recovery: Implement a volume manager

This is a copy of the pre-binderized vold which has been converted to
use direct calls instead of sockets and stripped down to only what is
needed to support recovery.

Includes:
  * recovery: volmgr: remove unused IsSupported

    Change-Id: If8206658fdfb6108221806c09c99bf0a30f4a586
    Signed-off-by: Jesse Chan <jc@lineageos.org>

  * recovery: volmgr: remove filesystem checks

    Those checks are not strictly necessary and we are
    not building fsck tools for recovery for now.

    Remove those checks so volmgr can be useful.

    Change-Id: I87756c61b933b6cdccd281c6276b686fbd36019f
    Signed-off-by: Jesse Chan <jc@lineageos.org>

  * recovery: fixup `EmulatedVolume creating`

    Avoid dangling pointer. Instead of pointing to FstabEntry create copy.

    Change-Id: I57f76006db09a6add2c173f43175f0f6b848d87b

  * recovery: fix volmgr cleaning up

    Don't reset pointer to netlink manager
    Delete disks in stop() rather then in ~VolumeManager
    Call destroy() before deleting disks cause delete expects the
      disk to be destroyed
    Clear the lists or we would read garbage data on the next scan

    Change-Id: Idadfa1f33b7cb5f2f3c780848a99344a6608420e

  * recovery: handle interrupts in apply update menu

    Change-Id: I1f78f9196634353b77986545332d7d52a5f0c161

Change-Id: Ic82d929e052b5ba70ecf7b475e0a223d77d9687e
diff --git a/volume_manager/fs/Exfat.cpp b/volume_manager/fs/Exfat.cpp
new file mode 100644
index 0000000..56ae430
--- /dev/null
+++ b/volume_manager/fs/Exfat.cpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ * Copyright (C) 2019 The LineageOS Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Exfat.h"
+#include "Utils.h"
+
+#define LOG_TAG "Vold"
+
+#include <android-base/logging.h>
+#include <android-base/stringprintf.h>
+
+#include <cutils/log.h>
+
+#include <logwrap/logwrap.h>
+
+#include <string>
+#include <vector>
+
+#include <sys/mount.h>
+
+using android::base::StringPrintf;
+
+namespace android {
+namespace volmgr {
+namespace exfat {
+
+status_t Mount(const std::string& source, const std::string& target, int ownerUid, int ownerGid,
+               int permMask) {
+    int mountFlags = MS_NODEV | MS_NOSUID | MS_DIRSYNC | MS_NOATIME | MS_NOEXEC;
+    auto mountData = android::base::StringPrintf("uid=%d,gid=%d,fmask=%o,dmask=%o", ownerUid,
+                                                 ownerGid, permMask, permMask);
+
+    if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
+        return 0;
+    }
+    PLOG(ERROR) << "Mount failed; attempting read-only";
+    mountFlags |= MS_RDONLY;
+    if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
+        return 0;
+    }
+
+    return -1;
+}
+
+}  // namespace exfat
+}  // namespace volmgr
+}  // namespace android