[committed] libstdc++: Support getentropy and arc4random in std::random_device
Jonathan Wakely
jwakely@redhat.com
Tue Nov 9 15:17:42 GMT 2021
On Fri, 5 Nov 2021 at 18:22, Jonathan Wakely wrote:
> 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.
>
It got tested on darwin, and has been pushed to trunk now.
>
>
> On Fri, 5 Nov 2021 at 18:21, Jonathan Wakely via Libstdc++ <
> libstdc++@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
>>
>>
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