From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 3 Oct 2018 22:55:43 +0000 (-0700)
Subject: Fix emacs_re_safe_alloca calculation
X-Git-Tag: emacs-27.0.90~4339
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=945a7622326f7d93dd318f01d54f6bf23e0021cf;p=emacs.git

Fix emacs_re_safe_alloca calculation

Problem and draft fix noted by Eli Zaretskii in:
https://lists.gnu.org/r/emacs-devel/2018-10/msg00022.html
* src/emacs.c (main): Fix arithmetic used in calculation
of emacs_re_safe_alloca.
---

diff --git a/src/emacs.c b/src/emacs.c
index b1c96d18285..ddaaf3fed51 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -888,11 +888,11 @@ main (int argc, char **argv)
 		lim = newlim;
 	    }
 	}
-      /* If the stack is big enough, let regex-emacs.c more of it before
-         falling back to heap allocation.  */
-      emacs_re_safe_alloca = max
-        (min (lim - extra, SIZE_MAX) * (min_ratio / ratio),
-         MAX_ALLOCA);
+      /* If the stack is big enough, let regex-emacs.c use more of it
+	 before falling back to heap allocation.  */
+      ptrdiff_t max_failures
+	= min (lim - extra, min (PTRDIFF_MAX, SIZE_MAX)) / ratio;
+      emacs_re_safe_alloca = max (max_failures * min_ratio, MAX_ALLOCA);
     }
 #endif /* HAVE_SETRLIMIT and RLIMIT_STACK and not CYGWIN */