klogd.c

制作2.6内核的CLFS时 sysklogd-1.5.tar.gz包

                  break;
               }
               if( *ptr == '[' )   /* possible kernel symbol */
               {
                  *line++ = *ptr++;
                  space -= 1;
                  len   -= 1;
	          if (!skip_symbol_lookup)
                     parse_state = PARSING_SYMSTART;      /* at < */
                  break;
               }
               break;
        
        case PARSING_SYMSTART:
               if( *ptr != '<' )
               {
                  parse_state = PARSING_TEXT;        /* not a symbol */
                  break;
               }

               /*
               ** Save this character for now.  If this turns out to
               ** be a valid symbol, this char will be replaced later.
               ** If not, we'll just leave it there.
               */

               sym_start = line; /* this will point at the '<' */

               *line++ = *ptr++;
               space -= 1;
               len   -= 1;
               parse_state = PARSING_SYMBOL;     /* symbol... */
               break;

        case PARSING_SYMBOL:
               delta = copyin( line, space, ptr, len, ">\n[" );
               line  += delta;
               ptr   += delta;
               space -= delta;
               len   -= delta;
               if( space == 0 || len == 0 )
               {
                  break;  /* full line_buff or end of input buffer */
               }
               if( *ptr != '>' )
               {
                  parse_state = PARSING_TEXT;
                  break;
               }

               *line++ = *ptr++;  /* copy the '>' */
               space -= 1;
               len   -= 1;

               parse_state = PARSING_SYMEND;

               break;

        case PARSING_SYMEND:
               if( *ptr != ']' )
               {
                  parse_state = PARSING_TEXT;        /* not a symbol */
                  break;
               }

               /*
               ** It's really a symbol!  Replace address with the
               ** symbol text.
               */
           {
	       auto int sym_space;

	       unsigned long value;
	       auto struct symbol sym;
	       auto char *symbol;

               *(line-1) = 0;    /* null terminate the address string */
               value  = strtoul(sym_start+1, (char **) 0, 16);
               *(line-1) = '>';  /* put back delim */

               symbol = LookupSymbol(value, &sym);
               if ( !symbol_lookup || symbol == (char *) 0 )
               {
                  parse_state = PARSING_TEXT;
                  break;
               }

               /*
               ** verify there is room in the line buffer
               */
               sym_space = space + ( line - sym_start );
               if( sym_space < strlen(symbol) + 30 ) /*(30 should be overkill)*/
               {
                  parse_state = PARSING_TEXT;  /* not enough space */
                  break;
               }

               delta = sprintf( sym_start, "%s+0x%x/0x%02x]",
                                symbol, sym.offset, sym.size );

               space = sym_space + delta;
               line  = sym_start + delta;
	       symbols_expanded = 1;
           }
               ptr++;
               len--;
               parse_state = PARSING_TEXT;
               break;

        default: /* Can't get here! */
               parse_state = PARSING_TEXT;

        }
    }

    return;
}


static void LogKernelLine(void)

{
	auto int rdcnt;

	/*
	 * Zero-fill the log buffer.  This should cure a multitude of
	 * problems with klogd logging the tail end of the message buffer
	 * which will contain old messages.  Then read the kernel log
	 * messages into this fresh buffer.
	 */
	memset(log_buffer, '\0', sizeof(log_buffer));
	if ( (rdcnt = ksyslog(2, log_buffer, sizeof(log_buffer)-1)) < 0 )
	{
		if ( errno == EINTR )
			return;
		fprintf(stderr, "klogd: Error return from sys_sycall: " \
			"%d - %s\n", errno, strerror(errno));
	}
	else
		LogLine(log_buffer, rdcnt);
	return;
}


static void LogProcLine(void)

{
	auto int rdcnt;

	/*
	 * Zero-fill the log buffer.  This should cure a multitude of
	 * problems with klogd logging the tail end of the message buffer
	 * which will contain old messages.  Then read the kernel messages
	 * from the message pseudo-file into this fresh buffer.
	 */
	memset(log_buffer, '\0', sizeof(log_buffer));
	if ( (rdcnt = read(kmsg, log_buffer, sizeof(log_buffer)-1)) < 0 )
	{
		if ( errno == EINTR )
			return;
		Syslog(LOG_ERR, "Cannot read proc file system: %d - %s.", \
		       errno, strerror(errno));
	}
	else
		LogLine(log_buffer, rdcnt);

	return;
}


int main(argc, argv)

	int argc;

	char *argv[];

{
	auto int	ch,
			use_output = 0;

	auto char	*log_level = (char *) 0,
			*output = (char *) 0;

#ifndef TESTING
	pid_t ppid = getpid();
	chdir ("/");
#endif
	/* Parse the command-line. */
	while ((ch = getopt(argc, argv, "c:df:iIk:nopsvx2")) != EOF)
		switch((char)ch)
		{
		    case '2':		/* Print lines with symbols twice. */
			symbols_twice = 1;
			break;
		    case 'c':		/* Set console message level. */
			log_level = optarg;
			break;
		    case 'd':		/* Activity debug mode. */
			debugging = 1;
			break;
		    case 'f':		/* Define an output file. */
			output = optarg;
			use_output++;
			break;
		    case 'i':		/* Reload module symbols. */
			SignalDaemon(SIGUSR1);
			return(0);
		    case 'I':
			SignalDaemon(SIGUSR2);
			return(0);
		    case 'k':		/* Kernel symbol file. */
			symfile = optarg;
			break;
		    case 'n':		/* don't fork */
			no_fork++;
			break;
		    case 'o':		/* One-shot mode. */
			one_shot = 1;
			break;
		    case 'p':
			SetParanoiaLevel(1);	/* Load symbols on oops. */
			break;	
		    case 's':		/* Use syscall interface. */
			use_syscall = 1;
			break;
		    case 'v':
			printf("klogd %s.%s\n", VERSION, PATCHLEVEL);
			exit (1);
		    case 'x':
			symbol_lookup = 0;
			break;
		}


	/* Set console logging level. */
	if ( log_level != (char *) 0 )
	{
		if ( (strlen(log_level) > 1) || \
		     (strchr("12345678", *log_level) == (char *) 0) )
		{
			fprintf(stderr, "klogd: Invalid console logging "
				"level <%s> specified.\n", log_level);
			return(1);
		}
		console_log_level = *log_level - '0';
	}		


#ifndef TESTING
	/*
	 * The following code allows klogd to auto-background itself.
	 * What happens is that the program forks and the parent quits.
	 * The child closes all its open file descriptors, and issues a
	 * call to setsid to establish itself as an independent session
	 * immune from control signals.
	 *
	 * fork() is only called if it should run in daemon mode, fork is
	 * not disabled with the command line argument and there's no
	 * such process running.
	 */
	if ( (!one_shot) && (!no_fork) )
	{
		if (!check_pid(PidFile))
		{
			signal (SIGTERM, doexit);
			if ( fork() == 0 )
			{
				auto int fl;
				int num_fds = getdtablesize();

				signal (SIGTERM, SIG_DFL);
		
				/* This is the child closing its file descriptors. */
				for (fl= 0; fl <= num_fds; ++fl)
				{
					if ( fileno(stdout) == fl && use_output )
						if ( strcmp(output, "-") == 0 )
							continue;
					close(fl);
				}
 
				setsid();
			}
			else
			{
				/*
				 * Parent process
				 */
				sleep(300);
				/*
				 * Not reached unless something major went wrong.
				 */
				exit(1);
			}
		}
		else
		{
			fputs("klogd: Already running.\n", stderr);
			exit(1);
		}
	}


	/* tuck my process id away */
	if (!check_pid(PidFile))
	{
		if (!write_pid(PidFile))
			Terminate();
	}
	else
	{
		fputs("klogd: Already running.\n", stderr);
		Terminate();
	}
#endif	

	/* Signal setups. */
	for (ch= 1; ch < NSIG; ++ch)
		signal(ch, SIG_IGN);
	signal(SIGINT, stop_daemon);
	signal(SIGKILL, stop_daemon);
	signal(SIGTERM, stop_daemon);
	signal(SIGHUP, stop_daemon);
	signal(SIGTSTP, stop_logging);
	signal(SIGCONT, restart);
	signal(SIGUSR1, reload_daemon);
	signal(SIGUSR2, reload_daemon);


	/* Open outputs. */
	if ( use_output )
	{
		if ( strcmp(output, "-") == 0 )
			output_file = stdout;
		else if ( (output_file = fopen(output, "w")) == (FILE *) 0 )
		{
			fprintf(stderr, "klogd: Cannot open output file " \
				"%s - %s\n", output, strerror(errno));
			return(1);
		}
	}
	else
		openlog("kernel", 0, LOG_KERN);


	/* Handle one-shot logging. */
	if ( one_shot )
	{
		if (symbol_lookup) {
			InitKsyms(symfile);
			InitMsyms();
		}
		if ( (logsrc = GetKernelLogSrc()) == kernel )
			LogKernelLine();
		else
			LogProcLine();
		Terminate();
	}

	/* Determine where kernel logging information is to come from. */
#if defined(KLOGD_DELAY)
	sleep(KLOGD_DELAY);
#endif
	logsrc = GetKernelLogSrc();
	if (symbol_lookup) {
		InitKsyms(symfile);
		InitMsyms();
	}

#ifndef TESTING
	if (getpid() != ppid)
		kill (ppid, SIGTERM);
#endif

        /* The main loop. */
	while (1)
	{
		if ( change_state )
			ChangeLogging();
		switch ( logsrc )
		{
			case kernel:
	  			LogKernelLine();
				break;
			case proc:
				LogProcLine();
				break;
		        case none:
				pause();
				break;
		}
	}
}
/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 *  tab-width: 8
 * End:
 */