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

ppapi/generators/idl_gen_pnacl.py

+#!/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 bridge the calling conventions
+between GCC and PNaCl.  """
+
+from datetime import datetime
+import os
+import sys
+
+from idl_log import ErrOut, InfoOut, WarnOut
+from idl_ast import IDLAst
+from idl_option import GetOption, Option, ParseOptions
+from idl_outfile import IDLOutFile
+from idl_c_proto import CGen
+from idl_generator import Generator
+
+Option('pnaclshim', 'Name of the pnacl shim file.',
+       default=os.path.join('..',
+                            'native_client',
+                            'src',
+                            'shared',
+                            'ppapi_proxy',
+                            'pnacl_shim.c'))
+
+
+# TODO(jvoung): this doesn't do anything yet (except change some dbg messages).
+Option('disable_pnacl_opt', 'Turn off optimization of pnacl shim.')
+
+
+class PPKind(object):
+  @staticmethod
+  def ChoosePPFunc(iface, ppb_func, ppp_func):
+    name = iface.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
+  - pnacl_id: the ID assigned to it in the PNaCl shim namespace
+  - struct_name: the struct type used by the ppapi headers to hold the
+      method pointers (the vtable).
+  - needs_wrapping: True if there is a method in the interface that needs
+      shimming
+  - header_file: the name of the header file that defined this interface
+  """
+  def __init__(self, interface_node, release, version,
+               pnacl_id, struct_name, needs_wrapping, header_file):
+    self.node = interface_node
+    self.release = release
+    self.version = version
+    self.pnacl_id = pnacl_id
+    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 PnaclGen(Generator):
+  """PnaclGen - A subclass of Generator which takes the IDL sources and
+  generates shim code for bridging the calling conventions between GCC
+  and PNaCl (LLVM).
+  """
+
+  def __init__(self):
+    Generator.__init__(self,
+                       'Pnacl Shim Gen',
+                       'pnacl',
+                       'Generate the PNaCl shim.')
+    self.cgen = CGen()
+    self._skip_opt = False
+    self._pnacl_attribute = ' __attribute__((pnaclcall)) '
+
+
+  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 GenerateHeaderFile(self, out):
+    """ Writes out an interface header file for the exported symbols.  """
+    self.WriteCopyrightGeneratedTime(out)
+    out.Write("""
+#ifndef %(include_guard)s
+#define %(include_guard)s
+
+#include "ppapi/c/ppb.h"
+
+PPB_GetInterface real_PPBGetInterface;
+/* There is not a typedef for PPP_GetInterface, but it is currently the same as
+   PPB_GetInterface. */
+PPB_GetInterface real_PPPGetInterface;
+
+void set_real_PPBGetInterface(PPB_GetInterface real);
+void set_real_PPPGetInterface(PPB_GetInterface real);
+
+const void *Pnacl_PPBGetInterface(const char *name);
+const void *Pnacl_PPPGetInterface(const char *name);
+
+#endif  /* %(include_guard)s */
+""" % {
+    "include_guard" : "PNACL_SHIM_H_",
+    "timestamp" : datetime.ctime(datetime.now()),
+    })
+
+
+  def GenerateFixedFunctions(self, out):
+    """ Write out the set of constant functions (do not depend on the
+    current Pepper IDL. """
+    out.Write("""
+
+void set_real_PPBGetInterface(PPB_GetInterface real) {
+  real_PPBGetInterface = real;
+}
+
+void set_real_PPPGetInterface(PPB_GetInterface real) {
+  real_PPPGetInterface = real;
+}
+
+const void *Pnacl_PPBGetInterface(const char *name) {
+  int wrapped;
+  int id = PnaclShimIfaceID(name, &wrapped);
+  if (id < 0) return NULL;
+
+  if (s_realPtrs[id] == NULL) {
+    const void *iface = (*real_PPBGetInterface)(name);
+    if (NULL == iface) return NULL;
+    s_realPtrs[id] = iface;
+  }
+
+  if (wrapped) {
+    return s_wrapPtrs[id];
+  } else {
+    return s_realPtrs[id];
+  }
+}
+
+const void *Pnacl_PPPGetInterface(const char *name) {
+  int wrapped;
+  int id = PnaclShimIfaceID(name, &wrapped);
+  if (id < 0) return NULL;
+
+  if (s_realPtrs[id] == NULL) {
+    const void *iface = (*real_PPPGetInterface)(name);
+    if (NULL == iface) return NULL;
+    s_realPtrs[id] = iface;
+  }
+
+  if (wrapped) {
+    return s_wrapPtrs[id];
+  } else {
+    return s_realPtrs[id];
+  }
+}
+""")
+
+  def PnaclIdForInterfaceVersion(self, iface, version):
+    return 'PNACL_%s_%s' % (iface.GetName(), str(version).replace('.', '_'))
+
+
+  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):
+        return True
+    return False
+
+
+  def TypeNeedsWrapping(self, type_node):
+    """ 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
+    return is_aggregate and not is_reference
+
+
+  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:
+        print 'PnaclGen: 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)
+          pnacl_id = self.PnaclIdForInterfaceVersion(iface, version)
+          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:
+            print 'Interface %s does not need wrapping' % pnacl_id
+          iface_releases.append(
+              Interface(iface, release, version, pnacl_id,
+                        struct_name, needs_wrap, file_name))
+    return iface_releases
+
+
+  def GenerateIncludes(self, iface_releases, out_header_filename, out):
+    """ Write out the includes and other headers and return a list
+    of the interface nodes that were ultimately included. """
+    self.WriteCopyrightGeneratedTime(out)
+    # First include own header.
+    out.Write('#include "%s"\n\n' % out_header_filename)
+
+    # Include libc headers for strcmp.
+    out.Write('#include <string.h>\n\n')
+
+    # 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.
+    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)
+
+
+  def EnumerateInterfaces(self, iface_releases, out):
+    # Get a conservative list of all IDs needed (even it not wrapped).
+    # We will need the IDs anyway to write the "real" version out.
+    out.Write('\nenum PnaclId {\n')
+    for iface in iface_releases:
+      out.Write('  %s,\n' % iface.pnacl_id)
+    out.Write('  PNACL_IFACE_COUNT\n')
+    out.Write('};\n\n')
+    out.Write('static const void *s_realPtrs[PNACL_IFACE_COUNT];\n\n');
+
+    # Also create a function that maps interface name to ID. The ID will be
+    # used to look up the wrapped interface in a table
+    # (so really it's string -> interface, but there is an ID in the middle).
+    out.Write('/* Map interface string -> pnacl ID */\n')
+    out.Write('static enum PnaclId PnaclShimIfaceID(const char *name, ' +
+              'int *wrapped) {\n')
+    for iface in iface_releases:
+      if iface.needs_wrapping:
+        wrap_str = '*wrapped = 1'
+      else:
+        wrap_str = '*wrapped = 0'
+      iface_macro = self.cgen.GetInterfaceMacro(iface.node, iface.version)
+      out.Write("""  if (!strcmp(name, %s)) {
+    %s;
+    return %s;
+  }\n""" %  (iface_macro, wrap_str, iface.pnacl_id))
+
+    out.Write('  return -1;\n}\n\n')
+
+
+  def WrapperMethodPrefix(self, iface, release):
+    return 'PNACL_%s_%s_' % (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 GenerateWrapperForPPBMethods(self, iface, out):
+    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
+      func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+      sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                   func_prefix, False)
+      out.Write('static %s %s {\n' % (self._pnacl_attribute, sig))
+      out.Write('  const struct %s *iface = s_realPtrs[%s];\n' % (
+          iface.struct_name, iface.pnacl_id))
+      ret, name, array, cspec = self.cgen.GetComponents(member,
+                                                        iface.release,
+                                                        'store')
+      ret_str, args_str = self.GetReturnArgs(ret, cspec)
+      out.Write('  %siface->%s(%s);\n}\n\n' % (ret_str,
+                                               member.GetName(), args_str))
+
+
+  def GenerateWrapperForPPPMethods(self, iface, out):
+    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
+      func_prefix = self.WrapperMethodPrefix(iface.node, iface.release)
+      sig = self.cgen.GetSignature(member, iface.release, 'store',
+                                   func_prefix, False)
+      out.Write('static %s {\n' % sig)
+      out.Write('  const struct %s *iface = s_realPtrs[%s];\n' % (
+          iface.struct_name, iface.pnacl_id))
+      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)
+      out.Write('  %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)
+      out.Write('  %stemp_fp(%s);\n}\n\n' % (ret_str,
+                                             args_str))
+
+
+  def GenerateWrapperForMethods(self, iface_releases, releases, out):
+    for iface in iface_releases:
+      if not iface.needs_wrapping:
+        out.Write('/* Not generating wrappers for %s */\n' % iface.struct_name)
+        continue
+      generator =  PPKind.ChoosePPFunc(iface.node,
+                                       self.GenerateWrapperForPPBMethods,
+                                       self.GenerateWrapperForPPPMethods)
+      generator(iface, out)
+
+
+  def GenerateWrapperInterfaces(self, iface_releases, releases, out):
+    for iface in iface_releases:
+      if not iface.needs_wrapping:
+        out.Write('/* Not generating wrappers for %s */\n' % iface.struct_name)
+        continue
+
+      out.Write('struct %s PNACL_Wrappers_%s = {\n' % (iface.struct_name,
+                                                       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')
+
+    # Write out a collection of the pnacl wrapper functions.
+    out.Write('static const void *s_wrapPtrs[PNACL_IFACE_COUNT + 1] = {\n')
+    for iface in iface_releases:
+      if not iface.needs_wrapping:
+        out.Write('/* Not generating wrappers for %s */\n' % iface.struct_name)
+        continue
+      out.Write('  (void *) &PNACL_Wrappers_%s,\n' % iface.struct_name)
+    out.Write('  NULL\n};\n\n')
+
+
+  def GenerateRange(self, ast, releases, options):
+    """ Generate shim code for a range of releases.  """
+
+    self._skip_opt = GetOption('disable_pnacl_opt')
+
+    out_filename = GetOption('pnaclshim')
+    out_header_filename = os.path.splitext(out_filename)[0] + '.h'
+    print "Generating %s and %s" % (out_filename, out_header_filename)
+
+    out_header = IDLOutFile(out_header_filename)
+    self.GenerateHeaderFile(out_header)
+    out_header.Close()
+
+    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_header_filename, out)
+
+    # Assign each interface an ID number which is listed in an ENUM.
+    self.EnumerateInterfaces(iface_releases, out)
+
+    # Generate wrapper functions for each wrapped method in the interfaces.
+    self.GenerateWrapperForMethods(iface_releases, releases, out)
+
+    # Collect all the wrapper functions into interface structs. Then generate
+    # a table of the wrapped interface structs that can be looked up.
+    self.GenerateWrapperInterfaces(iface_releases, releases, out)
+
+    # Write out the IDL-invariant functions.
+    self.GenerateFixedFunctions(out)
+    out.Close()
+    return 0
+
+
+pnaclgen = PnaclGen()