Make M-x shell work in emacs.

ports/nacl-spawn/nacl_apipe.c

 /*
  * Copyright 2015 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 <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ skipping 26 matching lines @@
   return 0;
 }
 
 static int apipe_read(
     const char* path, char* buf, size_t count, off_t offset,
     struct fuse_file_info* info) {
   struct PP_Var req_var = nspawn_dict_create();
   nspawn_dict_setstring(req_var, "command", "nacl_apipe_read");
   nspawn_dict_setint(req_var, "pipe_id", info->fh);
   nspawn_dict_setint(req_var, "count", count);
+  nspawn_dict_setint(req_var, "nonblock",
+                     (info->flags & O_NONBLOCK) != O_NONBLOCK);
 
   struct PP_Var result_var = nspawn_send_request(req_var);
+  int err = nspawn_dict_getint(result_var, "error");
+  if (err != 0) {
+    nspawn_var_release(result_var);
+    return -err;
+  }
   struct PP_Var data = nspawn_dict_get(result_var, "data");
   assert(data.type == PP_VARTYPE_ARRAY_BUFFER);
   uint32_t len;
   if (!PSInterfaceVarArrayBuffer()->ByteLength(data, &len)) {
     nspawn_var_release(data);
     nspawn_var_release(result_var);
     return -EIO;
   }
   void *p = PSInterfaceVarArrayBuffer()->Map(data);
   if (len > 0 && !p) {
@@ skipping 37 matching lines @@
   int ret = nspawn_dict_getint(result_var, "count");
   nspawn_var_release(result_var);
 
   return ret;
 }
 
 static int apipe_release(const char* path, struct fuse_file_info* info) {
   struct PP_Var req_var = nspawn_dict_create();
   nspawn_dict_setstring(req_var, "command", "nacl_apipe_close");
   nspawn_dict_setint(req_var, "pipe_id", info->fh);
-  nspawn_dict_setint(req_var, "writer", info->flags == O_WRONLY);
+  nspawn_dict_setint(req_var, "writer", (info->flags & O_WRONLY) == O_WRONLY);
 
   struct PP_Var result_var = nspawn_send_request(req_var);
   int ret = nspawn_dict_getint(result_var, "result");
   nspawn_var_release(result_var);
 
   return ret;
 }
 
 static int apipe_fgetattr(
     const char* path, struct stat* st, struct fuse_file_info* info) {
@@ skipping 23 matching lines @@
   }
   mkdir("/apipe", 0777);
   result = mount("", "/apipe", fs_type, 0, NULL);
   if (result != 0) {
     fprintf(stderr, "error: mount of '%s' failed: %d.\n", fs_type, result);
     return 1;;
   }
 
   return 0;
 }