3 files changed, 60 insertions, 6 deletions

diff --git a/lib/libthr/thread/thr_fork.c b/lib/libthr/thread/thr_fork.c
index 7b6b47024c12..9861e93c427d 100644
--- a/lib/libthr/thread/thr_fork.c
+++ b/lib/libthr/thread/thr_fork.c
@@ -132,10 +132,19 @@ __pthread_cxa_finalize(struct dl_phdr_info *phdr_info)
 	_thr_sigact_unload(phdr_info);
 }
 
-__weak_reference(__thr_fork, _fork);
+enum thr_fork_mode {
+	MODE_FORK,
+	MODE_PDFORK,
+};
 
-pid_t
-__thr_fork(void)
+struct thr_fork_args {
+	enum thr_fork_mode mode;
+	void *fdp;
+	int flags;
+};
+
+static pid_t
+thr_fork_impl(const struct thr_fork_args *a)
 {
 	struct pthread *curthread;
 	struct pthread_atfork *af;
@@ -144,8 +153,17 @@ __thr_fork(void)
 	int was_threaded;
 	int rtld_locks[MAX_RTLD_LOCKS];
 
-	if (!_thr_is_inited())
-		return (__sys_fork());
+	if (!_thr_is_inited()) {
+		switch (a->mode) {
+		case MODE_FORK:
+			return (__sys_fork());
+		case MODE_PDFORK:
+			return (__sys_pdfork(a->fdp, a->flags));
+		default:
+			errno = EDOOFUS;
+			return (-1);
+		}
+	}
 
 	curthread = _get_curthread();
 	cancelsave = curthread->no_cancel;
@@ -186,7 +204,19 @@ __thr_fork(void)
 	 * indirection, the syscall symbol is resolved in
 	 * _thr_rtld_init() with side-effect free call.
 	 */
-	ret = syscall(SYS_fork);
+	switch (a->mode) {
+	case MODE_FORK:
+		ret = syscall(SYS_fork);
+		break;
+	case MODE_PDFORK:
+		ret = syscall(SYS_pdfork, a->fdp, a->flags);
+		break;
+	default:
+		ret = -1;
+		errno = EDOOFUS;
+		break;
+	}
+
 	if (ret == 0) {
 		/* Child process */
 		errsave = errno;
@@ -272,3 +302,25 @@ __thr_fork(void)
 
 	return (ret);
 }
+
+__weak_reference(__thr_fork, _fork);
+
+pid_t
+__thr_fork(void)
+{
+	struct thr_fork_args a;
+
+	a.mode = MODE_FORK;
+	return (thr_fork_impl(&a));
+}
+
+pid_t
+__thr_pdfork(int *fdp, int flags)
+{
+	struct thr_fork_args a;
+
+	a.mode = MODE_PDFORK;
+	a.fdp = fdp;
+	a.flags = flags;
+	return (thr_fork_impl(&a));
+}
diff --git a/lib/libthr/thread/thr_private.h b/lib/libthr/thread/thr_private.h
index 33cb03fce990..a1258940a896 100644
--- a/lib/libthr/thread/thr_private.h
+++ b/lib/libthr/thread/thr_private.h
@@ -984,6 +984,7 @@ void __pthread_distribute_static_tls(size_t offset, void *src, size_t len,
 int *__error_threaded(void) __hidden;
 void __thr_interpose_libc(void) __hidden;
 pid_t __thr_fork(void);
+pid_t __thr_pdfork(int *, int);
 int __thr_setcontext(const ucontext_t *ucp);
 int __thr_sigaction(int sig, const struct sigaction *act,
     struct sigaction *oact) __hidden;
diff --git a/lib/libthr/thread/thr_syscalls.c b/lib/libthr/thread/thr_syscalls.c
index 025dfc75fab6..c60308fcd1d2 100644
--- a/lib/libthr/thread/thr_syscalls.c
+++ b/lib/libthr/thread/thr_syscalls.c
@@ -687,6 +687,7 @@ __thr_interpose_libc(void)
 	SLOT(map_stacks_exec);
 	SLOT(fdatasync);
 	SLOT(clock_nanosleep);
+	SLOT(pdfork);
 #undef SLOT
 	*(__libc_interposing_slot(
 	    INTERPOS__pthread_mutex_init_calloc_cb)) =