From 1a796bca57ef45d559e70dc05ad2df5cb77b8f64 Mon Sep 17 00:00:00 2001
From: Tom Cherry <tomcherry@google.com>
Date: Wed, 13 May 2020 09:28:37 -0700
Subject: logd: add a SerializedLogBuffer suitable for compression

Initial commit for a SerializedLogBuffer.  The intention here is for
the serialized data to be compressed (currently using zlib) to allow
for substantially longer logs in the same memory footprint.

Test: unit tests
Change-Id: I2528e4e1ff1cf3bc91130173a107f371f04d911a
---
 logd/CompressionEngine.cpp | 104 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 logd/CompressionEngine.cpp

(limited to 'logd/CompressionEngine.cpp')

diff --git a/logd/CompressionEngine.cpp b/logd/CompressionEngine.cpp
new file mode 100644
index 000000000..f37208b84
--- /dev/null
+++ b/logd/CompressionEngine.cpp
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+#include "CompressionEngine.h"
+
+#include <limits>
+
+#include <android-base/logging.h>
+#include <zlib.h>
+#include <zstd.h>
+
+CompressionEngine& CompressionEngine::GetInstance() {
+    CompressionEngine* engine = new ZstdCompressionEngine();
+    return *engine;
+}
+
+bool ZlibCompressionEngine::Compress(std::span<uint8_t> in, std::vector<uint8_t>& out) {
+    z_stream strm;
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+    int ret = deflateInit(&strm, Z_DEFAULT_COMPRESSION);
+    if (ret != Z_OK) {
+        LOG(FATAL) << "deflateInit() failed";
+    }
+
+    CHECK_LE(in.size(), static_cast<int64_t>(std::numeric_limits<uint32_t>::max()));
+    uint32_t out_size = deflateBound(&strm, in.size());
+
+    out.resize(out_size);
+    strm.avail_in = in.size();
+    strm.next_in = const_cast<uint8_t*>(in.data());
+    strm.avail_out = out_size;
+    strm.next_out = out.data();
+    ret = deflate(&strm, Z_FINISH);
+    CHECK_EQ(ret, Z_STREAM_END);
+
+    uint32_t compressed_data_size = strm.total_out;
+    deflateEnd(&strm);
+    out.resize(compressed_data_size);
+
+    return true;
+}
+
+bool ZlibCompressionEngine::Decompress(const std::vector<uint8_t>& in, std::vector<uint8_t>& out,
+                                       size_t out_size) {
+    out.resize(out_size);
+
+    z_stream strm;
+    strm.zalloc = Z_NULL;
+    strm.zfree = Z_NULL;
+    strm.opaque = Z_NULL;
+    strm.avail_in = in.size();
+    strm.next_in = const_cast<uint8_t*>(in.data());
+    strm.avail_out = out.size();
+    strm.next_out = out.data();
+
+    inflateInit(&strm);
+    int ret = inflate(&strm, Z_NO_FLUSH);
+
+    CHECK_EQ(strm.avail_in, 0U);
+    CHECK_EQ(strm.avail_out, 0U);
+    CHECK_EQ(ret, Z_STREAM_END);
+    inflateEnd(&strm);
+
+    return true;
+}
+
+bool ZstdCompressionEngine::Compress(std::span<uint8_t> in, std::vector<uint8_t>& out) {
+    size_t out_size = ZSTD_compressBound(in.size());
+    out.resize(out_size);
+
+    out_size = ZSTD_compress(out.data(), out_size, in.data(), in.size(), 1);
+    if (ZSTD_isError(out_size)) {
+        LOG(FATAL) << "ZSTD_compress failed: " << ZSTD_getErrorName(out_size);
+    }
+    out.resize(out_size);
+
+    return true;
+}
+
+bool ZstdCompressionEngine::Decompress(const std::vector<uint8_t>& in, std::vector<uint8_t>& out,
+                                       size_t out_size) {
+    out.resize(out_size);
+    size_t result = ZSTD_decompress(out.data(), out.size(), in.data(), in.size());
+    if (ZSTD_isError(result)) {
+        LOG(FATAL) << "ZSTD_decompress failed: " << ZSTD_getErrorName(result);
+    }
+    CHECK_EQ(result, out.size());
+    return true;
+}
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