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/*
*
* 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
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