Turn $$ into a magical readonly variable that always fetches getpid() instead of caching it

The intent is that by not caching $$, we eliminate one opportunity for bugs:
If one embeds Perl or uses XS and calls fork(3) from C, Perls notion of $$
may go out of sync with what getpid() returns. By always fetching the
value of $$ via getpid(), this bug opportunity is eliminated. The overhead
of always fetching $$ should be small and is likely only used for tempfile
creation, which should be dwarfed by file system accesses.

1 files changed, 0 insertions, 5 deletions

diff --git a/perl.c b/perl.c
index 4dc5badfcf..417b2fd4b9 100644
--- a/perl.c
+++ b/perl.c
@@ -4155,11 +4155,6 @@ S_init_postdump_symbols(pTHX_ register int argc, register char **argv, register
 #endif /* !PERL_MICRO */
     }
     TAINT_NOT;
-    if ((tmpgv = gv_fetchpvs("$", GV_ADD|GV_NOTQUAL, SVt_PV))) {
-        SvREADONLY_off(GvSV(tmpgv));
-	sv_setiv(GvSV(tmpgv), (IV)PerlProc_getpid());
-        SvREADONLY_on(GvSV(tmpgv));
-    }
 #ifdef THREADS_HAVE_PIDS
     PL_ppid = (IV)getppid();
 #endif