Add a libbootconfig for constructing bootconfig
Implement a library for constructing the bootconfig section at the end
of loaded ramdisk for bootin Android.
Bug: 305093905
Change-Id: Ic4cd5c63b9ba02da794967b24189ed7e910f03cc
diff --git a/gbl/libbootconfig/BUILD b/gbl/libbootconfig/BUILD
new file mode 100644
index 0000000..6a71fac
--- /dev/null
+++ b/gbl/libbootconfig/BUILD
@@ -0,0 +1,31 @@
+# Copyright (C) 2023 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.
+
+load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")
+
+package(
+ default_visibility = ["//visibility:public"],
+)
+
+rust_library(
+ name = "libbootconfig",
+ srcs = ["src/lib.rs"],
+ crate_name = "bootconfig",
+ edition = "2021",
+)
+
+rust_test(
+ name = "libbootconfig_test",
+ crate = ":libbootconfig",
+)
diff --git a/gbl/libbootconfig/src/lib.rs b/gbl/libbootconfig/src/lib.rs
new file mode 100644
index 0000000..e5d4682
--- /dev/null
+++ b/gbl/libbootconfig/src/lib.rs
@@ -0,0 +1,248 @@
+// Copyright 2023, 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.
+
+//! Library for constructing kernel bootconfig. See the following for more detail:
+//!
+//! https://source.android.com/docs/core/architecture/bootloader/implementing-bootconfig#bootloader-changes
+
+#![cfg_attr(not(test), no_std)]
+
+/// Library error type.
+#[derive(Debug)]
+pub enum BootConfigError {
+ ArithmeticOverflow,
+ BufferTooSmall,
+ InvalidConfigString,
+ GenericReaderError(i64),
+}
+
+/// The type of Result used in this library.
+pub type Result<T> = core::result::Result<T, BootConfigError>;
+
+/// A class for constructing bootconfig section.
+pub struct BootConfigBuilder<'a> {
+ current_size: usize,
+ buffer: &'a mut [u8],
+}
+
+const BOOTCONFIG_MAGIC: &str = "#BOOTCONFIG\n";
+// Trailer structure:
+// struct {
+// config_size: u32,
+// checksum: u32,
+// bootconfig_magic: [u8]
+// }
+const BOOTCONFIG_TRAILER_SIZE: usize = 4 + 4 + BOOTCONFIG_MAGIC.len();
+
+impl<'a> BootConfigBuilder<'a> {
+ /// Initialize with a given buffer.
+ pub fn new(buffer: &'a mut [u8]) -> Result<Self> {
+ if buffer.len() < BOOTCONFIG_TRAILER_SIZE {
+ return Err(BootConfigError::BufferTooSmall);
+ }
+ let mut ret = Self { current_size: 0, buffer: buffer };
+ ret.update_trailer()?;
+ Ok(ret)
+ }
+
+ /// Get the remaining capacity for adding new bootconfig.
+ pub fn remaining_capacity(&self) -> usize {
+ self.buffer
+ .len()
+ .checked_sub(self.current_size)
+ .unwrap()
+ .checked_sub(BOOTCONFIG_TRAILER_SIZE)
+ .unwrap()
+ }
+
+ /// Get the whole config bytes including trailer.
+ pub fn config_bytes(&self) -> &[u8] {
+ // Arithmetic not expected to fail.
+ &self.buffer[..self.current_size.checked_add(BOOTCONFIG_TRAILER_SIZE).unwrap()]
+ }
+
+ /// Append a new config via a reader callback.
+ ///
+ /// A `&mut [u8]` that covers the remaining space is passed to the callback for reading the
+ /// config bytes. It should return the total size read if operation is successful or a custom
+ /// error code via `BootConfigError::GenericReaderError(<code>)`. Attempting to return a size
+ /// greater than the input will cause it to panic. Empty read is allowed. It's up to the caller
+ /// to make sure the read content will eventually form a valid boot config. The API is for
+ /// situations where configs are read from sources such as disk and separate buffer allocation
+ /// is not possible or desired.
+ pub fn add_with<F>(&mut self, reader: F) -> Result<()>
+ where
+ F: FnOnce(&mut [u8]) -> Result<usize>,
+ {
+ let remains = self.remaining_capacity();
+ let size = reader(&mut self.buffer[self.current_size..][..remains])?;
+ assert!(size <= remains);
+ self.current_size += size;
+ // Content may have been modified. Re-compute trailer.
+ self.update_trailer()
+ }
+
+ /// Append a new config from string.
+ pub fn add(&mut self, config: &str) -> Result<()> {
+ if self.remaining_capacity() < config.len() {
+ return Err(BootConfigError::BufferTooSmall);
+ }
+ self.add_with(|out| {
+ out[..config.len()].clone_from_slice(config.as_bytes());
+ Ok(config.len())
+ })
+ }
+
+ /// Update the boot config trailer at the end of parameter list.
+ /// See specification at:
+ /// https://source.android.com/docs/core/architecture/bootloader/implementing-bootconfig#bootloader-changes
+ fn update_trailer(&mut self) -> Result<()> {
+ // Config size
+ let size: u32 =
+ self.current_size.try_into().map_err(|_| BootConfigError::ArithmeticOverflow)?;
+ // Check sum.
+ let checksum = self.checksum();
+ let trailer = &mut self.buffer[self.current_size..];
+ trailer[..4].clone_from_slice(&size.to_le_bytes());
+ trailer[4..8].clone_from_slice(&checksum.to_le_bytes());
+ trailer[8..][..BOOTCONFIG_MAGIC.len()].clone_from_slice(BOOTCONFIG_MAGIC.as_bytes());
+ Ok(())
+ }
+
+ /// Compute the checksum value.
+ fn checksum(&self) -> u32 {
+ self.buffer[..self.current_size]
+ .iter()
+ .map(|v| *v as u32)
+ .reduce(|acc, v| acc.overflowing_add(v).0)
+ .unwrap_or(0)
+ }
+}
+
+impl core::fmt::Display for BootConfigBuilder<'_> {
+ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+ let bytes = self.config_bytes();
+ for val in &bytes[..bytes.len().checked_sub(BOOTCONFIG_TRAILER_SIZE).unwrap()] {
+ write!(f, "{}", core::ascii::escape_default(*val))?;
+ }
+ Ok(())
+ }
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ // Taken from Cuttlefish on QEMU aarch64.
+ const TEST_CONFIG: &str = "androidboot.hardware=cutf_cvm
+kernel.mac80211_hwsim.radios=0
+kernel.vmw_vsock_virtio_transport_common.virtio_transport_max_vsock_pkt_buf_size=16384
+androidboot.vendor.apex.com.google.emulated.camera.provider.hal=com.google.emulated.camera.provider.hal
+androidboot.slot_suffix=_a
+androidboot.force_normal_boot=1
+androidboot.hw_timeout_multiplier=50
+androidboot.fstab_suffix=cf.f2fs.hctr2
+androidboot.hypervisor.protected_vm.supported=0
+androidboot.modem_simulator_ports=9600
+androidboot.vsock_lights_port=6900
+androidboot.lcd_density=320
+androidboot.vendor.audiocontrol.server.port=9410
+androidboot.vendor.audiocontrol.server.cid=3
+androidboot.cuttlefish_config_server_port=6800
+androidboot.hardware.gralloc=minigbm
+androidboot.vsock_lights_cid=3
+androidboot.enable_confirmationui=0
+androidboot.hypervisor.vm.supported=0
+androidboot.setupwizard_mode=DISABLED
+androidboot.serialno=CUTTLEFISHCVD011
+androidboot.enable_bootanimation=1
+androidboot.hardware.hwcomposer.display_finder_mode=drm
+androidboot.hardware.angle_feature_overrides_enabled=preferLinearFilterForYUV:mapUnspecifiedColorSpaceToPassThrough
+androidboot.hardware.egl=mesa
+androidboot.boot_devices=4010000000.pcie
+androidboot.opengles.version=196608
+androidboot.wifi_mac_prefix=5554
+androidboot.vsock_tombstone_port=6600
+androidboot.hardware.hwcomposer=ranchu
+androidboot.hardware.hwcomposer.mode=client
+androidboot.console=ttyAMA0
+androidboot.ddr_size=4915MB
+androidboot.cpuvulkan.version=0
+androidboot.serialconsole=1
+androidboot.vbmeta.device=PARTUUID=2b7e273a-42a1-654b-bbad-8cb6ab2b6911
+androidboot.vbmeta.avb_version=1.1
+androidboot.vbmeta.device_state=unlocked
+androidboot.vbmeta.hash_alg=sha256
+androidboot.vbmeta.size=23040
+androidboot.vbmeta.digest=6d6cdbad779475dd945ed79e6bd79c0574541d34ff488fa5aeeb024d739dd0d2
+androidboot.vbmeta.invalidate_on_error=yes
+androidboot.veritymode=enforcing
+androidboot.verifiedbootstate=orange
+";
+
+ const TEST_CONFIG_TRAILER: &[u8; BOOTCONFIG_TRAILER_SIZE] =
+ b"i\x07\x00\x00\xf9\xc4\x02\x00#BOOTCONFIG\n";
+
+ #[test]
+ fn test_add() {
+ let mut buffer = [0u8; TEST_CONFIG.len() + TEST_CONFIG_TRAILER.len()];
+ let mut builder = BootConfigBuilder::new(&mut buffer[..]).unwrap();
+ builder.add(TEST_CONFIG).unwrap();
+ assert_eq!(
+ builder.config_bytes().to_vec(),
+ [TEST_CONFIG.as_bytes(), TEST_CONFIG_TRAILER].concat().to_vec()
+ );
+ }
+
+ #[test]
+ fn test_add_incremental() {
+ let mut buffer = [0u8; TEST_CONFIG.len() + TEST_CONFIG_TRAILER.len()];
+ let mut builder = BootConfigBuilder::new(&mut buffer[..]).unwrap();
+ for ele in TEST_CONFIG.strip_suffix('\n').unwrap().split('\n') {
+ let config = std::string::String::from(ele) + "\n";
+ builder.add(config.as_str()).unwrap()
+ }
+ assert_eq!(
+ builder.config_bytes().to_vec(),
+ [TEST_CONFIG.as_bytes(), TEST_CONFIG_TRAILER].concat().to_vec()
+ );
+ }
+
+ #[test]
+ fn test_new_buffer_too_small() {
+ let mut buffer = [0u8; BOOTCONFIG_TRAILER_SIZE - 1];
+ assert!(BootConfigBuilder::new(&mut buffer[..]).is_err());
+ }
+
+ #[test]
+ fn test_add_buffer_too_small() {
+ let mut buffer = [0u8; BOOTCONFIG_TRAILER_SIZE + 1];
+ let mut builder = BootConfigBuilder::new(&mut buffer[..]).unwrap();
+ assert!(builder.add("a\n").is_err());
+ }
+
+ #[test]
+ fn test_add_empty_string() {
+ let mut buffer = [0u8; BOOTCONFIG_TRAILER_SIZE + 1];
+ let mut builder = BootConfigBuilder::new(&mut buffer[..]).unwrap();
+ builder.add("").unwrap();
+ }
+
+ #[test]
+ fn test_add_with_error() {
+ let mut buffer = [0u8; BOOTCONFIG_TRAILER_SIZE + 1];
+ let mut builder = BootConfigBuilder::new(&mut buffer[..]).unwrap();
+ assert!(builder.add_with(|_| Err(BootConfigError::GenericReaderError(123))).is_err());
+ }
+}
diff --git a/gbl/tests/BUILD b/gbl/tests/BUILD
index 0529101..13b289b 100644
--- a/gbl/tests/BUILD
+++ b/gbl/tests/BUILD
@@ -15,6 +15,7 @@
test_suite(
name = "tests",
tests = [
+ "@gbl//libbootconfig:libbootconfig_test",
"@gbl//libefi:libefi_test",
"@gbl//libstorage:gbl_libstorage_test",
"@gbl//third_party/libzbi:libzbi_test",
