Fix memory corruption in headless (nographics) build

graphics.c

@@ -153,6 +153,16 @@ void draw_turtle(void) {
     return;
 #endif
 
+#if !defined(HAVE_WX) && !defined(WIN32) && !defined(x_window)
+    // No real graphics backend (headless/nographics build): there is no
+    // turtle icon to actually draw, and the recursive forward(-1)/
+    // forward(1) calls below (used elsewhere to erase/redraw the turtle
+    // shape) serve no purpose here -- they only risk unbounded recursion
+    // through forward() once turtle_shown becomes true. Mirror the
+    // HAVE_WX early-out above.
+    return;
+#endif
+
     if (!turtle_shown) {
 		if (!graphics_setup) {
 			graphics_setup++;
@@ -1650,6 +1660,19 @@ NODE *lprinttext(NODE *args) {
 BOOLEAN safe_to_save(void) {
     char *newbuf;
 
+#if !defined(HAVE_WX) && !defined(WIN32) && !defined(x_window)
+    // No real graphics backend (headless/nographics build): nographics.h
+    // defines GR_SIZE as 1, so record_buffer (declared as
+    // char record_buffer[GR_SIZE]) is a single byte -- yet the code below
+    // unconditionally writes a full pointer into it on the very first
+    // call, corrupting whatever global follows record_buffer in memory
+    // (observed: silently stomps AllowGetSet, causing an unrelated crash
+    // on a later, seemingly unrelated primitive lookup). There is no
+    // window to redraw in a headless build anyway, so there is nothing
+    // to gain from recording draw operations here.
+    return FALSE;
+#endif
+
     if (!refresh_p || drawing_turtle) return FALSE;
     if (record == 0) {	/* first time */
 	record = record_buffer;