sha: support Win32 for SHA256

Adding SHA256 support prompted an overdue refactoring of some of the
unnecessary complexity around the CNG/CryptoAPI abstraction.

Author: ethomson

cmake/SelectHashes.cmake

@@ -62,6 +62,8 @@ elseif(USE_SHA256 STREQUAL "CommonCrypto")
 	set(GIT_SHA256_COMMON_CRYPTO 1)
 elseif(USE_SHA256 STREQUAL "mbedTLS")
 	set(GIT_SHA256_MBEDTLS 1)
+elseif(USE_SHA256 STREQUAL "Win32")
+	set(GIT_SHA256_WIN32 1)
 else()
 	message(FATAL_ERROR "Asked for unknown SHA256 backend: ${USE_SHA256}")
 endif()

src/features.h.in

@@ -49,6 +49,7 @@
 #cmakedefine GIT_SHA1_MBEDTLS 1
 
 #cmakedefine GIT_SHA256_BUILTIN 1
+#cmakedefine GIT_SHA256_WIN32 1
 #cmakedefine GIT_SHA256_COMMON_CRYPTO 1
 #cmakedefine GIT_SHA256_OPENSSL 1
 #cmakedefine GIT_SHA256_MBEDTLS 1

src/util/CMakeLists.txt

@@ -55,6 +55,8 @@ elseif(USE_SHA256 STREQUAL "CommonCrypto")
 	file(GLOB UTIL_SRC_SHA256 hash/common_crypto.*)
 elseif(USE_SHA256 STREQUAL "mbedTLS")
 	file(GLOB UTIL_SRC_SHA256 hash/mbedtls.*)
+elseif(USE_SHA256 STREQUAL "Win32")
+	file(GLOB UTIL_SRC_SHA256 hash/win32.*)
 else()
 	message(FATAL_ERROR "Asked for unknown SHA256 backend: ${USE_SHA256}")
 endif()