1 files changed, 182 insertions, 0 deletions
diff --git a/Final/cpp/lib/broker/Daemon.cpp b/Final/cpp/lib/broker/Daemon.cpp
new file mode 100644
index 0000000000..3a0e687bf2
--- /dev/null
+++ b/Final/cpp/lib/broker/Daemon.cpp
@@ -0,0 +1,182 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 "Daemon.h"
+#include "Exception.h"
+
+#include <boost/iostreams/stream.hpp>
+#include <boost/iostreams/device/file_descriptor.hpp>
+
+#include <sstream>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+namespace qpid {
+namespace broker {
+
+using namespace std;
+typedef boost::iostreams::stream<boost::iostreams::file_descriptor> fdstream;
+
+namespace {
+/** Throw an exception containing msg and strerror if throwIf is true.
+ * Name is supposed to be reminiscent of perror().
+ */
+void terror(bool throwIf, const string& msg, int errNo=errno) {
+    if (throwIf)
+        throw Exception(msg + (errNo? ": "+strError(errNo) : string(".")));
+}
+
+
+struct LockFile : public fdstream {
+
+    LockFile(const std::string& path_, bool create)
+        : path(path_), fd(-1), created(create)
+    {
+        errno = 0;
+        int flags=create ? O_WRONLY|O_CREAT|O_NOFOLLOW : O_RDWR;
+        fd = ::open(path.c_str(), flags, 0644);
+        terror(fd < 0,"Cannot open "+path);
+        terror(::lockf(fd, F_TLOCK, 0) < 0, "Cannot lock "+path);
+        open(boost::iostreams::file_descriptor(fd));
+    }
+
+    ~LockFile() {
+        if (fd >= 0) {
+            ::lockf(fd, F_ULOCK, 0);
+            close();
+        }
+    }
+
+    std::string path;
+    int fd;
+    bool created;
+};
+
+} // namespace
+
+Daemon::Daemon() {
+    pid = -1;
+    pipeFds[0] = pipeFds[1] = -1;
+}
+
+string Daemon::dir() {
+    return (getuid() == 0 ? "/var/run" : "/tmp");
+}
+
+string Daemon::pidFile(uint16_t port) {
+    ostringstream path;
+    path << dir() << "/qpidd." << port << ".pid";
+    return path.str();
+}
+
+void Daemon::fork()
+{
+    terror(pipe(pipeFds) < 0, "Can't create pipe");
+    terror((pid = ::fork()) < 0, "Daemon fork failed");
+    if (pid == 0) {             // Child
+        try {
+            // File descriptors
+            terror(::close(pipeFds[0])<0, "Cannot close read pipe");
+            terror(::close(0)<0, "Cannot close stdin");
+            terror(::close(1)<0, "Cannot close stdout");
+            terror(::close(2)<0, "Cannot close stderr");
+            int fd=::open("/dev/null",O_RDWR); // stdin
+            terror(fd != 0, "Cannot re-open stdin");
+            terror(::dup(fd)<0, "Cannot re-open stdout");
+            terror(::dup(fd)<0, "Cannot re-open stderror");
+
+            // Misc
+            terror(setsid()<0, "Cannot set session ID");
+            terror(chdir(dir().c_str()) < 0, "Cannot change directory to "+dir());
+            umask(027);
+
+            // Child behavior
+            child();
+        }
+        catch (const exception& e) {
+            fdstream pipe(pipeFds[1]);
+            assert(pipe.is_open());
+            pipe << "0 " << e.what() << endl;
+        }
+    }
+    else {                      // Parent
+        close(pipeFds[1]);      // Write side.
+        parent();
+    }
+}
+
+Daemon::~Daemon() {
+    if (!lockFile.empty()) 
+        unlink(lockFile.c_str());
+}
+
+uint16_t Daemon::wait(int timeout) {            // parent waits for child.
+    errno = 0;                  
+    struct timeval tv;
+    tv.tv_sec = timeout;
+    tv.tv_usec = 0;
+
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(pipeFds[0], &fds);
+    terror(1 != select(FD_SETSIZE, &fds, 0, 0, &tv), "No response from daemon process");
+
+    fdstream pipe(pipeFds[0]);
+    uint16_t value = 0;
+    pipe >> value >> skipws;
+    if (value == 0) {
+        string errmsg;
+        getline(pipe, errmsg);
+        throw Exception("Daemon startup failed"+ (errmsg.empty() ? string(".") : ": " + errmsg));
+    }
+    return value;
+}
+
+void Daemon::ready(uint16_t port) { // child
+    lockFile = pidFile(port);
+    LockFile lf(lockFile, true);
+    lf << getpid() << endl;
+    if (lf.fail())
+        throw Exception("Cannot write lock file "+lockFile);
+    fdstream pipe(pipeFds[1]);
+    pipe << port << endl;;
+}
+
+pid_t Daemon::getPid(uint16_t port) {
+    string name = pidFile(port);
+    LockFile lockFile(name, false);
+    pid_t pid;
+    lockFile >> pid;
+    if (lockFile.fail())
+        throw Exception("Cannot read lock file "+name);
+    if (kill(pid, 0) < 0 && errno != EPERM) {
+        unlink(name.c_str());
+        throw Exception("Removing stale lock file "+name);
+    }
+    return pid;
+}
+
+
+}} // namespace qpid::broker