Make a NaClDesc ctor for creating descs from NaClFileInfo.

src/trusted/desc/nacl_desc_file_info.c

+/*
+ * Copyright (c) 2014 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.
+ */
+
+#include "native_client/src/trusted/desc/nacl_desc_file_info.h"
+
+#include "native_client/src/include/portability.h"
+#include "native_client/src/public/desc_metadata_types.h"
+#include "native_client/src/public/nacl_file_info.h"
+#include "native_client/src/shared/platform/nacl_log.h"
+#include "native_client/src/trusted/desc/nacl_desc_base.h"
+#include "native_client/src/trusted/desc/nacl_desc_io.h"
+#include "native_client/src/trusted/service_runtime/include/sys/fcntl.h"
+
+
+int NaClDescSetFileToken(struct NaClDesc *desc,
+                         struct NaClFileToken const *token) {
+  int error;
+  error = (*NACL_VTBL(NaClDesc, desc)->

[Mark Seaborn, 2014/05/15 00:36:10]

Nit: Combine with "int error"

[jvoung (off chromium), 2014/05/16 18:02:05]

Done.

+           SetMetadata)(desc,
+                        NACL_DESC_METADATA_FILE_TOKEN_TYPE,
+                        sizeof *token, (uint8_t const *) token);
+  if (0 != error) {
+    NaClLog(4, "NaClDescSetFileToken: failed, errno %d\n", -error);
+    return 0;
+  }
+  return 1;
+}
+
+int NaClDescGetFileToken(struct NaClDesc *desc,
+                         struct NaClFileToken *out_token) {
+  int32_t metadata_type;
+  uint32_t metadata_bytes;
+
+  metadata_bytes = (uint32_t) sizeof *out_token;
+  metadata_type = (*NACL_VTBL(NaClDesc, desc)->
+                   GetMetadata)(desc, &metadata_bytes,
+                                (uint8_t *) out_token);
+  if (NACL_DESC_METADATA_NONE_TYPE == metadata_type) {
+    NaClLog(4, "NaClDescGetFileToken: no meta data, cannot map\n");
+    return 0;
+  } else if (NACL_DESC_METADATA_FILE_TOKEN_TYPE != metadata_type) {
+    return 0;
+  } else if (metadata_bytes != (uint32_t) sizeof *out_token) {
+    /* there is supposed to be a file token, but wrong size? */
+    NaClLog(LOG_WARNING,
+            "NaClDescGetFileToken: purported file token present,"
+            " but token size is incorrect.\n");
+    return 0;
+  }
+  NaClLog(4,
+          "NaClDescGetFileToken: got token 0x%"NACL_PRIx64":%"NACL_PRIx64"\n",
+          out_token->hi, out_token->lo);
+  return 1;
+}
+
+struct NaClDesc *NaClDescIoFromFileInfo(struct NaClFileInfo info,
+                                        int mode) {
+  struct NaClDesc* desc = NaClDescIoDescFromHandleAllocCtor(

[Mark Seaborn, 2014/05/15 00:36:10]

Nit: use " *" spacing

[jvoung (off chromium), 2014/05/16 18:02:05]

Done.

+      (NaClHandle)info.desc, mode);
+  if (NULL == desc) {
+    return NULL;
+  }
+  if (NaClFileTokenIsValid(&info.file_token)) {
+    if (!NaClDescSetFileToken(desc, &info.file_token)) {
+      NaClDescSafeUnref(desc);
+      return NULL;
+    }
+  }
+  return desc;
+}