twrpDigest refactor

This patch is to refactor twrpDigest using polymorphism
and inheritance to use the same call patterns for creating and
reading a digest. Now a library.
Use SHA2 from libcrypto. SHA2 is default if device has libcrypto.

Change string MD5 everywhere to use digest or Digest instead. Updated
string tags to digest. Translation will be required.

Switch out digest code into a driver class from partitionmanager.

SHA2 is better for digest creation due to decreased collision space
compared to MD5 and SHA1.

See https://en.wikipedia.org/wiki/SHA-2

Change-Id: I74b5546789990b12aa4ce2e389d25f80a3fe213f
diff --git a/twrpDigestDriver.cpp b/twrpDigestDriver.cpp
new file mode 100644
index 0000000..71ec984
--- /dev/null
+++ b/twrpDigestDriver.cpp
@@ -0,0 +1,218 @@
+/*
+	Copyright 2013 to 2017 TeamWin
+	This file is part of TWRP/TeamWin Recovery Project.
+
+	TWRP is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	TWRP is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with TWRP.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+
+#include <fcntl.h>
+#include <string>
+#include <unistd.h>
+#include "data.hpp"
+#include "partitions.hpp"
+#include "set_metadata.h"
+#include "twrpDigestDriver.hpp"
+#include "twrp-functions.hpp"
+#include "twcommon.h"
+#include "variables.h"
+#include "gui/gui.hpp"
+#include "twrpDigest/twrpDigest.hpp"
+#include "twrpDigest/twrpMD5.hpp"
+#include "twrpDigest/twrpSHA.hpp"
+
+
+bool twrpDigestDriver::Check_Restore_File_Digest(const string& Filename) {
+	twrpDigest *digest;
+	string digestfile = Filename, file_name = Filename;
+	string digest_str;
+	bool use_sha2 = false;
+
+#ifndef TW_NO_SHA2_LIBRARY
+
+	digestfile += ".sha2";
+	if (TWFunc::Path_Exists(digestfile)) {
+		digest = new twrpSHA256();
+		use_sha2 = true;
+	}
+	else {
+		digest = new twrpMD5();
+		digestfile = Filename + ".md5";
+
+	}
+#else
+	digest = new twrpMD5();
+	digestfile = Filename + ".md5";
+
+#endif
+
+	if (!TWFunc::Path_Exists(digestfile)) {
+		gui_msg(Msg(msg::kError, "no_digest_found=No digest file found for '{1}'. Please unselect Enable Digest verification to restore.")(Filename));
+		delete digest;
+		return false;
+	}
+
+
+	if (TWFunc::read_file(digestfile, digest_str) != 0) {
+		gui_msg("digest_error=Digest Error!");
+		delete digest;
+		return false;
+	}
+
+	if (!stream_file_to_digest(file_name, digest)) {
+		delete digest;
+		return false;
+	}
+	string digest_check = digest->return_digest_string();
+	if (digest_check == digest_str) {
+		if (use_sha2)
+			LOGINFO("SHA2 Digest: %s  %s\n", digest_str.c_str(), TWFunc::Get_Filename(Filename).c_str());
+		else
+			LOGINFO("MD5 Digest: %s  %s\n", digest_str.c_str(), TWFunc::Get_Filename(Filename).c_str());
+		delete digest;
+		return true;
+	}
+
+	gui_msg(Msg(msg::kError, "digest_fail_match=Digest failed to match on '{1}'.")(Filename));
+	delete digest;
+	return false;
+
+}
+
+bool twrpDigestDriver::Check_Digest(string Full_Filename) {
+	char split_filename[512];
+	int index = 0;
+
+	sync();
+	if (!TWFunc::Path_Exists(Full_Filename)) {
+		// This is a split archive, we presume
+		memset(split_filename, 0, sizeof(split_filename));
+		while (index < 1000) {
+			sprintf(split_filename, "%s%03i", Full_Filename.c_str(), index);
+			if (!TWFunc::Path_Exists(split_filename))
+				break;
+				LOGINFO("split_filename: %s\n", split_filename);
+				if (!Check_Restore_File_Digest(split_filename))
+					return false;
+				index++;
+		}
+		return true;
+	}
+	return Check_Restore_File_Digest(Full_Filename); // Single file archive
+}
+
+bool twrpDigestDriver::Write_Digest(string Full_Filename) {
+	twrpDigest *digest;
+	string digest_filename, digest_str;
+	int use_sha2;
+
+#ifdef TW_NO_SHA2_LIBRARY
+	use_sha2 = 0;
+#else
+	DataManager::GetValue(TW_USE_SHA2, use_sha2);
+#endif
+
+	if (use_sha2) {
+#ifndef TW_NO_SHA2_LIBRARY
+		digest = new twrpSHA256();
+		digest_filename = Full_Filename + ".sha2";
+		if (!stream_file_to_digest(Full_Filename, digest)) {
+			delete digest;
+			return false;
+		}
+		digest_str = digest->return_digest_string();
+		if (digest_str.empty()) {
+			delete digest;
+			return false;
+		}
+		LOGINFO("SHA2 Digest: %s  %s\n", digest_str.c_str(), TWFunc::Get_Filename(Full_Filename).c_str());
+#endif
+	}
+	else  {
+		digest = new twrpMD5();
+		digest_filename = Full_Filename + ".md5";
+		if (!stream_file_to_digest(Full_Filename, digest)) {
+			delete digest;
+			return false;
+		}
+		digest_str = digest->return_digest_string();
+		if (digest_str.empty()) {
+			delete digest;
+			return false;
+		}
+		LOGINFO("MD5 Digest: %s  %s\n", digest_str.c_str(), TWFunc::Get_Filename(Full_Filename).c_str());
+	}
+
+	digest_str = digest_str + "  " + TWFunc::Get_Filename(Full_Filename) + "\n";
+	LOGINFO("digest_filename: %s\n", digest_filename.c_str());
+
+	if (TWFunc::write_file(digest_filename, digest_str) == 0) {
+		tw_set_default_metadata(digest_filename.c_str());
+		gui_msg("digest_created= * Digest Created.");
+	}
+	else {
+		gui_err("digest_error= * Digest Error!");
+		delete digest;
+		return false;
+	}
+	delete digest;
+	return true;
+}
+
+bool twrpDigestDriver::Make_Digest(string Full_Filename) {
+	string command, result;
+
+	TWFunc::GUI_Operation_Text(TW_GENERATE_DIGEST_TEXT, gui_parse_text("{@generating_digest1}"));
+	gui_msg("generating_digest2= * Generating digest...");
+	if (TWFunc::Path_Exists(Full_Filename)) {
+		if (!Write_Digest(Full_Filename))
+			return false;
+	} else {
+		char filename[512];
+		int index = 0;
+		sprintf(filename, "%s%03i", Full_Filename.c_str(), index);
+		while (index < 1000) {
+			string digest_src(filename);
+			if (TWFunc::Path_Exists(filename)) {
+				if (!Write_Digest(filename))
+					return false;
+				}
+				else
+					break;
+				index++;
+				sprintf(filename, "%s%03i", Full_Filename.c_str(), index);
+			}
+			if (index == 0) {
+				LOGERR("Backup file: '%s' not found!\n", filename);
+					return false;
+			}
+			gui_msg("digest_created= * Digest Created.");
+	}
+	return true;
+}
+
+bool twrpDigestDriver::stream_file_to_digest(string filename, twrpDigest* digest) {
+	char buf[4096];
+	int bytes;
+
+	int fd = open(filename.c_str(), O_RDONLY);
+	if (fd < 0) {
+		return false;
+	}
+	while ((bytes = read(fd, &buf, sizeof(buf))) != 0) {
+		digest->update((unsigned char*)buf, bytes);
+	}
+	close(fd);
+	return true;
+}