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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.
*/
//! flag table query module defines the flag table file read from mapped bytes
use crate::{AconfigStorageError, FILE_VERSION};
use aconfig_storage_file::{
flag_table::FlagTableHeader, flag_table::FlagTableNode, read_u32_from_bytes,
};
use anyhow::anyhow;
pub type FlagOffset = u16;
/// Query flag within package offset
pub fn find_flag_offset(
buf: &[u8],
package_id: u32,
flag: &str,
) -> Result<Option<FlagOffset>, AconfigStorageError> {
let interpreted_header = FlagTableHeader::from_bytes(buf)?;
if interpreted_header.version > crate::FILE_VERSION {
return Err(AconfigStorageError::HigherStorageFileVersion(anyhow!(
"Cannot read storage file with a higher version of {} with lib version {}",
interpreted_header.version,
FILE_VERSION
)));
}
let num_buckets = (interpreted_header.node_offset - interpreted_header.bucket_offset) / 4;
let bucket_index = FlagTableNode::find_bucket_index(package_id, flag, num_buckets);
let mut pos = (interpreted_header.bucket_offset + 4 * bucket_index) as usize;
let mut flag_node_offset = read_u32_from_bytes(buf, &mut pos)? as usize;
if flag_node_offset < interpreted_header.node_offset as usize
|| flag_node_offset >= interpreted_header.file_size as usize
{
return Ok(None);
}
loop {
let interpreted_node = FlagTableNode::from_bytes(&buf[flag_node_offset..])?;
if interpreted_node.package_id == package_id && interpreted_node.flag_name == flag {
return Ok(Some(interpreted_node.flag_id));
}
match interpreted_node.next_offset {
Some(offset) => flag_node_offset = offset as usize,
None => return Ok(None),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use aconfig_storage_file::{FlagTable, StorageFileType};
// create test baseline, syntactic sugar
fn new_expected_node(
package_id: u32,
flag_name: &str,
flag_type: u16,
flag_id: u16,
next_offset: Option<u32>,
) -> FlagTableNode {
FlagTableNode {
package_id,
flag_name: flag_name.to_string(),
flag_type,
flag_id,
next_offset,
}
}
pub fn create_test_flag_table() -> FlagTable {
let header = FlagTableHeader {
version: crate::FILE_VERSION,
container: String::from("system"),
file_type: StorageFileType::FlagMap as u8,
file_size: 321,
num_flags: 8,
bucket_offset: 31,
node_offset: 99,
};
let buckets: Vec<Option<u32>> = vec![
Some(99),
Some(125),
None,
None,
None,
Some(178),
None,
Some(204),
None,
Some(262),
None,
None,
None,
None,
None,
Some(294),
None,
];
let nodes = vec![
new_expected_node(0, "enabled_ro", 1, 1, None),
new_expected_node(0, "enabled_rw", 1, 2, Some(151)),
new_expected_node(1, "disabled_ro", 1, 0, None),
new_expected_node(2, "enabled_ro", 1, 1, None),
new_expected_node(1, "enabled_fixed_ro", 1, 1, Some(236)),
new_expected_node(1, "enabled_ro", 1, 2, None),
new_expected_node(2, "enabled_fixed_ro", 1, 0, None),
new_expected_node(0, "disabled_rw", 1, 0, None),
];
FlagTable { header, buckets, nodes }
}
#[test]
// this test point locks down table query
fn test_flag_query() {
let flag_table = create_test_flag_table().as_bytes();
let baseline = vec![
(0, "enabled_ro", 1u16),
(0, "enabled_rw", 2u16),
(1, "disabled_ro", 0u16),
(2, "enabled_ro", 1u16),
(1, "enabled_fixed_ro", 1u16),
(1, "enabled_ro", 2u16),
(2, "enabled_fixed_ro", 0u16),
(0, "disabled_rw", 0u16),
];
for (package_id, flag_name, expected_offset) in baseline.into_iter() {
let flag_offset =
find_flag_offset(&flag_table[..], package_id, flag_name).unwrap().unwrap();
assert_eq!(flag_offset, expected_offset);
}
}
#[test]
// this test point locks down table query of a non exist flag
fn test_not_existed_flag_query() {
let flag_table = create_test_flag_table().as_bytes();
let flag_offset = find_flag_offset(&flag_table[..], 1, "disabled_fixed_ro").unwrap();
assert_eq!(flag_offset, None);
let flag_offset = find_flag_offset(&flag_table[..], 2, "disabled_rw").unwrap();
assert_eq!(flag_offset, None);
}
#[test]
// this test point locks down query error when file has a higher version
fn test_higher_version_storage_file() {
let mut table = create_test_flag_table();
table.header.version = crate::FILE_VERSION + 1;
let flag_table = table.as_bytes();
let error = find_flag_offset(&flag_table[..], 0, "enabled_ro").unwrap_err();
assert_eq!(
format!("{:?}", error),
format!(
"HigherStorageFileVersion(Cannot read storage file with a higher version of {} with lib version {})",
crate::FILE_VERSION + 1,
crate::FILE_VERSION
)
);
}
}
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