Add C define to remove taint support from perl

By defining NO_TAINT_SUPPORT, all the various checks that perl does for
tainting become no-ops. It's not an entirely complete change: it doesn't
attempt to remove the taint-related interpreter variables, but instead
virtually eliminates access to it.

Why, you ask? Because it appears to speed up perl's run-time
significantly by avoiding various "are we running under taint" checks
and the like.

This change is not in a state to go into blead yet. The actual way I
implemented it might raise some (valid) objections. Basically, I
replaced all uses of the global taint variables (but not PL_taint_warn!)
with an extra layer of get/set macros (TAINT_get/TAINTING_get).
Furthermore, the change is not complete:

- PL_taint_warn would likely deserve the same treatment.
- Obviously, tests fail. We have tests for -t/-T
- Right now, I added a Perl warn() on startup when -t/-T are detected
  but the perl was not compiled support it. It might be argued that it
  should be silently ignored! Needs some thinking.
- Code quality concerns - needs review.
- Configure support required.
- Needs thinking: How does this tie in with CPAN XS modules that use
  PL_taint and friends? It's easy to backport the new macros via PPPort,
  but that doesn't magically change all code out there. Might be
  harmless, though, because whenever you're running under
  NO_TAINT_SUPPORT, any check of PL_taint/etc is going to come up false.
  Thus, the only CPAN code that SHOULD be adversely affected is code
  that changes taint state.

1 files changed, 11 insertions, 11 deletions

diff --git a/taint.c b/taint.c
index 4631b66385..9a296db76b 100644
--- a/taint.c
+++ b/taint.c
@@ -38,7 +38,7 @@ Perl_taint_proper(pTHX_ const char *f, const char *const s)
 
 	DEBUG_u(PerlIO_printf(Perl_debug_log,
 			       "%s %d %"UVuf" %"UVuf"\n",
-			       s, PL_tainted, uid, euid));
+			       s, TAINT_get, uid, euid));
     }
 #   else
     {
@@ -47,12 +47,12 @@ Perl_taint_proper(pTHX_ const char *f, const char *const s)
 
 	DEBUG_u(PerlIO_printf(Perl_debug_log,
 			       "%s %d %"IVdf" %"IVdf"\n",
-			       s, PL_tainted, uid, euid));
+			       s, TAINT_get, uid, euid));
     }
 #   endif
 #endif
 
-    if (PL_tainted) {
+    if (TAINT_get) {
 	const char *ug;
 
 	if (!f)
@@ -61,11 +61,11 @@ Perl_taint_proper(pTHX_ const char *f, const char *const s)
 	    ug = " while running setuid";
 	else if (PerlProc_getgid() != PerlProc_getegid())
 	    ug = " while running setgid";
-	else if (PL_taint_warn)
+	else if (TAINT_WARN_get)
             ug = " while running with -t switch";
         else
 	    ug = " while running with -T switch";
-	if (PL_unsafe || PL_taint_warn) {
+	if (PL_unsafe || TAINT_WARN_get) {
 	    Perl_ck_warner_d(aTHX_ packWARN(WARN_TAINT), f, s, ug);
         }
         else {
@@ -95,13 +95,13 @@ Perl_taint_env(pTHX)
     /* Don't bother if there's no *ENV glob */
     if (!PL_envgv)
 	return;
-    /* If there's no %ENV hash of if it's not magical, croak, because
+    /* If there's no %ENV hash or if it's not magical, croak, because
      * it probably doesn't reflect the actual environment */
     if (!GvHV(PL_envgv) || !(SvRMAGICAL(GvHV(PL_envgv))
 	    && mg_find((const SV *)GvHV(PL_envgv), PERL_MAGIC_env))) {
-	const bool was_tainted = PL_tainted;
+	const bool was_tainted = TAINT_get;
 	const char * const name = GvENAME(PL_envgv);
-	PL_tainted = TRUE;
+	TAINT;
 	if (strEQ(name,"ENV"))
 	    /* hash alias */
 	    taint_proper("%%ENV is aliased to %s%s", "another variable");
@@ -109,7 +109,7 @@ Perl_taint_env(pTHX)
 	    /* glob alias: report it in the error message */
 	    taint_proper("%%ENV is aliased to %%%s%s", name);
 	/* this statement is reached under -t or -U */
-	PL_tainted = was_tainted;
+	TAINT_set(was_tainted);
     }
 
 #ifdef VMS
@@ -154,10 +154,10 @@ Perl_taint_env(pTHX)
     svp = hv_fetchs(GvHVn(PL_envgv),"TERM",FALSE);
     if (svp && *svp && SvTAINTED(*svp)) {
 	STRLEN len;
-	const bool was_tainted = PL_tainted;
+	const bool was_tainted = TAINT_get;
 	const char *t = SvPV_const(*svp, len);
 	const char * const e = t + len;
-	PL_tainted = was_tainted;
+	TAINT_set(was_tainted);
 	if (t < e && isALNUM(*t))
 	    t++;
 	while (t < e && (isALNUM(*t) || strchr("-_.+", *t)))