Added resolv/mtctxres.c to userspace for ___mtctxres().

freebsd-userspace/Makefile

@@ -89,6 +89,7 @@ C_FILES += lib/libc/resolv/res_query.c
 C_FILES += lib/libc/resolv/res_send.c
 C_FILES += lib/libc/resolv/res_state.c
 C_FILES += lib/libc/resolv/res_update.c
+C_FILES += lib/libc/resolv/mtctxres.c
 C_FILES += lib/libc/string/strsep.c
 
 C_FILES += lib/libc/isc/ev_streams.c

freebsd-userspace/lib/libc/resolv/mtctxres.c

@@ -0,0 +1,141 @@
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <port_before.h>
+#ifdef DO_PTHREADS
+#include <pthread.h>
+#ifdef _LIBC
+#include <pthread_np.h>
+#endif
+#endif
+#include <errno.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <string.h>
+#include <resolv_mt.h>
+#include <port_after.h>
+
+#ifdef DO_PTHREADS
+static pthread_key_t	key;
+static int		mt_key_initialized = 0;
+
+static int		__res_init_ctx(void);
+static void		__res_destroy_ctx(void *);
+
+#if defined(sun) && !defined(__GNUC__)
+#pragma init	(_mtctxres_init)
+#endif
+#endif
+
+static mtctxres_t	sharedctx;
+
+#ifdef DO_PTHREADS
+/*
+ * Initialize the TSD key. By doing this at library load time, we're
+ * implicitly running without interference from other threads, so there's
+ * no need for locking.
+ */
+static void
+_mtctxres_init(void) {
+	int pthread_keycreate_ret;
+
+	pthread_keycreate_ret = pthread_key_create(&key, __res_destroy_ctx);
+	if (pthread_keycreate_ret == 0)
+		mt_key_initialized = 1;
+}
+#endif
+
+#ifndef _LIBC
+/*
+ * To support binaries that used the private MT-safe interface in
+ * Solaris 8, we still need to provide the __res_enable_mt()
+ * and __res_disable_mt() entry points. They're do-nothing routines.
+ */
+int
+__res_enable_mt(void) {
+	return (-1);
+}
+
+int
+__res_disable_mt(void) {
+	return (0);
+}
+#endif
+
+#ifdef DO_PTHREADS
+static int
+__res_init_ctx(void) {
+
+	mtctxres_t	*mt;
+	int		ret;
+
+
+	if (pthread_getspecific(key) != 0) {
+		/* Already exists */
+		return (0);
+	}
+
+	if ((mt = malloc(sizeof (mtctxres_t))) == 0) {
+		errno = ENOMEM;
+		return (-1);
+	}
+
+	memset(mt, 0, sizeof (mtctxres_t));
+
+	if ((ret = pthread_setspecific(key, mt)) != 0) {
+		free(mt);
+		errno = ret;
+		return (-1);
+	}
+
+	return (0);
+}
+
+static void
+__res_destroy_ctx(void *value) {
+
+	mtctxres_t	*mt = (mtctxres_t *)value;
+
+	if (mt != 0)
+		free(mt);
+}
+#endif
+
+mtctxres_t *
+___mtctxres(void) {
+#ifdef DO_PTHREADS
+	mtctxres_t	*mt;
+
+#ifdef _LIBC
+	if (pthread_main_np() != 0)
+		return (&sharedctx);
+#endif
+
+	/*
+	 * This if clause should only be executed if we are linking
+	 * statically.  When linked dynamically _mtctxres_init() should
+	 * be called at binding time due the #pragma above.
+	 */
+	if (!mt_key_initialized) {
+		static pthread_mutex_t keylock = PTHREAD_MUTEX_INITIALIZER;
+                if (pthread_mutex_lock(&keylock) == 0) {
+			_mtctxres_init();
+			(void) pthread_mutex_unlock(&keylock);
+		}
+	}
+
+	/*
+	 * If we have already been called in this thread return the existing
+	 * context.  Otherwise recreat a new context and return it.  If
+	 * that fails return a global context.
+	 */
+	if (mt_key_initialized) {
+		if (((mt = pthread_getspecific(key)) != 0) ||
+		    (__res_init_ctx() == 0 &&
+		     (mt = pthread_getspecific(key)) != 0)) {
+			return (mt);
+		}
+	}
+#endif
+	return (&sharedctx);
+}