From 4503a3a2878ecd6d42e540e36d95c1fd1046fda0 Mon Sep 17 00:00:00 2001 From: Joe Abraham Date: Thu, 1 Feb 2024 10:48:11 +0530 Subject: [PATCH] Introduce utility class for encoding --- velox/common/encode/CMakeLists.txt | 4 + velox/common/encode/EncoderUtils.h | 128 ++++++++++++++++++ velox/common/encode/tests/CMakeLists.txt | 23 ++++ .../common/encode/tests/EncoderUtilsTests.cpp | 77 +++++++++++ 4 files changed, 232 insertions(+) create mode 100644 velox/common/encode/EncoderUtils.h create mode 100644 velox/common/encode/tests/CMakeLists.txt create mode 100644 velox/common/encode/tests/EncoderUtilsTests.cpp diff --git a/velox/common/encode/CMakeLists.txt b/velox/common/encode/CMakeLists.txt index d9918d53b59c5..bc27527e14ace 100644 --- a/velox/common/encode/CMakeLists.txt +++ b/velox/common/encode/CMakeLists.txt @@ -12,5 +12,9 @@ # See the License for the specific language governing permissions and # limitations under the License. +if(${VELOX_BUILD_TESTING}) + add_subdirectory(tests) +endif() + add_library(velox_encode Base64.cpp) target_link_libraries(velox_encode PUBLIC Folly::folly) diff --git a/velox/common/encode/EncoderUtils.h b/velox/common/encode/EncoderUtils.h new file mode 100644 index 0000000000000..ed06d64fbd5fc --- /dev/null +++ b/velox/common/encode/EncoderUtils.h @@ -0,0 +1,128 @@ +/* + * Copyright (c) Facebook, Inc. and its affiliates. + * + * 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. + */ +#pragma once + +#include +#include +#include + +#include + +namespace facebook::velox::encoding { + +class EncoderException : public std::exception { + public: + explicit EncoderException(const char* msg) : msg_(msg) {} + const char* what() const noexcept override { + return msg_; + } + + protected: + const char* msg_; +}; + +using Charset = std::array; +using ReverseIndex = std::array; + +// Padding character used in encoding +constexpr static char kPadding = '='; + +// Checks is there padding in encoded data +inline bool isPadded(const char* data, size_t len) { + return (len > 0 && data[len - 1] == kPadding) ? true : false; +} + +// Counts the number of padding characters in encoded data. +inline size_t countPadding(const char* src, size_t len) { + size_t padding_count = 0; + while (len > 0 && src[len - 1] == kPadding) { + padding_count++; + len--; + } + + return padding_count; +} + +// Gets value corresponding to an encoded character +inline uint8_t +baseReverseLookup(int base, char p, const ReverseIndex& reverse_lookup) { + auto curr = reverse_lookup[(uint8_t)p]; + // Value of encoded character shall be less than base. + if (curr >= base) { + throw EncoderException( + "decode() - invalid input string: invalid characters"); + } + + return curr; +} + +// Validate the character in charset with ReverseIndex table +constexpr bool checkForwardIndex( + uint8_t idx, + const Charset& charset, + const ReverseIndex& table) { + for (uint8_t i = 0; i <= idx; ++i) { + if (!(table[static_cast(charset[i])] == i)) { + return false; + } + } + return true; +} + +/// Similar to strchr(), but for null-terminated const strings. +/// Another difference is that we do not consider "\0" to be present in the +/// string. +/// Returns true if "str" contains the character c. +constexpr bool findCharacterInCharSet( + const Charset& charset, + int base, + uint8_t idx, + const char c) { + while (idx < base) { + if (charset[idx] == c) { + return true; + } + idx++; + } + return false; +} + +// Validate the value in ReverseIndex table with charset. +constexpr bool checkReverseIndex( + uint8_t idx, + const Charset& charset, + int base, + const ReverseIndex& table) { + for (uint8_t currentIdx = idx;; --currentIdx) { + if (table[currentIdx] == 255) { + if (findCharacterInCharSet( + charset, base, 0, static_cast(currentIdx))) { + return false; // Character should not be found + } + } else { + if (!(charset[table[currentIdx]] == currentIdx)) { + return false; // Character at table index does not match currentIdx + } + } + + if (currentIdx == 0) { + break; // Stop the loop when reaching 0 to avoid underflow + } + } + return true; +} + +} // namespace facebook::velox::encoding diff --git a/velox/common/encode/tests/CMakeLists.txt b/velox/common/encode/tests/CMakeLists.txt new file mode 100644 index 0000000000000..314e3a95b53ce --- /dev/null +++ b/velox/common/encode/tests/CMakeLists.txt @@ -0,0 +1,23 @@ +# Copyright (c) Facebook, Inc. and its affiliates. +# +# 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. + +add_executable(velox_common_encode_test EncoderUtilsTests.cpp) +add_test(velox_common_encode_test velox_common_encode_test) +target_link_libraries( + velox_common_encode_test + PUBLIC Folly::folly + PRIVATE velox_encode + velox_exception + gtest + gtest_main) diff --git a/velox/common/encode/tests/EncoderUtilsTests.cpp b/velox/common/encode/tests/EncoderUtilsTests.cpp new file mode 100644 index 0000000000000..841095c1d6430 --- /dev/null +++ b/velox/common/encode/tests/EncoderUtilsTests.cpp @@ -0,0 +1,77 @@ +/* + * Copyright (c) Facebook, Inc. and its affiliates. + * + * 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 +#include "velox/common/base/tests/GTestUtils.h" +#include "velox/common/encode/EncoderUtils.h" + +namespace facebook::velox::encoding { +class EncoderUtilsTest : public ::testing::Test {}; + +TEST_F(EncoderUtilsTest, ChecksPadding) { + EXPECT_TRUE(isPadded("ABC=", 4)); + EXPECT_FALSE(isPadded("ABC", 3)); +} + +TEST_F(EncoderUtilsTest, CountsPaddingCorrectly) { + EXPECT_EQ(0, countPadding("ABC", 3)); + EXPECT_EQ(1, countPadding("ABC=", 4)); + EXPECT_EQ(2, countPadding("AB==", 4)); +} + +constexpr Charset testCharset = { + 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', + 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', + 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', + 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', + '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'}; + +constexpr ReverseIndex testReverseIndex = { + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, + 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, + 255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, + 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, + 25, 255, 255, 255, 255, 255, 255, 26, 27, 28, 29, 30, 31, 32, 33, + 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, + 49, 50, 51, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, + 255}; + +TEST_F(EncoderUtilsTest, HandlesLookupAndExceptions) { + int base = 64; + EXPECT_NO_THROW(baseReverseLookup(base, 'A', testReverseIndex)); + EXPECT_THROW( + baseReverseLookup(base, '=', testReverseIndex), EncoderException); +} + +TEST_F(EncoderUtilsTest, ValidatesCharsetWithReverseIndex) { + EXPECT_TRUE(checkForwardIndex(63, testCharset, testReverseIndex)); +} + +TEST_F(EncoderUtilsTest, ValidatesReverseIndexWithCharset) { + EXPECT_TRUE(checkReverseIndex(255, testCharset, 64, testReverseIndex)); +} + +} // namespace facebook::velox::encoding