Provides some of the missing POSIX file syscalls

src/shared/platform/linux/nacl_host_dir.c

 /*
  * Copyright (c) 2011 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * NaCl Service Runtime.  Directory descriptor / Handle abstraction.
  *
  * Note that we avoid using the thread-specific data / thread local
@@ skipping 306 matching lines @@
 
   if (NULL == d) {
     NaClLog(LOG_FATAL, "NaClHostDirClose: 'this' is NULL\n");
   }
   NaClLog(3, "NaClHostDirClose(%d)\n", d->fd);
   retval = close(d->fd);
   d->fd = -1;
   NaClMutexDtor(&d->mu);
   return (-1 == retval) ? -NaClXlateErrno(errno) : retval;
 }
+
+int NaClHostDirFchdir(struct NaClHostDir *d) {
+  if (-1 == fchdir(d->fd)) {
+    return -NaClXlateErrno(errno);
+  }
+  return 0;
+}
+
+int NaClHostDirFchmod(struct NaClHostDir *d, int mode) {
+  if (-1 == fchmod(d->fd, mode)) {
+    return -NaClXlateErrno(errno);
+  }
+  return 0;
+}
+
+int NaClHostDirFsync(struct NaClHostDir *d) {
+  if (-1 == fsync(d->fd)) {
+    return -NaClXlateErrno(errno);
+  }
+  return 0;
+}
+
+int NaClHostDirFdatasync(struct NaClHostDir *d) {
+  if (-1 == fdatasync(d->fd)) {
+    return -NaClXlateErrno(errno);
+  }
+  return 0;
+}