[Nagiosplug-devel] Patch to check_procs

Alain Williams addw at phcomp.co.uk
Tue May 19 12:47:10 CEST 2009


Please find attached a patch to check_procs.

Motivation
**********

Detect a process that enters an infinite loop.
With today's multi process CPUs this might not be noticed for some time.

Discussion
**********

Taking a snapshot and detecting that a process is using 100% of a CPU can generate
false positives, eg catching the overnight batch job that is CPU intensive for a few minutes.
Using the nagios config option 'max_check_attempts' may also generate false positives
if different processes eat CPU in succession.

The patch saves notes about 'interesting processes' in a status file that is checked/updated by
successive runs of check_procs. This allows detection of processes that exceed the
limits over a long time. It records the start time of when individual process exceed
limits. Only processes that exceed a limit are deemed interesting and so have details
in the status file.

The start of Warning and Critical times are separate. Start of Critical implies Warning.
Processes are identified by PID. If the PPID or program change it is assumed to be a
different process (ie any history is forgotten).


Configuration
*************

resource.cfg may contain:

	# Somewhere that plugins can write to:
	$USER8$=/var/log/nagios


commands.cfg may contain:

	# 'check_cpu_hog_procs' command definition
	# Args:  
	# 1     A unique name, used for the state file name in $USER8$ (with .status appended)
	# 2     How many minutes that an individual process needs to exceed a threshold for it to be reported
	# 3     Warning threshold
	# 4     Critical threshold
	define command{
	        command_name    check_cpu_hog_procs
	        command_line    $USER1$/check_procs --state-file=$USER8$/$ARG1$.status --state-time=$ARG2$ -w $ARG3$ -c $ARG4$ -m CPU
	        }

The config file for the machine may contain (note the setting of max_check_attempts):

	# Detect CPU hogs
	# A process needs to exceed the limit for 15 minutes to be reported.
	# 80% CPU for warning. 90% CPU for critical.
	define service{
	        use                             local-service         ; Name of service template to use
	        max_check_attempts              1                     ; Report any change of state immediately, check_cpu_hog_procs already does exceeded time
	        host_name                       mint.phcomp.co.uk.
	        service_description             CPU Hog
	        check_command                   check_cpu_hog_procs!cpu_hog!15!80!90
	        }


Testing/Porting
***************

This has been written on a 64 bit x86 CentOS 5 machine and tested on similar machines.
No attempt to port it elsewhere has been made.

The patch is against: nagios-plugins-trunk-200905081200

Copyright
*********

I am content to assign copyright of this code to the Nagios Plugins Development Team
on the understanding that this will not prevent me from using the code that I have written
in any way that I wish (in this or another project).

-- 
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256  http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
Past chairman of UKUUG: http://www.ukuug.org/
#include <std_disclaimer.h>
-------------- next part --------------
--- check_procs.c	2009-02-21 09:59:24.000000000 +0000
+++ check_procs.c.new	2009-05-19 10:41:14.000000000 +0000
@@ -27,7 +27,8 @@
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
-* 
+*
+* State file stuff originally by: Alain Williams <addw at phcomp.co.uk>
 * 
 *****************************************************************************/
 
@@ -42,13 +43,7 @@
 #include "regex.h"
 
 #include <pwd.h>
-
-int process_arguments (int, char **);
-int validate_arguments (void);
-int check_thresholds (int);
-int convert_to_seconds (char *); 
-void print_help (void);
-void print_usage (void);
+#include <time.h>
 
 int wmax = -1;
 int cmax = -1;
@@ -77,6 +72,7 @@
 	METRIC_ELAPSED
 };
 enum metric metric = METRIC_PROCS;
+char	metric_state_name = 'P';	/* Metric name in the state file */
 
 int verbose = 0;
 int uid;
@@ -92,9 +88,98 @@
 char *fmt;
 char *fails;
 char tmp[MAX_INPUT_BUFFER];
+time_t now;
+time_t state_limit_start;
 
 FILE *ps_input = NULL;
 
+/* Optionally trigger an alert if a process has been in a state for
+ * some time. This time will be measured in minutes, ie much longer than
+ * this program runs for - thus a state file is needed to store this
+ * between runs of this program.
+ * This happens if --state-file is specified.
+ *
+ * The state file records information about processes that exceed some criteria
+ * for a warning or critical notice.
+ * The file will contain one 'V' line.
+ * If the metric is PROCS there will be one N line, else zero or more P lines.
+ * Format of the state file:
+ *	Max line length of 500
+ *	Empty lines and lines starting '#' are ignored
+ *	Lines consist of a type character, a space and optional extra information
+ *	V version_number
+ *	P pid ppid name MS secs
+ *	    name is limited to a max 20 characters
+ *	    M is the metric:
+ *		V	virtual memory size
+ *		R	resident set memory size
+ *		C	percentage CPU
+ *		E	time elapsed in seconds
+ *	    S is the state:
+ *		W	Warning
+ *		C	Critical
+ *	N MS secs
+ *	    M will be 'P'
+ *	    S is the state as above
+ *    secs is the epoch time the metric was first exceeded - hex number
+ *    The 'MS secs' or 'S secs' may appear twice as it is possible for a process (or the
+ *    max # processes) to exceed both the warning and critical thresholds but for different times.
+ * If something is C then it is implicitly W.
+ *
+ * There might be a trailing space on a N line.
+ *
+ * Eg:
+ * 	P 1234 1200 cpu_hog CW 4a05a817 CC 4a05a91f
+ *	N PW 4a05a91f
+ */
+#define	STATE_VERSION	1	/* Change me if the file format changes */
+#define	STATE_MAX_LINE	500	/* Longest line */
+#define	MAX_PROG_NAME	20	/* Longest name of program - search for this if you change it */
+#define	METRIC_CODES	"PVRCE"	/* For input validation */
+#define	STATE_CODES	"WC"	/* For input validation */
+#define	STATE2state(x)	((x) == STATE_WARNING ? 'W' : 'C')	/* Convert STATE_WARNING or STATE_CRITICAL to 'W' or 'C' */
+
+/* A process can exceed various limits. This describes on of them
+ */
+typedef	struct	plimit	{
+	struct	plimit*	pl_next;	/* NULL terminated list */
+	time_t		pl_when;	/* When it first exceeded this limit */
+	int		pl_state;	/* STATE_WARNING or STATE_CRITICAL */
+	int		pl_seen;	/* Exceeded this run */
+	char		pl_metric;	/* What is exceeded - as in file */
+} PLimit;
+
+/* Something to describe a process that is exceeding something
+ */
+typedef	struct	exproc	{
+	struct	exproc*	ep_next;	/* NULL terminated list */
+	pid_t		ep_pid;		/* Process ID */
+	pid_t		ep_ppid;	/* Parent PID */
+	char*		ep_prog;	/* Program name */
+	PLimit*		ep_limits;	/* Limits exceeded list */
+	int		ep_seen;	/* Updated/noticed this run */
+} ExProc;
+
+char*	state_filename;		/* File that we store this in */
+int	state_time = 5;		/* Trigger time - minutes */
+ExProc*	state_list;		/* Used for process specific metrics - ie metric is *not* PROCS */
+PLimit*	state_nprocs;		/* Info on # procs exceeded - used if metric is PROCS */
+int	state_changed;		/* Ie need to write back to file */
+int	must_rewrite;		/* Set this if there is a syntax error in the file, or
+				 * some other reason which means we must rewrite it */
+
+int process_arguments (int, char **);
+int validate_arguments (void);
+int check_thresholds (int);
+int convert_to_seconds (char *); 
+void print_help (void);
+void print_usage (void);
+void read_state_file(void);
+void write_state_file(char** argv);
+void record_state(pid_t procpid, pid_t procppid, char* procprog, char prog_metric, int state, time_t start_time);
+void record_limit(PLimit** l_ref, int state, char proc_metric, time_t start_time);
+void read_limit_line(const char* in_line, PLimit** ppl, char* state_filename, int line_no);
+int check_limit(PLimit* pl);
 
 int
 main (int argc, char **argv)
@@ -129,13 +214,16 @@
 	int result = STATE_UNKNOWN;
 	output chld_out, chld_err;
 
+	now = time(NULL);
+
 	setlocale (LC_ALL, "");
 	bindtextdomain (PACKAGE, LOCALEDIR);
 	textdomain (PACKAGE);
 	setlocale(LC_NUMERIC, "POSIX");
 
-	input_buffer = malloc (MAX_INPUT_BUFFER);
-	procprog = malloc (MAX_INPUT_BUFFER);
+	if( ! (input_buffer = malloc (MAX_INPUT_BUFFER)) ||
+	    ! (procprog = malloc (MAX_INPUT_BUFFER)))
+		die(STATE_UNKNOWN, _("Out of memory in startup\n"));
 
 	asprintf (&metric_name, "PROCS");
 	metric = METRIC_PROCS;
@@ -168,6 +256,9 @@
 		result = cmd_file_read( input_filename, &chld_out, 0);
 	}
 
+	/* What do we remember from last time ? */
+	read_state_file();
+
 	/* flush first line: j starts at 1 */
 	for (j = 1; j < chld_out.lines; j++) {
 		input_line = chld_out.line[j];
@@ -237,6 +328,10 @@
 					procetime, procprog, procargs);
 			}
 
+			/* This is all made simpler because metric can only talk about
+			 * one metric, ie can't check more than one thing at a time.
+			 * This means that metric_state_name is the char equivalent of metric.
+			 */
 			if (metric == METRIC_VSZ)
 				i = check_thresholds (procvsz);
 			else if (metric == METRIC_RSS)
@@ -248,15 +343,29 @@
 				i = check_thresholds (procseconds);
 
 			if (metric != METRIC_PROCS) {
-				if (i == STATE_WARNING) {
-					warn++;
-					asprintf (&fails, "%s%s%s", fails, (strcmp(fails,"") ? ", " : ""), procprog);
-					result = max_state (result, i);
-				}
-				if (i == STATE_CRITICAL) {
-					crit++;
-					asprintf (&fails, "%s%s%s", fails, (strcmp(fails,"") ? ", " : ""), procprog);
-					result = max_state (result, i);
+				if(state_filename) {
+					/* State is being stored - ie don't report immediately.
+					 * Note what we have found:
+					 */
+					if(i == STATE_WARNING || i == STATE_CRITICAL)
+						record_state(procpid, procppid, procprog, metric_state_name, i, now);
+				} else {
+					if (i == STATE_WARNING) {
+						char* str = fails;
+						warn++;
+						asprintf (&fails, "%s%s%s", fails, (strcmp(fails,"") ? ", " : ""), procprog);
+						result = max_state (result, i);
+						if(str)
+							free(str);
+					}
+					if (i == STATE_CRITICAL) {
+						char* str = fails;
+						crit++;
+						asprintf (&fails, "%s%s%s", fails, (strcmp(fails,"") ? ", " : ""), procprog);
+						result = max_state (result, i);
+						if(str)
+							free(str);
+					}
 				}
 			}
 		} 
@@ -276,7 +385,59 @@
 
 	/* Needed if procs found, but none match filter */
 	if ( metric == METRIC_PROCS ) {
-		result = max_state (result, check_thresholds (procs) );
+		int	threshold = check_thresholds(procs);
+		int	putative_result = max_state(result,  threshold);
+
+		if(state_filename) {	/* Do not report immediately - note what we found */
+			/* Only record something if we may need to report it */
+			if(putative_result == STATE_WARNING || putative_result == STATE_CRITICAL)
+				record_limit(&state_nprocs, putative_result, 'P', now);
+		} else
+			result = putative_result;
+	}
+
+	/* If we have a state file, the above has just stored the results away, so have
+	 * a look and see if there is anything that we should note.
+	 * The slight subtlety is that we could have something recorded as both a warning
+	 * & a critical - in this case only report the critical.
+	 */
+	if(state_filename) {
+		/* Compute the start time of any state that we must report.
+		 * Ie any state younger than this we keep quiet about.
+		 */
+		state_limit_start = (time_t)((unsigned long)now - state_time * 60);
+
+		if(verbose >= 3)
+			printf("Checking metric %c, limit_start %s", metric_state_name, ctime(&state_limit_start));
+
+		if(metric == METRIC_PROCS) {
+			result = check_limit(state_nprocs);
+		} else {
+			ExProc*	pp;
+
+			for(pp = state_list; pp; pp = pp->ep_next) {
+				char* str = fails;
+
+				/* What is the state of this recorded process ? */
+				int	res = check_limit(pp->ep_limits);
+
+				switch(res) {
+				case STATE_OK:
+					continue;	/* Don't do the stuff below */
+				case STATE_WARNING:
+					warn++;
+					break;
+				case STATE_CRITICAL:
+					crit++;
+					break;
+				}
+
+				asprintf (&fails, "%s%s%s", fails, (strcmp(fails,"") ? ", " : ""), pp->ep_prog);
+				result = max_state(result, res);
+				if(str)
+					free(str);
+			}
+		}
 	}
 
 	if ( result == STATE_OK ) {
@@ -302,6 +463,9 @@
 		printf (" [%s]", fails);
 
 	printf ("\n");
+
+	write_state_file(argv);
+
 	return result;
 }
 
@@ -336,6 +500,8 @@
 		{"verbose", no_argument, 0, 'v'},
 		{"ereg-argument-array", required_argument, 0, CHAR_MAX+1},
 		{"input-file", required_argument, 0, CHAR_MAX+2},
+		{"state-file", required_argument, 0, 'S'},
+		{"state-time", required_argument, 0, 'T'},
 		{0, 0, 0, 0}
 	};
 
@@ -344,7 +510,7 @@
 			strcpy (argv[c], "-t");
 
 	while (1) {
-		c = getopt_long (argc, argv, "Vvht:c:w:p:s:u:C:a:z:r:m:P:", 
+		c = getopt_long (argc, argv, "Vvht:c:w:p:s:u:C:a:z:r:m:P:S:T:",
 			longopts, &option);
 
 		if (c == -1 || c == EOF)
@@ -479,22 +645,27 @@
 			asprintf (&metric_name, "%s", optarg);
 			if ( strcmp(optarg, "PROCS") == 0) {
 				metric = METRIC_PROCS;
+				metric_state_name = 'P';
 				break;
 			} 
 			else if ( strcmp(optarg, "VSZ") == 0) {
 				metric = METRIC_VSZ;
+				metric_state_name = 'V';
 				break;
 			} 
 			else if ( strcmp(optarg, "RSS") == 0 ) {
 				metric = METRIC_RSS;
+				metric_state_name = 'R';
 				break;
 			}
 			else if ( strcmp(optarg, "CPU") == 0 ) {
 				metric = METRIC_CPU;
+				metric_state_name = 'C';
 				break;
 			}
 			else if ( strcmp(optarg, "ELAPSED") == 0) {
 				metric = METRIC_ELAPSED;
+				metric_state_name = 'E';
 				break;
 			}
 				
@@ -505,6 +676,16 @@
 		case CHAR_MAX+2:
 			input_filename = optarg;
 			break;
+		case 'S':									/* state-file */
+			state_filename = optarg;
+			break;
+		case 'T':									/* state-time */
+			if (!is_integer (optarg))
+				usage2 (_("state-time must be a positive integer"), optarg);
+			else
+				if((state_time = atoi (optarg)) < 0)	/* Treat -ve time as zero */
+					state_time = 0;
+			break;
 		}
 	}
 
@@ -727,6 +908,12 @@
   printf (" %s\n", "-C, --command=COMMAND");
   printf ("   %s\n", _("Only scan for exact matches of COMMAND (without path)."));
 
+  printf ("\n");
+  printf ( "%s\n", "State memory (complain if a process exceeds a limit for a long time):");
+  printf ( " %s\n", "-S, --state-file=StateFile");
+  printf ( "  %s\n", _("Store process information in this file"));
+  printf ( " %s\n",  "-T, --state-time=minutes");
+
 	printf(_("\n\
 RANGEs are specified 'min:max' or 'min:' or ':max' (or 'max'). If\n\
 specified 'max:min', a warning status will be generated if the\n\
@@ -755,7 +942,9 @@
   printf (" %s\n", "check_procs -w 50000 -c 100000 --metric=VSZ");
   printf ("  %s\n\n", _("Alert if VSZ of any processes over 50K or 100K"));
   printf (" %s\n", "check_procs -w 10 -c 20 --metric=CPU");
-  printf ("  %s\n", _("Alert if CPU of any processes over 10%% or 20%%"));
+  printf ("  %s\n\n", _("Alert if CPU of any processes over 10% or 20%"));
+  printf (" %s\n", "check_procs -w 80 -c 90 --metric=CPU --state-time=10 --state-file=/tmp/CPU-state");
+  printf ("  %s\n", _("Alert if CPU of any processes over 80% or 90% for at least 10 minutes, record state in /tmp/CPU-state"));
 
 	printf (_(UT_SUPPORT));
 }
@@ -766,5 +955,423 @@
   printf (_("Usage: "));
 	printf ("%s -w <range> -c <range> [-m metric] [-s state] [-p ppid]\n", progname);
   printf (" [-u user] [-r rss] [-z vsz] [-P %%cpu] [-a argument-array]\n");
-  printf (" [-C command] [-t timeout] [-v]\n");
+  printf (" [-C command] [-t timeout] [-v] [-S state_file] [-T state_time_minutes]\n");
+}
+
+/* Read the state file - if there is one.
+ *
+ * This file is not locked. On a horribly over loaded system it might happen that reads & writes
+ * could overlap in the wrong way. Locking could make things worse, you may end up with many
+ * instances of this program waiting on the lock.
+ */
+void
+read_state_file(void)
+{
+	FILE*	sf;
+	char*	errstr;
+	char*	str;
+	char	in_buf[STATE_MAX_LINE];	/* Input buffer */
+	int	line_no = 0;
+	char	prog_name[MAX_PROG_NAME + 1];
+	int	eaten;
+	ExProc*	pp;
+
+	if( ! state_filename)	/* No file specified */
+		return;
+
+	if( ! (sf = fopen(state_filename, "r"))) {
+		/* It is OK if it doesn't exist, we just haven't created it yet */
+		if(errno == ENOENT) {
+			must_rewrite = 1;	/* Force it to be created */
+			return;
+		}
+
+		/* Anything else - should not happen */
+		errstr = strerror(errno);
+		die(STATE_UNKNOWN, _("Can't open %s for reading as: %s"), state_filename, errstr);
+	}
+
+	/* Read a line at a time */
+	while(fgets(in_buf, STATE_MAX_LINE, sf)) {
+		line_no++;
+		if( ! (str = strchr(in_buf, '\n'))) {
+			printf(_("State file %s corrupt, line too long, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;	/* Force write */
+			goto read_off;	/* Will be fixed when we rewrite it in a moment */
+		}
+		*str = '\0';
+
+		/* Empty line or comment ? */
+		if(in_buf[0] == '\0' || in_buf[0] == '#')
+			continue;
+
+		if(in_buf[1] != ' ') {
+			printf(_("State file %s corrupt, no space at position 1, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;	/* Force write */
+			goto read_off;
+		}
+
+		/* What line type ? */
+		switch(in_buf[0]) {
+		case 'V':	/* In case we are running 1st time after upgrade */
+			if(atoi(in_buf + 2) != STATE_VERSION) {
+				printf(_("State file %s is wrong version, expecting %d. File ignored\n"), state_filename, STATE_VERSION);
+				must_rewrite = 1;	/* Force write */
+				goto read_off;
+			}
+			break;
+		case 'P':	/* Info about a process */
+			/* P 1234 1200 cpu_hog CW 4a05a817 CC 4a05a92f */
+			if( ! (pp = calloc(sizeof(ExProc), 1)))
+				die(STATE_UNKNOWN, _("Out of memory reading %s line %d"), state_filename, line_no);
+
+			pp->ep_next = state_list;
+			state_list = pp;
+
+			/* MAX_PROG_NAME on next line */
+			if(sscanf(in_buf, "P %d %d %20s%n", &pp->ep_pid, &pp->ep_ppid, prog_name, &eaten) != 3) {
+				printf(_("State file corrupt, bad process line, file %s line %d\n"), state_filename, line_no);
+				must_rewrite = 1;	/* Force write */
+				goto read_off;
+			}
+
+			if( ! (pp->ep_prog = strdup(prog_name)))
+				die(STATE_UNKNOWN, _("Out of memory reading %s line %d\n"), state_filename, line_no);
+
+			if(verbose >= 3)
+				printf("Read pid %d ppid %d proc %s\n", pp->ep_pid, pp->ep_ppid, pp->ep_prog);
+
+			read_limit_line(in_buf + eaten, &pp->ep_limits, state_filename, line_no);
+			break;
+		case 'N':	/* Number of procs exceeded */
+			if(verbose >= 3)
+				printf("Read N:\n");
+			read_limit_line(in_buf + 1, &state_nprocs, state_filename, line_no);
+			break;
+		default:
+			printf(_("State file %s corrupt, unknown line type, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;	/* Force write */
+			goto read_off;
+		}
+	}
+
+	/* Ignore changes so far */
+read_off:
+	state_changed = 0;
+
+	fclose(sf);
+}
+
+/* Read a line (or rest of) a process or global limit line.
+ * Expect the first character of in_line to be NUL or a space.
+ * Args:
+ * in_line	the line to read
+ * ppl		pointer to pointer to linked list where to store what is read
+ * filename	the name of the file being read
+ * line_no	that was read
+ *
+ * Read lines like:
+ *	PW 4a05a91f PC 4a05a817
+ */
+void
+read_limit_line(const char* in_line, PLimit** ppl, char* state_filename, int line_no)
+{
+	PLimit*		pl;
+	unsigned long	when;
+	int		eaten;
+
+	while(*in_line) {
+		if(*in_line == ' ') {	/* Ignore spaces */
+			in_line++;
+			continue;
+		}
+
+		/* We have found something, allocate somewhere to put it */
+		if( ! (pl = calloc(sizeof(PLimit), 1)))
+			die(STATE_UNKNOWN, _("Out of memory reading %s line %d\n"), state_filename, line_no);
+
+		/* Read a metric code */
+		if( ! strchr(METRIC_CODES, *in_line)) {
+			printf(_("State file %s corrupt, unknown metric code, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;
+			free(pl);
+			return;
+		}
+		pl->pl_metric = *in_line++;
+
+		/* Read the state code */
+		if(*in_line == '\0' || ! strchr(STATE_CODES, *in_line)) {
+			printf(_("State file %s corrupt, unknown state code, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;
+			free(pl);
+			return;
+		}
+		pl->pl_state = *in_line++ == 'W' ? STATE_WARNING : STATE_CRITICAL;
+
+		/* Read the time */
+		if(sscanf(in_line, " %lx%n", &when, &eaten) != 1) {
+			printf(_("State file %s corrupt, bad time, at line %d\n"), state_filename, line_no);
+			must_rewrite = 1;
+			free(pl);
+			return;
+		}
+		pl->pl_when = (time_t)when;
+		in_line += eaten;
+
+		if(verbose >= 3)
+			printf(" metric=%c state=%c since %s", pl->pl_metric, STATE2state(pl->pl_state), ctime(&pl->pl_when));
+
+		/* Link it in */
+		pl->pl_next = *ppl;
+		*ppl = pl;
+	}
+
+	if(verbose >= 3)
+		printf("\n");
+}
+
+/* Write back to the state file
+ */
+void
+write_state_file(char** argv)
+{
+	FILE*	sf;
+	char*	errstr;
+	ExProc*	pp;
+	PLimit*	pl;
+
+	if( ! state_filename)	/* No file specified */
+		return;
+
+	/* Work out if we are going to write back what we read in.
+	 * If there is something that has not been seen then it was read in
+	 * from the file - need to write back to loose the entry, scan for that.
+	 * Otherwise: state_changed will tell us what we want to know and was set
+	 * when a change was made.
+	 */
+	if(metric == METRIC_PROCS) {
+		for(pl = state_nprocs; pl; pl = pl->pl_next)
+			if( ! pl->pl_seen)
+				state_changed = 1;
+	} else {
+		for(pp = state_list; pp; pp = pp->ep_next) {
+			if( ! pp->ep_seen)
+				state_changed = 1;
+
+			for(pl = pp->ep_limits; pl; pl = pl->pl_next)
+				if( ! pl->pl_seen)
+					state_changed = 1;
+		}
+	}
+
+	if(verbose >= 3)
+		printf("Write state, changed=%d\n", state_changed);
+
+	/* No change to the state file ? */
+	if( ! state_changed && ! must_rewrite)
+		return;
+
+	if( ! (sf = fopen(state_filename, "w"))) {
+		errstr = strerror(errno);
+		die(STATE_UNKNOWN, _("Can't open %s for writing as: %s"), state_filename, errstr);
+	}
+
+	fprintf(sf, "# Process state file written by %s - DO NOT HAND EDIT\n", progname);
+	fprintf(sf, "# Args:");
+	for(; *argv; argv++)
+		fprintf(sf, " %s", *argv);
+	fprintf(sf, "\n");
+	fprintf(sf, "V %d\n", STATE_VERSION);
+
+	if(metric != METRIC_PROCS) {
+		/* Traverse the processes that we know about */
+		for(pp = state_list; pp; pp = pp->ep_next) {
+			if( ! pp->ep_seen)
+				continue;
+
+			fprintf(sf, "P %d %d %.*s", pp->ep_pid, pp->ep_ppid, MAX_PROG_NAME, pp->ep_prog);
+			for(pl = pp->ep_limits; pl; pl = pl->pl_next)
+				if(pl->pl_seen)
+					fprintf(sf, " %c%c %lx", pl->pl_metric, STATE2state(pl->pl_state), (unsigned long)pl->pl_when);
+
+			fprintf(sf, "\n");
+		}
+	} else {
+		/* Print when the # processes is what is being checked */
+		fprintf(sf, "N");
+		for(pl = state_nprocs; pl; pl = pl->pl_next)
+			if(pl->pl_seen)
+				fprintf(sf, " %c%c %lx", pl->pl_metric, STATE2state(pl->pl_state), (unsigned long)pl->pl_when);
+
+		/* Space before \n is important - else get error on read if no limits follow -- which
+		 * will happen if all is well.
+		 */
+		fprintf(sf, " \n");
+	}
+
+	fclose(sf);
+}
+
+/* Record a state for a program.
+ * Create a new entry if we need to, or update an existing one.
+ * Program must match on the first 3 args to update.
+ * Args:
+ * procpid	Process ID
+ * procppid	Parent process ID
+ * progprog	Program name
+ * prog_metric	What we are measuring (METRIC_something but represented as the character in the file)
+ * state	Error or warning (STATE_something)
+ */
+void
+record_state(pid_t procpid, pid_t procppid, char* procprog, char prog_metric, int state, time_t start_time)
+{
+	ExProc*	pp;
+
+	/* Look for the process */
+	for(pp = state_list; pp; pp = pp->ep_next) {
+		if(pp->ep_pid != procpid)
+			continue;
+
+		/* Right process, but if it has mutated - throw it away and start again.
+		 * This doesn't detect processes that exec() a lot w/out fork(), but that is rare.
+		 */
+		if(pp->ep_ppid != procppid || strcmp(pp->ep_prog, procprog)) {
+			PLimit*	pl;
+			while(pl = pp->ep_limits) {
+				pp->ep_limits = pl->pl_next;
+				free(pl);
+			}
+			pp->ep_ppid = procppid;
+			if(strcmp(pp->ep_prog, procprog)) {
+				free(pp->ep_prog);
+				if( ! (pp->ep_prog = strdup(procprog)))
+					die(STATE_UNKNOWN, _("Out of memory"));
+			}
+
+			state_changed = 1;
+		}
+
+		if(verbose >= 3)
+			printf("Record found: pid %d %s\n", pp->ep_pid, pp->ep_prog);
+
+		break;
+	}
+
+	/* Didn't find the process, allocate a new entry */
+	if( ! pp) {
+		if( ! (pp = calloc(sizeof(ExProc), 1)))
+			die(STATE_UNKNOWN, _("Out of memory"));
+		pp->ep_pid = procpid;
+		pp->ep_ppid = procppid;
+		if( ! (pp->ep_prog = strdup(procprog)))
+			die(STATE_UNKNOWN, _("Out of memory"));
+
+		pp->ep_next = state_list;
+		state_list = pp;
+		state_changed = 1;
+
+		if(verbose >= 3)
+			printf("Record alloc: pid %d %s\n", pp->ep_pid, pp->ep_prog);
+	}
+
+	pp->ep_seen = 1;	/* Ensure that this gets written out */
+
+	record_limit(&pp->ep_limits, state, prog_metric, start_time);
+}
+
+/* Store a limit
+ * l_ref	address of head of limits chain
+ * prog_metric	What we are measuring (METRIC_something but represented as the character in the file)
+ * state	Error or warning (STATE_something)
+ * start_time	The time to record when it started, if we already record this - don't change the time
+ *		unless this is older.
+ *
+ * If something is C then it is implicitly W. This is important: if something goes from
+ * W to C, it might remain at C for less than the state time (which it might do W -> C
+ * & back again several times) - but the time above the W level might be notifiable.
+ */
+void
+record_limit(PLimit** l_ref, int state, char proc_metric, time_t start_time)
+{
+	PLimit*	pl;
+	PLimit*	pl_found = NULL;
+	int	seen_warning = 0;
+
+	/* Find the individual process limit.
+	 * Scan the whole lot since we want to 'seen' a Warning if we have Critical.
+	 */
+	for(pl = *l_ref; pl; pl = pl->pl_next)
+		if(pl->pl_metric == proc_metric) {
+			if(state == STATE_CRITICAL && pl->pl_state == STATE_WARNING) {
+				pl->pl_seen = 1;	/* Ensure that it is output */
+				seen_warning = 1;
+			}
+
+			if(pl->pl_state == state)
+				pl_found = pl;		/* We found what we were looking for */
+		}
+
+	pl = pl_found;
+
+	/* Didn't find it, allocate a new one */
+	if( ! pl) {
+		if( ! (pl = calloc(sizeof(PLimit), 1)))
+			die(STATE_UNKNOWN, _("Out of memory"));
+		pl->pl_next = *l_ref;
+		*l_ref = pl;
+		pl->pl_when = start_time;
+		pl->pl_state = state;
+		pl->pl_metric = proc_metric;
+
+		state_changed = 1;
+	} else	/* It is possible that the time was set earlier when a 'C' generated
+		 * an implicit 'W'. Since the 'W' prob started earlier that the 'C'
+		 * we may have recorded the later 'C' time rather than the 'W' time.
+		 */
+		if(pl->pl_when > start_time)
+			pl->pl_when = start_time;
+
+	pl->pl_seen = 1;	/* Ensure that it is output */
+
+	if(verbose >= 3)
+		printf("Record limit: metric=%c state=%c since %s", pl->pl_metric, STATE2state(pl->pl_state), ctime(&pl->pl_when));
+
+	/* If this is a critical, but we didn't see the warning - generate the warning */
+	if(state == 'C' && ! seen_warning)
+		record_limit(l_ref, 'W', proc_metric, start_time);
+}
+
+/* Check if limits have been exceeded for at least the state-time
+ * Check only metric_state_name regardless of what is stored.
+ *
+ * Args:
+ * pl		List of limit values
+ *
+ * Return: STATE_OK, STATE_WARNING or STATE_CRITICAL
+ */
+int
+check_limit(PLimit* pl)
+{
+	int	result = STATE_OK;
+
+	for(; pl; pl = pl->pl_next) {
+		if( ! pl->pl_seen)
+			continue;	/* Of no interest, not updated this run */
+
+		if(pl->pl_metric != metric_state_name)
+			continue;	/* Not what we are looking for */
+
+		/* Is this something that has been going on for long enough that we
+		 * are to report it ?
+		 */
+		if(pl->pl_when <= state_limit_start) {
+			if(result == STATE_OK)
+				result = pl->pl_state;
+
+			if(result == STATE_WARNING && pl->pl_state == STATE_CRITICAL)
+				result = STATE_CRITICAL;
+		}
+	}
+
+	return(result);
 }


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