Provides some of the missing POSIX file syscalls

src/trusted/desc/nacl_desc_io.c

Index: src/trusted/desc/nacl_desc_io.c
diff --git a/src/trusted/desc/nacl_desc_io.c b/src/trusted/desc/nacl_desc_io.c
index 387c1319de26d2a58fcd3f10da16354f67cb1566..a32f8970fd186c68d64a8b9bed5c4cbfeeb9c6d6 100644
--- a/src/trusted/desc/nacl_desc_io.c
+++ b/src/trusted/desc/nacl_desc_io.c
@@ -311,6 +311,32 @@ static int NaClDescIoDescFstat(struct NaClDesc         *vself,
   return NaClAbiStatHostDescStatXlateCtor(statbuf, &hstatbuf);
 }
 
+static int NaClDescIoDescFchmod(struct NaClDesc *vself,
+                                int             mode) {
+  struct NaClDescIoDesc *self = (struct NaClDescIoDesc *) vself;
+
+  return NaClHostDescFchmod(self->hd, mode);
+}
+
+static int NaClDescIoDescFsync(struct NaClDesc *vself) {
+  struct NaClDescIoDesc *self = (struct NaClDescIoDesc *) vself;
+
+  return NaClHostDescFsync(self->hd);
+}
+
+static int NaClDescIoDescFdatasync(struct NaClDesc *vself) {
+  struct NaClDescIoDesc *self = (struct NaClDescIoDesc *) vself;
+
+  return NaClHostDescFdatasync(self->hd);
+}
+
+static int NaClDescIoDescFtruncate(struct NaClDesc  *vself,
+                                   nacl_abi_off_t   length) {
+  struct NaClDescIoDesc *self = (struct NaClDescIoDesc *) vself;
+
+  return NaClHostDescFtruncate(self->hd, length);
+}
+
 static int NaClDescIoDescExternalizeSize(struct NaClDesc *vself,
                                          size_t          *nbytes,
                                          size_t          *nhandles) {
@@ -368,6 +394,11 @@ static struct NaClDescVtbl const kNaClDescIoDescVtbl = {
   NaClDescIoDescPWrite,
   NaClDescIoDescIoctl,
   NaClDescIoDescFstat,
+  NaClDescFchdirNotImplemented,
+  NaClDescIoDescFchmod,
+  NaClDescIoDescFsync,
+  NaClDescIoDescFdatasync,
+  NaClDescIoDescFtruncate,
   NaClDescGetdentsNotImplemented,
   NaClDescIoDescExternalizeSize,
   NaClDescIoDescExternalize,