Index: lib/sanitizer_common/sanitizer_common.h =================================================================== --- lib/sanitizer_common/sanitizer_common.h +++ lib/sanitizer_common/sanitizer_common.h @@ -919,6 +919,10 @@ void CheckNoDeepBind(const char *filename, int flag); +// Returns the requested amount of random data (up to 256 bytes) that can then +// be used to seed a PRNG. +bool GetRandom(u8 *buffer, uptr length); + } // namespace __sanitizer inline void *operator new(__sanitizer::operator_new_size_type size, Index: lib/sanitizer_common/sanitizer_linux.cc =================================================================== --- lib/sanitizer_common/sanitizer_linux.cc +++ lib/sanitizer_common/sanitizer_linux.cc @@ -1604,6 +1604,32 @@ return 0; } +bool GetRandom(u8 *buffer, uptr length) { + if (!buffer || !length || length > 256) + return false; +#if defined(__NR_getrandom) + static atomic_uint8_t skip_getrandom_syscall; + if (!atomic_load_relaxed(&skip_getrandom_syscall)) { + // Up to 256 bytes, getrandom will not be interrupted. + uptr res = internal_syscall(SYSCALL(getrandom), buffer, length, 0); + int rverrno = 0; + if (internal_iserror(res, &rverrno) && rverrno == ENOSYS) + atomic_store_relaxed(&skip_getrandom_syscall, 1); + else if (res == length) + return true; + } +#endif + uptr fd = internal_open("/dev/urandom", O_RDONLY); + if (internal_iserror(fd)) + return false; + // internal_read deals with EINTR. + uptr res = internal_read(fd, reinterpret_cast(buffer), length); + if (internal_iserror(res)) + return false; + internal_close(fd); + return true; +} + } // namespace __sanitizer #endif // SANITIZER_FREEBSD || SANITIZER_LINUX Index: lib/sanitizer_common/sanitizer_mac.cc =================================================================== --- lib/sanitizer_common/sanitizer_mac.cc +++ lib/sanitizer_common/sanitizer_mac.cc @@ -923,6 +923,11 @@ // Do nothing. } +// FIXME: implement on this platform. +bool GetRandom(u8 *buffer, uptr length) { + return false; +} + } // namespace __sanitizer #endif // SANITIZER_MAC Index: lib/sanitizer_common/sanitizer_win.cc =================================================================== --- lib/sanitizer_common/sanitizer_win.cc +++ lib/sanitizer_common/sanitizer_win.cc @@ -1002,6 +1002,11 @@ // Do nothing. } +// FIXME: implement on this platform. +bool GetRandom(u8 *buffer, uptr length) { + return false; +} + } // namespace __sanitizer #endif // _WIN32 Index: lib/sanitizer_common/tests/sanitizer_common_test.cc =================================================================== --- lib/sanitizer_common/tests/sanitizer_common_test.cc +++ lib/sanitizer_common/tests/sanitizer_common_test.cc @@ -300,4 +300,20 @@ EXPECT_STREQ("012345678", str.data()); } +#if SANITIZER_LINUX +TEST(SanitizerCommon, GetRandom) { + u8 buffer_1[32], buffer_2[32]; + EXPECT_FALSE(GetRandom(nullptr, 32)); + EXPECT_FALSE(GetRandom(buffer_1, 0)); + EXPECT_FALSE(GetRandom(buffer_1, 512)); + for (uptr size = 4; size <= 32; size += 4) { + for (uptr i = 0; i < 100; i++) { + EXPECT_TRUE(GetRandom(buffer_1, size)); + EXPECT_TRUE(GetRandom(buffer_2, size)); + EXPECT_NE(internal_memcmp(buffer_1, buffer_2, size), 0); + } + } +} +#endif + } // namespace __sanitizer