backed_block.c revision ec0a2e83dc66d67addeb90e83144187691852a3e 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdlib.h>
18
19#include "ext4_utils.h"
20#include "backed_block.h"
21
22struct data_block {
23	u32 block;
24	u32 len;
25	u8 *data;
26	const char *filename;
27	off_t offset;
28	struct data_block *next;
29};
30
31static struct data_block *data_blocks = NULL;
32static struct data_block *last_used = NULL;
33
34static void queue_db(struct data_block *new_db)
35{
36	struct data_block *db;
37
38	if (data_blocks == NULL) {
39		data_blocks = new_db;
40		return;
41	}
42
43	if (data_blocks->block > new_db->block) {
44		new_db->next = data_blocks;
45		data_blocks = new_db;
46		return;
47	}
48
49	/* Optimization: blocks are mostly queued in sequence, so save the
50	   pointer to the last db that was added, and start searching from
51	   there if the next block number is higher */
52	if (last_used && new_db->block > last_used->block)
53		db = last_used;
54	else
55		db = data_blocks;
56	last_used = new_db;
57
58	for (; db->next && db->next->block < new_db->block; db = db->next)
59		;
60
61	if (db->next == NULL) {
62		db->next = new_db;
63	} else {
64		new_db->next = db->next;
65		db->next = new_db;
66	}
67}
68
69/* Queues a block of memory to be written to the specified data blocks */
70void queue_data_block(u8 *data, u32 len, u32 block)
71{
72	struct data_block *db = malloc(sizeof(struct data_block));
73	if (db == NULL)
74		critical_error_errno("malloc");
75
76	db->block = block;
77	db->len = len;
78	db->data = data;
79	db->filename = NULL;
80	db->next = NULL;
81
82	queue_db(db);
83}
84
85/* Queues a chunk of a file on disk to be written to the specified data blocks */
86void queue_data_file(const char *filename, off_t offset, u32 len,
87        u32 block)
88{
89	struct data_block *db = malloc(sizeof(struct data_block));
90	if (db == NULL)
91		critical_error_errno("malloc");
92
93	db->block = block;
94	db->len = len;
95	db->filename = strdup(filename);
96	db->offset = offset;
97	db->next = NULL;
98
99	queue_db(db);
100}
101
102/* Iterates over the queued data blocks, calling data_func for each contiguous
103   data block, and file_func for each contiguous file block */
104void for_each_data_block(data_block_callback_t data_func,
105        data_block_file_callback_t file_func, void *priv)
106{
107	struct data_block *db;
108	u32 last_block = 0;
109
110	for (db = data_blocks; db; db = db->next) {
111		if (db->block < last_block)
112			error("data blocks out of order: %u < %u", db->block, last_block);
113		last_block = db->block + DIV_ROUND_UP(db->len, info.block_size) - 1;
114
115		if (db->filename)
116			file_func(priv, db->block, db->filename, db->offset, db->len);
117		else
118			data_func(priv, db->block, db->data, db->len);
119	}
120}
121
122/* Frees the memory used by the linked list of data blocks */
123void free_data_blocks()
124{
125	struct data_block *db = data_blocks;
126	while (db) {
127		struct data_block *next = db->next;
128		free((void*)db->filename);
129		free((void*)db->data);
130		free(db);
131		db = next;
132	}
133}
134