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redo nowrap_add()

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Yahoo!'s mailer delivered the report about nowrap_add() to my spam
folder, apparently because it thinks that the signature attachments
"may contain harmful content".  :-(

nowrap_add() checks for signed overflow after the fact, so after
undefined behavior if that happens.

This rewrites nowrap_add() and moves it from end.c to integer.h.

I haven't generated any values big enough to exercise it, but the
algorithm is straightforward so I'll take it on faith.
This commit is contained in:
PatR
2024-07-07 17:34:37 -07:00
parent 0447a1f107
commit 8073c40477
3 changed files with 20 additions and 16 deletions
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6
src/end.c
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@@ -1,4 +1,4 @@
/* NetHack 3.7 end.c $NHDT-Date: 1711735821 2024/03/29 18:10:21 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.313 $ */
/* NetHack 3.7 end.c $NHDT-Date: 1720397752 2024/07/08 00:15:52 $ $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.315 $ */
/* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
/*-Copyright (c) Robert Patrick Rankin, 2012. */
/* NetHack may be freely redistributed. See license for details. */
@@ -15,10 +15,6 @@
#endif
#include "dlb.h"
/* add b to long a, convert wraparound to max value */
#define nowrap_add(a, b) (a = ((a + b) < 0 ? LONG_MAX : (a + b)))
#ifndef NO_SIGNAL
staticfn void done_intr(int);
# if defined(UNIX) || defined(VMS) || defined(__EMX__)