gyp/generator/android.py

# Copyright (c) 2012 Google Inc. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# Notes:
#
# This generates makefiles suitable for inclusion into the Android build system
# via an Android.mk file. It is based on make.py, the standard makefile
# generator.
#
# The code below generates a separate .mk file for each target, but
# all are sourced by the top-level GypAndroid.mk.  This means that all
# variables in .mk-files clobber one another, and furthermore that any
# variables set potentially clash with other Android build system variables.
# Try to avoid setting global variables where possible.

from __future__ import print_function

import gyp
import gyp.common
import gyp.generator.make as make  # Reuse global functions from make backend.
import os
import re
import subprocess

generator_default_variables = {
  'OS': 'android',
  'EXECUTABLE_PREFIX': '',
  'EXECUTABLE_SUFFIX': '',
  'STATIC_LIB_PREFIX': 'lib',
  'SHARED_LIB_PREFIX': 'lib',
  'STATIC_LIB_SUFFIX': '.a',
  'SHARED_LIB_SUFFIX': '.so',
  'INTERMEDIATE_DIR': '$(gyp_intermediate_dir)',
  'SHARED_INTERMEDIATE_DIR': '$(gyp_shared_intermediate_dir)',
  'PRODUCT_DIR': '$(gyp_shared_intermediate_dir)',
  'SHARED_LIB_DIR': '$(builddir)/lib.$(TOOLSET)',
  'LIB_DIR': '$(obj).$(TOOLSET)',
  'RULE_INPUT_ROOT': '%(INPUT_ROOT)s',  # This gets expanded by Python.
  'RULE_INPUT_DIRNAME': '%(INPUT_DIRNAME)s',  # This gets expanded by Python.
  'RULE_INPUT_PATH': '$(RULE_SOURCES)',
  'RULE_INPUT_EXT': '$(suffix $<)',
  'RULE_INPUT_NAME': '$(notdir $<)',
  'CONFIGURATION_NAME': '$(GYP_CONFIGURATION)',
}

# Make supports multiple toolsets
generator_supports_multiple_toolsets = True


# Generator-specific gyp specs.
generator_additional_non_configuration_keys = [
    # Boolean to declare that this target does not want its name mangled.
    'android_unmangled_name',
    # Map of android build system variables to set.
    'aosp_build_settings',
]
generator_additional_path_sections = []
generator_extra_sources_for_rules = []


ALL_MODULES_FOOTER = """\
# "gyp_all_modules" is a concatenation of the "gyp_all_modules" targets from
# all the included sub-makefiles. This is just here to clarify.
gyp_all_modules:
"""

header = """\
# This file is generated by gyp; do not edit.

"""

# Map gyp target types to Android module classes.
MODULE_CLASSES = {
    'static_library': 'STATIC_LIBRARIES',
    'shared_library': 'SHARED_LIBRARIES',
    'executable': 'EXECUTABLES',
}


def IsCPPExtension(ext):
  return make.COMPILABLE_EXTENSIONS.get(ext) == 'cxx'


def Sourceify(path):
  """Convert a path to its source directory form. The Android backend does not
     support options.generator_output, so this function is a noop."""
  return path


# Map from qualified target to path to output.
# For Android, the target of these maps is a tuple ('static', 'modulename'),
# ('dynamic', 'modulename'), or ('path', 'some/path') instead of a string,
# since we link by module.
target_outputs = {}
# Map from qualified target to any linkable output.  A subset
# of target_outputs.  E.g. when mybinary depends on liba, we want to
# include liba in the linker line; when otherbinary depends on
# mybinary, we just want to build mybinary first.
target_link_deps = {}


class AndroidMkWriter(object):
  """AndroidMkWriter packages up the writing of one target-specific Android.mk.

  Its only real entry point is Write(), and is mostly used for namespacing.
  """

  def __init__(self, android_top_dir):
    self.android_top_dir = android_top_dir

  def Write(self, qualified_target, relative_target, base_path, output_filename,
            spec, configs, part_of_all, write_alias_target, sdk_version):
    """The main entry point: writes a .mk file for a single target.

    Arguments:
      qualified_target: target we're generating
      relative_target: qualified target name relative to the root
      base_path: path relative to source root we're building in, used to resolve
                 target-relative paths
      output_filename: output .mk file name to write
      spec, configs: gyp info
      part_of_all: flag indicating this target is part of 'all'
      write_alias_target: flag indicating whether to create short aliases for
                          this target
      sdk_version: what to emit for LOCAL_SDK_VERSION in output
    """
    gyp.common.EnsureDirExists(output_filename)

    self.fp = open(output_filename, 'w')

    self.fp.write(header)

    self.qualified_target = qualified_target
    self.relative_target = relative_target
    self.path = base_path
    self.target = spec['target_name']
    self.type = spec['type']
    self.toolset = spec['toolset']

    deps, link_deps = self.ComputeDeps(spec)

    # Some of the generation below can add extra output, sources, or
    # link dependencies.  All of the out params of the functions that
    # follow use names like extra_foo.
    extra_outputs = []
    extra_sources = []

    self.android_class = MODULE_CLASSES.get(self.type, 'GYP')
    self.android_module = self.ComputeAndroidModule(spec)
    (self.android_stem, self.android_suffix) = self.ComputeOutputParts(spec)
    self.output = self.output_binary = self.ComputeOutput(spec)

    # Standard header.
    self.WriteLn('include $(CLEAR_VARS)\n')

    # Module class and name.
    self.WriteLn('LOCAL_MODULE_CLASS := ' + self.android_class)
    self.WriteLn('LOCAL_MODULE := ' + self.android_module)
    # Only emit LOCAL_MODULE_STEM if it's different to LOCAL_MODULE.
    # The library module classes fail if the stem is set. ComputeOutputParts
    # makes sure that stem == modulename in these cases.
    if self.android_stem != self.android_module:
      self.WriteLn('LOCAL_MODULE_STEM := ' + self.android_stem)
    self.WriteLn('LOCAL_MODULE_SUFFIX := ' + self.android_suffix)
    if self.toolset == 'host':
      self.WriteLn('LOCAL_IS_HOST_MODULE := true')
      self.WriteLn('LOCAL_MULTILIB := $(GYP_HOST_MULTILIB)')
    elif sdk_version > 0:
      self.WriteLn('LOCAL_MODULE_TARGET_ARCH := '
                   '$(TARGET_$(GYP_VAR_PREFIX)ARCH)')
      self.WriteLn('LOCAL_SDK_VERSION := %s' % sdk_version)

    # Grab output directories; needed for Actions and Rules.
    if self.toolset == 'host':
      self.WriteLn('gyp_intermediate_dir := '
                   '$(call local-intermediates-dir,,$(GYP_HOST_VAR_PREFIX))')
    else:
      self.WriteLn('gyp_intermediate_dir := '
                   '$(call local-intermediates-dir,,$(GYP_VAR_PREFIX))')
    self.WriteLn('gyp_shared_intermediate_dir := '
                 '$(call intermediates-dir-for,GYP,shared,,,$(GYP_VAR_PREFIX))')
    self.WriteLn()

    # List files this target depends on so that actions/rules/copies/sources
    # can depend on the list.
    # TODO: doesn't pull in things through transitive link deps; needed?
    target_dependencies = [x[1] for x in deps if x[0] == 'path']
    self.WriteLn('# Make sure our deps are built first.')
    self.WriteList(target_dependencies, 'GYP_TARGET_DEPENDENCIES',
                   local_pathify=True)

    # Actions must come first, since they can generate more OBJs for use below.
    if 'actions' in spec:
      self.WriteActions(spec['actions'], extra_sources, extra_outputs)

    # Rules must be early like actions.
    if 'rules' in spec:
      self.WriteRules(spec['rules'], extra_sources, extra_outputs)

    if 'copies' in spec:
      self.WriteCopies(spec['copies'], extra_outputs)

    # GYP generated outputs.
    self.WriteList(extra_outputs, 'GYP_GENERATED_OUTPUTS', local_pathify=True)

    # Set LOCAL_ADDITIONAL_DEPENDENCIES so that Android's build rules depend
    # on both our dependency targets and our generated files.
    self.WriteLn('# Make sure our deps and generated files are built first.')
    self.WriteLn('LOCAL_ADDITIONAL_DEPENDENCIES := $(GYP_TARGET_DEPENDENCIES) '
                 '$(GYP_GENERATED_OUTPUTS)')
    self.WriteLn()

    # Sources.
    if spec.get('sources', []) or extra_sources:
      self.WriteSources(spec, configs, extra_sources)

    self.WriteTarget(spec, configs, deps, link_deps, part_of_all,
                     write_alias_target)

    # Update global list of target outputs, used in dependency tracking.
    target_outputs[qualified_target] = ('path', self.output_binary)

    # Update global list of link dependencies.
    if self.type == 'static_library':
      target_link_deps[qualified_target] = ('static', self.android_module)
    elif self.type == 'shared_library':
      target_link_deps[qualified_target] = ('shared', self.android_module)

    self.fp.close()
    return self.android_module


  def WriteActions(self, actions, extra_sources, extra_outputs):
    """Write Makefile code for any 'actions' from the gyp input.

    extra_sources: a list that will be filled in with newly generated source
                   files, if any
    extra_outputs: a list that will be filled in with any outputs of these
                   actions (used to make other pieces dependent on these
                   actions)
    """
    for action in actions:
      name = make.StringToMakefileVariable('%s_%s' % (self.relative_target,
                                                      action['action_name']))
      self.WriteLn('### Rules for action "%s":' % action['action_name'])
      inputs = action['inputs']
      outputs = action['outputs']

      # Build up a list of outputs.
      # Collect the output dirs we'll need.
      dirs = set()
      for out in outputs:
        if not out.startswith('$'):
          print('WARNING: Action for target "%s" writes output to local path '
                 '"%s".' % (self.target, out))
        dir = os.path.split(out)[0]
        if dir:
          dirs.add(dir)
      if int(action.get('process_outputs_as_sources', False)):
        extra_sources += outputs

      # Prepare the actual command.
      command = gyp.common.EncodePOSIXShellList(action['action'])
      if 'message' in action:
        quiet_cmd = 'Gyp action: %s ($@)' % action['message']
      else:
        quiet_cmd = 'Gyp action: %s ($@)' % name
      if len(dirs) > 0:
        command = 'mkdir -p %s' % ' '.join(dirs) + '; ' + command

      cd_action = 'cd $(gyp_local_path)/%s; ' % self.path
      command = cd_action + command

      # The makefile rules are all relative to the top dir, but the gyp actions
      # are defined relative to their containing dir.  This replaces the gyp_*
      # variables for the action rule with an absolute version so that the
      # output goes in the right place.
      # Only write the gyp_* rules for the "primary" output (:1);
      # it's superfluous for the "extra outputs", and this avoids accidentally
      # writing duplicate dummy rules for those outputs.
      main_output = make.QuoteSpaces(self.LocalPathify(outputs[0]))
      self.WriteLn('%s: gyp_local_path := $(LOCAL_PATH)' % main_output)
      self.WriteLn('%s: gyp_var_prefix := $(GYP_VAR_PREFIX)' % main_output)
      self.WriteLn('%s: gyp_intermediate_dir := '
                   '$(abspath $(gyp_intermediate_dir))' % main_output)
      self.WriteLn('%s: gyp_shared_intermediate_dir := '
                   '$(abspath $(gyp_shared_intermediate_dir))' % main_output)

      # Android's envsetup.sh adds a number of directories to the path including
      # the built host binary directory. This causes actions/rules invoked by
      # gyp to sometimes use these instead of system versions, e.g. bison.
      # The built host binaries may not be suitable, and can cause errors.
      # So, we remove them from the PATH using the ANDROID_BUILD_PATHS variable
      # set by envsetup.
      self.WriteLn('%s: export PATH := $(subst $(ANDROID_BUILD_PATHS),,$(PATH))'
                   % main_output)

      # Don't allow spaces in input/output filenames, but make an exception for
      # filenames which start with '$(' since it's okay for there to be spaces
      # inside of make function/macro invocations.
      for input in inputs:
        if not input.startswith('$(') and ' ' in input:
          raise gyp.common.GypError(
              'Action input filename "%s" in target %s contains a space' %
              (input, self.target))
      for output in outputs:
        if not output.startswith('$(') and ' ' in output:
          raise gyp.common.GypError(
              'Action output filename "%s" in target %s contains a space' %
              (output, self.target))

      self.WriteLn('%s: %s $(GYP_TARGET_DEPENDENCIES)' %
                   (main_output, ' '.join(map(self.LocalPathify, inputs))))
      self.WriteLn('\t@echo "%s"' % quiet_cmd)
      self.WriteLn('\t$(hide)%s\n' % command)
      for output in outputs[1:]:
        # Make each output depend on the main output, with an empty command
        # to force make to notice that the mtime has changed.
        self.WriteLn('%s: %s ;' % (self.LocalPathify(output), main_output))

      extra_outputs += outputs
      self.WriteLn()

    self.WriteLn()


  def WriteRules(self, rules, extra_sources, extra_outputs):
    """Write Makefile code for any 'rules' from the gyp input.

    extra_sources: a list that will be filled in with newly generated source
                   files, if any
    extra_outputs: a list that will be filled in with any outputs of these
                   rules (used to make other pieces dependent on these rules)
    """
    if len(rules) == 0:
      return

    for rule in rules:
      if len(rule.get('rule_sources', [])) == 0:
        continue
      name = make.StringToMakefileVariable('%s_%s' % (self.relative_target,
                                                      rule['rule_name']))
      self.WriteLn('\n### Generated for rule "%s":' % name)
      self.WriteLn('# "%s":' % rule)

      inputs = rule.get('inputs')
      for rule_source in rule.get('rule_sources', []):
        (rule_source_dirname, rule_source_basename) = os.path.split(rule_source)
        (rule_source_root, rule_source_ext) = \
            os.path.splitext(rule_source_basename)

        outputs = [self.ExpandInputRoot(out, rule_source_root,
                                        rule_source_dirname)
                   for out in rule['outputs']]

        dirs = set()
        for out in outputs:
          if not out.startswith('$'):
            print('WARNING: Rule for target %s writes output to local path %s'
                   % (self.target, out))
          dir = os.path.dirname(out)
          if dir:
            dirs.add(dir)
        extra_outputs += outputs
        if int(rule.get('process_outputs_as_sources', False)):
          extra_sources.extend(outputs)

        components = []
        for component in rule['action']:
          component = self.ExpandInputRoot(component, rule_source_root,
                                           rule_source_dirname)
          if '$(RULE_SOURCES)' in component:
            component = component.replace('$(RULE_SOURCES)',
                                          rule_source)
          components.append(component)

        command = gyp.common.EncodePOSIXShellList(components)
        cd_action = 'cd $(gyp_local_path)/%s; ' % self.path
        command = cd_action + command
        if dirs:
          command = 'mkdir -p %s' % ' '.join(dirs) + '; ' + command

        # We set up a rule to build the first output, and then set up
        # a rule for each additional output to depend on the first.
        outputs = map(self.LocalPathify, outputs)
        main_output = outputs[0]
        self.WriteLn('%s: gyp_local_path := $(LOCAL_PATH)' % main_output)
        self.WriteLn('%s: gyp_var_prefix := $(GYP_VAR_PREFIX)' % main_output)
        self.WriteLn('%s: gyp_intermediate_dir := '
                     '$(abspath $(gyp_intermediate_dir))' % main_output)
        self.WriteLn('%s: gyp_shared_intermediate_dir := '
                     '$(abspath $(gyp_shared_intermediate_dir))' % main_output)

        # See explanation in WriteActions.
        self.WriteLn('%s: export PATH := '
                     '$(subst $(ANDROID_BUILD_PATHS),,$(PATH))' % main_output)

        main_output_deps = self.LocalPathify(rule_source)
        if inputs:
          main_output_deps += ' '
          main_output_deps += ' '.join([self.LocalPathify(f) for f in inputs])

        self.WriteLn('%s: %s $(GYP_TARGET_DEPENDENCIES)' %
                     (main_output, main_output_deps))
        self.WriteLn('\t%s\n' % command)
        for output in outputs[1:]:
          # Make each output depend on the main output, with an empty command
          # to force make to notice that the mtime has changed.
          self.WriteLn('%s: %s ;' % (output, main_output))
        self.WriteLn()

    self.WriteLn()


  def WriteCopies(self, copies, extra_outputs):
    """Write Makefile code for any 'copies' from the gyp input.

    extra_outputs: a list that will be filled in with any outputs of this action
                   (used to make other pieces dependent on this action)
    """
    self.WriteLn('### Generated for copy rule.')

    variable = make.StringToMakefileVariable(self.relative_target + '_copies')
    outputs = []
    for copy in copies:
      for path in copy['files']:
        # The Android build system does not allow generation of files into the
        # source tree. The destination should start with a variable, which will
        # typically be $(gyp_intermediate_dir) or
        # $(gyp_shared_intermediate_dir). Note that we can't use an assertion
        # because some of the gyp tests depend on this.
        if not copy['destination'].startswith('$'):
          print('WARNING: Copy rule for target %s writes output to '
                 'local path %s' % (self.target, copy['destination']))

        # LocalPathify() calls normpath, stripping trailing slashes.
        path = Sourceify(self.LocalPathify(path))
        filename = os.path.split(path)[1]
        output = Sourceify(self.LocalPathify(os.path.join(copy['destination'],
                                                          filename)))

        self.WriteLn('%s: %s $(GYP_TARGET_DEPENDENCIES) | $(ACP)' %
                     (output, path))
        self.WriteLn('\t@echo Copying: $@')
        self.WriteLn('\t$(hide) mkdir -p $(dir $@)')
        self.WriteLn('\t$(hide) $(ACP) -rpf $< $@')
        self.WriteLn()
        outputs.append(output)
    self.WriteLn('%s = %s' % (variable,
                              ' '.join(map(make.QuoteSpaces, outputs))))
    extra_outputs.append('$(%s)' % variable)
    self.WriteLn()


  def WriteSourceFlags(self, spec, configs):
    """Write out the flags and include paths used to compile source files for
    the current target.

    Args:
      spec, configs: input from gyp.
    """
    for configname, config in sorted(configs.items()):
      extracted_includes = []

      self.WriteLn('\n# Flags passed to both C and C++ files.')
      cflags, includes_from_cflags = self.ExtractIncludesFromCFlags(
          config.get('cflags', []) + config.get('cflags_c', []))
      extracted_includes.extend(includes_from_cflags)
      self.WriteList(cflags, 'MY_CFLAGS_%s' % configname)

      self.WriteList(config.get('defines'), 'MY_DEFS_%s' % configname,
                     prefix='-D', quoter=make.EscapeCppDefine)

      self.WriteLn('\n# Include paths placed before CFLAGS/CPPFLAGS')
      includes = list(config.get('include_dirs', []))
      includes.extend(extracted_includes)
      includes = map(Sourceify, map(self.LocalPathify, includes))
      includes = self.NormalizeIncludePaths(includes)
      self.WriteList(includes, 'LOCAL_C_INCLUDES_%s' % configname)

      self.WriteLn('\n# Flags passed to only C++ (and not C) files.')
      self.WriteList(config.get('cflags_cc'), 'LOCAL_CPPFLAGS_%s' % configname)

    self.WriteLn('\nLOCAL_CFLAGS := $(MY_CFLAGS_$(GYP_CONFIGURATION)) '
                 '$(MY_DEFS_$(GYP_CONFIGURATION))')
    # Undefine ANDROID for host modules
    # TODO: the source code should not use macro ANDROID to tell if it's host
    # or target module.
    if self.toolset == 'host':
      self.WriteLn('# Undefine ANDROID for host modules')
      self.WriteLn('LOCAL_CFLAGS += -UANDROID')
    self.WriteLn('LOCAL_C_INCLUDES := $(GYP_COPIED_SOURCE_ORIGIN_DIRS) '
                                     '$(LOCAL_C_INCLUDES_$(GYP_CONFIGURATION))')
    self.WriteLn('LOCAL_CPPFLAGS := $(LOCAL_CPPFLAGS_$(GYP_CONFIGURATION))')
    # Android uses separate flags for assembly file invocations, but gyp expects
    # the same CFLAGS to be applied:
    self.WriteLn('LOCAL_ASFLAGS := $(LOCAL_CFLAGS)')


  def WriteSources(self, spec, configs, extra_sources):
    """Write Makefile code for any 'sources' from the gyp input.
    These are source files necessary to build the current target.
    We need to handle shared_intermediate directory source files as
    a special case by copying them to the intermediate directory and
    treating them as a genereated sources. Otherwise the Android build
    rules won't pick them up.

    Args:
      spec, configs: input from gyp.
      extra_sources: Sources generated from Actions or Rules.
    """
    sources = filter(make.Compilable, spec.get('sources', []))
    generated_not_sources = [x for x in extra_sources if not make.Compilable(x)]
    extra_sources = filter(make.Compilable, extra_sources)

    # Determine and output the C++ extension used by these sources.
    # We simply find the first C++ file and use that extension.
    all_sources = sources + extra_sources
    local_cpp_extension = '.cpp'
    for source in all_sources:
      (root, ext) = os.path.splitext(source)
      if IsCPPExtension(ext):
        local_cpp_extension = ext
        break
    if local_cpp_extension != '.cpp':
      self.WriteLn('LOCAL_CPP_EXTENSION := %s' % local_cpp_extension)

    # We need to move any non-generated sources that are coming from the
    # shared intermediate directory out of LOCAL_SRC_FILES and put them
    # into LOCAL_GENERATED_SOURCES. We also need to move over any C++ files
    # that don't match our local_cpp_extension, since Android will only
    # generate Makefile rules for a single LOCAL_CPP_EXTENSION.
    local_files = []
    for source in sources:
      (root, ext) = os.path.splitext(source)
      if '$(gyp_shared_intermediate_dir)' in source:
        extra_sources.append(source)
      elif '$(gyp_intermediate_dir)' in source:
        extra_sources.append(source)
      elif IsCPPExtension(ext) and ext != local_cpp_extension:
        extra_sources.append(source)
      else:
        local_files.append(os.path.normpath(os.path.join(self.path, source)))

    # For any generated source, if it is coming from the shared intermediate
    # directory then we add a Make rule to copy them to the local intermediate
    # directory first. This is because the Android LOCAL_GENERATED_SOURCES
    # must be in the local module intermediate directory for the compile rules
    # to work properly. If the file has the wrong C++ extension, then we add
    # a rule to copy that to intermediates and use the new version.
    final_generated_sources = []
    # If a source file gets copied, we still need to add the original source
    # directory as header search path, for GCC searches headers in the
    # directory that contains the source file by default.
    origin_src_dirs = []
    for source in extra_sources:
      local_file = source
      if not '$(gyp_intermediate_dir)/' in local_file:
        basename = os.path.basename(local_file)
        local_file = '$(gyp_intermediate_dir)/' + basename
      (root, ext) = os.path.splitext(local_file)
      if IsCPPExtension(ext) and ext != local_cpp_extension:
        local_file = root + local_cpp_extension
      if local_file != source:
        self.WriteLn('%s: %s' % (local_file, self.LocalPathify(source)))
        self.WriteLn('\tmkdir -p $(@D); cp $< $@')
        origin_src_dirs.append(os.path.dirname(source))
      final_generated_sources.append(local_file)

    # We add back in all of the non-compilable stuff to make sure that the
    # make rules have dependencies on them.
    final_generated_sources.extend(generated_not_sources)
    self.WriteList(final_generated_sources, 'LOCAL_GENERATED_SOURCES')

    origin_src_dirs = gyp.common.uniquer(origin_src_dirs)
    origin_src_dirs = map(Sourceify, map(self.LocalPathify, origin_src_dirs))
    self.WriteList(origin_src_dirs, 'GYP_COPIED_SOURCE_ORIGIN_DIRS')

    self.WriteList(local_files, 'LOCAL_SRC_FILES')

    # Write out the flags used to compile the source; this must be done last
    # so that GYP_COPIED_SOURCE_ORIGIN_DIRS can be used as an include path.
    self.WriteSourceFlags(spec, configs)


  def ComputeAndroidModule(self, spec):
    """Return the Android module name used for a gyp spec.

    We use the complete qualified target name to avoid collisions between
    duplicate targets in different directories. We also add a suffix to
    distinguish gyp-generated module names.
    """

    if int(spec.get('android_unmangled_name', 0)):
      assert self.type != 'shared_library' or self.target.startswith('lib')
      return self.target

    if self.type == 'shared_library':
      # For reasons of convention, the Android build system requires that all
      # shared library modules are named 'libfoo' when generating -l flags.
      prefix = 'lib_'
    else:
      prefix = ''

    if spec['toolset'] == 'host':
      suffix = '_$(TARGET_$(GYP_VAR_PREFIX)ARCH)_host_gyp'
    else:
      suffix = '_gyp'

    if self.path:
      middle = make.StringToMakefileVariable('%s_%s' % (self.path, self.target))
    else:
      middle = make.StringToMakefileVariable(self.target)

    return ''.join([prefix, middle, suffix])


  def ComputeOutputParts(self, spec):
    """Return the 'output basename' of a gyp spec, split into filename + ext.

    Android libraries must be named the same thing as their module name,
    otherwise the linker can't find them, so product_name and so on must be
    ignored if we are building a library, and the "lib" prepending is
    not done for Android.
    """
    assert self.type != 'loadable_module' # TODO: not supported?

    target = spec['target_name']
    target_prefix = ''
    target_ext = ''
    if self.type == 'static_library':
      target = self.ComputeAndroidModule(spec)
      target_ext = '.a'
    elif self.type == 'shared_library':
      target = self.ComputeAndroidModule(spec)
      target_ext = '.so'
    elif self.type == 'none':
      target_ext = '.stamp'
    elif self.type != 'executable':
      print("ERROR: What output file should be generated?",
             "type", self.type, "target", target)

    if self.type != 'static_library' and self.type != 'shared_library':
      target_prefix = spec.get('product_prefix', target_prefix)
      target = spec.get('product_name', target)
      product_ext = spec.get('product_extension')
      if product_ext:
        target_ext = '.' + product_ext

    target_stem = target_prefix + target
    return (target_stem, target_ext)


  def ComputeOutputBasename(self, spec):
    """Return the 'output basename' of a gyp spec.

    E.g., the loadable module 'foobar' in directory 'baz' will produce
      'libfoobar.so'
    """
    return ''.join(self.ComputeOutputParts(spec))


  def ComputeOutput(self, spec):
    """Return the 'output' (full output path) of a gyp spec.

    E.g., the loadable module 'foobar' in directory 'baz' will produce
      '$(obj)/baz/libfoobar.so'
    """
    if self.type == 'executable':
      # We install host executables into shared_intermediate_dir so they can be
      # run by gyp rules that refer to PRODUCT_DIR.
      path = '$(gyp_shared_intermediate_dir)'
    elif self.type == 'shared_library':
      if self.toolset == 'host':
        path = '$($(GYP_HOST_VAR_PREFIX)HOST_OUT_INTERMEDIATE_LIBRARIES)'
      else:
        path = '$($(GYP_VAR_PREFIX)TARGET_OUT_INTERMEDIATE_LIBRARIES)'
    else:
      # Other targets just get built into their intermediate dir.
      if self.toolset == 'host':
        path = ('$(call intermediates-dir-for,%s,%s,true,,'
                '$(GYP_HOST_VAR_PREFIX))' % (self.android_class,
                                             self.android_module))
      else:
        path = ('$(call intermediates-dir-for,%s,%s,,,$(GYP_VAR_PREFIX))'
                % (self.android_class, self.android_module))

    assert spec.get('product_dir') is None # TODO: not supported?
    return os.path.join(path, self.ComputeOutputBasename(spec))

  def NormalizeIncludePaths(self, include_paths):
    """ Normalize include_paths.
    Convert absolute paths to relative to the Android top directory.

    Args:
      include_paths: A list of unprocessed include paths.
    Returns:
      A list of normalized include paths.
    """
    normalized = []
    for path in include_paths:
      if path[0] == '/':
        path = gyp.common.RelativePath(path, self.android_top_dir)
      normalized.append(path)
    return normalized

  def ExtractIncludesFromCFlags(self, cflags):
    """Extract includes "-I..." out from cflags

    Args:
      cflags: A list of compiler flags, which may be mixed with "-I.."
    Returns:
      A tuple of lists: (clean_clfags, include_paths). "-I.." is trimmed.
    """
    clean_cflags = []
    include_paths = []
    for flag in cflags:
      if flag.startswith('-I'):
        include_paths.append(flag[2:])
      else:
        clean_cflags.append(flag)

    return (clean_cflags, include_paths)

  def FilterLibraries(self, libraries):
    """Filter the 'libraries' key to separate things that shouldn't be ldflags.

    Library entries that look like filenames should be converted to android
    module names instead of being passed to the linker as flags.

    Args:
      libraries: the value of spec.get('libraries')
    Returns:
      A tuple (static_lib_modules, dynamic_lib_modules, ldflags)
    """
    static_lib_modules = []
    dynamic_lib_modules = []
    ldflags = []
    for libs in libraries:
      # Libs can have multiple words.
      for lib in libs.split():
        # Filter the system libraries, which are added by default by the Android
        # build system.
        if (lib == '-lc' or lib == '-lstdc++' or lib == '-lm' or
            lib.endswith('libgcc.a')):
          continue
        match = re.search(r'([^/]+)\.a$', lib)
        if match:
          static_lib_modules.append(match.group(1))
          continue
        match = re.search(r'([^/]+)\.so$', lib)
        if match:
          dynamic_lib_modules.append(match.group(1))
          continue
        if lib.startswith('-l'):
          ldflags.append(lib)
    return (static_lib_modules, dynamic_lib_modules, ldflags)


  def ComputeDeps(self, spec):
    """Compute the dependencies of a gyp spec.

    Returns a tuple (deps, link_deps), where each is a list of
    filenames that will need to be put in front of make for either
    building (deps) or linking (link_deps).
    """
    deps = []
    link_deps = []
    if 'dependencies' in spec:
      deps.extend([target_outputs[dep] for dep in spec['dependencies']
                   if target_outputs[dep]])
      for dep in spec['dependencies']:
        if dep in target_link_deps:
          link_deps.append(target_link_deps[dep])
      deps.extend(link_deps)
    return (gyp.common.uniquer(deps), gyp.common.uniquer(link_deps))


  def WriteTargetFlags(self, spec, configs, link_deps):
    """Write Makefile code to specify the link flags and library dependencies.

    spec, configs: input from gyp.
    link_deps: link dependency list; see ComputeDeps()
    """
    # Libraries (i.e. -lfoo)
    # These must be included even for static libraries as some of them provide
    # implicit include paths through the build system.
    libraries = gyp.common.uniquer(spec.get('libraries', []))
    static_libs, dynamic_libs, ldflags_libs = self.FilterLibraries(libraries)

    if self.type != 'static_library':
      for configname, config in sorted(configs.items()):
        ldflags = list(config.get('ldflags', []))
        self.WriteLn('')
        self.WriteList(ldflags, 'LOCAL_LDFLAGS_%s' % configname)
      self.WriteList(ldflags_libs, 'LOCAL_GYP_LIBS')
      self.WriteLn('LOCAL_LDFLAGS := $(LOCAL_LDFLAGS_$(GYP_CONFIGURATION)) '
                   '$(LOCAL_GYP_LIBS)')

    # Link dependencies (i.e. other gyp targets this target depends on)
    # These need not be included for static libraries as within the gyp build
    # we do not use the implicit include path mechanism.
    if self.type != 'static_library':
      static_link_deps = [x[1] for x in link_deps if x[0] == 'static']
      shared_link_deps = [x[1] for x in link_deps if x[0] == 'shared']
    else:
      static_link_deps = []
      shared_link_deps = []

    # Only write the lists if they are non-empty.
    if static_libs or static_link_deps:
      self.WriteLn('')
      self.WriteList(static_libs + static_link_deps,
                     'LOCAL_STATIC_LIBRARIES')
      self.WriteLn('# Enable grouping to fix circular references')
      self.WriteLn('LOCAL_GROUP_STATIC_LIBRARIES := true')
    if dynamic_libs or shared_link_deps:
      self.WriteLn('')
      self.WriteList(dynamic_libs + shared_link_deps,
                     'LOCAL_SHARED_LIBRARIES')


  def WriteTarget(self, spec, configs, deps, link_deps, part_of_all,
                  write_alias_target):
    """Write Makefile code to produce the final target of the gyp spec.

    spec, configs: input from gyp.
    deps, link_deps: dependency lists; see ComputeDeps()
    part_of_all: flag indicating this target is part of 'all'
    write_alias_target: flag indicating whether to create short aliases for this
                        target
    """
    self.WriteLn('### Rules for final target.')

    if self.type != 'none':
      self.WriteTargetFlags(spec, configs, link_deps)

    settings = spec.get('aosp_build_settings', {})
    if settings:
      self.WriteLn('### Set directly by aosp_build_settings.')
      for k, v in settings.items():
        if isinstance(v, list):
          self.WriteList(v, k)
        else:
          self.WriteLn('%s := %s' % (k, make.QuoteIfNecessary(v)))
      self.WriteLn('')

    # Add to the set of targets which represent the gyp 'all' target. We use the
    # name 'gyp_all_modules' as the Android build system doesn't allow the use
    # of the Make target 'all' and because 'all_modules' is the equivalent of
    # the Make target 'all' on Android.
    if part_of_all and write_alias_target:
      self.WriteLn('# Add target alias to "gyp_all_modules" target.')
      self.WriteLn('.PHONY: gyp_all_modules')
      self.WriteLn('gyp_all_modules: %s' % self.android_module)
      self.WriteLn('')

    # Add an alias from the gyp target name to the Android module name. This
    # simplifies manual builds of the target, and is required by the test
    # framework.
    if self.target != self.android_module and write_alias_target:
      self.WriteLn('# Alias gyp target name.')
      self.WriteLn('.PHONY: %s' % self.target)
      self.WriteLn('%s: %s' % (self.target, self.android_module))
      self.WriteLn('')

    # Add the command to trigger build of the target type depending
    # on the toolset. Ex: BUILD_STATIC_LIBRARY vs. BUILD_HOST_STATIC_LIBRARY
    # NOTE: This has to come last!
    modifier = ''
    if self.toolset == 'host':
      modifier = 'HOST_'
    if self.type == 'static_library':
      self.WriteLn('include $(BUILD_%sSTATIC_LIBRARY)' % modifier)
    elif self.type == 'shared_library':
      self.WriteLn('LOCAL_PRELINK_MODULE := false')
      self.WriteLn('include $(BUILD_%sSHARED_LIBRARY)' % modifier)
    elif self.type == 'executable':
      self.WriteLn('LOCAL_CXX_STL := libc++_static')
      # Executables are for build and test purposes only, so they're installed
      # to a directory that doesn't get included in the system image.
      self.WriteLn('LOCAL_MODULE_PATH := $(gyp_shared_intermediate_dir)')
      self.WriteLn('include $(BUILD_%sEXECUTABLE)' % modifier)
    else:
      self.WriteLn('LOCAL_MODULE_PATH := $(PRODUCT_OUT)/gyp_stamp')
      self.WriteLn('LOCAL_UNINSTALLABLE_MODULE := true')
      if self.toolset == 'target':
        self.WriteLn('LOCAL_2ND_ARCH_VAR_PREFIX := $(GYP_VAR_PREFIX)')
      else:
        self.WriteLn('LOCAL_2ND_ARCH_VAR_PREFIX := $(GYP_HOST_VAR_PREFIX)')
      self.WriteLn()
      self.WriteLn('include $(BUILD_SYSTEM)/base_rules.mk')
      self.WriteLn()
      self.WriteLn('$(LOCAL_BUILT_MODULE): $(LOCAL_ADDITIONAL_DEPENDENCIES)')
      self.WriteLn('\t$(hide) echo "Gyp timestamp: $@"')
      self.WriteLn('\t$(hide) mkdir -p $(dir $@)')
      self.WriteLn('\t$(hide) touch $@')
      self.WriteLn()
      self.WriteLn('LOCAL_2ND_ARCH_VAR_PREFIX :=')


  def WriteList(self, value_list, variable=None, prefix='',
                quoter=make.QuoteIfNecessary, local_pathify=False):
    """Write a variable definition that is a list of values.

    E.g. WriteList(['a','b'], 'foo', prefix='blah') writes out
         foo = blaha blahb
    but in a pretty-printed style.
    """
    values = ''
    if value_list:
      value_list = [quoter(prefix + l) for l in value_list]
      if local_pathify:
        value_list = [self.LocalPathify(l) for l in value_list]
      values = ' \\\n\t' + ' \\\n\t'.join(value_list)
    self.fp.write('%s :=%s\n\n' % (variable, values))


  def WriteLn(self, text=''):
    self.fp.write(text + '\n')


  def LocalPathify(self, path):
    """Convert a subdirectory-relative path into a normalized path which starts
    with the make variable $(LOCAL_PATH) (i.e. the top of the project tree).
    Absolute paths, or paths that contain variables, are just normalized."""
    if '$(' in path or os.path.isabs(path):
      # path is not a file in the project tree in this case, but calling
      # normpath is still important for trimming trailing slashes.
      return os.path.normpath(path)
    local_path = os.path.join('$(LOCAL_PATH)', self.path, path)
    local_path = os.path.normpath(local_path)
    # Check that normalizing the path didn't ../ itself out of $(LOCAL_PATH)
    # - i.e. that the resulting path is still inside the project tree. The
    # path may legitimately have ended up containing just $(LOCAL_PATH), though,
    # so we don't look for a slash.
    assert local_path.startswith('$(LOCAL_PATH)'), (
           'Path %s attempts to escape from gyp path %s !)' % (path, self.path))
    return local_path


  def ExpandInputRoot(self, template, expansion, dirname):
    if '%(INPUT_ROOT)s' not in template and '%(INPUT_DIRNAME)s' not in template:
      return template
    path = template % {
        'INPUT_ROOT': expansion,
        'INPUT_DIRNAME': dirname,
        }
    return os.path.normpath(path)


def PerformBuild(data, configurations, params):
  # The android backend only supports the default configuration.
  options = params['options']
  makefile = os.path.abspath(os.path.join(options.toplevel_dir,
                                          'GypAndroid.mk'))
  env = dict(os.environ)
  env['ONE_SHOT_MAKEFILE'] = makefile
  arguments = ['make', '-C', os.environ['ANDROID_BUILD_TOP'], 'gyp_all_modules']
  print('Building: %s' % arguments)
  subprocess.check_call(arguments, env=env)


def GenerateOutput(target_list, target_dicts, data, params):
  options = params['options']
  generator_flags = params.get('generator_flags', {})
  builddir_name = generator_flags.get('output_dir', 'out')
  limit_to_target_all = generator_flags.get('limit_to_target_all', False)
  write_alias_targets = generator_flags.get('write_alias_targets', True)
  sdk_version = generator_flags.get('aosp_sdk_version', 0)
  android_top_dir = os.environ.get('ANDROID_BUILD_TOP')
  assert android_top_dir, '$ANDROID_BUILD_TOP not set; you need to run lunch.'

  def CalculateMakefilePath(build_file, base_name):
    """Determine where to write a Makefile for a given gyp file."""
    # Paths in gyp files are relative to the .gyp file, but we want
    # paths relative to the source root for the master makefile.  Grab
    # the path of the .gyp file as the base to relativize against.
    # E.g. "foo/bar" when we're constructing targets for "foo/bar/baz.gyp".
    base_path = gyp.common.RelativePath(os.path.dirname(build_file),
                                        options.depth)
    # We write the file in the base_path directory.
    output_file = os.path.join(options.depth, base_path, base_name)
    assert not options.generator_output, (
        'The Android backend does not support options.generator_output.')
    base_path = gyp.common.RelativePath(os.path.dirname(build_file),
                                        options.toplevel_dir)
    return base_path, output_file

  # TODO:  search for the first non-'Default' target.  This can go
  # away when we add verification that all targets have the
  # necessary configurations.
  default_configuration = None
  toolsets = set([target_dicts[target]['toolset'] for target in target_list])
  for target in target_list:
    spec = target_dicts[target]
    if spec['default_configuration'] != 'Default':
      default_configuration = spec['default_configuration']
      break
  if not default_configuration:
    default_configuration = 'Default'

  srcdir = '.'
  makefile_name = 'GypAndroid' + options.suffix + '.mk'
  makefile_path = os.path.join(options.toplevel_dir, makefile_name)
  assert not options.generator_output, (
      'The Android backend does not support options.generator_output.')
  gyp.common.EnsureDirExists(makefile_path)
  root_makefile = open(makefile_path, 'w')

  root_makefile.write(header)

  # We set LOCAL_PATH just once, here, to the top of the project tree. This
  # allows all the other paths we use to be relative to the Android.mk file,
  # as the Android build system expects.
  root_makefile.write('\nLOCAL_PATH := $(call my-dir)\n')

  # Find the list of targets that derive from the gyp file(s) being built.
  needed_targets = set()
  for build_file in params['build_files']:
    for target in gyp.common.AllTargets(target_list, target_dicts, build_file):
      needed_targets.add(target)

  build_files = set()
  include_list = set()
  android_modules = {}
  for qualified_target in target_list:
    build_file, target, toolset = gyp.common.ParseQualifiedTarget(
        qualified_target)
    relative_build_file = gyp.common.RelativePath(build_file,
                                                  options.toplevel_dir)
    build_files.add(relative_build_file)
    included_files = data[build_file]['included_files']
    for included_file in included_files:
      # The included_files entries are relative to the dir of the build file
      # that included them, so we have to undo that and then make them relative
      # to the root dir.
      relative_include_file = gyp.common.RelativePath(
          gyp.common.UnrelativePath(included_file, build_file),
          options.toplevel_dir)
      abs_include_file = os.path.abspath(relative_include_file)
      # If the include file is from the ~/.gyp dir, we should use absolute path
      # so that relocating the src dir doesn't break the path.
      if (params['home_dot_gyp'] and
          abs_include_file.startswith(params['home_dot_gyp'])):
        build_files.add(abs_include_file)
      else:
        build_files.add(relative_include_file)

    base_path, output_file = CalculateMakefilePath(build_file,
        target + '.' + toolset + options.suffix + '.mk')

    spec = target_dicts[qualified_target]
    configs = spec['configurations']

    part_of_all = qualified_target in needed_targets
    if limit_to_target_all and not part_of_all:
      continue

    relative_target = gyp.common.QualifiedTarget(relative_build_file, target,
                                                 toolset)
    writer = AndroidMkWriter(android_top_dir)
    android_module = writer.Write(qualified_target, relative_target, base_path,
                                  output_file, spec, configs,
                                  part_of_all=part_of_all,
                                  write_alias_target=write_alias_targets,
                                  sdk_version=sdk_version)
    if android_module in android_modules:
      print('ERROR: Android module names must be unique. The following '
             'targets both generate Android module name %s.\n  %s\n  %s' %
             (android_module, android_modules[android_module],
              qualified_target))
      return
    android_modules[android_module] = qualified_target

    # Our root_makefile lives at the source root.  Compute the relative path
    # from there to the output_file for including.
    mkfile_rel_path = gyp.common.RelativePath(output_file,
                                              os.path.dirname(makefile_path))
    include_list.add(mkfile_rel_path)

  root_makefile.write('GYP_CONFIGURATION ?= %s\n' % default_configuration)
  root_makefile.write('GYP_VAR_PREFIX ?=\n')
  root_makefile.write('GYP_HOST_VAR_PREFIX ?=\n')
  root_makefile.write('GYP_HOST_MULTILIB ?= first\n')

  # Write out the sorted list of includes.
  root_makefile.write('\n')
  for include_file in sorted(include_list):
    root_makefile.write('include $(LOCAL_PATH)/' + include_file + '\n')
  root_makefile.write('\n')

  if write_alias_targets:
    root_makefile.write(ALL_MODULES_FOOTER)

  root_makefile.close()