From 506d73299cd5559b4d303260f2f05901886c937a Mon Sep 17 00:00:00 2001
From: Peter Stephenson <pws@users.sourceforge.net>
Date: Fri, 1 Aug 2008 13:53:43 +0000
Subject: fix problems with trapreturn, in particular in source inside trap

---
 Src/exec.c    | 18 +++++++++++++++++-
 Src/init.c    |  2 +-
 Src/signals.c |  2 ++
 3 files changed, 20 insertions(+), 2 deletions(-)

(limited to 'Src')

diff --git a/Src/exec.c b/Src/exec.c
index 8edbf1dc9..daa7ba55c 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -64,7 +64,23 @@ int nohistsave;
 /**/
 mod_export int errflag;
  
-/* Status of return from a trap */
+/*
+ * Status of return from a trap.
+ * This is only active if we are inside a trap, else its value
+ * is irrelevant.  It is initialised to -1 for a function trap and
+ * -2 for a non-function trap and if negative is decremented as
+ * we go deeper into functions and incremented as we come back up.
+ * The value is used to decide if an explicit "return" should cause
+ * a return from the caller of the trap; it does this by setting
+ * trapreturn to a status (i.e. a non-negative value).
+ *
+ * In summary, trapreturn is
+ * - zero unless we are in a trap
+ * - negative in a trap unless it has triggered.  Code uses this
+ *   to detect an active trap.
+ * - non-negative in a trap once it was triggered.  It should remain
+ *   non-negative until restored after execution of the trap.
+ */
  
 /**/
 int trapreturn;
diff --git a/Src/init.c b/Src/init.c
index cf6164321..fcbf9236c 100644
--- a/Src/init.c
+++ b/Src/init.c
@@ -191,7 +191,7 @@ loop(int toplevel, int justonce)
 	    exit(lastval);
 	if (((!interact || sourcelevel) && errflag) || retflag)
 	    break;
-	if (trapreturn) {
+	if (trapreturn >= 0) {
 	    lastval = trapreturn;
 	    trapreturn = 0;
 	}
diff --git a/Src/signals.c b/Src/signals.c
index 022ee8fb5..61fff64a2 100644
--- a/Src/signals.c
+++ b/Src/signals.c
@@ -1085,6 +1085,7 @@ dotrapargs(int sig, int *sigtr, void *sigfn)
     int trapret = 0;
     int obreaks = breaks;
     int oretflag = retflag;
+    int otrapreturn = trapreturn;
     int isfunc;
     int traperr;
 
@@ -1183,6 +1184,7 @@ dotrapargs(int sig, int *sigtr, void *sigfn)
 	trapret = trapreturn + 1;
     }
     traperr = errflag;
+    trapreturn = otrapreturn;
     execrestore();
     lexrestore();
 
-- 
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