Mojo + NaCl prototype.

mojo/monacl/generator/generate_monacl_bindings.py

+#!/usr/bin/python
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# pylint: disable=W0104,W0106,F0401,R0201
+
+import optparse
+import os.path
+import string
+import sys
+
+import interface
+
+# Accumulate lines of code with varying levels of indentation.
+class CodeWriter(object):
+  def __init__(self):
+    self._lines = []
+    self._margin = ''
+    self._margin_stack = []
+
+  def __lshift__(self, line):
+    self._lines.append((self._margin + line).rstrip())
+
+  def pushMargin(self):

[Mark Seaborn, 2014/09/10 23:19:20]

I realised that a lot of these method names are not following the style guide
(http://www.chromium.org/developers/coding-style).

So this should be "PushMargin".  Can you do a bulk fix-up?

[Nick Bray (chromium), 2014/09/11 00:56:39]

Done.

+    self._margin_stack.append(self._margin)
+    self._margin += '  '
+
+  def popMargin(self):
+    self._margin = self._margin_stack.pop()
+
+  def getValue(self):
+    return '\n'.join(self._lines).rstrip() + '\n'
+
+  def indent(self):
+    return Indent(self)
+
+
+# Context handler that automatically indents and dedents a CodeWriter
+class Indent(object):
+  def __init__(self, writer):
+    self.writer = writer

[Mark Seaborn, 2014/09/10 23:19:20]

This field can be private

[Nick Bray (chromium), 2014/09/11 00:56:39]

Done.

+
+  def __enter__(self):
+    self.writer.pushMargin()
+
+  def __exit__(self, type_, value, traceback):
+    self.writer.popMargin()
+
+
+def TemplateFile(name):
+  return os.path.join(os.path.dirname(__file__), name)
+
+
+def LoadTemplate(filename):
+  data = open(TemplateFile(filename)).read()
+  template = string.Template(data)
+  return template
+
+
+# Wraps comma separated lists as needed.
+def Wrap(pre, items, post):
+  complete = pre + ', '.join(items) + post
+  if len(complete) <= 80:
+    return [complete]
+  lines = [pre]
+  indent = '    '
+  for i, item in enumerate(items):
+    if i < len(items) - 1:
+      lines.append(indent + item + ',')
+    else:
+      lines.append(indent + item + post)
+  return lines
+
+def GeneratorWarning():
+  return ('// WARNING this file was generated by %s\n// Do not edit by hand.' %
+          os.path.basename(__file__))
+
+# Untrusted library implementing the public Mojo API.
+def GenerateLibMojo(functions, out):
+  template = LoadTemplate('libmojo.cc.template')
+
+  code = CodeWriter()
+
+  for f in functions:
+    for line in Wrap('%s %s(' % (f.returnType, f.name), f.paramList(), '){'):
+      code << line
+    numParams = len(f.params) + 2

[Mark Seaborn, 2014/09/10 23:19:20]

"num_params"

[Nick Bray (chromium), 2014/09/11 00:56:40]

Done.

+
+    with code.indent():
+      code << 'uint32_t params[%d];' % numParams
+      returnType = f.resultParam.baseType

[Mark Seaborn, 2014/09/10 23:19:20]

"return_type"

[Nick Bray (chromium), 2014/09/11 00:56:39]

Done.

+      if returnType == 'MojoResult':
+        default = 'MOJO_RESULT_INVALID_ARGUMENT'
+      elif returnType == 'MojoTimeTicks':
+        default = '0'
+      else:
+        raise Exception('Unhandled return type: ' + returnType)
+      code << '%s %s = %s;' % (returnType, f.resultParam.name, default)
+
+      # Message ID
+      code << 'params[0] = %d;' % f.uid
+      # Parameter pointers
+      castTemplate = 'params[%d] = reinterpret_cast<uint32_t>(%s);'

[Mark Seaborn, 2014/09/10 23:19:20]

"cast_template"

[Nick Bray (chromium), 2014/09/11 00:56:40]

Done.

+      for p in f.params:
+        ptr = p.name
+        if p.isPassedByValue():
+          ptr = '&' + ptr
+        code <<  castTemplate % (p.uid + 1, ptr)

[Mark Seaborn, 2014/09/10 23:19:20]

Nit: remove one space after "<<"

[Nick Bray (chromium), 2014/09/11 00:56:40]

Done.

+      # Return value pointer
+      code << castTemplate % (numParams - 1, '&' + f.resultParam.name)
+
+      code << 'DoMojoCall(params, sizeof(params));'
+      code << 'return %s;' % f.resultParam.name
+
+    code << '}'
+    code << ''
+
+  body = code.getValue()
+  text = template.substitute(
+    generator_warning=GeneratorWarning(),
+    body=body)
+  out.write(text)
+
+
+# Parameters passed into trusted code are handled differently depending on
+# details of the parameter. Encapsulate these differences in a polymorphic type.
+class ParamImpl(object):
+  def __init__(self, param):
+    self.param = param
+
+  def copyOut(self, code):
+    pass
+
+  def isArray(self):
+    return False
+
+
+class ScalarInputImpl(ParamImpl):
+  def declareVars(self, code):
+    code << '%s %s_value;' % (self.param.baseType, self.param.name)
+
+  def convertParam(self):
+    p = self.param
+    return ('ConvertScalarInput(nap, params[%d], &%s_value)' %
+            (p.uid + 1, p.name))
+
+  def callParam(self):
+    return '%s_value' % self.param.name
+
+
+class ScalarOutputImpl(ParamImpl):
+  def declareVars(self, code):
+    code << '%s volatile* %s_ptr;' % (self.param.baseType, self.param.name)
+    code << '%s %s_value;' % (self.param.baseType, self.param.name)
+
+  def convertParam(self):
+    p = self.param
+    return 'ConvertScalarOutput(nap, params[%d], &%s_ptr)' % (p.uid + 1, p.name)
+
+  def callParam(self):
+    return '&%s_value' % self.param.name
+
+  def copyOut(self, code):
+    name = self.param.name
+    code << '*%s_ptr = %s_value;' % (name, name)
+
+
+class ScalarInOutImpl(ParamImpl):
+  def declareVars(self, code):
+    code << '%s volatile* %s_ptr;' % (self.param.baseType, self.param.name)
+    code << '%s %s_value;' % (self.param.baseType, self.param.name)
+
+  def convertParam(self):
+    p = self.param
+    return ('ConvertScalarInOut(nap, params[%d], %s, &%s_value, &%s_ptr)' %
+            (p.uid + 1, CBool(p.isOptional), p.name, p.name))
+
+  def callParam(self):
+    name = self.param.name
+    expr = '&%s_value' % name
+    if self.param.isOptional:
+      expr = '%s_ptr ? %s : NULL' % (name, expr)
+    return expr
+
+  def copyOut(self, code):
+    name = self.param.name
+    if self.param.isOptional:
+      code << 'if (%s_ptr != NULL) {' % (name)
+      with code.indent():
+        code << '*%s_ptr = %s_value;' % (name, name)
+      code << '}'
+    else:
+      code << '*%s_ptr = %s_value;' % (name, name)
+
+
+class ArrayImpl(ParamImpl):
+  def declareVars(self, code):
+    code << '%s %s;' % (self.param.paramType, self.param.name)
+
+  def convertParam(self):
+    p = self.param
+    if p.baseType == 'void':
+      return ('ConvertBytes(nap, params[%d], %s, %s, &%s)' %
+              (p.uid + 1, p.size + '_value', CBool(p.isOptional), p.name))
+    else:
+      return ('ConvertArray(nap, params[%d], %s, %s, &%s)' %
+              (p.uid + 1, p.size + '_value', CBool(p.isOptional), p.name))
+
+  def callParam(self):
+    return self.param.name
+
+  def isArray(self):
+    return True
+
+
+class StructInputImpl(ParamImpl):
+  def declareVars(self, code):
+    code << '%s %s;' % (self.param.paramType, self.param.name)
+
+  def convertParam(self):
+    p = self.param
+    return ('ConvertStruct(nap, params[%d], %s, &%s)' %
+            (p.uid + 1, CBool(p.isOptional), p.name))
+
+  def callParam(self):
+    return self.param.name
+
+
+def ImplForParam(p):
+  if p.isScalar():
+    if p.isOutput:
+      if p.isInput:
+        return ScalarInOutImpl(p)
+      else:
+        return ScalarOutputImpl(p)
+    else:
+      return ScalarInputImpl(p)
+  elif p.isArray:
+    return ArrayImpl(p)
+  elif p.isStruct:
+    return StructInputImpl(p)
+  else:
+    assert False, p
+
+
+def CBool(value):
+  return 'true' if value else 'false'
+
+# A trusted wrapper that validates the arguments passed from untrusted code
+# before passing them to the underlying public Mojo API.
+def GenerateMojoSyscall(functions, out):
+  template = LoadTemplate('mojo_syscall.cc.template')
+
+  code = CodeWriter()
+  code.pushMargin()
+
+  for f in functions:
+    impls = [ImplForParam(p) for p in f.params]
+    impls.append(ImplForParam(f.resultParam))
+
+    code << 'case %d:' % f.uid
+
+    code.pushMargin()
+
+    code << '{'
+
+    with code.indent():
+      numParams = len(f.params) + 2
+      code << 'if (num_params != %d) {' % numParams
+      with code.indent():
+        code << 'return -1;'
+      code << '}'
+
+      # Declare temporaries.
+      for impl in impls:
+        impl.declareVars(code)
+
+      def convertParam(code, impl):
+        code << 'if (!%s) {' % impl.convertParam()
+        with code.indent():
+          code << 'return -1;'
+        code << '}'
+
+      code << '{'
+      with code.indent():
+        code << 'ScopedCopyLock copy_lock(nap);'
+        # Convert and validate pointers in two passes.
+        # Arrays cannot be validated util the size parameter has been converted.
+        for impl in impls:
+          if not impl.isArray():
+            convertParam(code, impl)
+        for impl in impls:
+          if impl.isArray():
+            convertParam(code, impl)
+      code << '}'
+      code << ''
+
+      # Call
+      getParams = [impl.callParam() for impl in impls[:-1]]
+      code << 'result_value = %s(%s);' % (f.name, ', '.join(getParams))
+      code << ''
+
+      # Write outputs
+      code << '{'
+      with code.indent():
+        code << 'ScopedCopyLock copy_lock(nap);'
+        # TODO copy out on failure?

[Mark Seaborn, 2014/09/10 23:19:20]

Can you elaborate or remove this?

[Nick Bray (chromium), 2014/09/11 00:56:40]

Done.

+        for impl in impls:
+          impl.copyOut(code)
+      code << '}'
+      code << ''
+
+      code << 'return 0;'
+    code << '}'
+
+    code.popMargin()
+
+  body = code.getValue()
+  text = template.substitute(
+    generator_warning=GeneratorWarning(),
+    body=body)
+  out.write(text)
+
+def OutFile(dir_path, name):
+  if not os.path.exists(dir_path):
+    os.makedirs(dir_path)
+  return open(os.path.join(dir_path, name), 'w')
+
+def main(args):
+  usage = 'usage: %prog [options]'
+  parser = optparse.OptionParser(usage=usage)
+  parser.add_option(
+      '-d',
+      dest='out_dir',
+      metavar='DIR',
+      help='output generated code into directory DIR')
+  options, args = parser.parse_args(args=args)
+  if not options.out_dir:
+    parser.error('-d is required')
+  if args:
+    parser.error('unexpected positional arguments: %s' % ' '.join(args))
+
+  mojo = interface.MakeInterface()
+
+  out = OutFile(options.out_dir, 'libmojo.cc')
+  GenerateLibMojo(mojo.functions, out)
+
+  out = OutFile(options.out_dir, 'mojo_syscall.cc')
+  GenerateMojoSyscall(mojo.functions, out)
+
+
+if __name__ == '__main__':
+  main(sys.argv[1:])