perl.h: Finish implementing combo ENV/LOCALE mutexes

There are cases where an executing function is vulnerable to either the
locale or environment being changed by another thread.  This commit
implements macros that use mutexes to protect these critical sections.
There are two cases that exist:  one where the functions only read; and
one where they can also need exclusive control so that a competing
thread can't overwrite the returned static buffer before it is safely
copied.

5.32 had a placeholder for these, but didn't actually implement it.
Instead it locked just the ENV portion.  On modern platforms with
thread-safe locales, the locale portion is a no-op anyway, so things
worked on them.

This new commit extends that safety to other platforms.  This has long
been a vulnerability in Perl.

1 files changed, 3 insertions, 2 deletions

diff --git a/util.c b/util.c
index a2403465e4..4ae3c9d6c1 100644
--- a/util.c
+++ b/util.c
@@ -3975,11 +3975,12 @@ Perl_init_tm(pTHX_ struct tm *ptm)	/* see mktime, strftime and asctime */
     PERL_UNUSED_CONTEXT;
     PERL_ARGS_ASSERT_INIT_TM;
     (void)time(&now);
-    ENVr_LOCALEr_LOCK;
+
+    LOCALTIME_LOCK;
     my_tm = localtime(&now);
     if (my_tm)
         Copy(my_tm, ptm, 1, struct tm);
-    ENVr_LOCALEr_UNLOCK;
+    LOCALTIME_UNLOCK;
 #else
     PERL_UNUSED_CONTEXT;
     PERL_ARGS_ASSERT_INIT_TM;