Improve error handling and pipe stdout to process.stdout

Author: marcbachmann

lib/pdf.js

@@ -84,54 +84,65 @@ PDF.prototype.toFile = function PdfToFile (filename, callback) {
 }
 
 PDF.prototype.exec = function PdfExec (callback) {
-  var callbacked = false
   var child = childprocess.spawn(this.options.phantomPath, [].concat(this.options.phantomArgs, [this.script]))
-  var stdout = []
   var stderr = []
+
   var timeout = setTimeout(function execTimeout () {
-    child.stdin.end()
-    child.kill()
-    if (!stderr.length) {
-      stderr = [new Buffer('html-pdf: PDF generation timeout. Phantom.js script did not exit.')]
-    }
+    respond(null, new Error('html-pdf: PDF generation timeout. Phantom.js script did not exit.'))
   }, this.options.timeout)
 
-  child.stdout.on('data', function (buffer) {
-    return stdout.push(buffer)
-  })
-
-  child.stderr.on('data', function (buffer) {
+  function onError (buffer) {
     stderr.push(buffer)
-    child.stdin.end()
-    return child.kill()
-  })
+  }
+
+  function onData (buffer) {
+    var result
+    try {
+      var json = buffer.toString().trim()
+      if (json) result = JSON.parse(json)
+    } catch (err) {
+      // Proxy for debugging purposes
+      process.stdout.write(buffer)
+    }
+
+    if (result) respond(null, null, result)
+  }
 
-  function exit (err, data) {
+  var callbacked = false
+  function respond (code, err, data) {
     if (callbacked) return
     callbacked = true
     clearTimeout(timeout)
-    if (err) return callback(err)
-    return callback(null, data)
-  }
 
-  child.on('error', exit)
-
-  child.on('exit', function (code) {
-    if (code || stderr.length) {
-      var err = new Error(Buffer.concat(stderr).toString() || 'html-pdf: Unknown Error')
-      return exit(err)
-    } else {
-      try {
-        var buff = Buffer.concat(stdout).toString()
-        var data = (buff) != null ? buff.trim() : undefined
-        data = JSON.parse(data)
-      } catch (err) {
-        return exit(err)
-      }
-      return exit(null, data)
+    // If we don't have an exit code, we kill the process, ignore stderr after this point
+    if (code === null) kill(child, onData, onError)
+
+    if (!data) {
+      if (!err && code) err = new Error("html-pdf: Received the exit code '" + code + "'")
+      else if (!err) err = new Error('html-pdf: Unknown Error')
+
+      var postfix = stderr.length ? '\n' + Buffer.concat(stderr).toString() : ''
+      if (postfix) err.message += postfix
+      return callback(err, null)
     }
-  })
 
-  var res = JSON.stringify({html: this.html, options: this.options})
-  return child.stdin.write(res + '\n', 'utf8')
+    callback(null, data)
+  }
+
+  child.stdout.on('data', onData)
+  child.stderr.on('data', onError)
+  child.on('error', function onError (err) { respond(null, err) })
+
+  // An exit event is most likely an error because we didn't get any data at this point
+  child.on('exit', respond)
+
+  var config = JSON.stringify({html: this.html, options: this.options})
+  return child.stdin.write(config + '\n', 'utf8')
+}
+
+function kill (child, onData, onError) {
+  child.stdout.removeListener('data', onData)
+  child.stderr.removeListener('data', onError)
+  child.stdin.end()
+  child.kill()
 }