Mojo + NaCl prototype.

mojo/monacl/gen/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.
+

[Mark Seaborn, 2014/08/26 16:25:52]

Nit: Isn't "gen/" usually for generated code, not for the generator?

[Nick Bray (chromium), 2014/09/03 23:45:02]

Done.

+# 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):
+    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):

[Mark Seaborn, 2014/08/26 16:25:52]

Style nit: should be TemplateFile (see
http://www.chromium.org/chromium-os/python-style-guidelines)

[Nick Bray (chromium), 2014/09/03 23:45:02]

Done.

+  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 seperated 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
+
+
+# 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
+
+    with code.indent():
+      code << "uint32_t params[%d];" % numParams
+      returnType = f.resultParam.baseType
+      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);"
+      for p in f.params:
+        ptr = p.name
+        if p.isPassedByValue():
+          ptr = "&" + ptr
+        code <<  castTemplate % (p.uid + 1, ptr)
+      # 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(
+    script_name=os.path.basename(__file__),
+    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 (numParams != %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 copyLock(nap);"

[Mark Seaborn, 2014/08/26 16:25:52]

Style nit: "copy_lock"

[Nick Bray (chromium), 2014/09/03 23:45:02]

Done.

+        # 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 copyLock(nap);"
+        # TODO copy out on failure?
+        for impl in impls:
+          impl.copyOut(code)
+      code << "}"
+      code << ""
+
+      code << "return 0;"
+    code << "}"
+
+    code.popMargin()
+
+  body = code.getValue()
+  text = template.substitute(
+    script_name=os.path.basename(__file__),
+    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:])