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tighten up scm_i_dowinds, fixing invalid SCM_CAR (prompt)

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* libguile/dynwind.c: Update comment regarding what can be on the wind
  stack.
  (scm_i_dowinds): Clean up to remove @bind and catch/throw-handler
  cases, to add a case for prompts, and to be more strict in general
  regarding the set of things that can be on the wind stack. Fixes a bug
  whereby prompts were accessed via SCM_CAR; thanks to Ken Raeburn for
  the report.
This commit is contained in:
Andy Wingo 2010-03-04 11:37:03 +01:00
parent bbb2ecd1d1
commit 2b2746a831
1 changed files with 15 additions and 32 deletions
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47
libguile/dynwind.c
View file

@ -26,6 +26,7 @@
#include <assert.h>
#include "libguile/_scm.h"
#include "libguile/control.h"
#include "libguile/eval.h"
#include "libguile/alist.h"
#include "libguile/fluids.h"
@ -41,10 +42,9 @@
#<frame>
#<winder>
#<with-fluids>
#<prompt>
(enter-proc . leave-proc) dynamic-wind
(tag . jmpbuf) catch
(tag . pre-unwind-data) throw-handler / lazy-catch
tag is either a symbol or a boolean
*/
@ -240,7 +240,6 @@ scm_i_dowinds (SCM to, long delta, void (*turn_func) (void *), void *data)
else if (delta < 0)
{
SCM wind_elt;
SCM wind_key;
scm_i_dowinds (SCM_CDR (to), 1 + delta, turn_func, data);
wind_elt = SCM_CAR (to);
@ -262,21 +261,13 @@ scm_i_dowinds (SCM to, long delta, void (*turn_func) (void *), void *data)
scm_i_swap_with_fluids (wind_elt,
SCM_I_CURRENT_THREAD->dynamic_state);
}
else if (SCM_PROMPT_P (wind_elt))
; /* pass -- see vm_reinstate_partial_continuation */
else if (scm_is_pair (wind_elt))
scm_call_0 (SCM_CAR (wind_elt));
else
{
wind_key = SCM_CAR (wind_elt);
/* key = #t | symbol | thunk | list of variables */
if (SCM_NIMP (wind_key))
{
if (scm_is_pair (wind_key))
{
if (SCM_VARIABLEP (SCM_CAR (wind_key)))
scm_swap_bindings (wind_key, SCM_CDR (wind_elt));
}
else if (scm_is_true (scm_thunk_p (wind_key)))
scm_call_0 (wind_key);
}
}
/* trash on the wind list */
abort ();
scm_i_set_dynwinds (to);
}
@ -284,7 +275,6 @@ scm_i_dowinds (SCM to, long delta, void (*turn_func) (void *), void *data)
{
SCM wind;
SCM wind_elt;
SCM wind_key;
wind = scm_i_dynwinds ();
wind_elt = SCM_CAR (wind);
@ -304,20 +294,13 @@ scm_i_dowinds (SCM to, long delta, void (*turn_func) (void *), void *data)
scm_i_swap_with_fluids (wind_elt,
SCM_I_CURRENT_THREAD->dynamic_state);
}
else if (SCM_PROMPT_P (wind_elt))
; /* pass -- though we could invalidate the prompt */
else if (scm_is_pair (wind_elt))
scm_call_0 (SCM_CDR (wind_elt));
else
{
wind_key = SCM_CAR (wind_elt);
if (SCM_NIMP (wind_key))
{
if (scm_is_pair (wind_key))
{
if (SCM_VARIABLEP (SCM_CAR (wind_key)))
scm_swap_bindings (wind_key, SCM_CDR (wind_elt));
}
else if (scm_is_true (scm_thunk_p (wind_key)))
scm_call_0 (SCM_CDR (wind_elt));
}
}
/* trash on the wind list */
abort ();
delta--;
goto tail; /* scm_dowinds(to, delta-1); */