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.

Change-Id: Ic82d929e052b5ba70ecf7b475e0a223d77d9687e
diff --git a/volume_manager/NetlinkManager.cpp b/volume_manager/NetlinkManager.cpp
new file mode 100644
index 0000000..28640e9
--- /dev/null
+++ b/volume_manager/NetlinkManager.cpp
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2008 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 <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <sys/select.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+
+#include <linux/netlink.h>
+
+#define LOG_TAG "Vold"
+
+#include <cutils/log.h>
+
+#include "NetlinkHandler.h"
+#include "NetlinkManager.h"
+
+NetlinkManager* NetlinkManager::sInstance = NULL;
+
+NetlinkManager* NetlinkManager::Instance() {
+    if (!sInstance) sInstance = new NetlinkManager();
+    return sInstance;
+}
+
+NetlinkManager::NetlinkManager() {
+    // Empty
+}
+
+NetlinkManager::~NetlinkManager() {}
+
+bool NetlinkManager::start() {
+    struct sockaddr_nl nladdr;
+    int sz = 64 * 1024;
+    int on = 1;
+
+    memset(&nladdr, 0, sizeof(nladdr));
+    nladdr.nl_family = AF_NETLINK;
+    nladdr.nl_pid = getpid();
+    nladdr.nl_groups = 0xffffffff;
+
+    if ((mSock = socket(PF_NETLINK, SOCK_DGRAM | SOCK_CLOEXEC, NETLINK_KOBJECT_UEVENT)) < 0) {
+        SLOGE("Unable to create uevent socket: %s", strerror(errno));
+        return false;
+    }
+
+    // When running in a net/user namespace, SO_RCVBUFFORCE is not available.
+    // Try using SO_RCVBUF first.
+    if ((setsockopt(mSock, SOL_SOCKET, SO_RCVBUF, &sz, sizeof(sz)) < 0) &&
+        (setsockopt(mSock, SOL_SOCKET, SO_RCVBUFFORCE, &sz, sizeof(sz)) < 0)) {
+        SLOGE("Unable to set uevent socket SO_RCVBUF/SO_RCVBUFFORCE option: %s", strerror(errno));
+        goto out;
+    }
+
+    if (setsockopt(mSock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
+        SLOGE("Unable to set uevent socket SO_PASSCRED option: %s", strerror(errno));
+        goto out;
+    }
+
+    if (bind(mSock, (struct sockaddr*)&nladdr, sizeof(nladdr)) < 0) {
+        SLOGE("Unable to bind uevent socket: %s", strerror(errno));
+        goto out;
+    }
+
+    mHandler = new NetlinkHandler(mSock);
+    if (!mHandler->start()) {
+        SLOGE("Unable to start NetlinkHandler: %s", strerror(errno));
+        goto out;
+    }
+
+    return true;
+
+out:
+    close(mSock);
+    return false;
+}
+
+void NetlinkManager::stop() {
+    mHandler->stop();
+    delete mHandler;
+    mHandler = NULL;
+
+    close(mSock);
+    mSock = -1;
+}