Merge "Implement SipHasher" into main (d53df1b1) · Commits · e / os / android_build

tools/aconfig/aconfig_storage_file/src/flag_table.rs

+1 −1

Original line number	Diff line number	Diff line
		@@ -150,7 +150,7 @@ impl FlagTableNode {
		/// Calculate node bucket index
		pub fn find_bucket_index(package_id: u32, flag_name: &str, num_buckets: u32) -> u32 {
		let full_flag_name = package_id.to_string() + "/" + flag_name;
		get_bucket_index(&full_flag_name, num_buckets)
		get_bucket_index(full_flag_name.as_bytes(), num_buckets)
		}
		}

tools/aconfig/aconfig_storage_file/src/lib.rs

+9 −6

Original line number	Diff line number	Diff line
		@@ -37,19 +37,20 @@ pub mod flag_table;
		pub mod flag_value;
		pub mod package_table;
		pub mod protos;
		pub mod sip_hasher13;
		pub mod test_utils;

		use anyhow::anyhow;
		use std::cmp::Ordering;
		use std::collections::hash_map::DefaultHasher;
		use std::fs::File;
		use std::hash::{Hash, Hasher};
		use std::hash::Hasher;
		use std::io::Read;

		pub use crate::flag_info::{FlagInfoBit, FlagInfoHeader, FlagInfoList, FlagInfoNode};
		pub use crate::flag_table::{FlagTable, FlagTableHeader, FlagTableNode};
		pub use crate::flag_value::{FlagValueHeader, FlagValueList};
		pub use crate::package_table::{PackageTable, PackageTableHeader, PackageTableNode};
		pub use crate::sip_hasher13::SipHasher13;

		use crate::AconfigStorageError::{
		BytesParseFail, HashTableSizeLimit, InvalidFlagValueType, InvalidStoredFlagType,
		@@ -211,10 +212,12 @@ pub fn get_table_size(entries: u32) -> Result<u32, AconfigStorageError> {
		}

		/// Get the corresponding bucket index given the key and number of buckets
		pub(crate) fn get_bucket_index<T: Hash>(val: &T, num_buckets: u32) -> u32 {
		let mut s = DefaultHasher::new();
		val.hash(&mut s);
		(s.finish() % num_buckets as u64) as u32
		pub(crate) fn get_bucket_index(val: &[u8], num_buckets: u32) -> u32 {
		let mut s = SipHasher13::new();
		s.write(val);
		s.write_u8(0xff);
		let ret = (s.finish() % num_buckets as u64) as u32;
		ret
		}

		/// Read and parse bytes as u8

tools/aconfig/aconfig_storage_file/src/package_table.rs

+1 −1

Original line number	Diff line number	Diff line
		@@ -146,7 +146,7 @@ impl PackageTableNode {
		/// construction side (aconfig binary) and consumption side (flag read lib)
		/// use the same method of hashing
		pub fn find_bucket_index(package: &str, num_buckets: u32) -> u32 {
		get_bucket_index(&package, num_buckets)
		get_bucket_index(package.as_bytes(), num_buckets)
		}
		}

tools/aconfig/aconfig_storage_file/src/sip_hasher13.rs

0 → 100644

+327 −0

Original line number	Diff line number	Diff line
		/*
		* 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.
		*/

		//! An implementation of SipHash13

		use std::cmp;
		use std::mem;
		use std::ptr;
		use std::slice;

		use std::hash::Hasher;

		/// An implementation of SipHash 2-4.
		///
		#[derive(Debug, Clone, Default)]
		pub struct SipHasher13 {
		k0: u64,
		k1: u64,
		length: usize, // how many bytes we've processed
		state: State, // hash State
		tail: u64, // unprocessed bytes le
		ntail: usize, // how many bytes in tail are valid
		}

		#[derive(Debug, Clone, Copy, Default)]
		#[repr(C)]
		struct State {
		// v0, v2 and v1, v3 show up in pairs in the algorithm,
		// and simd implementations of SipHash will use vectors
		// of v02 and v13. By placing them in this order in the struct,
		// the compiler can pick up on just a few simd optimizations by itself.
		v0: u64,
		v2: u64,
		v1: u64,
		v3: u64,
		}

		macro_rules! compress {
		($state:expr) => {{
		compress!($state.v0, $state.v1, $state.v2, $state.v3)
		}};
		($v0:expr, $v1:expr, $v2:expr, $v3:expr) => {{
		$v0 = $v0.wrapping_add($v1);
		$v1 = $v1.rotate_left(13);
		$v1 ^= $v0;
		$v0 = $v0.rotate_left(32);
		$v2 = $v2.wrapping_add($v3);
		$v3 = $v3.rotate_left(16);
		$v3 ^= $v2;
		$v0 = $v0.wrapping_add($v3);
		$v3 = $v3.rotate_left(21);
		$v3 ^= $v0;
		$v2 = $v2.wrapping_add($v1);
		$v1 = $v1.rotate_left(17);
		$v1 ^= $v2;
		$v2 = $v2.rotate_left(32);
		}};
		}

		/// Load an integer of the desired type from a byte stream, in LE order. Uses
		/// `copy_nonoverlapping` to let the compiler generate the most efficient way
		/// to load it from a possibly unaligned address.
		///
		/// Unsafe because: unchecked indexing at i..i+size_of(int_ty)
		macro_rules! load_int_le {
		($buf:expr, $i:expr, $int_ty:ident) => {{
		debug_assert!($i + mem::size_of::<$int_ty>() <= $buf.len());
		let mut data = 0 as $int_ty;
		ptr::copy_nonoverlapping(
		$buf.get_unchecked($i),
		&mut data as mut _ as mut u8,
		mem::size_of::<$int_ty>(),
		);
		data.to_le()
		}};
		}

		/// Load an u64 using up to 7 bytes of a byte slice.
		///
		/// Unsafe because: unchecked indexing at start..start+len
		#[inline]
		unsafe fn u8to64_le(buf: &[u8], start: usize, len: usize) -> u64 {
		debug_assert!(len < 8);
		let mut i = 0; // current byte index (from LSB) in the output u64
		let mut out = 0;
		if i + 3 < len {
		out = load_int_le!(buf, start + i, u32) as u64;
		i += 4;
		}
		if i + 1 < len {
		out \|= (load_int_le!(buf, start + i, u16) as u64) << (i * 8);
		i += 2
		}
		if i < len {
		out \|= (buf.get_unchecked(start + i) as u64) << (i 8);
		i += 1;
		}
		debug_assert_eq!(i, len);
		out
		}

		impl SipHasher13 {
		/// Creates a new `SipHasher13` with the two initial keys set to 0.
		#[inline]
		pub fn new() -> SipHasher13 {
		SipHasher13::new_with_keys(0, 0)
		}

		/// Creates a `SipHasher13` that is keyed off the provided keys.
		#[inline]
		pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher13 {
		let mut sip_hasher = SipHasher13 {
		k0: key0,
		k1: key1,
		length: 0,
		state: State { v0: 0, v1: 0, v2: 0, v3: 0 },
		tail: 0,
		ntail: 0,
		};
		sip_hasher.reset();
		sip_hasher
		}

		#[inline]
		fn c_rounds(state: &mut State) {
		compress!(state);
		}

		#[inline]
		fn d_rounds(state: &mut State) {
		compress!(state);
		compress!(state);
		compress!(state);
		}

		#[inline]
		fn reset(&mut self) {
		self.length = 0;
		self.state.v0 = self.k0 ^ 0x736f6d6570736575;
		self.state.v1 = self.k1 ^ 0x646f72616e646f6d;
		self.state.v2 = self.k0 ^ 0x6c7967656e657261;
		self.state.v3 = self.k1 ^ 0x7465646279746573;
		self.ntail = 0;
		}

		// Specialized write function that is only valid for buffers with len <= 8.
		// It's used to force inlining of write_u8 and write_usize, those would normally be inlined
		// except for composite types (that includes slices and str hashing because of delimiter).
		// Without this extra push the compiler is very reluctant to inline delimiter writes,
		// degrading performance substantially for the most common use cases.
		#[inline]
		fn short_write(&mut self, msg: &[u8]) {
		debug_assert!(msg.len() <= 8);
		let length = msg.len();
		self.length += length;

		let needed = 8 - self.ntail;
		let fill = cmp::min(length, needed);
		if fill == 8 {
		// safe to call since msg hasn't been loaded
		self.tail = unsafe { load_int_le!(msg, 0, u64) };
		} else {
		// safe to call since msg hasn't been loaded, and fill <= msg.len()
		self.tail \|= unsafe { u8to64_le(msg, 0, fill) } << (8 * self.ntail);
		if length < needed {
		self.ntail += length;
		return;
		}
		}
		self.state.v3 ^= self.tail;
		Self::c_rounds(&mut self.state);
		self.state.v0 ^= self.tail;

		// Buffered tail is now flushed, process new input.
		self.ntail = length - needed;
		// safe to call since number of `needed` bytes has been loaded
		// and self.ntail + needed == msg.len()
		self.tail = unsafe { u8to64_le(msg, needed, self.ntail) };
		}
		}

		impl Hasher for SipHasher13 {
		// see short_write comment for explanation
		#[inline]
		fn write_usize(&mut self, i: usize) {
		// safe to call, since convert the pointer to u8
		let bytes = unsafe {
		slice::from_raw_parts(&i as const usize as const u8, mem::size_of::<usize>())
		};
		self.short_write(bytes);
		}

		// see short_write comment for explanation
		#[inline]
		fn write_u8(&mut self, i: u8) {
		self.short_write(&[i]);
		}

		#[inline]
		fn write(&mut self, msg: &[u8]) {
		let length = msg.len();
		self.length += length;

		let mut needed = 0;

		// loading unprocessed byte from last write
		if self.ntail != 0 {
		needed = 8 - self.ntail;
		// safe to call, since msg hasn't been processed
		// and cmp::min(length, needed) < 8
		self.tail \|= unsafe { u8to64_le(msg, 0, cmp::min(length, needed)) } << 8 * self.ntail;
		if length < needed {
		self.ntail += length;
		return;
		} else {
		self.state.v3 ^= self.tail;
		Self::c_rounds(&mut self.state);
		self.state.v0 ^= self.tail;
		self.ntail = 0;
		}
		}

		// Buffered tail is now flushed, process new input.
		let len = length - needed;
		let left = len & 0x7;

		let mut i = needed;
		while i < len - left {
		// safe to call since if i < len - left, it means msg has at least 1 byte to load
		let mi = unsafe { load_int_le!(msg, i, u64) };

		self.state.v3 ^= mi;
		Self::c_rounds(&mut self.state);
		self.state.v0 ^= mi;

		i += 8;
		}

		// safe to call since if left == 0, since this call will load nothing
		// if left > 0, it means there are number of `left` bytes in msg
		self.tail = unsafe { u8to64_le(msg, i, left) };
		self.ntail = left;
		}

		#[inline]
		fn finish(&self) -> u64 {
		let mut state = self.state;

		let b: u64 = ((self.length as u64 & 0xff) << 56) \| self.tail;

		state.v3 ^= b;
		Self::c_rounds(&mut state);
		state.v0 ^= b;

		state.v2 ^= 0xff;
		Self::d_rounds(&mut state);

		state.v0 ^ state.v1 ^ state.v2 ^ state.v3
		}
		}

		#[cfg(test)]
		mod tests {
		use super::*;

		use std::hash::{Hash, Hasher};
		use std::string::String;

		#[test]
		// this test point locks down the value list serialization
		fn test_sip_hash13_string_hash() {
		let mut sip_hash13 = SipHasher13::new();
		let test_str1 = String::from("com.google.android.test");
		test_str1.hash(&mut sip_hash13);
		assert_eq!(17898838669067067585, sip_hash13.finish());

		let test_str2 = String::from("adfadfadf adfafadadf 1231241241");
		test_str2.hash(&mut sip_hash13);
		assert_eq!(13543518987672889310, sip_hash13.finish());
		}

		#[test]
		fn test_sip_hash13_write() {
		let mut sip_hash13 = SipHasher13::new();
		let test_str1 = String::from("com.google.android.test");
		sip_hash13.write(test_str1.as_bytes());
		sip_hash13.write_u8(0xff);
		assert_eq!(17898838669067067585, sip_hash13.finish());

		let mut sip_hash132 = SipHasher13::new();
		let test_str1 = String::from("com.google.android.test");
		sip_hash132.write(test_str1.as_bytes());
		assert_eq!(9685440969685209025, sip_hash132.finish());
		sip_hash132.write(test_str1.as_bytes());
		assert_eq!(6719694176662736568, sip_hash132.finish());

		let mut sip_hash133 = SipHasher13::new();
		let test_str2 = String::from("abcdefg");
		test_str2.hash(&mut sip_hash133);
		assert_eq!(2492161047327640297, sip_hash133.finish());

		let mut sip_hash134 = SipHasher13::new();
		let test_str3 = String::from("abcdefgh");
		test_str3.hash(&mut sip_hash134);
		assert_eq!(6689927370435554326, sip_hash134.finish());
		}

		#[test]
		fn test_sip_hash13_write_short() {
		let mut sip_hash13 = SipHasher13::new();
		sip_hash13.write_u8(0x61);
		assert_eq!(4644417185603328019, sip_hash13.finish());
		}
		}

tools/aconfig/aconfig_storage_file/srcs/android/aconfig/storage/SipHasher13.java

0 → 100644

+119 −0

Original line number	Diff line number	Diff line
		/*
		* 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.
		*/

		package android.aconfig.storage;

		public class SipHasher13 {
		static class State {
		private long v0;
		private long v2;
		private long v1;
		private long v3;

		public State(long k0, long k1) {
		v0 = k0 ^ 0x736f6d6570736575L;
		v1 = k1 ^ 0x646f72616e646f6dL;
		v2 = k0 ^ 0x6c7967656e657261L;
		v3 = k1 ^ 0x7465646279746573L;
		}

		public void compress(long m) {
		v3 ^= m;
		cRounds();
		v0 ^= m;
		}

		public long finish() {
		v2 ^= 0xff;
		dRounds();
		return v0 ^ v1 ^ v2 ^ v3;
		}

		private void cRounds() {
		v0 += v1;
		v1 = rotateLeft(v1, 13);
		v1 ^= v0;
		v0 = rotateLeft(v0, 32);
		v2 += v3;
		v3 = rotateLeft(v3, 16);
		v3 ^= v2;
		v0 += v3;
		v3 = rotateLeft(v3, 21);
		v3 ^= v0;
		v2 += v1;
		v1 = rotateLeft(v1, 17);
		v1 ^= v2;
		v2 = rotateLeft(v2, 32);
		}

		private void dRounds() {
		for (int i = 0; i < 3; i++) {
		v0 += v1;
		v1 = rotateLeft(v1, 13);
		v1 ^= v0;
		v0 = rotateLeft(v0, 32);
		v2 += v3;
		v3 = rotateLeft(v3, 16);
		v3 ^= v2;
		v0 += v3;
		v3 = rotateLeft(v3, 21);
		v3 ^= v0;
		v2 += v1;
		v1 = rotateLeft(v1, 17);
		v1 ^= v2;
		v2 = rotateLeft(v2, 32);
		}
		}

		private static long rotateLeft(long value, int shift) {
		return (value << shift) \| value >>> (64 - shift);
		}
		}

		public static long hash(byte[] data) {
		State state = new State(0, 0);
		int len = data.length;
		int left = len & 0x7;
		int index = 0;

		while (index < len - left) {
		long mi = loadLe(data, index, 8);
		index += 8;
		state.compress(mi);
		}

		// padding the end with 0xff to be consistent with rust
		long m = (0xffL << (left * 8)) \| loadLe(data, index, left);
		if (left == 0x7) {
		// compress the m w-2
		state.compress(m);
		m = 0L;
		}
		// len adds 1 since padded 0xff
		m \|= (((len + 1) & 0xffL) << 56);
		state.compress(m);

		return state.finish();
		}

		private static long loadLe(byte[] data, int offset, int size) {
		long m = 0;
		for (int i = 0; i < size; i++) {
		m \|= (data[i + offset] & 0xffL) << (i * 8);
		}
		return m;
		}
		}