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/*
* Copyright (C) 2024 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.
*/
use std::fs::File;
use std::io::{BufReader, Read};
use anyhow::anyhow;
use memmap2::Mmap;
use crate::AconfigStorageError::{
self, FileReadFail, MapFileFail, ProtobufParseFail, StorageFileNotFound,
};
use crate::StorageFileType;
use aconfig_storage_file::protos::{
storage_record_pb::try_from_binary_proto, ProtoStorageFileInfo, ProtoStorageFiles,
};
/// Find where storage files are stored for a particular container
pub fn find_container_storage_location(
location_pb_file: &str,
container: &str,
) -> Result<ProtoStorageFileInfo, AconfigStorageError> {
let file = File::open(location_pb_file).map_err(|errmsg| {
FileReadFail(anyhow!("Failed to open file {}: {}", location_pb_file, errmsg))
})?;
let mut reader = BufReader::new(file);
let mut bytes = Vec::new();
reader.read_to_end(&mut bytes).map_err(|errmsg| {
FileReadFail(anyhow!("Failed to read file {}: {}", location_pb_file, errmsg))
})?;
let storage_locations: ProtoStorageFiles = try_from_binary_proto(&bytes).map_err(|errmsg| {
ProtobufParseFail(anyhow!(
"Failed to parse storage location pb file {}: {}",
location_pb_file,
errmsg
))
})?;
for location_info in storage_locations.files.iter() {
if location_info.container() == container {
return Ok(location_info.clone());
}
}
Err(StorageFileNotFound(anyhow!("Storage file does not exist for {}", container)))
}
/// Get the read only memory mapping of a storage file
///
/// # Safety
///
/// The memory mapped file may have undefined behavior if there are writes to this
/// file after being mapped. Ensure no writes can happen to this file while this
/// mapping stays alive.
unsafe fn map_file(file_path: &str) -> Result<Mmap, AconfigStorageError> {
let file = File::open(file_path)
.map_err(|errmsg| FileReadFail(anyhow!("Failed to open file {}: {}", file_path, errmsg)))?;
unsafe {
let mapped_file = Mmap::map(&file).map_err(|errmsg| {
MapFileFail(anyhow!("fail to map storage file {}: {}", file_path, errmsg))
})?;
Ok(mapped_file)
}
}
/// Get a mapped storage file given the container and file type
///
/// # Safety
///
/// The memory mapped file may have undefined behavior if there are writes to this
/// file after being mapped. Ensure no writes can happen to this file while this
/// mapping stays alive.
pub unsafe fn get_mapped_file(
location_pb_file: &str,
container: &str,
file_type: StorageFileType,
) -> Result<Mmap, AconfigStorageError> {
let files_location = find_container_storage_location(location_pb_file, container)?;
match file_type {
StorageFileType::PackageMap => unsafe { map_file(files_location.package_map()) },
StorageFileType::FlagMap => unsafe { map_file(files_location.flag_map()) },
StorageFileType::FlagVal => unsafe { map_file(files_location.flag_val()) },
StorageFileType::FlagInfo => unsafe { map_file(files_location.flag_info()) },
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test_utils::copy_to_temp_file;
use aconfig_storage_file::protos::storage_record_pb::write_proto_to_temp_file;
use tempfile::NamedTempFile;
#[test]
fn test_find_storage_file_location() {
let text_proto = r#"
files {
version: 0
container: "system"
package_map: "/system/etc/package.map"
flag_map: "/system/etc/flag.map"
flag_val: "/metadata/aconfig/system.val"
timestamp: 12345
}
files {
version: 1
container: "product"
package_map: "/product/etc/package.map"
flag_map: "/product/etc/flag.map"
flag_val: "/metadata/aconfig/product.val"
timestamp: 54321
}
"#;
let file = write_proto_to_temp_file(&text_proto).unwrap();
let file_full_path = file.path().display().to_string();
let file_info = find_container_storage_location(&file_full_path, "system").unwrap();
assert_eq!(file_info.version(), 0);
assert_eq!(file_info.container(), "system");
assert_eq!(file_info.package_map(), "/system/etc/package.map");
assert_eq!(file_info.flag_map(), "/system/etc/flag.map");
assert_eq!(file_info.flag_val(), "/metadata/aconfig/system.val");
assert_eq!(file_info.timestamp(), 12345);
let file_info = find_container_storage_location(&file_full_path, "product").unwrap();
assert_eq!(file_info.version(), 1);
assert_eq!(file_info.container(), "product");
assert_eq!(file_info.package_map(), "/product/etc/package.map");
assert_eq!(file_info.flag_map(), "/product/etc/flag.map");
assert_eq!(file_info.flag_val(), "/metadata/aconfig/product.val");
assert_eq!(file_info.timestamp(), 54321);
let err = find_container_storage_location(&file_full_path, "vendor").unwrap_err();
assert_eq!(
format!("{:?}", err),
"StorageFileNotFound(Storage file does not exist for vendor)"
);
}
fn map_and_verify(location_pb_file: &str, file_type: StorageFileType, actual_file: &str) {
let mut opened_file = File::open(actual_file).unwrap();
let mut content = Vec::new();
opened_file.read_to_end(&mut content).unwrap();
let mmaped_file =
unsafe { get_mapped_file(location_pb_file, "system", file_type).unwrap() };
assert_eq!(mmaped_file[..], content[..]);
}
fn create_test_storage_files() -> [NamedTempFile; 4] {
let package_map = copy_to_temp_file("./tests/package.map").unwrap();
let flag_map = copy_to_temp_file("./tests/flag.map").unwrap();
let flag_val = copy_to_temp_file("./tests/package.map").unwrap();
let text_proto = format!(
r#"
files {{
version: 0
container: "system"
package_map: "{}"
flag_map: "{}"
flag_val: "{}"
timestamp: 12345
}}
"#,
package_map.path().display(),
flag_map.path().display(),
flag_val.path().display()
);
let pb_file = write_proto_to_temp_file(&text_proto).unwrap();
[package_map, flag_map, flag_val, pb_file]
}
#[test]
fn test_mapped_file_contents() {
let [package_map, flag_map, flag_val, pb_file] = create_test_storage_files();
let pb_file_path = pb_file.path().display().to_string();
map_and_verify(
&pb_file_path,
StorageFileType::PackageMap,
&package_map.path().display().to_string(),
);
map_and_verify(
&pb_file_path,
StorageFileType::FlagMap,
&flag_map.path().display().to_string(),
);
map_and_verify(
&pb_file_path,
StorageFileType::FlagVal,
&flag_val.path().display().to_string(),
);
}
}
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