Add _stdlib_random for more platforms

stdlib/public/stubs/LibcShims.cpp

@@ -11,35 +11,67 @@
 //===----------------------------------------------------------------------===//
 
 #if defined(__APPLE__)
-#define _REENTRANT
-#include <math.h>
+#  define _REENTRANT
+#  include <math.h>
+#  include <Security/Security.h>
 #endif
-#include <random>
-#include <type_traits>
-#include <cmath>
-#if defined(_WIN32)
-#include <io.h>
-#define WIN32_LEAN_AND_MEAN
-#include <Windows.h>
+
+#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 <Bcrypt.h>
 #else
-#include <unistd.h>
-#include <pthread.h>
-#include <semaphore.h>
-#include <sys/ioctl.h>
+#  include <pthread.h>
+#  include <semaphore.h>
+#  include <sys/ioctl.h>
+#  include <unistd.h>
 #endif
 
-#include <stdlib.h>
+#include <cmath>
+#include <errno.h>
+#include <fcntl.h>
+#include <random>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
-#include <fcntl.h>
-#include <errno.h>
-#include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/types.h>
+#include <type_traits>
+
+#include "llvm/Support/DataTypes.h"
 #include "swift/Basic/Lazy.h"
 #include "swift/Runtime/Config.h"
 #include "swift/Runtime/Debug.h"
 #include "../SwiftShims/LibcShims.h"
-#include "llvm/Support/DataTypes.h"
 
 using namespace swift;
 
@@ -332,44 +364,72 @@ swift::_stdlib_cxx11_mt19937_uniform(__swift_uint32_t upper_bound) {
 }
 
 #if defined(__APPLE__)
-#include <Security/Security.h>
+
 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 {
+  } else {
     OSStatus status = SecRandomCopyBytes(kSecRandomDefault, nbytes, buf);
     if (status != errSecSuccess) {
-      fatalError(0, "Fatal error: SecRandomCopyBytes failed with error %d\n", status);
+      fatalError(0, "Fatal error: %d in '%s'\n", status, __func__);
     }
   }
 }
-#elif defined(__linux__)
-#include <linux/version.h>
-#include <sys/syscall.h>
+
+#elif defined(_WIN32) && !defined(__CYGWIN__)
+#error TODO: link with Bcrypt.lib and test on Windows.
+
 SWIFT_RUNTIME_STDLIB_INTERNAL
 void swift::_stdlib_random(void *buf, __swift_size_t nbytes) {
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0)
-  auto _read = [&]() -> __swift_ssize_t {
-    return syscall(SYS_getrandom, buf, bytes, 0);
-  };
-#else
-  auto _read = [&]() -> __swift_ssize_t {
-    static const int fd = _stdlib_open("/dev/urandom", O_RDONLY);
-    if (fd < 0) {
-      fatalError(0, "Unable to open '/dev/urandom'\n");
+  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__);
     }
-    return _stdlib_read(fd, buf, bytes);
-  };
+    buf = static_cast<uint8_t *>(buf) + actual_nbytes;
+    nbytes -= actual_nbytes;
+  }
+}
+
+#else
+
+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) {
-    auto result = _read();
-    if (result < 1) {
+#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);
+#endif
+    if (actual_nbytes < 1) {
       if (errno == EINTR) { continue; }
-      fatalError(0, "Unable to read '/dev/urandom'\n");
+      fatalError(0, "Fatal error: %d in '%s'\n", errno, __func__);
     }
-    buf = static_cast<uint8_t *>(buf) + result;
-    nbytes -= result;
+    buf = static_cast<uint8_t *>(buf) + actual_nbytes;
+    nbytes -= actual_nbytes;
   }
 }
+
 #endif