Fix bug #31052: Crash on histograms with only one datum

[pspp] / src / math / histogram.c

diff --git a/src/math/histogram.c b/src/math/histogram.c
index 67079398d169ec58737c6f3b94a7d243b9fc8516..0c641b56e127ddbdf9a180363629101fad746b6c 100644 (file)
--- a/src/math/histogram.c
+++ b/src/math/histogram.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2004, 2008 Free Software Foundation, Inc.
+   Copyright (C) 2004, 2008, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -19,6 +19,7 @@
 
 #include <gl/xalloc.h>
 #include <libpspp/assertion.h>
+#include <libpspp/cast.h>
 
 #include <gsl/gsl_histogram.h>
 #include "chart-geometry.h"
@@ -28,7 +29,8 @@
 void
 histogram_add (struct histogram *h, double y, double c)
 {
-  ((struct statistic *)h)->accumulate ((struct statistic *) h, NULL, c, 0, y);
+  struct statistic *stat = &h->parent;
+  stat->accumulate (stat, NULL, c, 0, y);
 }
 
 
@@ -36,7 +38,7 @@ histogram_add (struct histogram *h, double y, double c)
 static void
 acc (struct statistic *s, const struct ccase *cx UNUSED, double c, double cc UNUSED, double y)
 {
-  struct histogram *hist = (struct histogram *) s;
+  struct histogram *hist = UP_CAST (s, struct histogram, parent);
 
   gsl_histogram_accumulate (hist->gsl_hist, y, c);
 }
@@ -45,17 +47,17 @@ acc (struct statistic *s, const struct ccase *cx UNUSED, double c, double cc UNU
 static void
 destroy (struct statistic *s)
 {
-  struct histogram *h = (struct histogram *) s;
+  struct histogram *h = UP_CAST (s, struct histogram, parent);
   gsl_histogram_free (h->gsl_hist);
   free (s);
 }
 
 
-struct statistic *
+struct histogram *
 histogram_create (int bins, double min, double max)
 {
   struct histogram *h = xmalloc (sizeof *h);
-  struct statistic *stat = (struct statistic *) h;
+  struct statistic *stat = &h->parent;
   double upper_limit, lower_limit;
 
   double bin_width = chart_rounded_tick ((max - min) / (double) bins);
@@ -63,7 +65,7 @@ histogram_create (int bins, double min, double max)
 
   int n =  ceil (max / (bin_width_2) ) ;
 
-  assert (max > min);
+  assert (max >= min);
 
   if ( ! (n % 2 ) ) n++;
   upper_limit = n * bin_width_2;
@@ -78,6 +80,6 @@ histogram_create (int bins, double min, double max)
   stat->accumulate = acc;
   stat->destroy = destroy;
 
-  return stat;
+  return h;
 }