From eaaf52fc683b44c95551ad6bf932aef93f5847b0 Mon Sep 17 00:00:00 2001
From: Ger Hobbelt <ger@hobbelt.com>
Date: Mon, 21 Aug 2023 13:07:06 +0200
Subject: [PATCH 1/2] numaGetCount(): improved checking for the fringe case
 where the NUMA histogram is empty (count = 0)

(Discovered through code review.)
---
 src/colorquant1.c | 3 ++-
 src/numabasic.c   | 6 ++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/colorquant1.c b/src/colorquant1.c
index 8ec2b247c..106c17f02 100644
--- a/src/colorquant1.c
+++ b/src/colorquant1.c
@@ -3110,7 +3110,8 @@ PIXCMAP   *cmap;
     makeRGBToIndexTables(level, &rtab, &gtab, &btab);
 
         /* The octarray will give a ptr from the octcube to the colorarray */
-    ncubes = numaGetCount(na);
+    if ((ncubes = numaGetCount(na)) == 0)
+        return ERROR_PTR("no slots in pixel occupation histogram", __func__, NULL);
     octarray = (l_int32 *)LEPT_CALLOC(ncubes, sizeof(l_int32));
 
         /* The colorarray will hold the colors of the first pixel
diff --git a/src/numabasic.c b/src/numabasic.c
index 11ac541e8..d09919c32 100644
--- a/src/numabasic.c
+++ b/src/numabasic.c
@@ -812,7 +812,8 @@ l_int32  *array;
     if (!na)
         return (l_int32 *)ERROR_PTR("na not defined", __func__, NULL);
 
-    n = numaGetCount(na);
+    if ((n = numaGetCount(na)) == 0)
+        return ERROR_PTR("array not made (na is empty)", __func__, NULL);
     if ((array = (l_int32 *)LEPT_CALLOC(n, sizeof(l_int32))) == NULL)
         return (l_int32 *)ERROR_PTR("array not made", __func__, NULL);
     for (i = 0; i < n; i++) {
@@ -859,7 +860,8 @@ l_float32  *array;
     if (copyflag == L_NOCOPY) {
         array = na->array;
     } else {  /* copyflag == L_COPY */
-        n = numaGetCount(na);
+        if ((n = numaGetCount(na)) == 0)
+            return ERROR_PTR("array not made (na is empty)", __func__, NULL);
         if ((array = (l_float32 *)LEPT_CALLOC(n, sizeof(l_float32))) == NULL)
             return (l_float32 *)ERROR_PTR("array not made", __func__, NULL);
         for (i = 0; i < n; i++)

From 9d7ecbe56ecba86973c0c0bb6a1b4a442d3b7118 Mon Sep 17 00:00:00 2001
From: Ger Hobbelt <ger@hobbelt.com>
Date: Mon, 21 Aug 2023 13:09:04 +0200
Subject: [PATCH 2/2] numaGetCount(): make sure surrounding code/variables are
 properly pre-initialized to cope with the fringe case where the NUMA
 histogram is empty (count = 0)

(Discovered through code review & accidental misuse in vitro (when I fed numaHistogramGetValFromRank() an empty histogram by accident).)
---
 src/graphics.c  | 1 +
 src/numafunc2.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/src/graphics.c b/src/graphics.c
index d8b5781b1..ccb84e210 100644
--- a/src/graphics.c
+++ b/src/graphics.c
@@ -1152,6 +1152,7 @@ PTA       *pta1, *pta2, *ptad;
 
         /* Generate the plot points */
     pta1 = ptaCreate(n);
+    maxw = maxh = 0;       
     for (i = 0; i < n; i++) {
         numaGetFValue(na, i, &val);
         if (orient == L_HORIZONTAL_LINE) {
diff --git a/src/numafunc2.c b/src/numafunc2.c
index 0c0d6dd1d..7f897af95 100644
--- a/src/numafunc2.c
+++ b/src/numafunc2.c
@@ -1613,6 +1613,7 @@ l_float32  startval, binsize, rankcount, total, sum, fract, val;
     numaGetSum(na, &total);
     rankcount = rank * total;  /* count that corresponds to rank */
     sum = 0.0;
+    val = 0.0;
     for (i = 0; i < n; i++) {
         numaGetFValue(na, i, &val);
         if (sum + val >= rankcount)