aconfig: create aconfig_storage_write_api crate
aconfig_storage_write_api crate is the lib to be used by aconfig storage
daemon to update flag value at a given offset.
Note that mmap api is unsafe from memmap2 crate. This is due to the
possibility of other code write to the file after mmaping the file into
memory. Therefore the api to write to storage value file is also marked
as unsafe. In reality, the persistent storage value file is protected by
SELinux policy to allow write access only to aconfig storage daemon. In
addition, aconfig storage daemon is single threaded. So at any time,
only one thread is writing to a storage file, and only thru the mmapped
file in memory (not thru direct file write). So it would safe for
storage daemon to call this api.
Bug: b/312444587
Test: m libaconfig_storage_write_api; atest
aconfig_storage_write_api.test
Change-Id: I93cffea0d94e4c40e711d809418c0b18b6d9bfe1
diff --git a/tools/aconfig/Cargo.toml b/tools/aconfig/Cargo.toml
index 7112fd4..6bd0d06 100644
--- a/tools/aconfig/Cargo.toml
+++ b/tools/aconfig/Cargo.toml
@@ -5,6 +5,7 @@
"aconfig_protos",
"aconfig_storage_file",
"aconfig_storage_read_api",
+ "aconfig_storage_write_api",
"aflags",
"printflags"
]
diff --git a/tools/aconfig/TEST_MAPPING b/tools/aconfig/TEST_MAPPING
index 26d6172..4acbe60 100644
--- a/tools/aconfig/TEST_MAPPING
+++ b/tools/aconfig/TEST_MAPPING
@@ -70,6 +70,10 @@
],
"postsubmit": [
{
+ // aconfig_storage_write_api unit tests
+ "name": "aconfig_storage_write_api.test"
+ },
+ {
// aconfig_storage_read_api unit tests
"name": "aconfig_storage_read_api.test"
},
diff --git a/tools/aconfig/aconfig_storage_file/src/lib.rs b/tools/aconfig/aconfig_storage_file/src/lib.rs
index 202f6a4..c40caba 100644
--- a/tools/aconfig/aconfig_storage_file/src/lib.rs
+++ b/tools/aconfig/aconfig_storage_file/src/lib.rs
@@ -163,6 +163,12 @@
#[error("fail to map storage file")]
MapFileFail(#[source] anyhow::Error),
+ #[error("fail to get mapped file")]
+ ObtainMappedFileFail(#[source] anyhow::Error),
+
+ #[error("fail to flush mapped storage file")]
+ MapFlushFail(#[source] anyhow::Error),
+
#[error("number of items in hash table exceed limit")]
HashTableSizeLimit(#[source] anyhow::Error),
diff --git a/tools/aconfig/aconfig_storage_write_api/Android.bp b/tools/aconfig/aconfig_storage_write_api/Android.bp
new file mode 100644
index 0000000..1382aba
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/Android.bp
@@ -0,0 +1,37 @@
+package {
+ default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_defaults {
+ name: "aconfig_storage_write_api.defaults",
+ edition: "2021",
+ lints: "none",
+ srcs: ["src/lib.rs"],
+ rustlibs: [
+ "libanyhow",
+ "libtempfile",
+ "libmemmap2",
+ "libcxx",
+ "libthiserror",
+ "libaconfig_storage_file",
+ ],
+}
+
+rust_library {
+ name: "libaconfig_storage_write_api",
+ crate_name: "aconfig_storage_write_api",
+ host_supported: true,
+ defaults: ["aconfig_storage_write_api.defaults"],
+}
+
+rust_test_host {
+ name: "aconfig_storage_write_api.test",
+ test_suites: ["general-tests"],
+ defaults: ["aconfig_storage_write_api.defaults"],
+ data: [
+ "tests/flag.val",
+ ],
+ rustlibs: [
+ "libaconfig_storage_read_api",
+ ],
+}
diff --git a/tools/aconfig/aconfig_storage_write_api/Cargo.toml b/tools/aconfig/aconfig_storage_write_api/Cargo.toml
new file mode 100644
index 0000000..494c19c
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/Cargo.toml
@@ -0,0 +1,21 @@
+[package]
+name = "aconfig_storage_write_api"
+version = "0.1.0"
+edition = "2021"
+
+[features]
+default = ["cargo"]
+cargo = []
+
+[dependencies]
+anyhow = "1.0.69"
+memmap2 = "0.8.0"
+tempfile = "3.9.0"
+thiserror = "1.0.56"
+protobuf = "3.2.0"
+once_cell = "1.19.0"
+aconfig_storage_file = { path = "../aconfig_storage_file" }
+aconfig_storage_read_api = { path = "../aconfig_storage_read_api" }
+
+[build-dependencies]
+cxx-build = "1.0"
diff --git a/tools/aconfig/aconfig_storage_write_api/src/flag_value_update.rs b/tools/aconfig/aconfig_storage_write_api/src/flag_value_update.rs
new file mode 100644
index 0000000..1e9612a
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/src/flag_value_update.rs
@@ -0,0 +1,113 @@
+/*
+ * 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 value update module defines the flag value file write to mapped bytes
+
+use aconfig_storage_file::{AconfigStorageError, FlagValueHeader, FILE_VERSION};
+use anyhow::anyhow;
+
+/// Set flag value
+pub fn update_boolean_flag_value(
+ buf: &mut [u8],
+ flag_offset: u32,
+ flag_value: bool,
+) -> Result<(), AconfigStorageError> {
+ let interpreted_header = FlagValueHeader::from_bytes(buf)?;
+ if interpreted_header.version > FILE_VERSION {
+ return Err(AconfigStorageError::HigherStorageFileVersion(anyhow!(
+ "Cannot write to storage file with a higher version of {} with lib version {}",
+ interpreted_header.version,
+ FILE_VERSION
+ )));
+ }
+
+ let head = (interpreted_header.boolean_value_offset + flag_offset) as usize;
+
+ // TODO: right now, there is only boolean flags, with more flag value types added
+ // later, the end of boolean flag value section should be updated (b/322826265).
+ if head >= interpreted_header.file_size as usize {
+ return Err(AconfigStorageError::InvalidStorageFileOffset(anyhow!(
+ "Flag value offset goes beyond the end of the file."
+ )));
+ }
+
+ buf[head] = u8::from(flag_value).to_le_bytes()[0];
+ Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use aconfig_storage_file::FlagValueList;
+
+ pub fn create_test_flag_value_list() -> FlagValueList {
+ let header = FlagValueHeader {
+ version: FILE_VERSION,
+ container: String::from("system"),
+ file_size: 34,
+ num_flags: 8,
+ boolean_value_offset: 26,
+ };
+ let booleans: Vec<bool> = vec![false; 8];
+ FlagValueList { header, booleans }
+ }
+
+ #[test]
+ // this test point locks down flag value update
+ fn test_boolean_flag_value_update() {
+ let flag_value_list = create_test_flag_value_list();
+ let value_offset = flag_value_list.header.boolean_value_offset;
+ let mut content = flag_value_list.as_bytes();
+ let true_byte = u8::from(true).to_le_bytes()[0];
+ let false_byte = u8::from(false).to_le_bytes()[0];
+
+ for i in 0..flag_value_list.header.num_flags {
+ let offset = (value_offset + i) as usize;
+ update_boolean_flag_value(&mut content, i, true).unwrap();
+ assert_eq!(content[offset], true_byte);
+ update_boolean_flag_value(&mut content, i, false).unwrap();
+ assert_eq!(content[offset], false_byte);
+ }
+ }
+
+ #[test]
+ // this test point locks down update beyond the end of boolean section
+ fn test_boolean_out_of_range() {
+ let mut flag_value_list = create_test_flag_value_list().as_bytes();
+ let error = update_boolean_flag_value(&mut flag_value_list[..], 8, true).unwrap_err();
+ assert_eq!(
+ format!("{:?}", error),
+ "InvalidStorageFileOffset(Flag value offset goes beyond the end of the file.)"
+ );
+ }
+
+ #[test]
+ // this test point locks down query error when file has a higher version
+ fn test_higher_version_storage_file() {
+ let mut value_list = create_test_flag_value_list();
+ value_list.header.version = FILE_VERSION + 1;
+ let mut flag_value = value_list.as_bytes();
+ let error = update_boolean_flag_value(&mut flag_value[..], 4, true).unwrap_err();
+ assert_eq!(
+ format!("{:?}", error),
+ format!(
+ "HigherStorageFileVersion(Cannot write to storage file with a higher version of {} with lib version {})",
+ FILE_VERSION + 1,
+ FILE_VERSION
+ )
+ );
+ }
+}
diff --git a/tools/aconfig/aconfig_storage_write_api/src/lib.rs b/tools/aconfig/aconfig_storage_write_api/src/lib.rs
new file mode 100644
index 0000000..17a6538
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/src/lib.rs
@@ -0,0 +1,120 @@
+/*
+ * 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.
+ */
+
+//! `aconfig_storage_write_api` is a crate that defines write apis to update flag value
+//! in storage file. It provides one api to interface with storage files.
+
+pub mod flag_value_update;
+pub mod mapped_file;
+
+#[cfg(test)]
+mod test_utils;
+
+use aconfig_storage_file::AconfigStorageError;
+
+use anyhow::anyhow;
+use memmap2::MmapMut;
+
+/// Storage file location pb file
+pub const STORAGE_LOCATION_FILE: &str = "/metadata/aconfig/persistent_storage_file_records.pb";
+
+/// Get mmaped flag value file given the container name
+///
+/// \input container: the flag package container
+/// \return a result of mapped file
+///
+///
+/// # Safety
+///
+/// The memory mapped file may have undefined behavior if there are writes to this
+/// file not thru this memory mapped file or there are concurrent writes to this
+/// memory mapped file. Ensure all writes to the underlying file are thru this memory
+/// mapped file and there are no concurrent writes.
+pub unsafe fn get_mapped_flag_value_file(container: &str) -> Result<MmapMut, AconfigStorageError> {
+ unsafe { crate::mapped_file::get_mapped_file(STORAGE_LOCATION_FILE, container) }
+}
+
+/// Set boolean flag value thru mapped file and flush the change to file
+///
+/// \input mapped_file: the mapped flag value file
+/// \input offset: flag value offset
+/// \input value: updated flag value
+/// \return a result of ()
+///
+pub fn set_boolean_flag_value(
+ file: &mut MmapMut,
+ offset: u32,
+ value: bool,
+) -> Result<(), AconfigStorageError> {
+ crate::flag_value_update::update_boolean_flag_value(file, offset, value)?;
+ file.flush().map_err(|errmsg| {
+ AconfigStorageError::MapFlushFail(anyhow!("fail to flush storage file: {}", errmsg))
+ })
+}
+
+#[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 aconfig_storage_read_api::flag_value_query::find_boolean_flag_value;
+ use std::fs::File;
+ use std::io::Read;
+
+ fn get_boolean_flag_value_at_offset(file: &str, offset: u32) -> bool {
+ let mut f = File::open(&file).unwrap();
+ let mut bytes = Vec::new();
+ f.read_to_end(&mut bytes).unwrap();
+ find_boolean_flag_value(&bytes, offset).unwrap()
+ }
+
+ #[test]
+ fn test_set_boolean_flag_value() {
+ let flag_value_file = copy_to_temp_file("./tests/flag.val", false).unwrap();
+ let flag_value_path = flag_value_file.path().display().to_string();
+ let text_proto = format!(
+ r#"
+files {{
+ version: 0
+ container: "system"
+ package_map: "some_package.map"
+ flag_map: "some_flag.map"
+ flag_val: "{}"
+ timestamp: 12345
+}}
+"#,
+ flag_value_path
+ );
+ let record_pb_file = write_proto_to_temp_file(&text_proto).unwrap();
+ let record_pb_path = record_pb_file.path().display().to_string();
+
+ // SAFETY:
+ // The safety here is guaranteed as only this single threaded test process will
+ // write to this file
+ unsafe {
+ let mut file = crate::mapped_file::get_mapped_file(&record_pb_path, "system").unwrap();
+ for i in 0..8 {
+ set_boolean_flag_value(&mut file, i, true).unwrap();
+ let value = get_boolean_flag_value_at_offset(&flag_value_path, i);
+ assert_eq!(value, true);
+
+ set_boolean_flag_value(&mut file, i, false).unwrap();
+ let value = get_boolean_flag_value_at_offset(&flag_value_path, i);
+ assert_eq!(value, false);
+ }
+ }
+ }
+}
diff --git a/tools/aconfig/aconfig_storage_write_api/src/mapped_file.rs b/tools/aconfig/aconfig_storage_write_api/src/mapped_file.rs
new file mode 100644
index 0000000..4c98be4
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/src/mapped_file.rs
@@ -0,0 +1,189 @@
+/*
+ * 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::{self, File, OpenOptions};
+use std::io::{BufReader, Read};
+
+use anyhow::anyhow;
+use memmap2::MmapMut;
+
+use aconfig_storage_file::protos::{storage_record_pb::try_from_binary_proto, ProtoStorageFiles};
+use aconfig_storage_file::AconfigStorageError::{
+ self, FileReadFail, MapFileFail, ProtobufParseFail, StorageFileNotFound,
+};
+
+/// Find where persistent storage value file is for a particular container
+fn find_persist_flag_value_file(
+ location_pb_file: &str,
+ container: &str,
+) -> Result<String, 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.flag_val().to_string());
+ }
+ }
+ Err(StorageFileNotFound(anyhow!("Persistent flag value file does not exist for {}", container)))
+}
+
+/// 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 not thru this memory mapped file or there are concurrent writes to this
+/// memory mapped file. Ensure all writes to the underlying file are thru this memory
+/// mapped file and there are no concurrent writes.
+pub unsafe fn get_mapped_file(
+ location_pb_file: &str,
+ container: &str,
+) -> Result<MmapMut, AconfigStorageError> {
+ let file_path = find_persist_flag_value_file(location_pb_file, container)?;
+
+ // make sure file has read write permission
+ let perms = fs::metadata(&file_path).unwrap().permissions();
+ if perms.readonly() {
+ return Err(MapFileFail(anyhow!("fail to map non read write storage file {}", file_path)));
+ }
+
+ let file =
+ OpenOptions::new().read(true).write(true).open(&file_path).map_err(|errmsg| {
+ FileReadFail(anyhow!("Failed to open file {}: {}", file_path, errmsg))
+ })?;
+
+ unsafe {
+ MmapMut::map_mut(&file).map_err(|errmsg| {
+ MapFileFail(anyhow!("fail to map storage file {}: {}", file_path, errmsg))
+ })
+ }
+}
+
+#[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;
+
+ #[test]
+ fn test_find_persist_flag_value_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 flag_value_file = find_persist_flag_value_file(&file_full_path, "system").unwrap();
+ assert_eq!(flag_value_file, "/metadata/aconfig/system.val");
+ let flag_value_file = find_persist_flag_value_file(&file_full_path, "product").unwrap();
+ assert_eq!(flag_value_file, "/metadata/aconfig/product.val");
+ let err = find_persist_flag_value_file(&file_full_path, "vendor").unwrap_err();
+ assert_eq!(
+ format!("{:?}", err),
+ "StorageFileNotFound(Persistent flag value file does not exist for vendor)"
+ );
+ }
+
+ #[test]
+ fn test_mapped_file_contents() {
+ let mut rw_file = copy_to_temp_file("./tests/flag.val", false).unwrap();
+ let text_proto = format!(
+ r#"
+files {{
+ version: 0
+ container: "system"
+ package_map: "some_package.map"
+ flag_map: "some_flag.map"
+ flag_val: "{}"
+ timestamp: 12345
+}}
+"#,
+ rw_file.path().display().to_string()
+ );
+ let storage_record_file = write_proto_to_temp_file(&text_proto).unwrap();
+ let storage_record_file_path = storage_record_file.path().display().to_string();
+
+ let mut content = Vec::new();
+ rw_file.read_to_end(&mut content).unwrap();
+
+ // SAFETY:
+ // The safety here is guaranteed here as no writes happens to this temp file
+ unsafe {
+ let mmaped_file = get_mapped_file(&storage_record_file_path, "system").unwrap();
+ assert_eq!(mmaped_file[..], content[..]);
+ }
+ }
+
+ #[test]
+ fn test_mapped_read_only_file() {
+ let ro_file = copy_to_temp_file("./tests/flag.val", true).unwrap();
+ let text_proto = format!(
+ r#"
+files {{
+ version: 0
+ container: "system"
+ package_map: "some_package.map"
+ flag_map: "some_flag.map"
+ flag_val: "{}"
+ timestamp: 12345
+}}
+"#,
+ ro_file.path().display().to_string()
+ );
+ let storage_record_file = write_proto_to_temp_file(&text_proto).unwrap();
+ let storage_record_file_path = storage_record_file.path().display().to_string();
+
+ // SAFETY:
+ // The safety here is guaranteed here as no writes happens to this temp file
+ unsafe {
+ let error = get_mapped_file(&storage_record_file_path, "system").unwrap_err();
+ assert_eq!(
+ format!("{:?}", error),
+ format!(
+ "MapFileFail(fail to map non read write storage file {})",
+ ro_file.path().display().to_string()
+ )
+ );
+ }
+ }
+}
diff --git a/tools/aconfig/aconfig_storage_write_api/src/test_utils.rs b/tools/aconfig/aconfig_storage_write_api/src/test_utils.rs
new file mode 100644
index 0000000..06e2e22
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/src/test_utils.rs
@@ -0,0 +1,32 @@
+/*
+ * 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 anyhow::Result;
+use std::fs;
+use tempfile::NamedTempFile;
+
+/// Create temp file copy
+pub(crate) fn copy_to_temp_file(source_file: &str, read_only: bool) -> Result<NamedTempFile> {
+ let file = NamedTempFile::new()?;
+ fs::copy(source_file, file.path())?;
+ if read_only {
+ let file_name = file.path().display().to_string();
+ let mut perms = fs::metadata(file_name).unwrap().permissions();
+ perms.set_readonly(true);
+ fs::set_permissions(file.path(), perms.clone()).unwrap();
+ }
+ Ok(file)
+}
diff --git a/tools/aconfig/aconfig_storage_write_api/tests/flag.val b/tools/aconfig/aconfig_storage_write_api/tests/flag.val
new file mode 100644
index 0000000..f39f8d3
--- /dev/null
+++ b/tools/aconfig/aconfig_storage_write_api/tests/flag.val
Binary files differ