Linux 判断进程是否已经运行的程序

bool
ServerProcess::isAlreadyRunning()
{
#ifndef __linux__
WarningLog(<<"can't check if process already running on this platform (not implemented yet)");
return false;
#else
if(mPidFile.size() == 0)
{
// if no PID file specified, we do not make any check
return false;
}

pid_t running_pid;
std::ifstream _pid(mPidFile.c_str(), std::ios_base::in);
if(!_pid.good())
{
// if the file doesn't exist or can't be opened, just ignore
return false;
}
_pid >> running_pid;
_pid.close();

StackLog(<< mPidFile << " contains PID " << running_pid);

Data ourProc = Data("/proc/self/exe");
Data otherProc = Data("/proc/") + Data(running_pid) + Data("/exe");
char our_exe[513], other_exe[513];
int buf_size;

buf_size = readlink(ourProc.c_str(), our_exe, 512);
if(buf_size < 0 || buf_size == 512)
{
// if readlink fails, just ignore
return false;
}
our_exe[buf_size] = 0;

buf_size = readlink(otherProc.c_str(), other_exe, 512);
if(buf_size < 0 || buf_size == 512)
{
// if readlink fails, just ignore
return false;
}
other_exe[buf_size] = 0;

if(strcmp(our_exe, other_exe) == 0)
{
ErrLog(<<"already running PID: " << running_pid);
return true;
}
return false;
#endif
}