[PATCH] do not access aTHR when in a non-Perl process

[Eric Wong <e@80x24.org>]

This is needed to avoid segfaults in non-Perl processes
such as `cmake'.

Fixes: 3197316f33fdc5d4 "create the `totals' rculfhash as early as possible"
---
 Mwrap.xs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/Mwrap.xs b/Mwrap.xs
index 092aaf4..31e9394 100644
--- a/Mwrap.xs
+++ b/Mwrap.xs
@@ -344,18 +344,20 @@ update_stats_rcu_lock(size_t *generation, size_t size, uintptr_t caller)
 	struct src_loc *k, *ret = 0;
 	static const size_t xlen = sizeof(caller);
 	char *dst;
-	const COP *cop;
+	const COP *cop = NULL;
 	struct cds_lfht *t = CMM_LOAD_SHARED(totals);
 
 	if (caa_unlikely(!t)) return 0;
 	if (locating++) goto out; /* do not recurse into another *alloc */
 
 	*generation = uatomic_add_return(&total_bytes_inc, size);
+	if (&PL_thr_key) { /* are we even in a Perl process? */
 #ifdef PERL_IMPLICIT_CONTEXT
-	cop = aTHX ? PL_curcop : 0;
+		if (aTHX) cop = PL_curcop;
 #else
-	cop = &locating == root_locating ? PL_curcop : 0;
+		if (&locating == root_locating) cop = PL_curcop;
 #endif
+	}
 	rcu_read_lock();
 	if (cop) {
 		const char *ptr = OutCopFILE(cop);