used && new_bb->block > bbl->last_used->block)
+		bb = bbl->last_used;
+	else
+		bb = bbl->data_blocks;
+	bbl->last_used = new_bb;
+
+	for (; bb->next && bb->next->block < new_bb->block; bb = bb->next)
+		;
+
+	if (bb->next == NULL) {
+		bb->next = new_bb;
+	} else {
+		new_bb->next = bb->next;
+		bb->next = new_bb;
+	}
+
+	merge_bb(bbl, new_bb, new_bb->next);
+	merge_bb(bbl, bb, new_bb);
+
+	return 0;
+}
+
+/* Queues a fill block of memory to be written to the specified data blocks */
+int backed_block_add_fill(struct backed_block_list *bbl, unsigned int fill_val,
+		unsigned int len, unsigned int block)
+{
+	struct backed_block *bb = calloc(1, sizeof(struct backed_block));
+	if (bb == NULL) {
+		return -ENOMEM;
+	}
+
+	bb->block = block;
+	bb->len = len;
+	bb->type = BACKED_BLOCK_FILL;
+	bb->fill.val = fill_val;
+	bb->next = NULL;
+
+	return queue_bb(bbl, bb);
+}
+
+/* Queues a block of memory to be written to the specified data blocks */
+int backed_block_add_data(struct backed_block_list *bbl, void *data,
+		unsigned int len, unsigned int block)
+{
+	struct backed_block *bb = calloc(1, sizeof(struct backed_block));
+	if (bb == NULL) {
+		return -ENOMEM;
+	}
+
+	bb->block = block;
+	bb->len = len;
+	bb->type = BACKED_BLOCK_DATA;
+	bb->data.data = data;
+	bb->next = NULL;
+
+	return queue_bb(bbl, bb);
+}
+
+/* Queues a chunk of a file on disk to be written to the specified data blocks */
+int backed_block_add_file(struct backed_block_list *bbl, const char *filename,
+		int64_t offset, unsigned int len, unsigned int block)
+{
+	struct backed_block *bb = calloc(1, sizeof(struct backed_block));
+	if (bb == NULL) {
+		return -ENOMEM;
+	}
+
+	bb->block = block;
+	bb->len = len;
+	bb->type = BACKED_BLOCK_FILE;
+	bb->file.filename = strdup(filename);
+	bb->file.offset = offset;
+	bb->next = NULL;
+
+	return queue_bb(bbl, bb);
+}
+
+/* Queues a chunk of a fd to be written to the specified data blocks */
+int backed_block_add_fd(struct backed_block_list *bbl, int fd, int64_t offset,
+		unsigned int len, unsigned int block)
+{
+	struct backed_block *bb = calloc(1, sizeof(struct backed_block));
+	if (bb == NULL) {
+		return -ENOMEM;
+	}
+
+	bb->block = block;
+	bb->len = len;
+	bb->type = BACKED_BLOCK_FD;
+	bb->fd.fd = fd;
+	bb->fd.offset = offset;
+	bb->next = NULL;
+
+	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;
+}