From e0ef4899f3ef2561ae32275c2c3d11914e7343c7 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Fri, 24 Sep 2021 17:06:10 +0900
Subject: [Win32] Prefer Cryptography Next Generation API

[BCryptGenRandom] is available since Windows Vista / Windows
Server 2008.

Regarding [CryptGenRandom]:
> This API is deprecated. New and existing software should start
> using Cryptography Next Generation APIs. Microsoft may remove
> this API in future releases.

[BCryptGenRandom]: https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom
[CryptGenRandom]: https://docs.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-cryptgenrandom
---
 configure.ac       |  2 +-
 random.c           | 22 +++++++++++++++++++++-
 win32/Makefile.sub |  2 +-
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index b65ccf4b31..fc9a9967f3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1115,7 +1115,7 @@ main()
 		AC_CHECK_FUNCS(cygwin_conv_path)
 		AC_LIBOBJ([langinfo])
 		],
-[mingw*], [	LIBS="-lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi $LIBS"
+[mingw*], [	LIBS="-lshell32 -lws2_32 -liphlpapi -limagehlp -lshlwapi -lbcrypt $LIBS"
 		ac_cv_header_pwd_h=no
 		ac_cv_header_utime_h=no
 		ac_cv_header_sys_ioctl_h=no
diff --git a/random.c b/random.c
index fd9db0cf75..0503436c47 100644
--- a/random.c
+++ b/random.c
@@ -42,6 +42,7 @@
 # include <winsock2.h>
 # include <windows.h>
 # include <wincrypt.h>
+# include <bcrypt.h>
 #endif
 
 #if defined(__OpenBSD__) || defined(__FreeBSD__) || defined(__NetBSD__)
@@ -544,6 +545,7 @@ fill_random_bytes_syscall(void *buf, size_t size, int unused)
 #endif
 }
 #elif defined(_WIN32)
+# if defined(CRYPT_VERIFYCONTEXT)
 STATIC_ASSERT(sizeof_HCRYPTPROV, sizeof(HCRYPTPROV) == sizeof(size_t));
 
 /* Although HCRYPTPROV is not a HANDLE, it looks like
@@ -561,7 +563,7 @@ release_crypt(void *p)
 }
 
 static int
-fill_random_bytes_syscall(void *seed, size_t size, int unused)
+fill_random_bytes_crypt(void *seed, size_t size)
 {
     static HCRYPTPROV perm_prov;
     HCRYPTPROV prov = perm_prov, old_prov;
@@ -588,6 +590,24 @@ fill_random_bytes_syscall(void *seed, size_t size, int unused)
     CryptGenRandom(prov, size, seed);
     return 0;
 }
+# else
+#   define fill_random_bytes_crypt(seed, size) -1
+# endif
+
+static int
+fill_random_bytes_bcrypt(void *seed, size_t size)
+{
+    if (!BCryptGenRandom(NULL, seed, size, BCRYPT_USE_SYSTEM_PREFERRED_RNG))
+	return 0;
+    return -1;
+}
+
+static int
+fill_random_bytes_syscall(void *seed, size_t size, int unused)
+{
+    if (fill_random_bytes_bcrypt(seed, size) == 0) return 0;
+    return fill_random_bytes_crypt(seed, size);
+}
 #elif defined HAVE_GETRANDOM
 static int
 fill_random_bytes_syscall(void *seed, size_t size, int need_secure)
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index a610577603..2aef63985b 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -277,7 +277,7 @@ LIBS = user32.lib advapi32.lib shell32.lib ws2_32.lib
 !if $(MSC_VER) >= 1400
 LIBS = $(LIBS) iphlpapi.lib
 !endif
-LIBS = $(LIBS) imagehlp.lib shlwapi.lib $(EXTLIBS)
+LIBS = $(LIBS) imagehlp.lib shlwapi.lib bcrypt.lib $(EXTLIBS)
 !endif
 !if !defined(MISSING)
 MISSING = crypt.obj ffs.obj langinfo.obj lgamma_r.obj strlcat.obj strlcpy.obj win32/win32.obj win32/file.obj setproctitle.obj
-- 
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