fix compile error

src/os/linux/src/os.c

@@ -278,7 +278,7 @@ ssize_t tsendfile(int dfd, int sfd, off_t *offset, size_t size) {
 ssize_t twrite(int fd, void *buf, size_t n) {
   size_t nleft = n; 
   ssize_t nwritten = 0;
-  char *tbuf = (char *)buf
+  char *tbuf = (char *)buf;
 
   while (nleft > 0) {
     nwritten = write(fd, (void *)tbuf, nleft);