Enable --debug option for "lshal" command.

This calls into live binderized services and logs their "IBase::debug(...)"
output.

Bug: 36520620
Test: make, adb shell lshal, adb shell bugreport
Change-Id: Ida3b0c61eafd9f3de562a5df3af24bbaf383de22
diff --git a/cmds/lshal/PipeRelay.cpp b/cmds/lshal/PipeRelay.cpp
new file mode 100644
index 0000000..c7b29df
--- /dev/null
+++ b/cmds/lshal/PipeRelay.cpp
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2017 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 "PipeRelay.h"
+
+#include <sys/socket.h>
+#include <utils/Thread.h>
+
+namespace android {
+namespace lshal {
+
+struct PipeRelay::RelayThread : public Thread {
+    explicit RelayThread(int fd, std::ostream &os);
+
+    bool threadLoop() override;
+
+private:
+    int mFd;
+    std::ostream &mOutStream;
+
+    DISALLOW_COPY_AND_ASSIGN(RelayThread);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+PipeRelay::RelayThread::RelayThread(int fd, std::ostream &os)
+    : mFd(fd),
+      mOutStream(os) {
+}
+
+bool PipeRelay::RelayThread::threadLoop() {
+    char buffer[1024];
+    ssize_t n = read(mFd, buffer, sizeof(buffer));
+
+    if (n <= 0) {
+        return false;
+    }
+
+    mOutStream.write(buffer, n);
+
+    return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+PipeRelay::PipeRelay(std::ostream &os)
+    : mOutStream(os),
+      mInitCheck(NO_INIT) {
+    int res = socketpair(AF_UNIX, SOCK_STREAM, 0 /* protocol */, mFds);
+
+    if (res < 0) {
+        mInitCheck = -errno;
+        return;
+    }
+
+    mThread = new RelayThread(mFds[0], os);
+    mInitCheck = mThread->run("RelayThread");
+}
+
+// static
+void PipeRelay::CloseFd(int *fd) {
+    if (*fd >= 0) {
+        close(*fd);
+        *fd = -1;
+    }
+}
+
+PipeRelay::~PipeRelay() {
+    if (mFds[1] >= 0) {
+        shutdown(mFds[1], SHUT_WR);
+    }
+
+    if (mFds[0] >= 0) {
+        shutdown(mFds[0], SHUT_RD);
+    }
+
+    if (mThread != NULL) {
+        mThread->join();
+        mThread.clear();
+    }
+
+    CloseFd(&mFds[1]);
+    CloseFd(&mFds[0]);
+}
+
+status_t PipeRelay::initCheck() const {
+    return mInitCheck;
+}
+
+int PipeRelay::fd() const {
+    return mFds[1];
+}
+
+}  // namespace lshal
+}  // namespace android