1 files changed, 16 insertions, 0 deletions

diff --git a/lib/libc/sys/ftruncate.c b/lib/libc/sys/ftruncate.c
index 2f3ae6d5a024..72a6a9158153 100644
--- a/lib/libc/sys/ftruncate.c
+++ b/lib/libc/sys/ftruncate.c
@@ -37,6 +37,11 @@ static char sccsid[] = "@(#)ftruncate.c	8.1 (Berkeley) 6/17/93";
 
 #include <sys/types.h>
 #include <sys/syscall.h>
+#include <unistd.h>
+#ifdef _THREAD_SAFE
+#include <pthread.h>
+#include "pthread_private.h"
+#endif
 
 /*
  * This function provides 64-bit offset padding that
@@ -48,5 +53,16 @@ ftruncate(fd, length)
 	off_t	length;
 {
 
+#ifdef _THREAD_SAFE
+	int retval;
+	if (_thread_fd_lock(fd, FD_RDWR, NULL,__FILE__,__LINE__) != 0) {
+		retval = -1;
+	} else {
+	    retval = __syscall((quad_t)SYS_ftruncate, fd, 0, length);
+	    _thread_fd_unlock(fd, FD_RDWR);
+	}
+	return(retval);
+#else
 	return(__syscall((quad_t)SYS_ftruncate, fd, 0, length));
+#endif
 }