Fix #1268 - Segmentation Fault with Constant Lines

* This issue occurs with the --add-jsontime for lines that are a constant value. In this case, the variable `im->gdes[vidx].step` is always 0, which results in a division by zero segmentation fault.
oetiker · Nov 15, 2024 · 866756e · 866756e
1 parent 5041750
commit 866756e
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diff --git a/CHANGES b/CHANGES
@@ -6,6 +6,7 @@ Bugfixes
 * Fix MacOS Build error (no SOCK_CLOEXEC on mac) @ensc fixes oetiker#1261
 * Fix build on 32bits platforms (like armhf) when time_t is 64bits, fixes #1264
 * Fix compilation on illumos @hadfl
+* Fix division by zero segfault when exporting a LINEx with a constant value
 
 Features
 --------

diff --git a/src/rrd_xport.c b/src/rrd_xport.c
@@ -386,14 +386,10 @@ static int rrd_xport_fn(
             long      vidx = im->gdes[ref_list[i]].vidx;
             time_t    now = *start + dst_row * *step;
 
-            (*dstptr++) = im->gdes[vidx].data[(unsigned long)
-                                              floor((double)
-                                                    (now -
-                                                     im->gdes[vidx].start)
-                                                    / im->gdes[vidx].step)
-                                              * im->gdes[vidx].ds_cnt +
-                                              im->gdes[vidx].ds];
-
+            if (im->gdes[vidx].step > 0) {
+                (*dstptr++) = im->gdes[vidx].data[(unsigned long)
+                    floor((double) (now - im->gdes[vidx].start) / im->gdes[vidx].step) * im->gdes[vidx].ds_cnt + im->gdes[vidx].ds];
+            }
         }
     }