logd: initial checkin.

* Create a new userspace log daemon for handling logging messages.

Original-Change-Id: I75267df16359684490121e6c31cca48614d79856
Signed-off-by: Nick Kralevich <nnk@google.com>

* Merge conflicts
* rename new syslog daemon to logd to prevent confusion with bionic syslog
* replace racy getGroups call with KISS call to client->getGid()
* Timestamps are filed at logging source
* insert entries into list in timestamp order
* Added LogTimeEntry tail filtration handling
* Added region locking around LogWriter list
* separate threads for each writer
* /dev/socket/logd* permissions

Signed-off-by: Mark Salyzyn <salyzyn@google.com>

(cherry picked from commit 3e76e0a49760c4970b7cda6153e51026af98e4f3)

Author: Nick Kralevich <nnk@google.com>
Change-Id: Ice88b1412d8f9daa7f9119b2b5aaf684a5e28098
diff --git a/logd/LogBufferElement.cpp b/logd/LogBufferElement.cpp
new file mode 100644
index 0000000..1c55623
--- /dev/null
+++ b/logd/LogBufferElement.cpp
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2012-2014 The Android Open Source 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 <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <log/logger.h>
+
+#include "LogBufferElement.h"
+#include "LogReader.h"
+
+const struct timespec LogBufferElement::FLUSH_ERROR = { 0, 0 };
+
+LogBufferElement::LogBufferElement(log_id_t log_id, struct timespec realtime, uid_t uid, pid_t pid, const char *msg, unsigned short len)
+        : mLogId(log_id)
+        , mUid(uid)
+        , mPid(pid)
+        , mMsgLen(len)
+        , mMonotonicTime(CLOCK_MONOTONIC)
+        , mRealTime(realtime) {
+    mMsg = new char[len];
+    memcpy(mMsg, msg, len);
+}
+
+LogBufferElement::~LogBufferElement() {
+    delete [] mMsg;
+}
+
+struct timespec LogBufferElement::flushTo(SocketClient *reader) {
+    struct logger_entry_v3 entry;
+    memset(&entry, 0, sizeof(struct logger_entry_v3));
+    entry.hdr_size = sizeof(struct logger_entry_v3);
+    entry.len = mMsgLen;
+    entry.lid = mLogId;
+    entry.pid = mPid;
+    entry.sec = mRealTime.tv_sec;
+    entry.nsec = mRealTime.tv_nsec;
+
+    struct iovec iovec[2];
+    iovec[0].iov_base = &entry;
+    iovec[0].iov_len = sizeof(struct logger_entry_v3);
+    iovec[1].iov_base = mMsg;
+    iovec[1].iov_len = mMsgLen;
+    if (reader->sendDatav(iovec, 2)) {
+        return FLUSH_ERROR;
+    }
+
+    return mMonotonicTime;
+}