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 use anyhow::anyhow;
18 use memmap2::Mmap;
19 use std::fs::File;
20
21 use crate::AconfigStorageError::{self, FileReadFail, MapFileFail, StorageFileNotFound};
22 use crate::StorageFileType;
23
24 /// Get the read only memory mapping of a storage file
25 ///
26 /// # Safety
27 ///
28 /// The memory mapped file may have undefined behavior if there are writes to this
29 /// file after being mapped. Ensure no writes can happen to this file while this
30 /// mapping stays alive.
map_file(file_path: &str) -> Result<Mmap, AconfigStorageError>31 pub unsafe fn map_file(file_path: &str) -> Result<Mmap, AconfigStorageError> {
32 let file = File::open(file_path)
33 .map_err(|errmsg| FileReadFail(anyhow!("Failed to open file {}: {}", file_path, errmsg)))?;
34 unsafe {
35 let mapped_file = Mmap::map(&file).map_err(|errmsg| {
36 MapFileFail(anyhow!("fail to map storage file {}: {}", file_path, errmsg))
37 })?;
38 Ok(mapped_file)
39 }
40 }
41
42 /// Get a mapped storage file given the container and file type
43 ///
44 /// # Safety
45 ///
46 /// The memory mapped file may have undefined behavior if there are writes to this
47 /// file after being mapped. Ensure no writes can happen to this file while this
48 /// mapping stays alive.
get_mapped_file( storage_dir: &str, container: &str, file_type: StorageFileType, ) -> Result<Mmap, AconfigStorageError>49 pub unsafe fn get_mapped_file(
50 storage_dir: &str,
51 container: &str,
52 file_type: StorageFileType,
53 ) -> Result<Mmap, AconfigStorageError> {
54 let storage_file = match file_type {
55 StorageFileType::PackageMap => {
56 String::from(storage_dir) + "/maps/" + container + ".package.map"
57 }
58 StorageFileType::FlagMap => String::from(storage_dir) + "/maps/" + container + ".flag.map",
59 StorageFileType::FlagVal => String::from(storage_dir) + "/boot/" + container + ".val",
60 StorageFileType::FlagInfo => String::from(storage_dir) + "/boot/" + container + ".info",
61 };
62 if std::fs::metadata(&storage_file).is_err() {
63 return Err(StorageFileNotFound(anyhow!("storage file {} does not exist", storage_file)));
64 }
65 unsafe { map_file(&storage_file) }
66 }
67
68 #[cfg(test)]
69 mod tests {
70 use super::*;
71 use rand::Rng;
72 use std::fs;
73 use std::io::Read;
74
map_and_verify(storage_dir: &str, file_type: StorageFileType, actual_file: &str)75 fn map_and_verify(storage_dir: &str, file_type: StorageFileType, actual_file: &str) {
76 let mut opened_file = File::open(actual_file).unwrap();
77 let mut content = Vec::new();
78 opened_file.read_to_end(&mut content).unwrap();
79 let mmaped_file = unsafe { get_mapped_file(storage_dir, "mockup", file_type).unwrap() };
80 assert_eq!(mmaped_file[..], content[..]);
81 }
82
create_test_storage_files() -> String83 fn create_test_storage_files() -> String {
84 let mut rng = rand::thread_rng();
85 let number: u32 = rng.gen();
86 let storage_dir = String::from("/tmp/") + &number.to_string();
87 if std::fs::metadata(&storage_dir).is_ok() {
88 fs::remove_dir_all(&storage_dir).unwrap();
89 }
90 let maps_dir = storage_dir.clone() + "/maps";
91 let boot_dir = storage_dir.clone() + "/boot";
92 fs::create_dir(&storage_dir).unwrap();
93 fs::create_dir(&maps_dir).unwrap();
94 fs::create_dir(&boot_dir).unwrap();
95
96 let package_map = storage_dir.clone() + "/maps/mockup.package.map";
97 let flag_map = storage_dir.clone() + "/maps/mockup.flag.map";
98 let flag_val = storage_dir.clone() + "/boot/mockup.val";
99 let flag_info = storage_dir.clone() + "/boot/mockup.info";
100 fs::copy("./tests/data/v1/package_v1.map", &package_map).unwrap();
101 fs::copy("./tests/data/v1/flag_v1.map", &flag_map).unwrap();
102 fs::copy("./tests/data/v1/flag_v1.val", &flag_val).unwrap();
103 fs::copy("./tests/data/v1/flag_v1.info", &flag_info).unwrap();
104
105 return storage_dir;
106 }
107
108 #[test]
test_mapped_file_contents()109 fn test_mapped_file_contents() {
110 let storage_dir = create_test_storage_files();
111 map_and_verify(&storage_dir, StorageFileType::PackageMap, "./tests/data/v1/package_v1.map");
112 map_and_verify(&storage_dir, StorageFileType::FlagMap, "./tests/data/v1/flag_v1.map");
113 map_and_verify(&storage_dir, StorageFileType::FlagVal, "./tests/data/v1/flag_v1.val");
114 map_and_verify(&storage_dir, StorageFileType::FlagInfo, "./tests/data/v1/flag_v1.info");
115 }
116 }
117