Make M-x shell work in emacs.

build_tools/pipeserver.js

 /*
  * 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.
  */
 
 'use strict';
 
 /**
  * PipeServer manages a set of anonymous pipes.
  */
 function PipeServer() {
   // Start id for anonymous pipes.
   this.anonymousPipeId = 1;
 
   // Status of anonymous pipes.
   this.anonymousPipes = {};
 }
 
 /**
  * Pipe error.
  * @type {number}
  */
 PipeServer.prototype.EPIPE = 32;
 
 /**
+ * EAGAIN / EWOULDBLOCK.
+ * @type {number}
+ */
+PipeServer.prototype.EAGAIN = 11;
+
+/**
  * Handle an anonymous pipe creation call.
  */
 PipeServer.prototype.handleMessageAPipe = function(msg, reply, src) {
   var id = this.anonymousPipeId++;
   this.anonymousPipes[id] = {
     readers: {},
     writers: {},
     readsPending: [],
     writesPending: [],
   };
@@ skipping 19 matching lines @@
       count: this.EPIPE,
     });
     return;
   }
   var pipe = this.anonymousPipes[id];
   while (data.byteLength > 0 && pipe.readsPending.length > 0) {
     var item = pipe.readsPending.shift();
     var part = data.slice(0, item.count);
     item.reply({
       data: part,
+      error: 0,
     });
     data = data.slice(part.byteLength);
   }
   if (data.byteLength === 0) {
     reply({
       count: dataInitialSize,
     });
   } else {
     if (Object.keys(pipe.readers).length > 0) {
       // TODO(bradnelson): consider limiting slack on buffer here.
@@ skipping 20 matching lines @@
   }
 };
 
 /**
  * Handle an anonymous pipe read call.
  */
 PipeServer.prototype.handleMessageAPipeRead = function(
     msg, reply, src) {
   var id = msg.pipe_id;
   var count = msg.count;
+  var nonblock = msg.nonblock;
   if (count === 0 ||
       !(id in this.anonymousPipes &&
         src.pid in this.anonymousPipes[id].readers)) {
     reply({
       data: new ArrayBuffer(0),
+      error: 0,
     });
     return;
   }
   var pipe = this.anonymousPipes[id];
   if (pipe.writesPending.length > 0) {
     var item = pipe.writesPending.shift();
     if (item.data.byteLength > count) {
       var part = item.data.slice(0, count);
       reply({
         data: part,
+        error: 0,
       });
       item.data = item.data.slice(part.byteLength);
       pipe.writesPending.unshift(item);
     } else {
       reply({
         data: item.data,
+        error: 0,
       });
       if (!item.replied) {
         item.reply({
           count: item.dataInitialSize,
         });
       }
     }
   } else {
     if (Object.keys(pipe.writers).length > 0) {
-      pipe.readsPending.push({
-        count: count,
-        reply: reply,
-        pid: src.pid,
-      });
+      if (nonblock !== 0) {
+        reply({
+          error: this.EAGAIN,
+        });
+      } else {
+        pipe.readsPending.push({
+          count: count,
+          reply: reply,
+          pid: src.pid,
+        });
+      }
     } else {
       reply({
         data: new ArrayBuffer(0),
+        error: 0,
       });
     }
   }
 };
 
 /**
  * Close handle to an anonymous pipe for a process.
  */
 PipeServer.prototype.closeAPipe = function(pid, pipeId, writer) {
   if (pipeId in this.anonymousPipes) {
     var pipe = this.anonymousPipes[pipeId];
     if (writer) {
       delete pipe.writers[pid];
     } else {
       delete pipe.readers[pid];
     }
     if (Object.keys(pipe.writers).length === 0 &&
         Object.keys(pipe.readers).length === 0) {
       delete this.anonymousPipes[pipeId];
     } else if (Object.keys(pipe.writers).length === 0) {
       for (var i = 0; i < pipe.readsPending.length; i++) {
         var item = pipe.readsPending[i];
         item.reply({
           data: new ArrayBuffer(0),
+          error: 0,
         });
       }
       pipe.readsPending = [];
     } else if (Object.keys(pipe.readers).length === 0) {
       for (var i = 0; i < pipe.writesPending.length; i++) {
         var item = pipe.writesPending[i];
         item.reply({
           count: this.EPIPE,
         });
       }
       pipe.writesPending = [];
     }
   }
 };
 
 /**
  * Handle an anonymous pipe close call.
  */
 PipeServer.prototype.handleMessageAPipeClose = function(
     msg, reply, src) {
   this.closeAPipe(src.pid, msg.pipe_id, msg.writer);
   reply({
     result: 0,
   });
 };
 
 
 /**
  * Add spawned pipe entries.
  * @params {Object} Dictionary of environment variables passed to process.

[Pete Williamson, 2016/02/29 20:53:47]

nit: With two input variables, I expect to see two @param comments. (Yes, I know
it was pre-exiting, but let's fix it while we are here.)

[bradnelson, 2016/03/03 18:04:02]

No by all means. And you have js readability too :-)

Done.

+ * @returns {boolean} True if stdin is routed.
  */
 PipeServer.prototype.addProcessPipes = function(pid, params) {
+  var routeStdin = false;
   var fdCount = 0;
   for (;;fdCount++) {
     var entry = 'NACL_SPAWN_FD_SETUP_' + fdCount;
     if (!(entry in params))
       break;
     // Pull out a a pipe spec of the form:
     // pipe:<fd number>:<pipe-id>:<is-writer>
     var m = params[entry].match(/pipe:([0-9]+):([0-9]+):([0-9]+)/);
     if (m) {
       var fd = parseInt(m[1]);
       var id = parseInt(m[2]);
       var isWriter = parseInt(m[3]);
+      if (fd === 0) {
+        routeStdin = true;
+      }
       if (id in this.anonymousPipes) {
         var pipe = this.anonymousPipes[id];
         if (isWriter) {
           pipe.writers[pid] = null;
         } else {
           pipe.readers[pid] = null;
         }
       }
     }
   }
+  return routeStdin;
 };
 
 
 /**
  * Add spawned pipe entries.
  * @params {Object} Dictionary of environment variables passed to process.
  */
 PipeServer.prototype.deleteProcess = function(pid) {
   for (var pipeId in this.anonymousPipes) {
     var pipe = this.anonymousPipes[pipeId];
     if (pid in pipe.readers) {
       this.closeAPipe(pid, pipeId, false);
     }
     if (pid in pipe.writers) {
       this.closeAPipe(pid, pipeId, true);
     }
   }
 };