Fix a couple of typos.

[p5sagit/p5-mst-13.2.git] / mg.c

diff --git a/mg.c b/mg.c
index d86e22d..b5a9290 100644 (file)
--- a/mg.c
+++ b/mg.c
@@ -15,6 +15,24 @@
 
 /*
 =head1 Magical Functions
+
+"Magic" is special data attached to SV structures in order to give them
+"magical" properties.  When any Perl code tries to read from, or assign to,
+an SV marked as magical, it calls the 'get' or 'set' function associated
+with that SV's magic. A get is called prior to reading an SV, in order to
+give it a chance to update its internal value (get on $. writes the line
+number of the last read filehandle into to the SV's IV slot), while
+set is called after an SV has been written to, in order to allow it to make
+use of its changed value (set on $/ copies the SV's new value to the
+PL_rs global variable).
+
+Magic is implemented as a linked list of MAGIC structures attached to the
+SV. Each MAGIC struct holds the type of the magic, a pointer to an array
+of functions that implement the get(), set(), length() etc functions,
+plus space for some flags and pointers. For example, a tied variable has
+a MAGIC structure that contains a pointer to the object associated with the
+tie.
+
 */
 
 #include "EXTERN.h"
@@ -129,6 +147,18 @@ Perl_mg_get(pTHX_ SV *sv)
     int new = 0;
     MAGIC *newmg, *head, *cur, *mg;
     I32 mgs_ix = SSNEW(sizeof(MGS));
+    int was_temp = SvTEMP(sv);
+    /* guard against sv having being freed midway by holding a private
+       reference. */
+
+    /* sv_2mortal has this side effect of turning on the TEMP flag, which can
+       cause the SV's buffer to get stolen (and maybe other stuff).
+       So restore it.
+    */
+    sv_2mortal(SvREFCNT_inc(sv));
+    if (!was_temp) {
+       SvTEMP_off(sv);
+    }
 
     save_magic(mgs_ix, sv);
 
@@ -143,10 +173,6 @@ Perl_mg_get(pTHX_ SV *sv)
        if (!(mg->mg_flags & MGf_GSKIP) && vtbl && vtbl->svt_get) {
            CALL_FPTR(vtbl->svt_get)(aTHX_ sv, mg);
 
-           /* guard against sv having been freed */
-           if (SvTYPE(sv) == SVTYPEMASK) {
-               Perl_croak(aTHX_ "Tied variable freed while still in use");
-           }
            /* guard against magic having been deleted - eg FETCH calling
             * untie */
            if (!SvMAGIC(sv))
@@ -178,6 +204,12 @@ Perl_mg_get(pTHX_ SV *sv)
     }
 
     restore_magic(aTHX_ INT2PTR(void *, (IV)mgs_ix));
+
+    if (SvREFCNT(sv) == 1) {
+       /* We hold the last reference to this SV, which implies that the
+          SV was deleted as a side effect of the routines we called.  */
+       SvOK_off(sv);
+    }
     return 0;
 }
 
@@ -491,12 +523,12 @@ Perl_magic_len(pTHX_ SV *sv, MAGIC *mg)
            }
            else {
                if (ckWARN(WARN_UNINITIALIZED))
-                   report_uninit();
+                   report_uninit(sv);
            }
        }
        else {
            if (ckWARN(WARN_UNINITIALIZED))
-               report_uninit();
+               report_uninit(sv);
        }
        return 0;
     case '+':
@@ -663,7 +695,7 @@ Perl_magic_get(pTHX_ SV *sv, MAGIC *mg)
     case '\023':               /* ^S */
         if (*(mg->mg_ptr+1) == '\0') {
            if (PL_lex_state != LEX_NOTPARSING)
-               (void)SvOK_off(sv);
+               SvOK_off(sv);
            else if (PL_in_eval)
                sv_setiv(sv, PL_in_eval & ~(EVAL_INREQUIRE));
            else
@@ -1050,6 +1082,7 @@ Perl_magic_clear_all_env(pTHX_ SV *sv, MAGIC *mg)
 #      endif
     {
 #      ifndef PERL_USE_SAFE_PUTENV
+    if (!PL_use_safe_putenv) {
     I32 i;
 
     if (environ == PL_origenviron)
@@ -1057,6 +1090,7 @@ Perl_magic_clear_all_env(pTHX_ SV *sv, MAGIC *mg)
     else
        for (i = 0; environ[i]; i++)
            safesysfree(environ[i]);
+    }
 #      endif /* PERL_USE_SAFE_PUTENV */
 
     environ[0] = Nullch;
@@ -1656,7 +1690,7 @@ Perl_magic_getpos(pTHX_ SV *sv, MAGIC *mg)
            return 0;
        }
     }
-    (void)SvOK_off(sv);
+    SvOK_off(sv);
     return 0;
 }
 
@@ -1829,7 +1863,7 @@ Perl_magic_getvec(pTHX_ SV *sv, MAGIC *mg)
     SV *lsv = LvTARG(sv);
 
     if (!lsv) {
-       (void)SvOK_off(sv);
+       SvOK_off(sv);
        return 0;
     }
 
@@ -1936,7 +1970,7 @@ Perl_magic_killbackrefs(pTHX_ SV *sv, MAGIC *mg)
                Perl_croak(aTHX_ "panic: magic_killbackrefs");
            /* XXX Should we check that it hasn't changed? */
            SvRV(svp[i]) = 0;
-           (void)SvOK_off(svp[i]);
+           SvOK_off(svp[i]);
            SvWEAKREF_off(svp[i]);
            svp[i] = Nullsv;
        }
@@ -2039,7 +2073,7 @@ Perl_magic_set(pTHX_ SV *sv, MAGIC *mg)
     case '\004':       /* ^D */
 #ifdef DEBUGGING
        s = SvPV_nolen(sv);
-       PL_debug = get_debug_opts(&s) | DEBUG_TOP_FLAG;
+       PL_debug = get_debug_opts(&s, 0) | DEBUG_TOP_FLAG;
        DEBUG_x(dump_all());
 #else
        PL_debug = (SvIOK(sv) ? SvIVX(sv) : sv_2iv(sv)) | DEBUG_TOP_FLAG;
@@ -2515,8 +2549,6 @@ Perl_sighandler(int sig)
        flags |= 1;
     if (PL_markstack_ptr < PL_markstack_max - 2)
        flags |= 4;
-    if (PL_retstack_ix < PL_retstack_max - 2)
-       flags |= 8;
     if (PL_scopestack_ix < PL_scopestack_max - 3)
        flags |= 16;
 
@@ -2534,10 +2566,6 @@ Perl_sighandler(int sig)
     }
     if (flags & 4)
        PL_markstack_ptr++;             /* Protect mark. */
-    if (flags & 8) {
-       PL_retstack_ix++;
-       PL_retstack[PL_retstack_ix] = NULL;
-    }
     if (flags & 16)
        PL_scopestack_ix += 1;
     /* sv_2cv is too complicated, try a simpler variant first: */
@@ -2598,8 +2626,6 @@ cleanup:
        PL_savestack_ix -= 8; /* Unprotect save in progress. */
     if (flags & 4)
        PL_markstack_ptr--;
-    if (flags & 8)
-       PL_retstack_ix--;
     if (flags & 16)
        PL_scopestack_ix -= 1;
     if (flags & 64)