From 224b08fb92ab699538e4cfa8774e99b50347ea75 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Sun, 17 Nov 2013 17:20:19 +0900
Subject: [PATCH] [bugfix] after save_cont any local variable must not be
 modified!

If save_cont returns a cont object, a local variable will receive the
object and the machine stack state will have just been changed then.
To avoid that, we need set cont object to the local before the machine
stack is copied.
---
 src/cont.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/cont.c b/src/cont.c
index 0afbc92a..9d3edb63 100644
--- a/src/cont.c
+++ b/src/cont.c
@@ -5,7 +5,7 @@
 #include "picrin/proc.h"
 #include "picrin/cont.h"
 
-static struct pic_cont *save_cont(pic_state *pic);
+static void save_cont(pic_state *, struct pic_cont **);
 static void restore_cont(pic_state *, struct pic_cont *);
 
 static size_t
@@ -22,13 +22,13 @@ native_stack_length(pic_state *pic, pic_value **pos)
     : (size_t)(&t - pic->native_stack_start + 1);
 }
 
-static struct pic_cont *
-save_cont(pic_state *pic)
+static void
+save_cont(pic_state *pic, struct pic_cont **c)
 {
   struct pic_cont *cont;
   pic_value *pos;
 
-  cont = (struct pic_cont *)pic_obj_alloc(pic, sizeof(struct pic_cont), PIC_TT_CONT);
+  cont = *c = (struct pic_cont *)pic_obj_alloc(pic, sizeof(struct pic_cont), PIC_TT_CONT);
 
   cont->blk = pic->blk;
   PIC_BLK_INCREF(pic, cont->blk);
@@ -57,8 +57,6 @@ save_cont(pic_state *pic)
   memcpy(cont->arena, pic->arena, sizeof(struct pic_object *) * PIC_ARENA_SIZE);
 
   cont->result = pic_undef_value();
-
-  return cont;
 }
 
 static void
@@ -162,7 +160,7 @@ pic_cont_callcc(pic_state *pic)
   }
   cb = pic_proc_ptr(v);
 
-  cont = save_cont(pic);
+  save_cont(pic, &cont);
   if (setjmp(cont->jmp)) {
     return cont->result;
   }