[bugfix] calling dead escape continuation causes segv

contrib/03.callcc/callcc.c

@@ -3,6 +3,8 @@
 struct pic_cont {
   jmp_buf jmp;
 
+  pic_jmpbuf *prev_jmp;
+
   struct pic_winder *wind;
 
   char *stk_pos, *stk_ptr;
@@ -115,6 +117,8 @@ save_cont(pic_state *pic, struct pic_cont **c)
 
   cont = *c = pic_malloc(pic, sizeof(struct pic_cont));
 
+  cont->prev_jmp = pic->jmp;
+
   cont->wind = pic->wind;
 
   cont->stk_len = native_stack_length(pic, &pos);
@@ -170,6 +174,8 @@ restore_cont(pic_state *pic, struct pic_cont *cont)
     if (&v > cont->stk_pos + cont->stk_len) native_stack_extend(pic, cont);
   }
 
+  pic->jmp = cont->prev_jmp;
+
   pic->wind = cont->wind;
 
   pic->stbase = pic_realloc(pic, pic->stbase, sizeof(pic_value) * cont->st_len);

extlib/benz/cont.c

@@ -51,7 +51,8 @@ pic_dynamic_wind(pic_state *pic, struct pic_proc *in, struct pic_proc *thunk, st
 void
 pic_save_point(pic_state *pic, struct pic_escape *escape)
 {
-  escape->valid = true;
+  escape->jmp.prev = pic->jmp;
+  pic->jmp = &escape->jmp;
 
   /* save runtime context */
   escape->wind = pic->wind;
@@ -67,7 +68,14 @@ pic_save_point(pic_state *pic, struct pic_escape *escape)
 void
 pic_load_point(pic_state *pic, struct pic_escape *escape)
 {
-  if (! escape->valid) {
+  pic_jmpbuf *jmp;
+
+  for (jmp = pic->jmp; jmp != NULL; jmp = jmp->prev) {
+    if (jmp == &escape->jmp) {
+      break;
+    }
+  }
+  if (jmp == NULL) {
     pic_errorf(pic, "calling dead escape continuation");
   }
 
@@ -80,8 +88,6 @@ pic_load_point(pic_state *pic, struct pic_escape *escape)
   pic->xp = pic->xpbase + escape->xp_offset;
   pic->arena_idx = escape->arena_idx;
   pic->ip = escape->ip;
-
-  escape->valid = false;
 }
 
 static pic_value
@@ -98,7 +104,7 @@ escape_call(pic_state *pic)
 
   pic_load_point(pic, e->data);
 
-  PIC_LONGJMP(pic, (void *)((struct pic_escape *)e->data)->jmp, 1);
+  PIC_LONGJMP(pic, (void *)((struct pic_escape *)e->data)->jmp.buf, 1);
 
   PIC_UNREACHABLE();
 }
@@ -127,7 +133,9 @@ pic_escape(pic_state *pic, struct pic_proc *proc)
 
   pic_save_point(pic, escape);
 
-  if (PIC_SETJMP(pic, (void *)escape->jmp)) {
+  if (PIC_SETJMP(pic, (void *)escape->jmp.buf)) {
+    pic->jmp = pic->jmp->prev;
+
     return pic_values_by_list(pic, escape->results);
   }
   else {
@@ -135,7 +143,7 @@ pic_escape(pic_state *pic, struct pic_proc *proc)
 
     val = pic_apply1(pic, proc, pic_obj_value(pic_make_econt(pic, escape)));
 
-    escape->valid = false;
+    pic->jmp = pic->jmp->prev;
 
     return val;
   }

extlib/benz/error.c

@@ -105,19 +105,7 @@ pic_push_try(pic_state *pic, struct pic_proc *cont)
 void
 pic_pop_try(pic_state *pic)
 {
-  pic_value cont, escape;
-
-  assert(pic->xp > pic->xpbase);
-
-  cont = pic_attr_ref(pic, pic_obj_value(*--pic->xp), "@@escape");
-
-  assert(pic_proc_p(cont));
-
-  escape = pic_attr_ref(pic, cont, "@@escape");
-
-  assert(pic_data_p(escape));
-
-  ((struct pic_escape *)pic_data_ptr(escape)->data)->valid = false;
+  --pic->xp;
 }
 
 struct pic_error *

extlib/benz/include/picrin.h

@@ -48,6 +48,11 @@ extern "C" {
 
 typedef struct pic_code pic_code;
 
+typedef struct pic_jmpbuf {
+  PIC_JMPBUF buf;
+  struct pic_jmpbuf *prev;
+} pic_jmpbuf;
+
 struct pic_winder {
   struct pic_proc *in;
   struct pic_proc *out;
@@ -73,6 +78,7 @@ typedef struct {
 
   pic_allocf allocf;
 
+  pic_jmpbuf *jmp;
   struct pic_winder *wind;
 
   pic_value *sp;

extlib/benz/include/picrin/config.h

@@ -21,7 +21,7 @@
 /* #define PIC_NONE_IS_FALSE 1 */
 
 /** custom setjmp/longjmp */
-/* #define PIC_JMPBUF_SIZE sizeof(jmp_buf) */
+/* #define PIC_JMPBUF jmp_buf */
 /* #define PIC_SETJMP(pic, buf) setjmp(buf) */
 /* #define PIC_LONGJMP(pic, buf, val) longjmp((buf), (val)) */
 
@@ -100,9 +100,9 @@
 # define PIC_NONE_IS_FALSE 1
 #endif
 
-#ifndef PIC_JMPBUF_SIZE
+#ifndef PIC_JMPBUF
 # include <setjmp.h>
-# define PIC_JMPBUF_SIZE sizeof(jmp_buf)
+# define PIC_JMPBUF jmp_buf
 #endif
 
 #ifndef PIC_SETJMP

extlib/benz/include/picrin/cont.h

@@ -10,9 +10,7 @@ extern "C" {
 #endif
 
 struct pic_escape {
-  char jmp[PIC_JMPBUF_SIZE];
-
-  bool valid;
+  pic_jmpbuf jmp;
 
   struct pic_winder *wind;
 

extlib/benz/include/picrin/error.h

@@ -32,13 +32,15 @@ struct pic_error *pic_make_error(pic_state *, pic_sym *, const char *, pic_list)
   do {                                                                  \
     struct pic_escape *escape = pic_malloc(pic, sizeof(struct pic_escape)); \
     pic_save_point(pic, escape);                                        \
-    if (PIC_SETJMP(pic, (void *)escape->jmp) == 0) {                    \
+    if (PIC_SETJMP(pic, (void *)escape->jmp.buf) == 0) {                \
       do {                                                              \
         pic_push_try(pic, pic_make_econt(pic, escape));
 #define pic_catch_(label)                                 \
         pic_pop_try(pic);                                 \
       } while (0);                                        \
+      pic->jmp = pic->jmp->prev;                          \
     } else {                                              \
+      pic->jmp = pic->jmp->prev;                          \
       goto label;                                         \
     }                                                     \
   } while (0);                                            \

extlib/benz/state.c

@@ -156,6 +156,9 @@ pic_open(int argc, char *argv[], char **envp, pic_allocf allocf)
   /* turn off GC */
   pic->gc_enable = false;
 
+  /* jmp */
+  pic->jmp = NULL;
+
   /* root block */
   pic->wind = NULL;