Oops sorry - this is NOT committed yet. I won't push it until I've tested
it on at least one BSD, preferably OpenBSD so I can test parts of the new
code.
On Fri, 5 Nov 2021 at 18:21, Jonathan Wakely via Libstdc++ <
libstd...@gcc.gnu.org> wrote:
> This adds additional "getentropy" and "arc4random" tokens to
> std::random_device. The former is supported on Glibc and OpenBSD (and
> apparently wasm), and the latter is supported on various BSDs.
>
> I'm trying to test this on OpenBSD but I can't bootstrap GCC using the
> system clang.
>
>
> libstdc++-v3/ChangeLog:
>
> * acinclude.m4 (GLIBCXX_CHECK_GETENTROPY,
> GLIBCXX_CHECK_ARC4RANDOM):
> Define.
> * configure.ac (GLIBCXX_CHECK_GETENTROPY,
> GLIBCXX_CHECK_ARC4RANDOM):
> Use them.
> * config.h.in: Regenerate.
> * configure: Regenerate.
> * src/c++11/random.cc (random_device): Add getentropy and
> arc4random as sources.
> * testsuite/26_numerics/random/random_device/cons/token.cc:
> Check new tokens.
> * testsuite/26_numerics/random/random_device/entropy.cc:
> Likewise.
> ---
> libstdc++-v3/acinclude.m4 | 46 ++++++++
> libstdc++-v3/config.h.in | 6 +
> libstdc++-v3/configure | 103 ++++++++++++++++++
> libstdc++-v3/configure.ac | 4 +
> libstdc++-v3/src/c++11/random.cc | 69 +++++++++++-
> .../random/random_device/cons/token.cc | 1 +
> .../random/random_device/entropy.cc | 7 ++
> 7 files changed, 234 insertions(+), 2 deletions(-)
>
> diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> index 90ecc4a87a2..497af5723e1 100644
> --- a/libstdc++-v3/acinclude.m4
> +++ b/libstdc++-v3/acinclude.m4
> @@ -4830,6 +4830,52 @@ AC_DEFUN([GLIBCXX_CHECK_EXCEPTION_PTR_SYMVER], [
> fi
> ])
>
> +dnl
> +dnl Check whether getentropy is present in <unistd.h>.
> +dnl
> +AC_DEFUN([GLIBCXX_CHECK_GETENTROPY], [
> +
> + AC_LANG_SAVE
> + AC_LANG_CPLUSPLUS
> + AC_MSG_CHECKING([for getentropy])
> + AC_CACHE_VAL(glibcxx_cv_getentropy, [
> + AC_TRY_COMPILE(
> + [#include <unistd.h>],
> + [unsigned i;
> + ::getentropy(&i, sizeof(i));],
> + [glibcxx_cv_getentropy=yes], [glibcxx_cv_getentropy=no])
> + ])
> +
> + if test $glibcxx_cv_getentropy = yes; then
> + AC_DEFINE(HAVE_GETENTROPY, 1, [Define if getentropy is available in
> <unistd.h>.])
> + fi
> + AC_MSG_RESULT($glibcxx_cv_getentropy)
> + AC_LANG_RESTORE
> +])
> +
> +dnl
> +dnl Check whether arc4random is present in <stdlib.h>.
> +dnl
> +AC_DEFUN([GLIBCXX_CHECK_ARC4RANDOM], [
> +
> + AC_LANG_SAVE
> + AC_LANG_CPLUSPLUS
> + AC_MSG_CHECKING([for arc4random])
> + AC_CACHE_VAL(glibcxx_cv_arc4random, [
> + AC_TRY_COMPILE(
> + [#include <stdlib.h>],
> + [unsigned i = ::arc4random();],
> + [glibcxx_cv_arc4random=yes], [glibcxx_cv_arc4random=no])
> + ])
> +
> + if test $glibcxx_cv_arc4random = yes; then
> + AC_DEFINE(HAVE_ARC4RANDOM, 1, [Define if arc4random is available in
> <stdlib.h>.])
> + fi
> + AC_MSG_RESULT($glibcxx_cv_arc4random)
> + AC_LANG_RESTORE
> +])
> +
> +
> # Macros from the top-level gcc directory.
> m4_include([../config/gc++filt.m4])
> m4_include([../config/tls.m4])
> diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
> index 228a758325e..420021fcb1a 100644
> --- a/libstdc++-v3/config.h.in
> +++ b/libstdc++-v3/config.h.in
> @@ -9,6 +9,9 @@
> /* Define to 1 if you have the `aligned_alloc' function. */
> #undef HAVE_ALIGNED_ALLOC
>
> +/* Define if arc4random is available in <stdlib.h>. */
> +#undef HAVE_ARC4RANDOM
> +
> /* Define to 1 if you have the <arpa/inet.h> header file. */
> #undef HAVE_ARPA_INET_H
>
> @@ -132,6 +135,9 @@
> /* Define to 1 if you have the `frexpl' function. */
> #undef HAVE_FREXPL
>
> +/* Define if getentropy is available in <unistd.h>. */
> +#undef HAVE_GETENTROPY
> +
> /* Define if _Unwind_GetIPInfo is available. */
> #undef HAVE_GETIPINFO
>
> diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
> index c1aea827070..21371031b66 100755
> --- a/libstdc++-v3/configure
> +++ b/libstdc++-v3/configure
> @@ -75429,6 +75429,109 @@ $as_echo "#define _GLIBCXX_X86_RDSEED 1"
> >>confdefs.h
> $as_echo "$ac_cv_x86_rdseed" >&6; }
>
>
> +# Check for other random number APIs
> +
> +
> +
> + ac_ext=cpp
> +ac_cpp='$CXXCPP $CPPFLAGS'
> +ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
> +
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for getentropy" >&5
> +$as_echo_n "checking for getentropy... " >&6; }
> + if ${glibcxx_cv_getentropy+:} false; then :
> + $as_echo_n "(cached) " >&6
> +else
> +
> + cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h. */
> +#include <unistd.h>
> +int
> +main ()
> +{
> +unsigned i;
> + ::getentropy(&i, sizeof(i));
> + ;
> + return 0;
> +}
> +_ACEOF
> +if ac_fn_cxx_try_compile "$LINENO"; then :
> + glibcxx_cv_getentropy=yes
> +else
> + glibcxx_cv_getentropy=no
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> +
> +fi
> +
> +
> + if test $glibcxx_cv_getentropy = yes; then
> +
> +$as_echo "#define HAVE_GETENTROPY 1" >>confdefs.h
> +
> + fi
> + { $as_echo "$as_me:${as_lineno-$LINENO}: result:
> $glibcxx_cv_getentropy" >&5
> +$as_echo "$glibcxx_cv_getentropy" >&6; }
> + ac_ext=c
> +ac_cpp='$CPP $CPPFLAGS'
> +ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_c_compiler_gnu
> +
> +
> +
> +
> +
> + ac_ext=cpp
> +ac_cpp='$CXXCPP $CPPFLAGS'
> +ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
> +
> + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for arc4random" >&5
> +$as_echo_n "checking for arc4random... " >&6; }
> + if ${glibcxx_cv_arc4random+:} false; then :
> + $as_echo_n "(cached) " >&6
> +else
> +
> + cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h. */
> +#include <stdlib.h>
> +int
> +main ()
> +{
> +unsigned i = ::arc4random();
> + ;
> + return 0;
> +}
> +_ACEOF
> +if ac_fn_cxx_try_compile "$LINENO"; then :
> + glibcxx_cv_arc4random=yes
> +else
> + glibcxx_cv_arc4random=no
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> +
> +fi
> +
> +
> + if test $glibcxx_cv_arc4random = yes; then
> +
> +$as_echo "#define HAVE_ARC4RANDOM 1" >>confdefs.h
> +
> + fi
> + { $as_echo "$as_me:${as_lineno-$LINENO}: result:
> $glibcxx_cv_arc4random" >&5
> +$as_echo "$glibcxx_cv_arc4random" >&6; }
> + ac_ext=c
> +ac_cpp='$CPP $CPPFLAGS'
> +ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
> +ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS
> conftest.$ac_ext $LIBS >&5'
> +ac_compiler_gnu=$ac_cv_c_compiler_gnu
> +
> +
> +
> # This depends on GLIBCXX_ENABLE_SYMVERS and GLIBCXX_IS_NATIVE.
>
> # Do checks for resource limit functions.
> diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
> index 2d68b3672b9..5b3c92f4bd7 100644
> --- a/libstdc++-v3/configure.ac
> +++ b/libstdc++-v3/configure.ac
> @@ -468,6 +468,10 @@ GLIBCXX_CHECK_X86_RDRAND
> # Check if assembler supports rdseed opcode.
> GLIBCXX_CHECK_X86_RDSEED
>
> +# Check for other random number APIs
> +GLIBCXX_CHECK_GETENTROPY
> +GLIBCXX_CHECK_ARC4RANDOM
> +
> # This depends on GLIBCXX_ENABLE_SYMVERS and GLIBCXX_IS_NATIVE.
> GLIBCXX_CONFIGURE_TESTSUITE
>
> diff --git a/libstdc++-v3/src/c++11/random.cc
> b/libstdc++-v3/src/c++11/random.cc
> index 4b88818646f..4a553e0d84f 100644
> --- a/libstdc++-v3/src/c++11/random.cc
> +++ b/libstdc++-v3/src/c++11/random.cc
> @@ -68,7 +68,12 @@
> # include <stdlib.h>
> #endif
>
> -#if defined _GLIBCXX_USE_CRT_RAND_S || defined _GLIBCXX_USE_DEV_RANDOM
> +#ifdef _GLIBCXX_HAVE_GETENTROPY
> +# include <unistd.h>
> +#endif
> +
> +#if defined _GLIBCXX_USE_CRT_RAND_S || defined _GLIBCXX_USE_DEV_RANDOM \
> + || _GLIBCXX_HAVE_GETENTROPY
> // The OS provides a source of randomness we can use.
> # pragma GCC poison _M_mt
> #elif defined USE_RDRAND || defined USE_RDSEED || defined USE_DARN
> @@ -166,6 +171,25 @@ namespace std _GLIBCXX_VISIBILITY(default)
> }
> #endif
>
> +#ifdef _GLIBCXX_HAVE_GETENTROPY
> + unsigned int
> + __libc_getentropy(void*)
> + {
> + unsigned int val;
> + if (::getentropy(&val, sizeof(val)) != 0)
> + std::__throw_runtime_error(__N("random_device: getentropy
> failed"));
> + return val;
> + }
> +#endif
> +
> +#ifdef _GLIBCXX_HAVE_ARC4RANDOM
> + unsigned int
> + __libc_arc4random(void*)
> + {
> + return ::arc4random();
> + }
> +#endif
> +
> #ifdef USE_LCG
> // TODO: use this to seed std::mt19937 engine too.
> unsigned
> @@ -214,7 +238,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
> #endif
>
> enum Which : unsigned {
> - device_file = 1, prng = 2, rand_s = 4,
> + device_file = 1, prng = 2, rand_s = 4, getentropy = 8, arc4random =
> 16,
> rdseed = 64, rdrand = 128, darn = 256,
> any = 0xffff
> };
> @@ -256,6 +280,16 @@ namespace std _GLIBCXX_VISIBILITY(default)
> return device_file;
> #endif
>
> +#ifdef _GLIBCXX_HAVE_ARC4RANDOM
> + if (func == __libc_arc4random)
> + return arc4random;
> +#endif
> +
> +#ifdef _GLIBCXX_HAVE_GETENTROPY
> + if (func == __libc_getentropy)
> + return getentropy;
> +#endif
> +
> #ifdef USE_LCG
> if (func == &__lcg)
> return prng;
> @@ -311,6 +345,14 @@ namespace std _GLIBCXX_VISIBILITY(default)
> else if (token == "rand_s")
> which = rand_s;
> #endif // _GLIBCXX_USE_CRT_RAND_S
> +#ifdef _GLIBCXX_HAVE_GETENTROPY
> + else if (token == "getentropy")
> + which = getentropy;
> +#endif // _GLIBCXX_HAVE_GETENTROPY
> +#ifdef _GLIBCXX_HAVE_ARC4RANDOM
> + else if (token == "arc4random")
> + which = arc4random;
> +#endif // _GLIBCXX_HAVE_ARC4RANDOM
> #ifdef _GLIBCXX_USE_DEV_RANDOM
> else if (token == "/dev/urandom" || token == "/dev/random")
> {
> @@ -395,6 +437,26 @@ namespace std _GLIBCXX_VISIBILITY(default)
> }
> #endif // USE_DARN
>
> +#ifdef _GLIBCXX_HAVE_ARC4RANDOM
> + if (which & arc4random)
> + {
> + _M_func = &__libc_arc4random;
> + return;
> + }
> +#endif // _GLIBCXX_HAVE_ARC4RANDOM
> +
> +#ifdef _GLIBCXX_HAVE_GETENTROPY
> + if (which & getentropy)
> + {
> + unsigned int i;
> + if (::getentropy(&i, sizeof(i)) == 0) // On linux the syscall can
> fail.
> + {
> + _M_func = &__libc_getentropy;
> + return;
> + }
> + }
> +#endif // _GLIBCXX_HAVE_GETENTROPY
> +
> #ifdef _GLIBCXX_USE_DEV_RANDOM
> if (which & device_file)
> {
> @@ -548,6 +610,9 @@ namespace std _GLIBCXX_VISIBILITY(default)
> case rdseed:
> case darn:
> return (double) max;
> + case arc4random:
> + case getentropy:
> + return (double) max;
> case rand_s:
> case prng:
> return 0.0;
> diff --git
> a/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
> b/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
> index d6ac3a37c64..e13484e03a5 100644
> --- a/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
> +++ b/libstdc++-v3/testsuite/26_numerics/random/random_device/cons/token.cc
> @@ -53,6 +53,7 @@ test03()
> const std::string tokens[] = {
> "rdseed", "rdrand", "darn",
> "rand_s", "/dev/urandom", "/dev/random",
> + "getentropy", "arc4random",
> "mt19937", "prng"
> };
> int count = 0;
> diff --git
> a/libstdc++-v3/testsuite/26_numerics/random/random_device/entropy.cc
> b/libstdc++-v3/testsuite/26_numerics/random/random_device/entropy.cc
> index 6f3ebb1b38e..63b7043bf9b 100644
> --- a/libstdc++-v3/testsuite/26_numerics/random/random_device/entropy.cc
> +++ b/libstdc++-v3/testsuite/26_numerics/random/random_device/entropy.cc
> @@ -28,6 +28,13 @@ test01()
> const double entropy = std::random_device(token).entropy();
> VERIFY( entropy == max );
> }
> +
> + for (auto token : { "getentropy", "arc4random" })
> + if (__gnu_test::random_device_available(token))
> + {
> + const double entropy = std::random_device(token).entropy();
> + VERIFY( entropy == max );
> + }
> }
>
> int
> --
> 2.31.1
>
>
