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
22 struct 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
31 static struct data_block *data_blocks = NULL;
32 static struct data_block *last_used = NULL;
33
queue_db(struct data_block * new_db)34 static 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 */
queue_data_block(u8 * data,u32 len,u32 block)70 void 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 */
queue_data_file(const char * filename,off_t offset,u32 len,u32 block)86 void 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 */
for_each_data_block(data_block_callback_t data_func,data_block_file_callback_t file_func,struct output_file * out)104 void for_each_data_block(data_block_callback_t data_func,
105 data_block_file_callback_t file_func, struct output_file *out)
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(out, (u64)db->block * info.block_size, db->filename, db->offset, db->len);
117 else
118 data_func(out, (u64)db->block * info.block_size, db->data, db->len);
119 }
120 }
121
122 /* Frees the memory used by the linked list of data blocks */
free_data_blocks()123 void free_data_blocks()
124 {
125 if (!data_blocks) return;
126 struct data_block *db = data_blocks;
127 while (db) {
128 struct data_block *next = db->next;
129 free((void*)db->filename);
130
131 // There used to be a free() of db->data here, but it
132 // made the function crash since queue_data_block() is
133 // sometimes passed pointers it can't take ownership of
134 // (like a pointer into the middle of an allocated
135 // block). It's not clear what the queue_data_block
136 // contract is supposed to be, but we'd rather leak
137 // memory than crash.
138
139 free(db);
140 db = next;
141 }
142 data_blocks = NULL;
143 last_used = NULL;
144 }
145