From 9059fdd51224493244d7d70cd1bb31612a729e27 Mon Sep 17 00:00:00 2001 From: Benjamin Barenblat Date: Tue, 9 Feb 2021 19:41:06 +0000 Subject: [PATCH] Remove endian-sensitivity from Abseil's RNG Forwarded: yes Applied-Upstream: https://github.com/abseil/abseil-cpp/commit/c36d825d9a5443f81d2656685ae021d6326da90c Ensure that the Abseil random number generator produces identical output on both big- and little-endian platforms by byte-swapping appropriately on big-endian systems. The author works at Google. Upstream applied this patch as Piper revision 355635051 and exported it to GitHub; the Applied-Upstream URL above points to the exported commit. Gbp-Pq: Name endian-random.diff --- absl/base/BUILD.bazel | 1 + absl/base/CMakeLists.txt | 1 + absl/base/internal/endian.h | 61 ++++++++++++++++++++++++ absl/random/CMakeLists.txt | 3 ++ absl/random/internal/BUILD.bazel | 7 ++- absl/random/internal/explicit_seed_seq.h | 3 +- absl/random/internal/randen_engine.h | 8 ++-- absl/random/internal/randen_slow_test.cc | 3 +- 8 files changed, 81 insertions(+), 6 deletions(-) diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel index 9d96abe..dd1633b 100644 --- a/absl/base/BUILD.bazel +++ b/absl/base/BUILD.bazel @@ -479,6 +479,7 @@ cc_library( copts = ABSL_DEFAULT_COPTS, linkopts = ABSL_DEFAULT_LINKOPTS, deps = [ + ":base", ":config", ":core_headers", ], diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt index 9ff5aa2..cd8b604 100644 --- a/absl/base/CMakeLists.txt +++ b/absl/base/CMakeLists.txt @@ -418,6 +418,7 @@ absl_cc_library( COPTS ${ABSL_DEFAULT_COPTS} DEPS + absl::base absl::config absl::core_headers PUBLIC diff --git a/absl/base/internal/endian.h b/absl/base/internal/endian.h index 9677530..dad0e9a 100644 --- a/absl/base/internal/endian.h +++ b/absl/base/internal/endian.h @@ -26,6 +26,7 @@ #endif #include +#include "absl/base/casts.h" #include "absl/base/config.h" #include "absl/base/internal/unaligned_access.h" #include "absl/base/port.h" @@ -173,6 +174,36 @@ inline constexpr bool IsLittleEndian() { return false; } #endif /* ENDIAN */ +inline uint8_t FromHost(uint8_t x) { return x; } +inline uint16_t FromHost(uint16_t x) { return FromHost16(x); } +inline uint32_t FromHost(uint32_t x) { return FromHost32(x); } +inline uint64_t FromHost(uint64_t x) { return FromHost64(x); } +inline uint8_t ToHost(uint8_t x) { return x; } +inline uint16_t ToHost(uint16_t x) { return ToHost16(x); } +inline uint32_t ToHost(uint32_t x) { return ToHost32(x); } +inline uint64_t ToHost(uint64_t x) { return ToHost64(x); } + +inline int8_t FromHost(int8_t x) { return x; } +inline int16_t FromHost(int16_t x) { + return bit_cast(FromHost16(bit_cast(x))); +} +inline int32_t FromHost(int32_t x) { + return bit_cast(FromHost32(bit_cast(x))); +} +inline int64_t FromHost(int64_t x) { + return bit_cast(FromHost64(bit_cast(x))); +} +inline int8_t ToHost(int8_t x) { return x; } +inline int16_t ToHost(int16_t x) { + return bit_cast(ToHost16(bit_cast(x))); +} +inline int32_t ToHost(int32_t x) { + return bit_cast(ToHost32(bit_cast(x))); +} +inline int64_t ToHost(int64_t x) { + return bit_cast(ToHost64(bit_cast(x))); +} + // Functions to do unaligned loads and stores in little-endian order. inline uint16_t Load16(const void *p) { return ToHost16(ABSL_INTERNAL_UNALIGNED_LOAD16(p)); @@ -233,6 +264,36 @@ inline constexpr bool IsLittleEndian() { return false; } #endif /* ENDIAN */ +inline uint8_t FromHost(uint8_t x) { return x; } +inline uint16_t FromHost(uint16_t x) { return FromHost16(x); } +inline uint32_t FromHost(uint32_t x) { return FromHost32(x); } +inline uint64_t FromHost(uint64_t x) { return FromHost64(x); } +inline uint8_t ToHost(uint8_t x) { return x; } +inline uint16_t ToHost(uint16_t x) { return ToHost16(x); } +inline uint32_t ToHost(uint32_t x) { return ToHost32(x); } +inline uint64_t ToHost(uint64_t x) { return ToHost64(x); } + +inline int8_t FromHost(int8_t x) { return x; } +inline int16_t FromHost(int16_t x) { + return bit_cast(FromHost16(bit_cast(x))); +} +inline int32_t FromHost(int32_t x) { + return bit_cast(FromHost32(bit_cast(x))); +} +inline int64_t FromHost(int64_t x) { + return bit_cast(FromHost64(bit_cast(x))); +} +inline int8_t ToHost(int8_t x) { return x; } +inline int16_t ToHost(int16_t x) { + return bit_cast(ToHost16(bit_cast(x))); +} +inline int32_t ToHost(int32_t x) { + return bit_cast(ToHost32(bit_cast(x))); +} +inline int64_t ToHost(int64_t x) { + return bit_cast(ToHost64(bit_cast(x))); +} + // Functions to do unaligned loads and stores in big-endian order. inline uint16_t Load16(const void *p) { return ToHost16(ABSL_INTERNAL_UNALIGNED_LOAD16(p)); diff --git a/absl/random/CMakeLists.txt b/absl/random/CMakeLists.txt index 7d7bec8..13093d6 100644 --- a/absl/random/CMakeLists.txt +++ b/absl/random/CMakeLists.txt @@ -611,6 +611,7 @@ absl_cc_library( ${ABSL_DEFAULT_LINKOPTS} DEPS absl::config + absl::endian TESTONLY ) @@ -758,6 +759,7 @@ absl_cc_library( LINKOPTS ${ABSL_DEFAULT_LINKOPTS} DEPS + absl::endian absl::random_internal_iostream_state_saver absl::random_internal_randen absl::raw_logging_internal @@ -1119,6 +1121,7 @@ absl_cc_test( LINKOPTS ${ABSL_DEFAULT_LINKOPTS} DEPS + absl::endian absl::random_internal_randen_slow gtest_main ) diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel index 8485e28..1537978 100644 --- a/absl/random/internal/BUILD.bazel +++ b/absl/random/internal/BUILD.bazel @@ -124,7 +124,10 @@ cc_library( ], copts = ABSL_DEFAULT_COPTS, linkopts = ABSL_DEFAULT_LINKOPTS, - deps = ["//absl/base:config"], + deps = [ + "//absl/base:config", + "//absl/base:endian", + ], ) cc_library( @@ -241,6 +244,7 @@ cc_library( deps = [ ":iostream_state_saver", ":randen", + "//absl/base:endian", "//absl/meta:type_traits", ], ) @@ -606,6 +610,7 @@ cc_test( ":platform", ":randen_slow", "@com_google_googletest//:gtest_main", + "//absl/base:endian", ], ) diff --git a/absl/random/internal/explicit_seed_seq.h b/absl/random/internal/explicit_seed_seq.h index 6a743ea..e3aa31a 100644 --- a/absl/random/internal/explicit_seed_seq.h +++ b/absl/random/internal/explicit_seed_seq.h @@ -23,6 +23,7 @@ #include #include "absl/base/config.h" +#include "absl/base/internal/endian.h" namespace absl { ABSL_NAMESPACE_BEGIN @@ -73,7 +74,7 @@ class ExplicitSeedSeq { template void generate(OutIterator begin, OutIterator end) { for (size_t index = 0; begin != end; begin++) { - *begin = state_.empty() ? 0 : state_[index++]; + *begin = state_.empty() ? 0 : little_endian::FromHost32(state_[index++]); if (index >= state_.size()) { index = 0; } diff --git a/absl/random/internal/randen_engine.h b/absl/random/internal/randen_engine.h index 6b33731..92bb890 100644 --- a/absl/random/internal/randen_engine.h +++ b/absl/random/internal/randen_engine.h @@ -23,6 +23,7 @@ #include #include +#include "absl/base/internal/endian.h" #include "absl/meta/type_traits.h" #include "absl/random/internal/iostream_state_saver.h" #include "absl/random/internal/randen.h" @@ -76,7 +77,7 @@ class alignas(16) randen_engine { impl_.Generate(state_); } - return state_[next_++]; + return little_endian::ToHost(state_[next_++]); } template @@ -181,7 +182,8 @@ class alignas(16) randen_engine { // In the case that `elem` is `uint8_t`, it must be cast to something // larger so that it prints as an integer rather than a character. For // simplicity, apply the cast all circumstances. - os << static_cast(elem) << os.fill(); + os << static_cast(little_endian::FromHost(elem)) + << os.fill(); } os << engine.next_; return os; @@ -200,7 +202,7 @@ class alignas(16) randen_engine { // necessary to read a wider type and then cast it to uint8_t. numeric_type value; is >> value; - elem = static_cast(value); + elem = little_endian::ToHost(static_cast(value)); } is >> next; if (is.fail()) { diff --git a/absl/random/internal/randen_slow_test.cc b/absl/random/internal/randen_slow_test.cc index 4a53583..4861ffa 100644 --- a/absl/random/internal/randen_slow_test.cc +++ b/absl/random/internal/randen_slow_test.cc @@ -17,6 +17,7 @@ #include #include "gtest/gtest.h" +#include "absl/base/internal/endian.h" #include "absl/random/internal/randen_traits.h" namespace { @@ -56,7 +57,7 @@ TEST(RandenSlowTest, Default) { uint64_t* id = d.state; for (const auto& elem : kGolden) { - EXPECT_EQ(elem, *id++); + EXPECT_EQ(absl::little_endian::FromHost64(elem), *id++); } } -- 2.30.2