Daemonizing Logic Error

[Devin Bayer]

Hello:

We faced an issue when nagios silently failed to fork.  Since it's  
part of  our startup scripts, this delayed the rest of the daemons  
until nagios exited.  For this reason nagios should take care, that if  
it doesn't daemonize correctly, it should die.  We are using nagios  
3.0.5, but I see the bug still exists in the trunk.  Here is our  
nagios.log showing the problem:

[1242115575] Nagios 3.0.5 starting... (PID=773)
[1242115575] Local time is Tue May 12 11:06:15 EEST 2009
[1242115575] LOG VERSION: 2.0
[1242115575] Finished daemonizing... (New PID=773)

Notice the "New PID" equals the old PID. I think this is the problem  
code, from base/utils.c:

2036 : 	   /* check for SIGHUP */
2037 : 	   if(val==1 && (pid=(pid_t)pidno)==getpid()){
2038 : 	    	close(lockfile);
2039 : 	   	return OK;
2040 : 	    	}

If nagios is started at boot time, it's somewhat likely it will have  
about the same PID on the next boot.  So if the lockfile isn't cleaned  
for some reason, then nagios will start, read the lockfile, and not  
fork.
    	
2042 : 	   /* exit on errors... */
2043 : 	   if((pid=fork())<0)
2044 : 	    	return(ERROR);

This looks like another bug.  If fork fails, we return ERROR, but the  
return code is just silently ignored.

Thanks,
Devin

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