X-Git-Url: https://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=ncurses%2Fbase%2Flib_newwin.c;h=a6c64beaaf4a1c0efc45fde3cb30164e8c9a4568;hp=2b120eac10c79c3adc303c2039040470f7a41c36;hb=cdbe3d3df7ca08989c4aaead5164309466e519eb;hpb=70322aa06a4a97ebff76d2869ad923cdf51ee0a9

diff --git a/ncurses/base/lib_newwin.c b/ncurses/base/lib_newwin.c
index 2b120eac..a6c64bea 100644
--- a/ncurses/base/lib_newwin.c
+++ b/ncurses/base/lib_newwin.c
@@ -43,7 +43,7 @@
 #include <curses.priv.h>
 #include <stddef.h>
 
-MODULE_ID("$Id: lib_newwin.c,v 1.68 2011/01/22 20:34:15 tom Exp $")
+MODULE_ID("$Id: lib_newwin.c,v 1.71 2011/05/28 21:32:51 tom Exp $")
 
 #define window_is(name) ((sp)->_##name == win)
 
@@ -141,7 +141,11 @@ NCURSES_SP_NAME(newwin) (NCURSES_SP_DCLx
     T((T_CALLED("newwin(%p, %d,%d,%d,%d)"), (void *) SP_PARM, num_lines, num_columns,
        begy, begx));
 
-    if (begy < 0 || begx < 0 || num_lines <= 0 || num_columns <= 0)
+    if (begy < 0
+	|| begx < 0
+	|| num_lines < 0
+	|| num_columns < 0
+	|| SP_PARM == 0)
 	returnWin(0);
 
     if (num_lines == 0)
@@ -198,7 +202,7 @@ derwin(WINDOW *orig, int num_lines, int num_columns, int begy, int begx)
     /*
      * make sure window fits inside the original one
      */
-    if (begy < 0 || begx < 0 || orig == 0 || num_lines <= 0 || num_columns <= 0)
+    if (begy < 0 || begx < 0 || orig == 0 || num_lines < 0 || num_columns < 0)
 	returnWin(0);
     if (begy + num_lines > orig->_maxy + 1
 	|| begx + num_columns > orig->_maxx + 1)
@@ -235,10 +239,15 @@ derwin(WINDOW *orig, int num_lines, int num_columns, int begy, int begx)
 NCURSES_EXPORT(WINDOW *)
 subwin(WINDOW *w, int l, int c, int y, int x)
 {
+    WINDOW *result = 0;
+
     T((T_CALLED("subwin(%p, %d, %d, %d, %d)"), (void *) w, l, c, y, x));
-    T(("parent has begy = %ld, begx = %ld", (long) w->_begy, (long) w->_begx));
+    if (w != 0) {
+	T(("parent has begy = %ld, begx = %ld", (long) w->_begy, (long) w->_begx));
 
-    returnWin(derwin(w, l, c, y - w->_begy, x - w->_begx));
+	result = derwin(w, l, c, y - w->_begy, x - w->_begx);
+    }
+    returnWin(result);
 }
 
 static bool