From 9c9cf60a757fbbd2846d2a71473c2c42cdabdaa4 Mon Sep 17 00:00:00 2001
From: oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa>
Date: Thu, 11 Nov 2010 16:06:55 +0000
Subject: [PATCH] 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). -- Peter Stamfest

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@2146 a5681a0c-68f1-0310-ab6d-d61299d08faa
---
 src/rrd_graph.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index d902a93..b101b32 100644
--- a/src/rrd_graph.c
+++ b/src/rrd_graph.c
@@ -1470,6 +1470,13 @@ time_t find_next_time(
 
     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:
@@ -1500,7 +1507,7 @@ time_t find_next_time(
             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;
 
@@ -2506,19 +2513,20 @@ void vertical_grid(
                              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);
@@ -2542,7 +2550,7 @@ void vertical_grid(
                               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 ? */
@@ -2568,9 +2576,9 @@ void vertical_grid(
                          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 */
-- 
2.11.0