Unify duplicate u8* to hex string functions in a new Hexify function variant, similar to bb1f86f515, used by Tests, CacheLoader, Terms and Conditions, Lobby and mod.io.

Removes the call to the sprintf_s function from test_MD5.h in 17718981cf
and JSInterface_Main.cpp in 468d963e78.
As reported by Vladislav that function might not null-terminate strings
on untested/newer platforms, but the caller requires it here.
The sprintf_s calls in other places have the same problem.

Differential Revision: https://code.wildfiregames.com/D1591
Accepted By: Vladislav
This was SVN commit r21863.

source/lobby/scripting/JSInterface_Lobby.cpp

@@ -23,6 +23,7 @@
 #include "lib/utf8.h"
 #include "lobby/IXmppClient.h"
 #include "ps/Profile.h"
+#include "ps/Util.h"
 #include "scriptinterface/ScriptInterface.h"
 
 #include "third_party/encryption/pkcs5_pbkdf2.h"
@@ -358,14 +359,7 @@ std::string JSI_Lobby::EncryptPassword(const std::string& password, const std::s
 	unsigned char encrypted[DIGESTSIZE];
 	pbkdf2(encrypted, (unsigned char*)password.c_str(), password.length(), salt_buffer, DIGESTSIZE, ITERATIONS);
 
-	static const char base16[] = "0123456789ABCDEF";
-	char hex[2 * DIGESTSIZE];
-	for (int i = 0; i < DIGESTSIZE; ++i)
-	{
-		hex[i*2] = base16[encrypted[i] >> 4];		// 4 high bits
-		hex[i*2 + 1] = base16[encrypted[i] & 0x0F];	// 4 low bits
-	}
-	return std::string(hex, sizeof(hex));
+	return Hexify(encrypted, DIGESTSIZE);
 }
 
 std::wstring JSI_Lobby::EncryptPassword(ScriptInterface::CxPrivate* UNUSED(pCxPrivate), const std::wstring& pass, const std::wstring& user)

source/maths/tests/test_MD5.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2010 Wildfire Games.
+/* Copyright (C) 2018 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -18,16 +18,14 @@
 #include "lib/self_test.h"
 
 #include "maths/MD5.h"
+#include "ps/Util.h"
 
 class TestMD5 : public CxxTest::TestSuite
 {
 public:
 	std::string decode(u8* digest)
 	{
-		char digeststr[MD5::DIGESTSIZE*2+1];
-		for (size_t i = 0; i < MD5::DIGESTSIZE; ++i)
-			sprintf_s(digeststr+2*i, 3, "%02x", (unsigned int)digest[i]);
-		return digeststr;
+		return Hexify(digest, MD5::DIGESTSIZE);
 	}
 
 	void compare(const char* input, const char* expected)

source/ps/CacheLoader.cpp

@@ -19,8 +19,9 @@
 
 #include "CacheLoader.h"
 
-#include "ps/CLogger.h"
 #include "maths/MD5.h"
+#include "ps/CLogger.h"
+#include "ps/Util.h"
 
 #include <iomanip>
 
@@ -134,19 +135,18 @@ VfsPath CCacheLoader::LooseCachePath(const VfsPath& sourcePath, const MD5& initi
 	hash.Update((const u8*)&version, sizeof(version));
 	// these are local cached files, so we don't care about endianness etc
 
-	// Use a short prefix of the full hash (we don't need high collision-resistance),
-	// converted to hex
 	u8 digest[MD5::DIGESTSIZE];
 	hash.Final(digest);
-	std::wstringstream digestPrefix;
-	digestPrefix << std::hex;
-	for (size_t i = 0; i < 8; ++i)
-		digestPrefix << std::setfill(L'0') << std::setw(2) << (int)digest[i];
 
 	// Get the mod path
 	OsPath path;
 	m_VFS->GetRealPath(sourcePath, path);
 
-	// Construct the final path
-	return VfsPath("cache") / path_name_only(path.BeforeCommon(sourcePath).Parent().string().c_str()) / sourcePath.ChangeExtension(sourcePath.Extension().string() + L"." + digestPrefix.str() + m_FileExtension);
+	return VfsPath("cache") /
+		path_name_only(path.BeforeCommon(sourcePath).Parent().string().c_str()) /
+			sourcePath.ChangeExtension(sourcePath.Extension().string() +
+			L"." +
+			// Use a short prefix of the full hash (we don't need high collision-resistance)
+			wstring_from_utf8(Hexify(digest, 8)) +
+			m_FileExtension);
 }

source/ps/ModIo.cpp

@@ -34,6 +34,7 @@
 #include "ps/GameSetup/Paths.h"
 #include "ps/Mod.h"
 #include "ps/ModInstaller.h"
+#include "ps/Util.h"
 #include "scriptinterface/ScriptConversions.h"
 #include "scriptinterface/ScriptInterface.h"
 
@@ -520,17 +521,15 @@ bool ModIo::VerifyDownloadedFile(std::string& err)
 	{
 		u8 digest[MD5::DIGESTSIZE];
 		m_CallbackData->md5.Final(digest);
-		std::stringstream md5digest;
-		md5digest << std::hex << std::setfill('0');
-		for (size_t i = 0; i < MD5::DIGESTSIZE; ++i)
-			md5digest << std::setw(2) << (int)digest[i];
+		std::string md5digest = Hexify(digest, MD5::DIGESTSIZE);
 
-		if (m_ModData[m_DownloadModID].properties.at("filehash_md5") != md5digest.str())
+
+		if (m_ModData[m_DownloadModID].properties.at("filehash_md5") != md5digest)
 		{
 			err = fmt::sprintf(
 				g_L10n.Translate("Invalid file. Expected md5 %s, got %s."),
 				m_ModData[m_DownloadModID].properties.at("filehash_md5").c_str(),
-				md5digest.str());
+				md5digest);
 			return false;
 		}
 	}

source/ps/Util.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2018 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -431,6 +431,15 @@ std::string Hexify(const std::string& s)
 	std::stringstream str;
 	str << std::hex;
 	for (const char& c : s)
-		str << std::setfill('0') << std::setw(2) << (int)(unsigned char)c;
+		str << std::setfill('0') << std::setw(2) << static_cast<int>(static_cast<unsigned char>(c));
+	return str.str();
+}
+
+std::string Hexify(const u8* s, size_t length)
+{
+	std::stringstream str;
+	str << std::hex;
+	for (size_t i = 0; i < length; ++i)
+		str << std::setfill('0') << std::setw(2) << static_cast<int>(s[i]);
 	return str.str();
 }

source/ps/Util.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2018 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -35,5 +35,6 @@ void WriteBigScreenshot(const VfsPath& extension, int tiles);
 Status tex_write(Tex* t, const VfsPath& filename);
 
 std::string Hexify(const std::string& s);
+std::string Hexify(const u8* s, size_t length);
 
 #endif // PS_UTIL_H

source/ps/scripting/JSInterface_Main.cpp

@@ -29,6 +29,7 @@
 #include "ps/GameSetup/Atlas.h"
 #include "ps/Globals.h"
 #include "ps/Hotkey.h"
+#include "ps/Util.h"
 #include "scriptinterface/ScriptInterface.h"
 #include "tools/atlas/GameInterface/GameLoop.h"
 
@@ -118,11 +119,7 @@ std::string JSI_Main::CalculateMD5(ScriptInterface::CxPrivate* UNUSED(pCxPrivate
 	m.Update((const u8*)input.c_str(), input.length());
 	m.Final(digest);
 
-	char digeststr[MD5::DIGESTSIZE*2+1];
-	for (size_t i = 0; i < MD5::DIGESTSIZE; ++i)
-		sprintf_s(digeststr+2*i, 3, "%02x", (unsigned int)digest[i]);
-
-	return digeststr;
+	return Hexify(digest, MD5::DIGESTSIZE);
 }
 
 void JSI_Main::RegisterScriptFunctions(const ScriptInterface& scriptInterface)