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

ppapi/generators/idl_gen_wrapper.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.
+
+"""Base class for generating wrapper functions for PPAPI methods.
+"""
+
+from datetime import datetime
+import os
+import sys
+
+from idl_ast import IDLAst
+from idl_c_proto import CGen
+from idl_generator import Generator
+from idl_log import ErrOut, InfoOut, WarnOut
+from idl_option import Option
+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 GetHeaderGuard(self, header_filename):
+    g = header_filename.upper().replace(os.path.sep, '_').replace('.','_') + '_'
+    return g
+
+  def GenerateHeaderFile(self, header_filename, out):
+    """Writes out an interface header file for the exported symbols.
+    """
+    self.WriteCopyrightGeneratedTime(out)
+    include_guard = self.GetHeaderGuard(header_filename)
+    out.Write("""
+#ifndef %(include_guard)s
+#define %(include_guard)s
+
+#include "ppapi/c/ppb.h"
+
+/* 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_%(wrapper_prefix)s_PPBGetInterface(PPB_GetInterface real);
+void __set_real_%(wrapper_prefix)s_PPPGetInterface(PPP_GetInterface_type real);
+
+const void *__%(wrapper_prefix)s_PPBGetInterface(const char *name);
+const void *__%(wrapper_prefix)s_PPPGetInterface(const char *name);
+
+struct %(wrapper_struct)s {
+  const char* iface_macro;
+  const void* wrapped_iface; /* If NULL then it was not wrapped! */
+  const void* real_iface;
+};
+
+#endif  /* %(include_guard)s */
+""" % {
+    'include_guard' : include_guard,
+    'timestamp' : datetime.ctime(datetime.now()),
+    'wrapper_prefix' : self.wrapper_prefix,
+    'wrapper_struct' : self.GetWrapperMetadataName(),
+    })
+
+
+  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 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_header_filename, out):
+    """Generate the list of #include that define the original interfaces.
+    """
+    self.WriteCopyrightGeneratedTime(out)
+    # First include own header.
+    out.Write('#include "%s"\n\n' % out_header_filename)
+
+    # 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
+
+    out_header_filename = os.path.splitext(out_filename)[0] + '.h'
+    InfoOut.Log("Generating %s and %s for %s" %
+                (out_filename, out_header_filename, self.wrapper_prefix))
+
+    out_header = IDLOutFile(out_header_filename)
+    self.GenerateHeaderFile(out_header_filename, 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)
+
+    # 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