Author: ed Date: Tue Mar 10 02:46:06 2015 New Revision: 231764 URL: http://llvm.org/viewvc/llvm-project?rev=231764&view=rev Log: Add support for arc4random() to random_device.
Nuxi CloudABI (https://github.com/NuxiNL/cloudlibc) does not allow processes to access the global filesystem namespace. This breaks random_device, as it attempts to use /dev/{u,}random. This change adds support for arc4random(), which is present on CloudABI. In my opinion it would also make sense to use arc4random() on other operating systems, such as *BSD and Mac OS X, but I'd rather leave that to the maintainers of the respective platforms. Switching to arc4random() does change the ABI. This change also attempts to make some cleanups to the code. It adds a single #define for every random interface, instead of testing against operating systems explicitly. As discussed, also validate the token argument to be equal to "/dev/urandom" on all systems that only provide pseudo-random numbers. This should cause little to no breakage, as "/dev/urandom" is also the default argument value. Reviewed by: jfb Differential Revision: http://reviews.llvm.org/D8134 Modified: libcxx/trunk/include/__config libcxx/trunk/include/random libcxx/trunk/src/random.cpp libcxx/trunk/test/std/numerics/rand/rand.device/ctor.pass.cpp Modified: libcxx/trunk/include/__config URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=231764&r1=231763&r2=231764&view=diff ============================================================================== --- libcxx/trunk/include/__config (original) +++ libcxx/trunk/include/__config Tue Mar 10 02:46:06 2015 @@ -110,12 +110,22 @@ # endif #endif // __sun__ -#if defined(__native_client__) +#if defined(__CloudABI__) + // Certain architectures provide arc4random(). Prefer using + // arc4random() over /dev/{u,}random to make it possible to obtain + // random data even when using sandboxing mechanisms such as chroots, + // Capsicum, etc. +# define _LIBCPP_USING_ARC4_RANDOM +#elif defined(__native_client__) // NaCl's sandbox (which PNaCl also runs in) doesn't allow filesystem access, // including accesses to the special files under /dev. C++11's // std::random_device is instead exposed through a NaCl syscall. # define _LIBCPP_USING_NACL_RANDOM -#endif // defined(__native_client__) +#elif defined(_WIN32) +# define _LIBCPP_USING_WIN32_RANDOM +#else +# define _LIBCPP_USING_DEV_RANDOM +#endif #if !defined(_LIBCPP_LITTLE_ENDIAN) || !defined(_LIBCPP_BIG_ENDIAN) # include <endian.h> Modified: libcxx/trunk/include/random URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/random?rev=231764&r1=231763&r2=231764&view=diff ============================================================================== --- libcxx/trunk/include/random (original) +++ libcxx/trunk/include/random Tue Mar 10 02:46:06 2015 @@ -3475,9 +3475,9 @@ typedef shuffle_order_engine<minstd_rand class _LIBCPP_TYPE_VIS random_device { -#if !(defined(_WIN32) || defined(_LIBCPP_USING_NACL_RANDOM)) +#ifdef _LIBCPP_USING_DEV_RANDOM int __f_; -#endif // !(defined(_WIN32) || defined(_LIBCPP_USING_NACL_RANDOM)) +#endif // defined(_LIBCPP_USING_DEV_RANDOM) public: // types typedef unsigned result_type; Modified: libcxx/trunk/src/random.cpp URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/random.cpp?rev=231764&r1=231763&r2=231764&view=diff ============================================================================== --- libcxx/trunk/src/random.cpp (original) +++ libcxx/trunk/src/random.cpp Tue Mar 10 02:46:06 2015 @@ -7,11 +7,10 @@ // //===----------------------------------------------------------------------===// -#if defined(_WIN32) +#if defined(_LIBCPP_USING_WIN32_RANDOM) // Must be defined before including stdlib.h to enable rand_s(). #define _CRT_RAND_S -#include <stdio.h> -#endif // defined(_WIN32) +#endif // defined(_LIBCPP_USING_WIN32_RANDOM) #include "random" #include "system_error" @@ -19,21 +18,27 @@ #if defined(__sun__) #define rename solaris_headers_are_broken #endif // defined(__sun__) -#if !defined(_WIN32) + +#include <errno.h> +#include <stdio.h> +#include <stdlib.h> + +#if defined(_LIBCPP_USING_DEV_RANDOM) #include <fcntl.h> #include <unistd.h> -#endif // !defined(_WIN32) -#include <errno.h> -#if defined(_LIBCPP_USING_NACL_RANDOM) +#elif defined(_LIBCPP_USING_NACL_RANDOM) #include <nacl/nacl_random.h> -#endif // defined(_LIBCPP_USING_NACL_RANDOM) +#endif + _LIBCPP_BEGIN_NAMESPACE_STD -#if defined(_WIN32) +#if defined(_LIBCPP_USING_ARC4_RANDOM) -random_device::random_device(const string&) +random_device::random_device(const string& __token) { + if (__token != "/dev/urandom") + __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); } random_device::~random_device() @@ -43,10 +48,43 @@ random_device::~random_device() unsigned random_device::operator()() { + return arc4random(); +} + +#elif defined(_LIBCPP_USING_DEV_RANDOM) + +random_device::random_device(const string& __token) + : __f_(open(__token.c_str(), O_RDONLY)) +{ + if (__f_ < 0) + __throw_system_error(errno, ("random_device failed to open " + __token).c_str()); +} + +random_device::~random_device() +{ + close(__f_); +} + +unsigned +random_device::operator()() +{ unsigned r; - errno_t err = rand_s(&r); - if (err) - __throw_system_error(err, "random_device rand_s failed."); + size_t n = sizeof(r); + char* p = reinterpret_cast<char*>(&r); + while (n > 0) + { + ssize_t s = read(__f_, p, n); + if (s == 0) + __throw_system_error(ENODATA, "random_device got EOF"); + if (s == -1) + { + if (errno != EINTR) + __throw_system_error(errno, "random_device got an unexpected error"); + continue; + } + n -= static_cast<size_t>(s); + p += static_cast<size_t>(s); + } return r; } @@ -79,44 +117,31 @@ random_device::operator()() return r; } -#else // !defined(_WIN32) && !defined(_LIBCPP_USING_NACL_RANDOM) +#elif defined(_LIBCPP_USING_WIN32_RANDOM) random_device::random_device(const string& __token) - : __f_(open(__token.c_str(), O_RDONLY)) { - if (__f_ < 0) - __throw_system_error(errno, ("random_device failed to open " + __token).c_str()); + if (__token != "/dev/urandom") + __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); } random_device::~random_device() { - close(__f_); } unsigned random_device::operator()() { unsigned r; - size_t n = sizeof(r); - char* p = reinterpret_cast<char*>(&r); - while (n > 0) - { - ssize_t s = read(__f_, p, n); - if (s == 0) - __throw_system_error(ENODATA, "random_device got EOF"); - if (s == -1) - { - if (errno != EINTR) - __throw_system_error(errno, "random_device got an unexpected error"); - continue; - } - n -= static_cast<size_t>(s); - p += static_cast<size_t>(s); - } + errno_t err = rand_s(&r); + if (err) + __throw_system_error(err, "random_device rand_s failed."); return r; } -#endif // defined(_WIN32) || defined(_LIBCPP_USING_NACL_RANDOM) +#else +#error "Random device not implemented for this architecture" +#endif double random_device::entropy() const _NOEXCEPT Modified: libcxx/trunk/test/std/numerics/rand/rand.device/ctor.pass.cpp URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/numerics/rand/rand.device/ctor.pass.cpp?rev=231764&r1=231763&r2=231764&view=diff ============================================================================== --- libcxx/trunk/test/std/numerics/rand/rand.device/ctor.pass.cpp (original) +++ libcxx/trunk/test/std/numerics/rand/rand.device/ctor.pass.cpp Tue Mar 10 02:46:06 2015 @@ -23,14 +23,12 @@ #include <unistd.h> bool is_valid_random_device(const std::string &token) { -#if defined(_WIN32) - return true; -#elif defined(_LIBCPP_USING_NACL_RANDOM) - return token == "/dev/urandom"; -#else // !defined(_WIN32) && !defined(_LIBCPP_USING_NACL_RANDOM) +#if defined(_LIBCPP_USING_DEV_RANDOM) // Not an exhaustive list: they're the only tokens that are tested below. return token == "/dev/urandom" || token == "/dev/random"; -#endif // defined(_WIN32) || defined(_LIBCPP_USING_NACL_RANDOM) +#else + return token == "/dev/urandom"; +#endif } void check_random_device_valid(const std::string &token) { _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
