Re: Strange code in emacs.c

[Paul Eggert <eggert@cs.ucla.edu>]

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Thanks for checking; I installed the attached into the master branch.


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From 8026f11696430bfdf6b38a4eef4cbf9e337cc947 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 3 Oct 2018 15:55:43 -0700
Subject: [PATCH] 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.
---
 src/emacs.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/emacs.c b/src/emacs.c
index b1c96d1828..ddaaf3fed5 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 */
 
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2.17.1