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author | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | 2022-04-14 03:07:06 +0000 |
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committer | Android Build Coastguard Worker <android-build-coastguard-worker@google.com> | 2022-04-14 03:07:06 +0000 |
commit | 39dbb21d63fcd4848f54cf7dfc7188f7216c36f4 (patch) | |
tree | 2ce94d7f0804ccb77d1fa9b2a1bca00eecdff1e2 /third_party/abseil-cpp/absl/random/internal/seed_material.cc | |
parent | f60eaea2240ba9e1c508e8e0c91d39ee9fc47be5 (diff) | |
parent | 6c9587948173932b64d97c288a947e43d2a2ac14 (diff) | |
download | webrtc-android13-qpr1-s4-release.tar.gz |
Snap for 8451773 from 6c9587948173932b64d97c288a947e43d2a2ac14 to tm-qpr1-releaseandroid-13.0.0_r30android-13.0.0_r29android-13.0.0_r28android-13.0.0_r27android-13.0.0_r24android-13.0.0_r23android-13.0.0_r22android-13.0.0_r21android-13.0.0_r20android-13.0.0_r19android-13.0.0_r18android-13.0.0_r17android-13.0.0_r16android13-qpr1-s8-releaseandroid13-qpr1-s7-releaseandroid13-qpr1-s6-releaseandroid13-qpr1-s5-releaseandroid13-qpr1-s4-releaseandroid13-qpr1-s3-releaseandroid13-qpr1-s2-releaseandroid13-qpr1-s1-releaseandroid13-qpr1-release
Change-Id: I2cdc23e9d294e3701ac746469aea1ce793eb9ce4
Diffstat (limited to 'third_party/abseil-cpp/absl/random/internal/seed_material.cc')
-rw-r--r-- | third_party/abseil-cpp/absl/random/internal/seed_material.cc | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/third_party/abseil-cpp/absl/random/internal/seed_material.cc b/third_party/abseil-cpp/absl/random/internal/seed_material.cc index 4d38a57419..c03cad8502 100644 --- a/third_party/abseil-cpp/absl/random/internal/seed_material.cc +++ b/third_party/abseil-cpp/absl/random/internal/seed_material.cc @@ -28,6 +28,7 @@ #include <cstdlib> #include <cstring> +#include "absl/base/dynamic_annotations.h" #include "absl/base/internal/raw_logging.h" #include "absl/strings/ascii.h" #include "absl/strings/escaping.h" @@ -50,6 +51,18 @@ #endif +#if defined(__GLIBC__) && \ + (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25)) +// glibc >= 2.25 has getentropy() +#define ABSL_RANDOM_USE_GET_ENTROPY 1 +#endif + +#if defined(__EMSCRIPTEN__) +#include <sys/random.h> +// Emscripten has getentropy, but it resides in a different header. +#define ABSL_RANDOM_USE_GET_ENTROPY 1 +#endif + #if defined(ABSL_RANDOM_USE_BCRYPT) #include <bcrypt.h> @@ -122,8 +135,32 @@ bool ReadSeedMaterialFromOSEntropyImpl(absl::Span<uint32_t> values) { #else +#if defined(ABSL_RANDOM_USE_GET_ENTROPY) +// On *nix, use getentropy() if supported. Note that libc may support +// getentropy(), but the kernel may not, in which case this function will return +// false. +bool ReadSeedMaterialFromGetEntropy(absl::Span<uint32_t> values) { + auto buffer = reinterpret_cast<uint8_t*>(values.data()); + size_t buffer_size = sizeof(uint32_t) * values.size(); + while (buffer_size > 0) { + // getentropy() has a maximum permitted length of 256. + size_t to_read = std::min<size_t>(buffer_size, 256); + int result = getentropy(buffer, to_read); + if (result < 0) { + return false; + } + // https://github.com/google/sanitizers/issues/1173 + // MemorySanitizer can't see through getentropy(). + ABSL_ANNOTATE_MEMORY_IS_INITIALIZED(buffer, to_read); + buffer += to_read; + buffer_size -= to_read; + } + return true; +} +#endif // defined(ABSL_RANDOM_GETENTROPY) + // On *nix, read entropy from /dev/urandom. -bool ReadSeedMaterialFromOSEntropyImpl(absl::Span<uint32_t> values) { +bool ReadSeedMaterialFromDevURandom(absl::Span<uint32_t> values) { const char kEntropyFile[] = "/dev/urandom"; auto buffer = reinterpret_cast<uint8_t*>(values.data()); @@ -150,6 +187,17 @@ bool ReadSeedMaterialFromOSEntropyImpl(absl::Span<uint32_t> values) { return success; } +bool ReadSeedMaterialFromOSEntropyImpl(absl::Span<uint32_t> values) { +#if defined(ABSL_RANDOM_USE_GET_ENTROPY) + if (ReadSeedMaterialFromGetEntropy(values)) { + return true; + } +#endif + // Libc may support getentropy, but the kernel may not, so we still have + // to fallback to ReadSeedMaterialFromDevURandom(). + return ReadSeedMaterialFromDevURandom(values); +} + #endif } // namespace |