1 /*
2 * Copyright (C) 2024 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 //! package table query module defines the package table file read from mapped bytes
18
19 use crate::{AconfigStorageError, FILE_VERSION};
20 use aconfig_storage_file::{
21 package_table::PackageTableHeader, package_table::PackageTableNode, read_u32_from_bytes,
22 };
23 use anyhow::anyhow;
24
25 /// Package table query return
26 #[derive(PartialEq, Debug)]
27 pub struct PackageReadContext {
28 pub package_id: u32,
29 pub boolean_start_index: u32,
30 }
31
32 /// Query package read context: package id and start index
find_package_read_context( buf: &[u8], package: &str, ) -> Result<Option<PackageReadContext>, AconfigStorageError>33 pub fn find_package_read_context(
34 buf: &[u8],
35 package: &str,
36 ) -> Result<Option<PackageReadContext>, AconfigStorageError> {
37 let interpreted_header = PackageTableHeader::from_bytes(buf)?;
38 if interpreted_header.version > FILE_VERSION {
39 return Err(AconfigStorageError::HigherStorageFileVersion(anyhow!(
40 "Cannot read storage file with a higher version of {} with lib version {}",
41 interpreted_header.version,
42 FILE_VERSION
43 )));
44 }
45
46 let num_buckets = (interpreted_header.node_offset - interpreted_header.bucket_offset) / 4;
47 let bucket_index = PackageTableNode::find_bucket_index(package, num_buckets);
48
49 let mut pos = (interpreted_header.bucket_offset + 4 * bucket_index) as usize;
50 let mut package_node_offset = read_u32_from_bytes(buf, &mut pos)? as usize;
51 if package_node_offset < interpreted_header.node_offset as usize
52 || package_node_offset >= interpreted_header.file_size as usize
53 {
54 return Ok(None);
55 }
56
57 loop {
58 let interpreted_node = PackageTableNode::from_bytes(&buf[package_node_offset..])?;
59 if interpreted_node.package_name == package {
60 return Ok(Some(PackageReadContext {
61 package_id: interpreted_node.package_id,
62 boolean_start_index: interpreted_node.boolean_start_index,
63 }));
64 }
65 match interpreted_node.next_offset {
66 Some(offset) => package_node_offset = offset as usize,
67 None => return Ok(None),
68 }
69 }
70 }
71
72 #[cfg(test)]
73 mod tests {
74 use super::*;
75 use aconfig_storage_file::test_utils::create_test_package_table;
76
77 #[test]
78 // this test point locks down table query
test_package_query()79 fn test_package_query() {
80 let package_table = create_test_package_table().into_bytes();
81 let package_context =
82 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_1")
83 .unwrap()
84 .unwrap();
85 let expected_package_context = PackageReadContext { package_id: 0, boolean_start_index: 0 };
86 assert_eq!(package_context, expected_package_context);
87 let package_context =
88 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_2")
89 .unwrap()
90 .unwrap();
91 let expected_package_context = PackageReadContext { package_id: 1, boolean_start_index: 3 };
92 assert_eq!(package_context, expected_package_context);
93 let package_context =
94 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_4")
95 .unwrap()
96 .unwrap();
97 let expected_package_context = PackageReadContext { package_id: 2, boolean_start_index: 6 };
98 assert_eq!(package_context, expected_package_context);
99 }
100
101 #[test]
102 // this test point locks down table query of a non exist package
test_not_existed_package_query()103 fn test_not_existed_package_query() {
104 // this will land at an empty bucket
105 let package_table = create_test_package_table().into_bytes();
106 let package_context =
107 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_3")
108 .unwrap();
109 assert_eq!(package_context, None);
110 // this will land at the end of a linked list
111 let package_context =
112 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_5")
113 .unwrap();
114 assert_eq!(package_context, None);
115 }
116
117 #[test]
118 // this test point locks down query error when file has a higher version
test_higher_version_storage_file()119 fn test_higher_version_storage_file() {
120 let mut table = create_test_package_table();
121 table.header.version = crate::FILE_VERSION + 1;
122 let package_table = table.into_bytes();
123 let error =
124 find_package_read_context(&package_table[..], "com.android.aconfig.storage.test_1")
125 .unwrap_err();
126 assert_eq!(
127 format!("{:?}", error),
128 format!(
129 "HigherStorageFileVersion(Cannot read storage file with a higher version of {} with lib version {})",
130 crate::FILE_VERSION + 1,
131 crate::FILE_VERSION
132 )
133 );
134 }
135 }
136