fix(examples): allocate geo_z instead of geo_y in 3D readGeometry

examples/amgx_capi.c

@@ -106,7 +106,7 @@ void readGeometry( const char *fname, double **geo_x, double **geo_y, double **g
 
     if (dimension == 3)
     {
-        *geo_y = (double *)malloc(n * sizeof(double));
+        *geo_z = (double *)malloc(n * sizeof(double));
 
         for (int i = 0; i < n; i ++)
             if (3 != fscanf(fin, "%lf %lf %lf\n", *geo_x + i, *geo_y + i, *geo_z + i))

examples/amgx_capi_multi.c

@@ -104,7 +104,7 @@ void readGeometry( const char *fname, double **geo_x, double **geo_y, double **g
 
     if (dimension == 3)
     {
-        *geo_y = (double *)malloc(n * sizeof(double));
+        *geo_z = (double *)malloc(n * sizeof(double));
 
         for (int i = 0; i < n; i ++)
             if (3 != fscanf(fin, "%lf %lf %lf\n", *geo_x + i, *geo_y + i, *geo_z + i))

tests/test_geo_z_alloc.sh

@@ -0,0 +1,84 @@
+#!/bin/sh
+# Regression test: 3D readGeometry() must allocate geo_z (not geo_y twice).
+#
+# Bug: in the 3D branch of readGeometry() in examples/amgx_capi.c and
+# examples/amgx_capi_multi.c, `*geo_y` was allocated a second time instead
+# of `*geo_z`, so the subsequent fscanf wrote through the NULL *geo_z
+# pointer -> segmentation fault on any 3D geometry input file.
+#
+# The test extracts readGeometry() verbatim from each example source,
+# compiles it into a small harness with gcc, and runs it against a 3D
+# geometry file. Pre-fix code segfaults (exit 139); fixed code parses and
+# returns the correct z values.
+
+set -u
+
+SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+REPO_ROOT=$(dirname -- "$SCRIPT_DIR")
+TMPDIR_TEST=$(mktemp -d)
+trap 'rm -rf "$TMPDIR_TEST"' EXIT
+
+cat > "$TMPDIR_TEST/harness.c" <<'EOF'
+#include <stdio.h>
+#include <stdlib.h>
+
+static void errAndExit(const char *err)
+{
+    fprintf(stderr, "%s", err);
+    exit(1);
+}
+
+/* readGeometry() extracted verbatim from the example source under test */
+#include "readGeometry.inc"
+
+int main(void)
+{
+    /* 3 rows of 3D geometry */
+    FILE *f = fopen("geo3.txt", "w");
+    if (!f) return 10;
+    fprintf(f, "3 3\n1.0 2.0 3.0\n4.0 5.0 6.0\n7.0 8.0 9.0\n");
+    fclose(f);
+
+    double *gx = NULL, *gy = NULL, *gz = NULL;
+    int dim = 0, n = 0;
+    readGeometry("geo3.txt", &gx, &gy, &gz, &dim, &n);
+
+    if (dim != 3 || n != 3) return 2;
+    if (gz == NULL) return 3;                       /* geo_z never allocated */
+    if (gz[0] != 3.0 || gz[1] != 6.0 || gz[2] != 9.0) return 4;
+    if (gy[0] != 2.0 || gy[1] != 5.0 || gy[2] != 8.0) return 5;
+
+    free(gx);
+    free(gy);
+    free(gz);
+    return 0;
+}
+EOF
+
+status=0
+for src in examples/amgx_capi.c examples/amgx_capi_multi.c; do
+    name=$(basename "$src" .c)
+    awk '/^void readGeometry/{f=1} f{print} f && /^}/{exit}' \
+        "$REPO_ROOT/$src" > "$TMPDIR_TEST/readGeometry.inc"
+    if ! grep -q readGeometry "$TMPDIR_TEST/readGeometry.inc"; then
+        echo "FAIL: could not extract readGeometry() from $src"
+        status=1
+        continue
+    fi
+    if ! gcc -Wall -Wextra -o "$TMPDIR_TEST/harness" "$TMPDIR_TEST/harness.c"; then
+        echo "FAIL: harness for $src did not compile"
+        status=1
+        continue
+    fi
+    (cd "$TMPDIR_TEST" && ./harness)
+    rc=$?
+    if [ "$rc" -eq 0 ]; then
+        echo "PASS: $name readGeometry() handles 3D input (geo_z allocated)"
+    else
+        echo "FAIL: $name readGeometry() exited $rc on 3D input" \
+             "(geo_z not allocated -> NULL write/segfault)"
+        status=1
+    fi
+done
+
+exit "$status"