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Consolidate _stdlib_random functions #2

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Merged
merged 9 commits into from
Apr 22, 2018
Merged

Consolidate _stdlib_random functions #2

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eb9ebe3
Use the `__has_include` and `GRND_RANDOM` macros
benrimmington Apr 10, 2018
fa06580
Use `getentropy` instead of `getrandom`
benrimmington Apr 10, 2018
5853f7a
Use `std::min` from the <algorithm> header
benrimmington Apr 10, 2018
411d2a4
Move `#if` out of the `_stdlib_random` function
benrimmington Apr 10, 2018
70270b2
Use `getrandom` with "/dev/urandom" fallback
benrimmington Apr 12, 2018
0012e00
Use `#pragma comment` to import "Bcrypt.lib"
benrimmington Apr 14, 2018
0f6302f
Use "/dev/urandom" instead of `SecRandomCopyBytes`
benrimmington Apr 19, 2018
90fd95a
Use `swift::StaticMutex` for shared "/dev/urandom"
benrimmington Apr 20, 2018
c9f177f
Add `getrandom_available`; use `O_CLOEXEC` flag
benrimmington Apr 22, 2018
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5 changes: 0 additions & 5 deletions stdlib/public/core/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -193,7 +193,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
list(APPEND swift_core_link_flags "-all_load")
list(APPEND swift_core_framework_depends Foundation)
list(APPEND swift_core_framework_depends CoreFoundation)
list(APPEND swift_core_framework_depends Security)
list(APPEND swift_core_private_link_libraries icucore)
else()
# With the GNU linker the equivalent of -all_load is to tell the linker
Expand Down Expand Up @@ -228,10 +227,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
${EXECINFO_LIBRARY})
endif()

if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
list(APPEND swift_core_link_flags "$ENV{SystemRoot}/system32/bcrypt.dll")
endif()

option(SWIFT_CHECK_ESSENTIAL_STDLIB
"Check core standard library layering by linking its essential subset"
FALSE)
Expand Down
122 changes: 46 additions & 76 deletions stdlib/public/stubs/LibcShims.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13,56 +13,32 @@
#if defined(__APPLE__)
# define _REENTRANT
# include <math.h>
# include <Security/Security.h>
#endif

#if defined(__CYGWIN__)
# include <cygwin/version.h>
# if (CYGWIN_VERSION_API_MAJOR > 0) || (CYGWIN_VERSION_API_MINOR >= 306)
# include <sys/random.h>
# define SWIFT_STDLIB_USING_GETRANDOM
# endif
#endif

#if defined(__Fuchsia__)
# include <sys/random.h>
# define SWIFT_STDLIB_USING_GETENTROPY
#endif

#if defined(__linux__)
# include <linux/version.h>
# if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
# include <features.h>
# if defined(__BIONIC__) || (defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2,25))
# include <sys/random.h>
# define SWIFT_STDLIB_USING_GETRANDOM
# endif
# endif
#endif

#if defined(_WIN32) && !defined(__CYGWIN__)
# include <io.h>
# define WIN32_LEAN_AND_MEAN
# define WIN32_NO_STATUS
# include <Windows.h>
# undef WIN32_NO_STATUS
# include <Ntstatus.h>
# include <Ntdef.h>
# include <Windows.h>
# include <Bcrypt.h>
# pragma comment(lib, "Bcrypt.lib")
#else
# include <pthread.h>
# include <semaphore.h>
# include <sys/ioctl.h>
# include <unistd.h>
#endif

#include <algorithm>
#include <cmath>
#include <errno.h>
#include <fcntl.h>
#include <random>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if __has_include(<sys/random.h>)
# include <sys/random.h>
#endif
#include <sys/stat.h>
#include <sys/types.h>
#include <type_traits>
Expand All @@ -71,6 +47,7 @@
#include "swift/Basic/Lazy.h"
#include "swift/Runtime/Config.h"
#include "swift/Runtime/Debug.h"
#include "swift/Runtime/Mutex.h"
#include "../SwiftShims/LibcShims.h"

using namespace swift;
Expand Down Expand Up @@ -342,68 +319,61 @@ swift::_stdlib_cxx11_mt19937_uniform(__swift_uint32_t upper_bound) {
return RandomUniform(getGlobalMT19937());
}

#if defined(__APPLE__)

SWIFT_RUNTIME_STDLIB_INTERNAL
void swift::_stdlib_random(void *buf, __swift_size_t nbytes) {
if (__builtin_available(macOS 10.12, iOS 10, tvOS 10, watchOS 3, *)) {
arc4random_buf(buf, nbytes);
} else {
OSStatus status = SecRandomCopyBytes(kSecRandomDefault, nbytes, buf);
if (status != errSecSuccess) {
fatalError(0, "Fatal error: %d in '%s'\n", status, __func__);
}
}
}

#elif defined(_WIN32) && !defined(__CYGWIN__)
// TODO: Test on Windows
#if defined(_WIN32) && !defined(__CYGWIN__)
#error TODO: Test _stdlib_random on Windows

SWIFT_RUNTIME_STDLIB_INTERNAL
void swift::_stdlib_random(void *buf, __swift_size_t nbytes) {
NTSTATUS status = BCryptGenRandom(nullptr,
static_cast<PUCHAR>(buf),
static_cast<ULONG>(nbytes),
BCRYPT_USE_SYSTEM_PREFERRED_RNG);
if (!NT_SUCCESS(status)) {
fatalError(0, "Fatal error: %#.8x in '%s'\n", status, __func__);
}
}

#elif defined(SWIFT_STDLIB_USING_GETENTROPY)

SWIFT_RUNTIME_STDLIB_INTERNAL
void swift::_stdlib_random(void *buf, __swift_size_t nbytes) {
while (nbytes > 0) {
constexpr __swift_size_t max_nbytes = 256;
__swift_size_t actual_nbytes = (nbytes < max_nbytes ?
nbytes : max_nbytes);
if (0 != getentropy(buf, actual_nbytes)) {
fatalError(0, "Fatal error: %d in '%s'\n", errno, __func__);
}
buf = static_cast<uint8_t *>(buf) + actual_nbytes;
nbytes -= actual_nbytes;
if (!BCRYPT_SUCCESS(status)) {
fatalError(0, "Fatal error: 0x%.8X in '%s'\n", status, __func__);
}
}

#else

#undef WHILE_EINTR
#define WHILE_EINTR(expression) ({ \
decltype(expression) result = -1; \
do { result = (expression); } while (result == -1 && errno == EINTR); \
result; \
})

SWIFT_RUNTIME_STDLIB_INTERNAL
void swift::_stdlib_random(void *buf, __swift_size_t nbytes) {
#if !defined(SWIFT_STDLIB_USING_GETRANDOM)
static const int fd = _stdlib_open("/dev/urandom", O_RDONLY, 0);
if (fd < 0) {
fatalError(0, "Fatal error: %d in '%s'\n", errno, __func__);
}
#endif
while (nbytes > 0) {
#if !defined(SWIFT_STDLIB_USING_GETRANDOM)
__swift_ssize_t actual_nbytes = _stdlib_read(fd, buf, nbytes);
#else
__swift_ssize_t actual_nbytes = getrandom(buf, nbytes, 0);
__swift_ssize_t actual_nbytes = -1;
#if defined(GRND_RANDOM)
static const bool getrandom_available =
!(getrandom(nullptr, 0, 0) == -1 && errno == ENOSYS);
if (getrandom_available) {
actual_nbytes = WHILE_EINTR(getrandom(buf, nbytes, 0));
}
#elif defined(__Fuchsia__)
__swift_size_t getentropy_nbytes = std::min(nbytes, __swift_size_t{256});
if (0 == getentropy(buf, getentropy_nbytes)) {
actual_nbytes = getentropy_nbytes;
}
#elif defined(__APPLE__)
if (__builtin_available(macOS 10.12, iOS 10, tvOS 10, watchOS 3, *)) {
arc4random_buf(buf, nbytes);
actual_nbytes = nbytes;
}
#endif
if (actual_nbytes < 1) {
if (errno == EINTR) { continue; }
if (actual_nbytes == -1) {
static const int fd =
WHILE_EINTR(_stdlib_open("/dev/urandom", O_RDONLY | O_CLOEXEC, 0));
if (fd != -1) {
static StaticMutex mutex;
mutex.withLock([&] {
actual_nbytes = WHILE_EINTR(_stdlib_read(fd, buf, nbytes));
});
}
}
if (actual_nbytes == -1) {
fatalError(0, "Fatal error: %d in '%s'\n", errno, __func__);
}
buf = static_cast<uint8_t *>(buf) + actual_nbytes;
Expand Down