Pnacl ppapi shim generator (from IDL), based on Noel's first cut.

BUG= http://code.google.com/p/nativeclient/issues/detail?id=2413
TEST= python idl_gen_pnacl.py --test --wnone

Also
** ./generator.py doesn't change
** ./generator.py --wnone --pnacl --pnaclshim=pnacl_shim.c
generates a shim that compiles and works in the NaCl repo.

Review URL: http://codereview.chromium.org/8568025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112244 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 950 insertions, 31 deletions

diff --git a/ppapi/PRESUBMIT.py b/ppapi/PRESUBMIT.py
index 90b809c..227cc41 100644
--- a/ppapi/PRESUBMIT.py
+++ b/ppapi/PRESUBMIT.py
@@ -6,9 +6,43 @@ import os
 import sys
 import subprocess
 
+def RunCmdAndCheck(cmd, ppapi_dir, err_string, output_api):
+  results = []
+  p = subprocess.Popen(cmd, cwd=os.path.join(ppapi_dir, 'generators'),
+                       stdout=subprocess.PIPE,
+                       stderr=subprocess.PIPE)
+  (p_stdout, p_stderr) = p.communicate()
+  if p.returncode:
+    results.append(
+        output_api.PresubmitError(err_string,
+                                  long_text=p_stderr))
+  return results
+
+
+def RunUnittests(input_api, output_api):
+  # Run some Generator unittests if the generator source was changed.
+  results = []
+  files = input_api.LocalPaths()
+  generator_files = []
+  for filename in files:
+    name_parts = filename.split(os.sep)
+    if name_parts[0:2] == ['ppapi', 'generators']:
+      generator_files.append(filename)
+  if generator_files != []:
+    cmd = [ sys.executable, 'idl_gen_pnacl.py', '--wnone', '--test']
+    ppapi_dir = input_api.PresubmitLocalPath()
+    results.extend(RunCmdAndCheck(cmd,
+                                  ppapi_dir,
+                                  'PPAPI IDL Pnacl unittest failed.',
+                                  output_api))
+  return results
+
+
 def CheckChange(input_api, output_api):
   results = []
 
+  results.extend(RunUnittests(input_api, output_api))
+
   # Verify all modified *.idl have a matching *.h
   files = input_api.LocalPaths()
   h_files = []
@@ -51,15 +85,10 @@ def CheckChange(input_api, output_api):
 
   # Only generate output for IDL files references (as *.h or *.idl) in this CL
   cmd.append('--out=' + ','.join([name + '.idl' for name in both]))
-
-  p = subprocess.Popen(cmd, cwd=os.path.join(ppapi_dir, 'generators'),
-                       stdout=subprocess.PIPE,
-                       stderr=subprocess.PIPE)
-  (p_stdout, p_stderr) = p.communicate()
-  if p.returncode:
-    results.append(
-        output_api.PresubmitError('PPAPI IDL Diff detected: Run the generator.',
-                                  long_text=p_stderr))
+  results.extend(RunCmdAndCheck(cmd,
+                                ppapi_dir,
+                                'PPAPI IDL Diff detected: Run the generator.',
+                                output_api))
   return results
 
 def CheckChangeOnUpload(input_api, output_api):
@@ -69,4 +98,3 @@ def CheckChangeOnUpload(input_api, output_api):
 def CheckChangeOnCommit(input_api, output_api):
 #  return []
   return CheckChange(input_api, output_api)
-
diff --git a/ppapi/generators/generator.py b/ppapi/generators/generator.py
index a6065cd..3bb4ff5 100755
--- a/ppapi/generators/generator.py
+++ b/ppapi/generators/generator.py
@@ -6,14 +6,13 @@
 
 import sys
 
-from idl_ast import IDLAst
+# Note: some of these files are imported to register cmdline options.
 from idl_generator import Generator
-from idl_log import ErrOut, InfoOut, WarnOut
-from idl_node import IDLAttribute, IDLNode
-from idl_option import GetOption, Option, ParseOptions
+from idl_option import ParseOptions
 from idl_outfile import IDLOutFile
 from idl_parser import ParseFiles
 from idl_c_header import HGen
+from idl_gen_pnacl import PnaclGen
 
 
 def Main(args):
@@ -29,4 +28,3 @@ if __name__ == '__main__':
   if not args: args = ['--wnone', '--cgen', '--range=start,end']
 
   sys.exit(Main(args))
-
diff --git a/ppapi/generators/idl_c_proto.py b/ppapi/generators/idl_c_proto.py
index 584cfaa..861f86f 100644
--- a/ppapi/generators/idl_c_proto.py
+++ b/ppapi/generators/idl_c_proto.py
@@ -342,7 +342,7 @@ class CGen(object):
   #   rtype - The store or return type of the object.
   #   name - The name of the object.
   #   arrays - A list of array dimensions as [] or [<fixed_num>].
-  #   args -  None of not a function, otherwise  a list of parameters.
+  #   args -  None if not a function, otherwise a list of parameters.
   #
   def GetComponents(self, node, release, mode):
     self.LogEnter('GetComponents mode %s for %s %s' % (mode, node, release))
@@ -375,17 +375,23 @@ class CGen(object):
     return (rtype, name, arrayspec, callspec)
 
 
-  def Compose(self, rtype, name, arrayspec, callspec, prefix, func_as_ptr):
+  def Compose(self, rtype, name, arrayspec, callspec, prefix, func_as_ptr,
+              ptr_prefix, include_name):
     self.LogEnter('Compose: %s %s' % (rtype, name))
     arrayspec = ''.join(arrayspec)
-    name = '%s%s%s' % (prefix, name, arrayspec)
+    if not include_name:
+      name = prefix + arrayspec
+    else:
+      name = prefix + name + arrayspec
     if callspec is None:
       out = '%s %s' % (rtype, name)
     else:
       params = []
       for ptype, pname, parray, pspec in callspec:
-        params.append(self.Compose(ptype, pname, parray, pspec, '', True))
-      if func_as_ptr: name = '(*%s)' % name
+        params.append(self.Compose(ptype, pname, parray, pspec, '', True,
+                                   ptr_prefix='', include_name=True))
+      if func_as_ptr:
+        name = '(%s*%s)' % (ptr_prefix, name)
       out = '%s %s(%s)' % (rtype, name, ', '.join(params))
     self.LogExit('Exit Compose: %s' % out)
     return out
@@ -396,11 +402,18 @@ class CGen(object):
   # Returns the 'C' style signature of the object
   #  prefix - A prefix for the object's name
   #  func_as_ptr - Formats a function as a function pointer
+  #  ptr_prefix - A prefix that goes before the "*" for a function pointer
+  #  include_name - If true, include member name in the signature.
+  #                 If false, leave it out. In any case, prefix and ptr_prefix
+  #                 are always included.
   #
-  def GetSignature(self, node, release, mode, prefix='', func_as_ptr=True):
-    self.LogEnter('GetSignature %s %s as func=%s' % (node, mode, func_as_ptr))
+  def GetSignature(self, node, release, mode, prefix='', func_as_ptr=True,
+                   ptr_prefix='', include_name=True):
+    self.LogEnter('GetSignature %s %s as func=%s' %
+                  (node, mode, func_as_ptr))
     rtype, name, arrayspec, callspec = self.GetComponents(node, release, mode)
-    out = self.Compose(rtype, name, arrayspec, callspec, prefix, func_as_ptr)
+    out = self.Compose(rtype, name, arrayspec, callspec, prefix,
+                       func_as_ptr, ptr_prefix, include_name)
     self.LogExit('Exit GetSignature: %s' % out)
     return out
 
@@ -451,12 +464,22 @@ class CGen(object):
     self.LogExit('Exit DefineMember')
     return out
 
-  def DefineStructInternals(self, node, release, suffix='', comment=True):
+  def GetStructName(self, node, release, include_version=False):
+    suffix = ''
+    if include_version:
+      ver_num = node.GetVersion(release)
+      suffix = ('_%s' % ver_num).replace('.', '_')
+    return node.GetName() + suffix
+
+  def DefineStructInternals(self, node, release,
+                            include_version=False, comment=True):
     out = ''
     if node.GetProperty('union'):
-      out += 'union %s%s {\n' % (node.GetName(), suffix)
+      out += 'union %s {\n' % (
+          self.GetStructName(node, release, include_version))
     else:
-      out += 'struct %s%s {\n' % (node.GetName(), suffix)
+      out += 'struct %s {\n' % (
+          self.GetStructName(node, release, include_version))
 
     # Generate Member Functions
     members = []
@@ -476,13 +499,13 @@ class CGen(object):
     build_list = node.GetUniqueReleases(releases)
 
     # Build the most recent one with comments
-    out = self.DefineStructInternals(node, build_list[-1], comment=True)
+    out = self.DefineStructInternals(node, build_list[-1],
+                                     include_version=False, comment=True)
 
     # Build the rest without comments and with the version number appended
     for rel in build_list[0:-1]:
-      ver_num = node.GetVersion(rel)
-      ver = ("_%s" % ver_num).replace('.', '_')
-      out += '\n' + self.DefineStructInternals(node, rel, suffix=ver,
+      out += '\n' + self.DefineStructInternals(node, rel,
+                                               include_version=True,
                                                comment=False)
 
     self.LogExit('Exit DefineStruct')
diff --git a/ppapi/generators/idl_gen_pnacl.py b/ppapi/generators/idl_gen_pnacl.py
new file mode 100644
index 0000000..8116ae8
--- /dev/null
+++ b/ppapi/generators/idl_gen_pnacl.py
@@ -0,0 +1,236 @@
+#!/usr/bin/python
+#
+# Copyright (c) 2011 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.
+
+"""Generator for Pnacl Shim functions that bridges the calling conventions
+between GCC and PNaCl.  """
+
+from datetime import datetime
+import difflib
+import glob
+import os
+import sys
+
+from idl_c_proto import CGen
+from idl_gen_wrapper import Interface, WrapperGen
+from idl_log import ErrOut, InfoOut, WarnOut
+from idl_option import GetOption, Option, ParseOptions
+from idl_parser import ParseFiles
+
+Option('pnaclshim', 'Name of the pnacl shim file.',
+       default='temp_pnacl_shim.c')
+
+Option('disable_pnacl_opt', 'Turn off optimization of pnacl shim.')
+
+
+class PnaclGen(WrapperGen):
+  """PnaclGen generates shim code to bridge the Gcc ABI with PNaCl.
+
+  This subclass of WrapperGenerator takes the IDL sources and
+  generates shim methods for bridging the calling conventions between GCC
+  and PNaCl (LLVM). Some of the PPAPI methods do not need shimming, so
+  this will also detect those situations and provide direct access to the
+  original PPAPI methods (rather than the shim methods).
+  """
+
+  def __init__(self):
+    WrapperGen.__init__(self,
+                        'Pnacl',
+                        'Pnacl Shim Gen',
+                        'pnacl',
+                        'Generate the PNaCl shim.')
+    self.cgen = CGen()
+    self._skip_opt = False
+    self._pnacl_attribute = '__attribute__((pnaclcall))'
+
+  ############################################################
+
+  def OwnHeaderFile(self):
+    """Return the header file that specifies the API of this wrapper.
+    We do not generate the header files.  """
+    return 'ppapi/generators/pnacl_shim.h'
+
+  def InterfaceNeedsWrapper(self, iface, releases):
+    """Return true if the interface has ANY methods that need wrapping.
+    """
+    if self._skip_opt:
+      return True
+    for release in iface.GetUniqueReleases(releases):
+      version = iface.GetVersion(release)
+      if self.InterfaceVersionNeedsWrapping(iface, version):
+        return True
+    return False
+
+
+  def InterfaceVersionNeedsWrapping(self, iface, version):
+    """Return true if the interface+version has ANY methods that
+    need wrapping.
+    """
+    if self._skip_opt:
+      return True
+    for member in iface.GetListOf('Member'):
+      release = member.GetRelease(version)
+      if self.MemberNeedsWrapping(member, release):
+        return True
+    return False
+
+
+  def MemberNeedsWrapping(self, member, release):
+    """Return true if a particular member function at a particular
+    release needs wrapping.
+    """
+    if self._skip_opt:
+      return True
+    if not member.InReleases([release]):
+      return False
+    ret, name, array, args_spec = self.cgen.GetComponents(member,
+                                                          release,
+                                                          'store')
+    return self.TypeNeedsWrapping(ret, []) or self.ArgsNeedWrapping(args_spec)
+
+
+  def ArgsNeedWrapping(self, args):
+    """Return true if any parameter in the list needs wrapping.
+    """
+    for arg in args:
+      (type_str, name, array_dims, more_args) = arg
+      if self.TypeNeedsWrapping(type_str, array_dims):
+        return True
+    return False
+
+
+  def TypeNeedsWrapping(self, type_node, array_dims):
+    """Return true if a parameter type needs wrapping.
+    Currently, this is true for byval aggregates.
+    """
+    is_aggregate = type_node.startswith('struct') or \
+        type_node.startswith('union')
+    is_reference = (type_node.find('*') != -1 or array_dims != [])
+    return is_aggregate and not is_reference
+
+  ############################################################
+
+
+  def GenerateWrapperForPPBMethod(self, iface, member):
+    result = []
+    func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+    sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                 func_prefix, False)
+    result.append('static %s\n%s {\n' % (self._pnacl_attribute, sig))
+    result.append('  const struct %s *iface = %s.real_iface;\n' %
+                  (iface.struct_name, self.GetWrapperInfoName(iface)))
+    ret, name, array, cspec = self.cgen.GetComponents(member,
+                                                      iface.release,
+                                                      'store')
+    ret_str, args_str = self.GetReturnArgs(ret, cspec)
+    result.append('  %siface->%s(%s);\n}\n\n' % (ret_str,
+                                                 member.GetName(), args_str))
+    return result
+
+
+  def GenerateWrapperForPPPMethod(self, iface, member):
+    result = []
+    func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+    sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                 func_prefix, False)
+    result.append('static %s {\n' % sig)
+    result.append('  const struct %s *iface = %s.real_iface;\n' %
+                  (iface.struct_name, self.GetWrapperInfoName(iface)))
+    temp_fp = self.cgen.GetSignature(member, iface.release, 'return',
+                                     'temp_fp',
+                                     func_as_ptr=True,
+                                     ptr_prefix=self._pnacl_attribute + ' ',
+                                     include_name=False)
+    cast = self.cgen.GetSignature(member, iface.release, 'return',
+                                  prefix='',
+                                  func_as_ptr=True,
+                                  ptr_prefix=self._pnacl_attribute + ' ',
+                                  include_name=False)
+    result.append('  %s = ((%s)iface->%s);\n' % (temp_fp,
+                                                 cast,
+                                                 member.GetName()))
+    ret, name, array, cspec = self.cgen.GetComponents(member,
+                                                      iface.release,
+                                                      'store')
+    ret_str, args_str = self.GetReturnArgs(ret, cspec)
+    result.append('  %stemp_fp(%s);\n}\n\n' % (ret_str, args_str))
+    return result
+
+
+  def GenerateRange(self, ast, releases, options):
+    """Generate shim code for a range of releases.
+    """
+    self._skip_opt = GetOption('disable_pnacl_opt')
+    self.SetOutputFile(GetOption('pnaclshim'))
+    return WrapperGen.GenerateRange(self, ast, releases, options)
+
+pnaclgen = PnaclGen()
+
+######################################################################
+# Tests.
+
+# Clean a string representing an object definition and return then string
+# as a single space delimited set of tokens.
+def CleanString(instr):
+  instr = instr.strip()
+  instr = instr.split()
+  return ' '.join(instr)
+
+
+def PrintErrorDiff(old, new):
+  oldlines = old.split(';')
+  newlines = new.split(';')
+  d = difflib.Differ()
+  diff = d.compare(oldlines, newlines)
+  ErrOut.Log('Diff is:\n%s' % '\n'.join(diff))
+
+
+def GetOldTestOutput(ast):
+  # Scan the top-level comments in the IDL file for comparison.
+  old = []
+  for filenode in ast.GetListOf('File'):
+    for node in filenode.GetChildren():
+      instr = node.GetOneOf('Comment')
+      if not instr: continue
+      instr.Dump()
+      old.append(instr.GetName())
+  return CleanString(''.join(old))
+
+
+def TestFiles(filenames, test_releases):
+  ast = ParseFiles(filenames)
+  iface_releases = pnaclgen.DetermineInterfaces(ast, test_releases)
+  new_output = CleanString(pnaclgen.GenerateWrapperForMethods(
+      iface_releases, comments=False))
+  old_output = GetOldTestOutput(ast)
+  if new_output != old_output:
+    PrintErrorDiff(old_output, new_output)
+    ErrOut.Log('Failed pnacl generator test.')
+    return 1
+  else:
+    InfoOut.Log('Passed pnacl generator test.')
+    return 0
+
+
+def Main(args):
+  filenames = ParseOptions(args)
+  test_releases = ['M13', 'M14', 'M15']
+  if not filenames:
+    idldir = os.path.split(sys.argv[0])[0]
+    idldir = os.path.join(idldir, 'test_gen_pnacl', '*.idl')
+    filenames = glob.glob(idldir)
+  filenames = sorted(filenames)
+  if GetOption('test'):
+    # Run the tests.
+    return TestFiles(filenames, test_releases)
+
+  # Otherwise, generate the output file (for potential use as golden file).
+  ast = ParseFiles(filenames)
+  return pnaclgen.GenerateRange(ast, test_releases, filenames)
+
+
+if __name__ == '__main__':
+  retval = Main(sys.argv[1:])
+  sys.exit(retval)
diff --git a/ppapi/generators/idl_gen_wrapper.py b/ppapi/generators/idl_gen_wrapper.py
new file mode 100644
index 0000000..0f3cec8
--- /dev/null
+++ b/ppapi/generators/idl_gen_wrapper.py
@@ -0,0 +1,456 @@
+#!/usr/bin/python
+#
+# Copyright (c) 2011 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.
+
+"""Base class for generating wrapper functions for PPAPI methods.
+"""
+
+from datetime import datetime
+import os
+import sys
+
+from idl_c_proto import CGen
+from idl_generator import Generator
+from idl_log import ErrOut, InfoOut, WarnOut
+from idl_outfile import IDLOutFile
+
+
+class PPKind(object):
+  @staticmethod
+  def ChoosePPFunc(iface, ppb_func, ppp_func):
+    name = iface.node.GetName()
+    if name.startswith("PPP"):
+      return ppp_func
+    elif name.startswith("PPB"):
+      return ppb_func
+    else:
+      raise Exception('Unknown PPKind for ' + name)
+
+
+class Interface(object):
+  """Tracks information about a particular interface version.
+
+  - struct_name: the struct type used by the ppapi headers to hold the
+  method pointers (the vtable).
+  - needs_wrapping: True if a method in the interface needs wrapping.
+  - header_file: the name of the header file that defined this interface.
+  """
+  def __init__(self, interface_node, release, version,
+               struct_name, needs_wrapping, header_file):
+    self.node = interface_node
+    self.release = release
+    self.version = version
+    self.struct_name = struct_name
+    # We may want finer grained filtering (method level), but it is not
+    # yet clear how to actually do that.
+    self.needs_wrapping = needs_wrapping
+    self.header_file = header_file
+
+
+class WrapperGen(Generator):
+  """WrapperGen - An abstract class that generates wrappers for PPAPI methods.
+
+  This generates a wrapper PPB and PPP GetInterface, which directs users
+  to wrapper PPAPI methods. Wrapper PPAPI methods may perform arbitrary
+  work before invoking the real PPAPI method (supplied by the original
+  GetInterface functions).
+
+  Subclasses must implement GenerateWrapperForPPBMethod (and PPP).
+  Optionally, subclasses can implement InterfaceNeedsWrapper to
+  filter out interfaces that do not actually need wrappers (those
+  interfaces can jump directly to the original interface functions).
+  """
+
+  def __init__(self, wrapper_prefix, s1, s2, s3):
+    Generator.__init__(self, s1, s2, s3)
+    self.wrapper_prefix = wrapper_prefix
+    self._skip_opt = False
+    self.output_file = None
+    self.cgen = CGen()
+
+  def SetOutputFile(self, fname):
+    self.output_file = fname
+
+
+  def GenerateRelease(self, ast, release, options):
+    return self.GenerateRange(ast, [release], options)
+
+
+  @staticmethod
+  def GetHeaderName(name):
+    """Get the corresponding ppapi .h file from each IDL filename.
+    """
+    name = os.path.splitext(name)[0] + '.h'
+    return 'ppapi/c/' + name
+
+
+  def WriteCopyrightGeneratedTime(self, out):
+    now = datetime.now()
+    c = """/* Copyright (c) %s 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.
+ */
+
+/* Last generated from IDL: %s. */
+""" % (now.year, datetime.ctime(now))
+    out.Write(c)
+
+  def GetWrapperMetadataName(self):
+    return '__%sWrapperInfo' % self.wrapper_prefix
+
+
+  def GenerateHelperFunctions(self, out):
+    """Generate helper functions to avoid dependencies on libc.
+    """
+    out.Write("""/* Use local strcmp to avoid dependency on libc. */
+static int mystrcmp(const char* s1, const char *s2) {
+  while((*s1 && *s2) && (*s1++ == *s2++));
+  return *(--s1) - *(--s2);
+}\n
+""")
+
+
+  def GenerateFixedFunctions(self, out):
+    """Write out the set of constant functions (those that do not depend on
+    the current Pepper IDL).
+    """
+    out.Write("""
+
+static PPB_GetInterface __real_PPBGetInterface;
+static PPP_GetInterface_Type __real_PPPGetInterface;
+
+void __set_real_%(wrapper_prefix)s_PPBGetInterface(PPB_GetInterface real) {
+  __real_PPBGetInterface = real;
+}
+
+void __set_real_%(wrapper_prefix)s_PPPGetInterface(PPP_GetInterface_Type real) {
+  __real_PPPGetInterface = real;
+}
+
+/* Map interface string -> wrapper metadata */
+static struct %(wrapper_struct)s *%(wrapper_prefix)sPPBShimIface(
+    const char *name) {
+  struct %(wrapper_struct)s **next = s_ppb_wrappers;
+  while (*next != NULL) {
+    if (mystrcmp(name, (*next)->iface_macro) == 0) return *next;
+    ++next;
+  }
+  return NULL;
+}
+
+/* Map interface string -> wrapper metadata */
+static struct %(wrapper_struct)s *%(wrapper_prefix)sPPPShimIface(
+    const char *name) {
+  struct %(wrapper_struct)s **next = s_ppp_wrappers;
+  while (*next != NULL) {
+    if (mystrcmp(name, (*next)->iface_macro) == 0) return *next;
+    ++next;
+  }
+  return NULL;
+}
+
+const void *__%(wrapper_prefix)s_PPBGetInterface(const char *name) {
+  struct %(wrapper_struct)s *wrapper = %(wrapper_prefix)sPPBShimIface(name);
+  if (wrapper == NULL) {
+    /* We don't have an IDL for this, for some reason. Take our chances. */
+    return (*__real_PPBGetInterface)(name);
+  }
+
+  /* Initialize the real_iface if it hasn't been. The wrapper depends on it. */
+  if (wrapper->real_iface == NULL) {
+    const void *iface = (*__real_PPBGetInterface)(name);
+    if (NULL == iface) return NULL;
+    wrapper->real_iface = iface;
+  }
+
+  if (wrapper->wrapped_iface) {
+    return wrapper->wrapped_iface;
+  } else {
+    return wrapper->real_iface;
+  }
+}
+
+const void *__%(wrapper_prefix)s_PPPGetInterface(const char *name) {
+  struct %(wrapper_struct)s *wrapper = %(wrapper_prefix)sPPPShimIface(name);
+  if (wrapper == NULL) {
+    /* We don't have an IDL for this, for some reason. Take our chances. */
+    return (*__real_PPPGetInterface)(name);
+  }
+
+  /* Initialize the real_iface if it hasn't been. The wrapper depends on it. */
+  if (wrapper->real_iface == NULL) {
+    const void *iface = (*__real_PPPGetInterface)(name);
+    if (NULL == iface) return NULL;
+    wrapper->real_iface = iface;
+  }
+
+  if (wrapper->wrapped_iface) {
+    return wrapper->wrapped_iface;
+  } else {
+    return wrapper->real_iface;
+  }
+}
+""" % { 'wrapper_struct' : self.GetWrapperMetadataName(),
+        'wrapper_prefix' : self.wrapper_prefix,
+        } )
+
+
+  ############################################################
+
+  def InterfaceNeedsWrapper(self, iface, releases):
+    """Return true if the interface has ANY methods that need wrapping.
+    """
+    return True
+
+
+  def OwnHeaderFile(self):
+    """Return the header file that specifies the API of this wrapper.
+    We do not generate the header files.  """
+    raise Exception('Child class must implement this')
+
+
+  ############################################################
+
+  def DetermineInterfaces(self, ast, releases):
+    """Get a list of interfaces along with whatever metadata we need.
+    """
+    iface_releases = []
+    for filenode in ast.GetListOf('File'):
+      # If this file has errors, skip it
+      if filenode in self.skip_list:
+        InfoOut.Log('WrapperGen: Skipping %s due to errors\n' %
+                    filenode.GetName())
+        continue
+
+      file_name = self.GetHeaderName(filenode.GetName())
+      ifaces = filenode.GetListOf('Interface')
+      for iface in ifaces:
+        releases_for_iface = iface.GetUniqueReleases(releases)
+        for release in releases_for_iface:
+          version = iface.GetVersion(release)
+          not_latest = release != releases_for_iface[-1]
+          struct_name = self.cgen.GetStructName(iface, release,
+                                                include_version=not_latest)
+          needs_wrap = self.InterfaceVersionNeedsWrapping(iface, version)
+          if not needs_wrap:
+            InfoOut.Log('Interface %s ver %s does not need wrapping' %
+                        (struct_name, version))
+          iface_releases.append(
+              Interface(iface, release, version,
+                        struct_name, needs_wrap, file_name))
+    return iface_releases
+
+
+  def GenerateIncludes(self, iface_releases, out):
+    """Generate the list of #include that define the original interfaces.
+    """
+    self.WriteCopyrightGeneratedTime(out)
+    # First include own header.
+    out.Write('#include "%s"\n\n' % self.OwnHeaderFile())
+
+    # Get typedefs for PPB_GetInterface.
+    out.Write('#include "%s"\n' % self.GetHeaderName('ppb.h'))
+
+    # Get a conservative list of all #includes that are needed,
+    # whether it requires wrapping or not. We currently depend on the macro
+    # string for comparison, even when it is not wrapped, to decide when
+    # to use the original/real interface.
+    header_files = set()
+    for iface in iface_releases:
+      header_files.add(iface.header_file)
+    for header in sorted(header_files):
+      out.Write('#include "%s"\n' % header)
+    out.Write('\n')
+
+
+  def WrapperMethodPrefix(self, iface, release):
+    return '%s_%s_%s_' % (self.wrapper_prefix, release, iface.GetName())
+
+
+  def GetReturnArgs(self, ret_type, args_spec):
+    if ret_type != 'void':
+      ret = 'return '
+    else:
+      ret = ''
+    if args_spec:
+      args = []
+      for arg in args_spec:
+        args.append(arg[1])
+      args = ', '.join(args)
+    else:
+      args = ''
+    return (ret, args)
+
+
+  def GenerateWrapperForPPBMethod(self, iface, member):
+    result = []
+    func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+    sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                 func_prefix, False)
+    result.append('static %s {\n' % sig)
+    result.append(' while(1) { /* Not implemented */ } \n')
+    result.append('}\n')
+    return result
+
+
+  def GenerateWrapperForPPPMethod(self, iface, member):
+    result = []
+    func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+    sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                 func_prefix, False)
+    result.append('static %s {\n' % sig)
+    result.append(' while(1) { /* Not implemented */ } \n')
+    result.append('}\n')
+    return result
+
+
+  def GenerateWrapperForMethods(self, iface_releases, comments=True):
+    """Return a string representing the code for each wrapper method
+    (using a string rather than writing to the file directly for testing.)
+    """
+    result = []
+    for iface in iface_releases:
+      if not iface.needs_wrapping:
+        if comments:
+          result.append('/* Not generating wrapper methods for %s */\n\n' %
+                        iface.struct_name)
+        continue
+      if comments:
+        result.append('/* Begin wrapper methods for %s */\n\n' %
+                      iface.struct_name)
+      generator =  PPKind.ChoosePPFunc(iface,
+                                       self.GenerateWrapperForPPBMethod,
+                                       self.GenerateWrapperForPPPMethod)
+      for member in iface.node.GetListOf('Member'):
+        # Skip the method if it's not actually in the release.
+        if not member.InReleases([iface.release]):
+          continue
+        result.extend(generator(iface, member))
+      if comments:
+        result.append('/* End wrapper methods for %s */\n\n' %
+                      iface.struct_name)
+    return ''.join(result)
+
+
+  def GenerateWrapperInterfaces(self, iface_releases, out):
+    for iface in iface_releases:
+      if not iface.needs_wrapping:
+        out.Write('/* Not generating wrapper interface for %s */\n\n' %
+                  iface.struct_name)
+        continue
+
+      out.Write('struct %s %s_Wrappers_%s = {\n' % (iface.struct_name,
+                                                    self.wrapper_prefix,
+                                                    iface.struct_name))
+      methods = []
+      for member in iface.node.GetListOf('Member'):
+        # Skip the method if it's not actually in the release.
+        if not member.InReleases([iface.release]):
+          continue
+        prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+        cast = self.cgen.GetSignature(member, iface.release, 'return',
+                                      prefix='',
+                                      func_as_ptr=True,
+                                      ptr_prefix='',
+                                      include_name=False)
+        methods.append('  .%s = (%s)&%s%s' % (member.GetName(),
+                                              cast,
+                                              prefix,
+                                              member.GetName()))
+      out.Write('  ' + ',\n  '.join(methods) + '\n')
+      out.Write('};\n\n')
+
+
+  def GetWrapperInfoName(self, iface):
+    return '%s_WrapperInfo_%s' % (self.wrapper_prefix, iface.struct_name)
+
+
+  def GenerateWrapperInfoAndCollection(self, iface_releases, out):
+    for iface in iface_releases:
+      iface_macro = self.cgen.GetInterfaceMacro(iface.node, iface.version)
+      if iface.needs_wrapping:
+        wrap_iface = '(void *) &%s_Wrappers_%s' % (self.wrapper_prefix,
+                                                   iface.struct_name)
+      else:
+        wrap_iface = 'NULL /* Still need slot for real_iface */'
+      out.Write("""static struct %s %s = {
+  .iface_macro = %s,
+  .wrapped_iface = %s,
+  .real_iface = NULL
+};\n\n""" % (self.GetWrapperMetadataName(),
+             self.GetWrapperInfoName(iface),
+             iface_macro,
+             wrap_iface))
+
+    # Now generate NULL terminated arrays of the above wrapper infos.
+    ppb_wrapper_infos = []
+    ppp_wrapper_infos = []
+    for iface in iface_releases:
+      appender = PPKind.ChoosePPFunc(iface,
+                                     ppb_wrapper_infos.append,
+                                     ppp_wrapper_infos.append)
+      appender('  &%s' % self.GetWrapperInfoName(iface))
+    ppb_wrapper_infos.append('  NULL')
+    ppp_wrapper_infos.append('  NULL')
+    out.Write(
+        'static struct %s *s_ppb_wrappers[] = {\n%s\n};\n\n' %
+        (self.GetWrapperMetadataName(), ',\n'.join(ppb_wrapper_infos)))
+    out.Write(
+        'static struct %s *s_ppp_wrappers[] = {\n%s\n};\n\n' %
+        (self.GetWrapperMetadataName(), ',\n'.join(ppp_wrapper_infos)))
+
+
+  def DeclareWrapperInfos(self, iface_releases, out):
+    """The wrapper methods usually need access to the real_iface, so we must
+    declare these wrapper infos ahead of time (there is a circular dependency).
+    """
+    out.Write('/* BEGIN Declarations for all Wrapper Infos */\n\n')
+    for iface in iface_releases:
+      out.Write('static struct %s %s;\n' %
+                (self.GetWrapperMetadataName(), self.GetWrapperInfoName(iface)))
+    out.Write('/* END Declarations for all Wrapper Infos. */\n\n')
+
+
+  def GenerateRange(self, ast, releases, options):
+    """Generate shim code for a range of releases.
+    """
+
+    # Remember to set the output filename before running this.
+    out_filename = self.output_file
+    if out_filename is None:
+      ErrOut.Log('Did not set filename for writing out wrapper\n')
+      return 1
+
+    InfoOut.Log("Generating %s for %s" % (out_filename, self.wrapper_prefix))
+
+    out = IDLOutFile(out_filename)
+
+    # Get a list of all the interfaces along with metadata.
+    iface_releases = self.DetermineInterfaces(ast, releases)
+
+    # Generate the includes.
+    self.GenerateIncludes(iface_releases, out)
+
+    # Write out static helper functions (mystrcmp).
+    self.GenerateHelperFunctions(out)
+
+    # Declare list of WrapperInfo before actual wrapper methods, since
+    # they reference each other.
+    self.DeclareWrapperInfos(iface_releases, out)
+
+    # Generate wrapper functions for each wrapped method in the interfaces.
+    result = self.GenerateWrapperForMethods(iface_releases)
+    out.Write(result)
+
+    # Collect all the wrapper functions into interface structs.
+    self.GenerateWrapperInterfaces(iface_releases, out)
+
+    # Generate a table of the wrapped interface structs that can be looked up.
+    self.GenerateWrapperInfoAndCollection(iface_releases, out)
+
+    # Write out the IDL-invariant functions.
+    self.GenerateFixedFunctions(out)
+    out.Close()
+    return 0
diff --git a/ppapi/generators/idl_generator.py b/ppapi/generators/idl_generator.py
index b6372ee..efc2325 100644
--- a/ppapi/generators/idl_generator.py
+++ b/ppapi/generators/idl_generator.py
@@ -262,4 +262,3 @@ def Main(args):
 if __name__ == '__main__':
   GeneratorReleaseTest('Test Gen', 'testgen', 'Generator Class Test.')
   sys.exit(Main(sys.argv[1:]))
-
diff --git a/ppapi/generators/pnacl_shim.h b/ppapi/generators/pnacl_shim.h
new file mode 100644
index 0000000..1002d07
--- /dev/null
+++ b/ppapi/generators/pnacl_shim.h
@@ -0,0 +1,29 @@
+/* Copyright (c) 2011 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.
+ */
+
+#ifndef PPAPI_GENERATORS_PNACL_SHIM_H_
+#define PPAPI_GENERATORS_PNACL_SHIM_H_
+
+#include "ppapi/c/ppb.h"
+
+/** Defines the interface exposed by the generated wrapper code. */
+
+/* There is not a typedef for PPP_GetInterface_type, but it is currently
+ * the same as PPB_GetInterface. */
+typedef PPB_GetInterface PPP_GetInterface_Type;
+
+void __set_real_Pnacl_PPBGetInterface(PPB_GetInterface real);
+void __set_real_Pnacl_PPPGetInterface(PPP_GetInterface_Type real);
+
+const void *__Pnacl_PPBGetInterface(const char *name);
+const void *__Pnacl_PPPGetInterface(const char *name);
+
+struct __PnaclWrapperInfo {
+  const char* iface_macro;
+  const void* wrapped_iface; /* If NULL then it was not wrapped! */
+  const void* real_iface;
+};
+
+#endif  /* PPAPI_GENERATORS_PNACL_SHIM_H_ */
diff --git a/ppapi/generators/test_gen_pnacl/test_interfaces.idl b/ppapi/generators/test_gen_pnacl/test_interfaces.idl
new file mode 100644
index 0000000..731fce0
--- /dev/null
+++ b/ppapi/generators/test_gen_pnacl/test_interfaces.idl
@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2011 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.
+ */
+
+/**
+ * This file will test that the pnacl-generated wrapper functions match
+ * the comments in this IDL.
+ */
+
+label Chrome {
+  M13 = 0.0,
+  M14 = 1.0,
+  M15 = 2.0
+};
+
+describe {
+  void;
+  mem_t;
+  int32_t;
+};
+
+[passByValue, returnByValue] struct some_struct {
+  mem_t X;
+  int32_t Y;
+};
+
+struct some_struct2 {
+  mem_t X;
+  int32_t Y;
+};
+
+[union, passByValue, returnByValue] struct some_union {
+  mem_t X;
+  int32_t Y;
+};
+
+/*
+ * static __attribute__((pnaclcall)) int32_t
+ * Pnacl_M15_PPB_Iface_struct_wrap_foo1(int32_t a, struct some_struct b) {
+ *   const struct PPB_Iface_struct_wrap *iface =
+ *     Pnacl_WrapperInfo_PPB_Iface_struct_wrap.real_iface;
+ *   return iface->foo1(a, b);
+ * }
+ */
+[version=2.0]
+interface PPB_Iface_struct_wrap {
+  int32_t foo1(int32_t a, [in] some_struct b);
+};
+
+/*
+ * static __attribute__((pnaclcall)) int32_t
+ * Pnacl_M15_PPB_Iface_union_wrap_foo1(int32_t a, union some_union b) {
+ *   const struct PPB_Iface_union_wrap *iface =
+ *     Pnacl_WrapperInfo_PPB_Iface_union_wrap.real_iface;
+ *   return iface->foo1(a, b);
+ * }
+ */
+[version=2.0]
+interface PPB_Iface_union_wrap {
+  int32_t foo1(int32_t a, [in] some_union b);
+};
+
+
+[version=2.0]
+interface PPB_Iface_nowrap {
+  int32_t foo1(int32_t a, [in] some_struct2 b);
+};
+
+
+/*
+ * static __attribute__((pnaclcall))
+ *   int32_t Pnacl_M13_PPB_SomeWrap_foo1(struct some_struct a) {
+ *   const struct PPB_SomeWrap_0_0 *iface =
+ *     Pnacl_WrapperInfo_PPB_SomeWrap_0_0.real_iface;
+ *   return iface->foo1(a);
+ * }
+ * 
+ * static __attribute__((pnaclcall))
+ * struct some_struct Pnacl_M13_PPB_SomeWrap_foo2(int32_t a) {
+ *   const struct PPB_SomeWrap_0_0 *iface =
+ *     Pnacl_WrapperInfo_PPB_SomeWrap_0_0.real_iface;
+ *   return iface->foo2(a);
+ * }
+ */
+[version=0.0]
+interface PPB_SomeWrap {
+  int32_t foo1([in] some_struct a);
+  some_struct foo2([in] int32_t a);
+
+  /* Not generating wrapper methods for PPB_SomeWrap_1_0 */
+  [version=1.0]
+  int32_t foo1([in] some_struct[] a);
+  [version=1.0]
+  void foo2([in] int32_t a, [out] some_struct b);
+
+  /* Not generating wrapper methods for PPB_SomeWrap */
+  [version=2.0]
+  int32_t foo1([in] some_struct2 a);
+};
+
+
+/*
+ * static int32_t Pnacl_M13_PPP_SomeWrap_foo1(struct some_struct a) {
+ *   const struct PPP_SomeWrap_0_0 *iface =
+ *     Pnacl_WrapperInfo_PPP_SomeWrap_0_0.real_iface;
+ *   int32_t (__attribute__((pnaclcall)) *temp_fp)(struct some_struct a) =
+ *  ((int32_t (__attribute__((pnaclcall)) *)(struct some_struct a))iface->foo1);
+ *   return temp_fp(a);
+ * }
+ *
+ * static struct some_struct Pnacl_M13_PPP_SomeWrap_foo2(int32_t a) {
+ *   const struct PPP_SomeWrap_0_0 *iface =
+ *     Pnacl_WrapperInfo_PPP_SomeWrap_0_0.real_iface;
+ *   struct some_struct (__attribute__((pnaclcall)) *temp_fp)(int32_t a) =
+ *  ((struct some_struct (__attribute__((pnaclcall)) *)(int32_t a))iface->foo2);
+ *   return temp_fp(a);
+ * }
+ *
+ * static struct some_struct Pnacl_M14_PPP_SomeWrap_foo2(int32_t a) {
+ *   const struct PPP_SomeWrap_1_0 *iface =
+ *     Pnacl_WrapperInfo_PPP_SomeWrap_1_0.real_iface;
+ * struct some_struct (__attribute__((pnaclcall)) *temp_fp)(int32_t a) =
+ * ((struct some_struct (__attribute__((pnaclcall)) *)(int32_t a))iface->foo2);
+ *   return temp_fp(a);
+ * }
+ *
+ * static int32_t Pnacl_M14_PPP_SomeWrap_foo1(const struct some_struct a[]) {
+ *   const struct PPP_SomeWrap_1_0 *iface =
+ *     Pnacl_WrapperInfo_PPP_SomeWrap_1_0.real_iface;
+ *   int32_t (__attribute__((pnaclcall)) *temp_fp)(const struct some_struct a[]) =
+ *  ((int32_t (__attribute__((pnaclcall)) *)(const struct some_struct a[]))iface->foo1);
+ *   return temp_fp(a);
+ * }
+ */
+[version=0.0]
+interface PPP_SomeWrap {
+  int32_t foo1([in] some_struct a);
+  some_struct foo2([in] int32_t a);
+
+  [version=1.0]
+  int32_t foo1([in] some_struct[] a);
+
+  /* Not generating wrapper interface for PPP_SomeWrap */
+  [version=2.0]
+  int32_t foo1([in] some_struct2 a);
+  [version=2.0]
+  void foo2([in] int32_t a);
+};