Mojo + NaCl prototype.

mojo/nacl/generator/generate_nacl_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 sys
+
+import interface
+
+
+def _ScriptDir():
+  return os.path.dirname(os.path.abspath(__file__))
+
+
+def _GetDirAbove(dirname):
+  """Returns the directory "above" this file containing |dirname| (which must
+  also be "above" this file)."""
+  path = _ScriptDir()
+  while True:
+    path, tail = os.path.split(path)
+    assert tail
+    if tail == dirname:
+      return path
+
+
+def _AddThirdPartyImportPath():
+  sys.path.append(os.path.join(_GetDirAbove('mojo'), 'third_party'))
+
+
+_AddThirdPartyImportPath()
+import jinja2
+
+loader = jinja2.FileSystemLoader(_ScriptDir())
+jinja_env = jinja2.Environment(loader=loader, keep_trailing_newline=True)
+
+
+# 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):
+    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
+
+  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)
+
+
+# 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 = jinja_env.get_template('libmojo.cc.tmpl')
+
+  code = CodeWriter()
+
+  for f in functions:
+    for line in Wrap('%s %s(' % (f.return_type, f.name), f.ParamList(), ') {'):
+      code << line
+
+    # 2 extra parameters: message ID and return value.
+    num_params = len(f.params) + 2
+
+    with code.Indent():
+      code << 'uint32_t params[%d];' % num_params
+      return_type = f.result_param.base_type
+      if return_type == 'MojoResult':
+        default = 'MOJO_RESULT_INVALID_ARGUMENT'
+      elif return_type == 'MojoTimeTicks':
+        default = '0'
+      else:
+        raise Exception('Unhandled return type: ' + return_type)
+      code << '%s %s = %s;' % (return_type, f.result_param.name, default)
+
+      # Message ID
+      code << 'params[0] = %d;' % f.uid
+      # Parameter pointers
+      cast_template = 'params[%d] = reinterpret_cast<uint32_t>(%s);'
+      for p in f.params:
+        ptr = p.name
+        if p.IsPassedByValue():
+          ptr = '&' + ptr
+        code << cast_template % (p.uid + 1, ptr)
+      # Return value pointer
+      code << cast_template % (num_params - 1, '&' + f.result_param.name)
+
+      code << 'DoMojoCall(params, sizeof(params));'
+      code << 'return %s;' % f.result_param.name
+
+    code << '}'
+    code << ''
+
+  body = code.GetValue()
+  text = template.render(
+    generator_warning=GeneratorWarning(),
+    body=body)
+  out.write(text)
+
+
+# Parameters passed into trusted code are handled differently depending on
+# details of the parameter.  ParamImpl instances encapsulate these differences
+# and are used to generate the code that transfers parameters across the
+# untrusted/trusted boundary.
+class ParamImpl(object):
+  def __init__(self, param):
+    self.param = param
+
+  # Declare whatever variables are needed to handle this particular parameter.
+  def DeclareVars(self, code):
+    raise NotImplementedError()
+
+  # Convert the untrusted representation of the parameter into a trusted
+  # representation, such as a scalar value or a trusted pointer into the
+  # untrusted address space.
+  def ConvertParam(self):
+    raise NotImplementedError()
+
+  # For this particular parameter, what expression should be passed when
+  # invoking the trusted Mojo API function?
+  def CallParam(self):
+    raise NotImplementedError()
+
+  # After invoking the trusted Mojo API function, transfer data back into
+  # untrusted memory.  Overriden for Out and InOut parameters.
+  def CopyOut(self, code):
+    pass
+
+  # Converting array parameters needs to be defered until after the scalar
+  # parameter containing the size of the array has itself been converted.
+  def IsArray(self):
+    return False
+
+
+class ScalarInputImpl(ParamImpl):
+  def DeclareVars(self, code):
+    code << '%s %s_value;' % (self.param.base_type, 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.base_type, self.param.name)
+    code << '%s %s_value;' % (self.param.base_type, 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.base_type, self.param.name)
+    code << '%s %s_value;' % (self.param.base_type, self.param.name)
+
+  def ConvertParam(self):
+    p = self.param
+    return ('ConvertScalarInOut(nap, params[%d], %s, &%s_value, &%s_ptr)' %
+            (p.uid + 1, CBool(p.is_optional), p.name, p.name))
+
+  def CallParam(self):
+    name = self.param.name
+    expr = '&%s_value' % name
+    if self.param.is_optional:
+      expr = '%s_ptr ? %s : NULL' % (name, expr)
+    return expr
+
+  def CopyOut(self, code):
+    name = self.param.name
+    if self.param.is_optional:
+      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.param_type, self.param.name)
+
+  def ConvertParam(self):
+    p = self.param
+    if p.base_type == 'void':
+      element_size = '1'
+    else:
+      element_size = 'sizeof(*%s)' % p.name
+
+    return ('ConvertArray(nap, params[%d], %s, %s, %s, &%s)' %
+            (p.uid + 1, p.size + '_value', element_size, CBool(p.is_optional),
+             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.param_type, self.param.name)
+
+  def ConvertParam(self):
+    p = self.param
+    return ('ConvertStruct(nap, params[%d], %s, &%s)' %
+            (p.uid + 1, CBool(p.is_optional), p.name))
+
+  def CallParam(self):
+    return self.param.name
+
+
+def ImplForParam(p):
+  if p.IsScalar():
+    if p.is_output:
+      if p.is_input:
+        return ScalarInOutImpl(p)
+      else:
+        return ScalarOutputImpl(p)
+    else:
+      return ScalarInputImpl(p)
+  elif p.is_array:
+    return ArrayImpl(p)
+  elif p.is_struct:
+    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 = jinja_env.get_template('mojo_syscall.cc.tmpl')
+
+  code = CodeWriter()
+  code.PushMargin()
+
+  for f in functions:
+    impls = [ImplForParam(p) for p in f.params]
+    impls.append(ImplForParam(f.result_param))
+
+    code << 'case %d:' % f.uid
+
+    code.PushMargin()
+
+    code << '{'
+
+    with code.Indent():
+      num_params = len(f.params) + 2
+      code << 'if (num_params != %d) {' % num_params
+      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 until 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);'
+        for impl in impls:
+          impl.CopyOut(code)
+      code << '}'
+      code << ''
+
+      code << 'return 0;'
+    code << '}'
+
+    code.PopMargin()
+
+  body = code.GetValue()
+  text = template.render(
+    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:])