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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, StoredFlagType,
};
use anyhow::anyhow;
/// Flag table query return
#[derive(PartialEq, Debug)]
pub struct FlagReadContext {
pub flag_type: StoredFlagType,
pub flag_index: u16,
}
/// Query flag read context: flag type and within package flag index
pub fn find_flag_read_context(
buf: &[u8],
package_id: u32,
flag: &str,
) -> Result<Option<FlagReadContext>, 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(FlagReadContext {
flag_type: interpreted_node.flag_type,
flag_index: interpreted_node.flag_index,
}));
}
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::test_utils::create_test_flag_table;
#[test]
// this test point locks down table query
fn test_flag_query() {
let flag_table = create_test_flag_table().into_bytes();
let baseline = vec![
(0, "enabled_ro", StoredFlagType::ReadOnlyBoolean, 1u16),
(0, "enabled_rw", StoredFlagType::ReadWriteBoolean, 2u16),
(2, "enabled_rw", StoredFlagType::ReadWriteBoolean, 1u16),
(1, "disabled_rw", StoredFlagType::ReadWriteBoolean, 0u16),
(1, "enabled_fixed_ro", StoredFlagType::FixedReadOnlyBoolean, 1u16),
(1, "enabled_ro", StoredFlagType::ReadOnlyBoolean, 2u16),
(2, "enabled_fixed_ro", StoredFlagType::FixedReadOnlyBoolean, 0u16),
(0, "disabled_rw", StoredFlagType::ReadWriteBoolean, 0u16),
];
for (package_id, flag_name, flag_type, flag_index) in baseline.into_iter() {
let flag_context =
find_flag_read_context(&flag_table[..], package_id, flag_name).unwrap().unwrap();
assert_eq!(flag_context.flag_type, flag_type);
assert_eq!(flag_context.flag_index, flag_index);
}
}
#[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().into_bytes();
let flag_context = find_flag_read_context(&flag_table[..], 1, "disabled_fixed_ro").unwrap();
assert_eq!(flag_context, None);
let flag_context = find_flag_read_context(&flag_table[..], 2, "disabled_rw").unwrap();
assert_eq!(flag_context, 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.into_bytes();
let error = find_flag_read_context(&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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