Fix stack mess when unwind() is called in scalar context

[perl/modules/Scope-Upper.git] / Upper.xs

diff --git a/Upper.xs b/Upper.xs
index 53dd22f41af57ed9c7aa1c6734eb27532a1c9e21..bb81609e6e1fc27f2726e3bbb946a07f05a90d40 100644 (file)
--- a/Upper.xs
+++ b/Upper.xs
@@ -520,6 +520,7 @@ done:
 typedef struct {
  I32 cxix;
  I32 items;
+ SV **sp;
 } su_ud_unwind;
 
 STATIC void su_unwind(pTHX_ void *ud_) {
@@ -527,25 +528,23 @@ STATIC void su_unwind(pTHX_ void *ud_) {
  OP fakeop;
  I32 cxix  = ud->cxix;
  I32 items = ud->items - 1;
- I32 gimme, mark;
+ I32 mark;
+
+ if (ud->sp)
+  PL_stack_sp = ud->sp;
 
  if (cxstack_ix > cxix)
   dounwind(cxix);
 
  /* Hide the level */
- PL_stack_sp--;
+ if (items >= 0)
+  PL_stack_sp--;
 
  mark = PL_markstack[cxstack[cxix].blk_oldmarksp];
-
- gimme = GIMME_V;
- if (gimme == G_SCALAR) {
-  *PL_markstack_ptr = PL_stack_sp - PL_stack_base;
-  PL_stack_sp += items;
- } else {
-  *PL_markstack_ptr = PL_stack_sp - PL_stack_base - items;
- }
+ *PL_markstack_ptr = PL_stack_sp - PL_stack_base - items;
 
  SU_D({
+  I32 gimme = GIMME_V;
   PerlIO_printf(Perl_debug_log,
                 "%p: cx=%d gimme=%s items=%d sp=%d oldmark=%d mark=%d\n",
                 ud, cxix,
@@ -564,23 +563,37 @@ STATIC void su_unwind(pTHX_ void *ud_) {
 
 /* --- XS ------------------------------------------------------------------ */
 
-#define SU_GET_LEVEL(A)  \
- if (items > A) {        \
-  SV *lsv = ST(A);       \
-  if (SvOK(lsv))         \
-   level = SvUV(lsv);    \
-  if (level < 0)         \
-   XSRETURN(0);          \
- }                       \
- if (level > cxstack_ix) \
-  level = cxstack_ix;
+#define SU_GET_LEVEL(A)   \
+ STMT_START {             \
+  if (items > A) {        \
+   SV *lsv = ST(A);       \
+   if (SvOK(lsv))         \
+    level = SvIV(lsv);    \
+   if (level < 0)         \
+    XSRETURN(0);          \
+  }                       \
+  if (level > cxstack_ix) \
+   level = cxstack_ix;    \
+ } STMT_END
+
+#define SU_GET_CONTEXT(A, B) \
+ STMT_START {                \
+  if (items > A) {           \
+   SV *lsv = ST(B);          \
+   if (SvOK(lsv))            \
+    level = SvIV(lsv);       \
+   if (level < 0)            \
+    level = 0;               \
+   else if (level > cxix)    \
+    level = cxix;            \
+  }                          \
+ } STMT_END
 
 #define SU_DOPOPTOCX(t)                    \
  STMT_START {                              \
-  I32 i, cxix = cxstack_ix, from = 0;      \
-  if (items)                               \
-   from = SvIV(ST(0));                     \
-  for (i = cxix - from; i >= 0; --i) {     \
+  I32 i, cxix = cxstack_ix, level = 0;     \
+  SU_GET_CONTEXT(0, 0);                    \
+  for (i = cxix - level; i >= 0; --i) {    \
    if (CxTYPE(&cxstack[i]) == t) {         \
     ST(0) = sv_2mortal(newSViv(cxix - i)); \
     XSRETURN(1);                           \
@@ -597,32 +610,32 @@ XS(XS_Scope__Upper_unwind) {
 #else
  dXSARGS;
 #endif
- I32 cxix;
+ I32 cxix = cxstack_ix, level = 0;
  su_ud_unwind *ud;
- SV *level;
- if (!items)
-  Perl_croak(aTHX_ "Usage: Scope::Upper::unwind(..., level)");
+
  PERL_UNUSED_VAR(cv); /* -W */
  PERL_UNUSED_VAR(ax); /* -Wall */
- level = ST(items - 1);
- cxix = SvOK(level) ? SvIV(level) : 0;
- if (cxix < 0)
-  cxix = 0;
- else if (cxix > cxstack_ix)
-  cxix = cxstack_ix;
- cxix = cxstack_ix - cxix;
+
+ SU_GET_CONTEXT(0, items - 1);
+ cxix -= level;
  do {
   PERL_CONTEXT *cx = cxstack + cxix;
   switch (CxTYPE(cx)) {
    case CXt_SUB:
    case CXt_EVAL:
    case CXt_FORMAT:
-    /* pp_entersub will try to sanitize the stack - screw that, we're insane */
-    if (GIMME_V == G_SCALAR)
-     PL_stack_sp = PL_stack_base + TOPMARK + 1;
     Newx(ud, 1, su_ud_unwind);
     ud->cxix  = cxix;
     ud->items = items;
+    /* pp_entersub will want to sanitize the stack after returning from there
+     * Screw that, we're insane */
+    if (GIMME_V == G_SCALAR) {
+     ud->sp = PL_stack_sp;
+     /* dXSARGS calls POPMARK, so we need to match PL_markstack_ptr[1] */
+     PL_stack_sp = PL_stack_base + PL_markstack_ptr[1] + 1;
+    } else {
+     ud->sp = NULL;
+    }
     SAVEDESTRUCTOR_X(su_unwind, ud);
     return;
    default:
@@ -692,6 +705,61 @@ PROTOTYPE: ;$
 PPCODE:
  SU_DOPOPTOCX(CXt_EVAL);
 
+void
+CALLER(...)
+PROTOTYPE: ;$
+PREINIT:
+ I32 cxix = cxstack_ix, caller = 0, level = 0;
+PPCODE:
+ if (items) {
+  SV *csv = ST(0);
+  if (SvOK(csv))
+   caller = SvIV(csv);
+ }
+ cxix = cxstack_ix;
+ while (cxix > 0) {
+  PERL_CONTEXT *cx = cxstack + cxix--;
+  switch (CxTYPE(cx)) {
+   case CXt_SUB:
+   case CXt_EVAL:
+   case CXt_FORMAT:
+    --caller;
+    if (caller < 0)
+     goto done;
+    break;
+  }
+  ++level;
+ }
+done:
+ ST(0) = sv_2mortal(newSViv(level));
+ XSRETURN(1);
+
+void
+want_at(...)
+PROTOTYPE: ;$
+PREINIT:
+ I32 cxix = cxstack_ix, level = 0;
+PPCODE:
+ SU_GET_CONTEXT(0, 0);
+ cxix -= level;
+ while (cxix > 0) {
+  PERL_CONTEXT *cx = cxstack + cxix--;
+  switch (CxTYPE(cx)) {
+   case CXt_SUB:
+   case CXt_EVAL:
+   case CXt_FORMAT: {
+    I32 gimme = cx->blk_gimme;
+    switch (gimme) {
+     case G_VOID:   XSRETURN_UNDEF; break;
+     case G_SCALAR: XSRETURN_NO;    break;
+     case G_ARRAY:  XSRETURN_YES;   break;
+    }
+    break;
+   }
+  }
+ }
+ XSRETURN_UNDEF;
+
 void
 reap(SV *hook, ...)
 PROTOTYPE: &;$