[PATCH] fix for an endless loop

"Peter Stamfest" <[email protected]> Fri, 29 Oct 2010 08:45:54 +0200

Newsgroups	gmane.comp.db.rrdtool.devel
Message-ID	<OFDF54D195.1C505B0F-ONC12577CB.0023DC29-C12577CB.002519BA@domino.stamfest.net>

Hello, 

Here is a patch that fixes a serious endless loop problem on 32 bit 
architectures near the timestamp 2^31 (oh yes - y2k038 is showing its ugly 
face) when using the graph command(s). Once the endtime of a graph is 
above the mentioned timestamp, mktime always returns -1 (and correctly 
so), causing some loops to loop forever. The patch fixes this, causing 
some strange output, but there is no other sane way to handle this (expect 
by switching to a 64 bit platform).

The patch has seen only light testing, but because it merely handles an 
error case that usually triggers rarely, its impact should not be too 
high. That said: I did not test it for daylight saving time switchovers.

Sorry for not inlining the patch - the mailer I use these days has its 
problems with formatting.

peter

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fix-endless-loop.patch (application/octet-stream, 2.7 KB)

diff -ur rrdtool-1.4.4.002139/src/rrd_graph.c rrdtool-1.4.4.002139-fixed/src/rrd_graph.c
--- rrdtool-1.4.4.002139/src/rrd_graph.c	2010-09-10 11:16:49.000000000 +0200
+++ rrdtool-1.4.4.002139-fixed/src/rrd_graph.c	2010-10-28 23:15:03.000000000 +0200
@@ -1463,6 +1463,13 @@
 
     localtime_r(&current, &tm);
 
+    int limit = 2;
+    switch (baseint) {
+    case TMT_SECOND: limit = 7200; break;
+    case TMT_MINUTE: limit = 120; break;
+    case TMT_HOUR: limit = 2; break;
+    default: limit = 2; break;
+    }
     do {
         switch (baseint) {
         case TMT_SECOND:
@@ -1493,7 +1500,7 @@
             tm.       tm_year += basestep;
         }
         madetime = mktime(&tm);
-    } while (madetime == -1);   /* this is necessary to skip impssible times
+    } while (madetime == -1 && limit-- >= 0);   /* this is necessary to skip impossible times
                                    like the daylight saving time skips */
     return madetime;
 
@@ -2490,19 +2497,20 @@
                              mgridtm,
                              im->xlab_user.
                              mgridst);
-             ti < im->end;
+             ti < im->end && ti != -1;
              ti =
              find_next_time(ti, im->xlab_user.gridtm, im->xlab_user.gridst)
             ) {
             /* are we inside the graph ? */
             if (ti < im->start || ti > im->end)
                 continue;
-            while (timajor < ti) {
+            while (timajor < ti && timajor != -1) {
                 timajor = find_next_time(timajor,
                                          im->
                                          xlab_user.
                                          mgridtm, im->xlab_user.mgridst);
             }
+            if (timajor == -1) break; /* fail in case of problems with time increments */
             if (ti == timajor)
                 continue;   /* skip as falls on major grid line */
             X0 = xtr(im, ti);
@@ -2526,7 +2534,7 @@
                               im->
                               xlab_user.
                               mgridst);
-         ti < im->end;
+         ti < im->end && ti != -1;
          ti = find_next_time(ti, im->xlab_user.mgridtm, im->xlab_user.mgridst)
         ) {
         /* are we inside the graph ? */
@@ -2552,9 +2560,9 @@
                          labtm,
                          im->xlab_user.
                          labst);
-         ti <=
+         (ti <=
          im->end -
-         im->xlab_user.precis / 2;
+         im->xlab_user.precis / 2) && ti != -1;
          ti = find_next_time(ti, im->xlab_user.labtm, im->xlab_user.labst)
         ) {
         tilab = ti + im->xlab_user.precis / 2;  /* correct time for the label */