Replace fix permissions with fix contexts for emulated storage

Fix permissions rarely fixed anything on more recent versions of
Android and usually made things worse. Instead we will replace it
with a more dumbed down option that should fix contexts on
/data/media with a few improvements to ensure that contexts get
fixed for multiple users and on adopted storage.

Change-Id: If5523781936a0b04196e2ad871cae767ebae2583

fixContexts.cpp

@@ -0,0 +1,163 @@
+/*
+	Copyright 2012-2016 bigbiff/Dees_Troy 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 <string>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <errno.h>
+#include <cctype>
+#include "fixContexts.hpp"
+#include "twrp-functions.hpp"
+#include "twcommon.h"
+#ifdef HAVE_SELINUX
+#include "selinux/selinux.h"
+#include "selinux/label.h"
+#include "selinux/android.h"
+#include "selinux/label.h"
+#endif
+
+using namespace std;
+
+#ifdef HAVE_SELINUX
+struct selabel_handle *sehandle;
+struct selinux_opt selinux_options[] = {
+	{ SELABEL_OPT_PATH, "/file_contexts" }
+};
+
+int fixContexts::restorecon(string entry, struct stat *sb) {
+	char *oldcontext, *newcontext;
+
+	if (lgetfilecon(entry.c_str(), &oldcontext) < 0) {
+		LOGINFO("Couldn't get selinux context for %s\n", entry.c_str());
+		return -1;
+	}
+	if (selabel_lookup(sehandle, &newcontext, entry.c_str(), sb->st_mode) < 0) {
+		LOGINFO("Couldn't lookup selinux context for %s\n", entry.c_str());
+		return -1;
+	}
+	if (strcmp(oldcontext, newcontext) != 0) {
+		LOGINFO("Relabeling %s from %s to %s\n", entry.c_str(), oldcontext, newcontext);
+		if (lsetfilecon(entry.c_str(), newcontext) < 0) {
+			LOGINFO("Couldn't label %s with %s: %s\n", entry.c_str(), newcontext, strerror(errno));
+		}
+	}
+	freecon(oldcontext);
+	freecon(newcontext);
+	return 0;
+}
+
+int fixContexts::fixContextsRecursively(string name, int level) {
+	DIR *d;
+	struct dirent *de;
+	struct stat sb;
+	string path;
+
+	if (!(d = opendir(name.c_str())))
+		return -1;
+	if (!(de = readdir(d)))
+		return -1;
+
+	do {
+		if (de->d_type ==  DT_DIR) {
+			if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
+				continue;
+			path = name + "/" + de->d_name;
+			restorecon(path, &sb);
+			fixContextsRecursively(path, level + 1);
+		}
+		else {
+			path = name + "/" + de->d_name;
+			restorecon(path, &sb);
+		}
+	} while ((de = readdir(d)));
+	closedir(d);
+	return 0;
+}
+
+int fixContexts::fixDataMediaContexts(string Mount_Point) {
+	DIR *d;
+	struct dirent *de;
+	struct stat sb;
+
+	LOGINFO("Fixing media contexts on '%s'\n", Mount_Point.c_str());
+
+	sehandle = selabel_open(SELABEL_CTX_FILE, selinux_options, 1);
+	if (!sehandle) {
+		LOGINFO("Unable to open /file_contexts\n");
+		return 0;
+	}
+
+	if (TWFunc::Path_Exists(Mount_Point + "/media/0")) {
+		string dir = Mount_Point + "/media";
+		if (!(d = opendir(dir.c_str()))) {
+			LOGINFO("opendir failed (%s)\n", strerror(errno));
+			return -1;
+		}
+		if (!(de = readdir(d))) {
+			LOGINFO("readdir failed (%s)\n", strerror(errno));
+			closedir(d);
+			return -1;
+		}
+
+		do {
+			if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0 || de->d_type != DT_DIR)
+				continue;
+			size_t len = strlen(de->d_name);
+			bool is_numeric = true;
+			char* folder_name = de->d_name;
+			for (size_t i = 0; i < len; i++) {
+				if (!isdigit(*folder_name)) {
+					is_numeric = false;
+					break;
+				}
+				folder_name++;
+			}
+			if (is_numeric) {
+				dir = Mount_Point + "/media/";
+				dir += de->d_name;
+				restorecon(dir, &sb);
+				fixContextsRecursively(dir, 0);
+			}
+		} while ((de = readdir(d)));
+		closedir(d);
+	} else if (TWFunc::Path_Exists(Mount_Point + "/media")) {
+		restorecon(Mount_Point + "/media", &sb);
+		fixContextsRecursively(Mount_Point + "/media", 0);
+	} else {
+		LOGINFO("fixDataMediaContexts: %s/media does not exist!\n", Mount_Point.c_str());
+		return 0;
+	}
+	selabel_close(sehandle);
+	return 0;
+}
+
+#else
+
+int fixContexts::restorecon(string entry __unused, struct stat *sb __unused) {
+	return -1;
+}
+
+int fixContexts::fixContextsRecursively(string name __unused, int level __unused) {
+	return -1;
+}
+
+int fixContexts::fixDataMediaContexts(string Mount_Point __unused) {
+	return -1;
+}
+#endif