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// Copyright (c) 2013 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.
#include "gn/ninja_target_writer.h"
#include <sstream>
#include "base/files/file_util.h"
#include "base/strings/string_util.h"
#include "gn/config_values_extractors.h"
#include "gn/err.h"
#include "gn/escape.h"
#include "gn/filesystem_utils.h"
#include "gn/general_tool.h"
#include "gn/ninja_action_target_writer.h"
#include "gn/ninja_binary_target_writer.h"
#include "gn/ninja_bundle_data_target_writer.h"
#include "gn/ninja_copy_target_writer.h"
#include "gn/ninja_create_bundle_target_writer.h"
#include "gn/ninja_generated_file_target_writer.h"
#include "gn/ninja_group_target_writer.h"
#include "gn/ninja_utils.h"
#include "gn/output_file.h"
#include "gn/scheduler.h"
#include "gn/string_output_buffer.h"
#include "gn/string_utils.h"
#include "gn/substitution_writer.h"
#include "gn/target.h"
#include "gn/trace.h"
NinjaTargetWriter::NinjaTargetWriter(const Target* target, std::ostream& out)
: settings_(target->settings()),
NinjaTargetWriter::~NinjaTargetWriter() = default;
// static
std::string NinjaTargetWriter::RunAndWriteFile(const Target* target) {
const Settings* settings = target->settings();
ScopedTrace trace(TraceItem::TRACE_FILE_WRITE,
if (g_scheduler->verbose_logging())
g_scheduler->Log("Computing", target->label().GetUserVisibleName(true));
// It's ridiculously faster to write to a string and then write that to
// disk in one operation than to use an fstream here.
StringOutputBuffer storage;
std::ostream rules(&storage);
// Call out to the correct sub-type of writer. Binary targets need to be
// written to separate files for compiler flag scoping, but other target
// types can have their rules coalesced.
// In ninja, if a rule uses a variable (like $include_dirs) it will use
// the value set by indenting it under the build line or it takes the value
// from the end of the invoking scope (otherwise the current file). It does
// not copy the value from what it was when the build line was encountered.
// To avoid writing lots of duplicate rules for defines and cflags, etc. on
// each source file build line, we use separate .ninja files with the shared
// variables set at the top.
// Groups and actions don't use this type of flag, they make unique rules
// or write variables scoped under each build line. As a result, they don't
// need the separate files.
bool needs_file_write = false;
if (target->output_type() == Target::BUNDLE_DATA) {
NinjaBundleDataTargetWriter writer(target, rules);
} else if (target->output_type() == Target::CREATE_BUNDLE) {
NinjaCreateBundleTargetWriter writer(target, rules);
} else if (target->output_type() == Target::COPY_FILES) {
NinjaCopyTargetWriter writer(target, rules);
} else if (target->output_type() == Target::ACTION ||
target->output_type() == Target::ACTION_FOREACH) {
NinjaActionTargetWriter writer(target, rules);
} else if (target->output_type() == Target::GROUP) {
NinjaGroupTargetWriter writer(target, rules);
} else if (target->output_type() == Target::GENERATED_FILE) {
NinjaGeneratedFileTargetWriter writer(target, rules);
} else if (target->IsBinary()) {
needs_file_write = true;
NinjaBinaryTargetWriter writer(target, rules);
} else {
CHECK(0) << "Output type of target not handled.";
if (needs_file_write) {
// Write the ninja file.
SourceFile ninja_file = GetNinjaFileForTarget(target);
base::FilePath full_ninja_file =
storage.WriteToFileIfChanged(full_ninja_file, nullptr);
EscapeOptions options;
options.mode = ESCAPE_NINJA;
// Return the subninja command to load the rules file.
std::string result = "subninja ";
OutputFile(target->settings()->build_settings(), ninja_file).value(),
options, nullptr));
return result;
// No separate file required, just return the rules.
return storage.str();
void NinjaTargetWriter::WriteEscapedSubstitution(const Substitution* type) {
EscapeOptions opts;
opts.mode = ESCAPE_NINJA;
out_ << type->ninja_name << " = ";
out_, SubstitutionWriter::GetTargetSubstitution(target_, type), opts);
out_ << std::endl;
void NinjaTargetWriter::WriteSharedVars(const SubstitutionBits& bits) {
bool written_anything = false;
// Target label.
if (bits.used.count(&SubstitutionLabel)) {
written_anything = true;
// Target label name.
if (bits.used.count(&SubstitutionLabelName)) {
written_anything = true;
// Target label name without toolchain.
if (bits.used.count(&SubstitutionLabelNoToolchain)) {
written_anything = true;
// Root gen dir.
if (bits.used.count(&SubstitutionRootGenDir)) {
written_anything = true;
// Root out dir.
if (bits.used.count(&SubstitutionRootOutDir)) {
written_anything = true;
// Target gen dir.
if (bits.used.count(&SubstitutionTargetGenDir)) {
written_anything = true;
// Target out dir.
if (bits.used.count(&SubstitutionTargetOutDir)) {
written_anything = true;
// Target output name.
if (bits.used.count(&SubstitutionTargetOutputName)) {
written_anything = true;
// If we wrote any vars, separate them from the rest of the file that follows
// with a blank line.
if (written_anything)
out_ << std::endl;
std::vector<OutputFile> NinjaTargetWriter::WriteInputDepsStampAndGetDep(
const std::vector<const Target*>& additional_hard_deps,
size_t num_stamp_uses) const {
CHECK(target_->toolchain()) << "Toolchain not set on target "
<< target_->label().GetUserVisibleName(true);
// ----------
// Collect all input files that are input deps of this target. Knowing the
// number before writing allows us to either skip writing the input deps
// stamp or optimize it. Use pointers to avoid copies here.
std::vector<const SourceFile*> input_deps_sources;
// Actions get implicit dependencies on the script itself.
if (target_->output_type() == Target::ACTION ||
target_->output_type() == Target::ACTION_FOREACH)
// Input files are only considered for non-binary targets which use an
// implicit dependency instead. The implicit dependency in this case is
// handled separately by the binary target writer.
if (!target_->IsBinary()) {
for (ConfigValuesIterator iter(target_); !iter.done(); iter.Next()) {
for (const auto& input : iter.cur().inputs())
// For an action (where we run a script only once) the sources are the same
// as the inputs. For action_foreach, the sources will be operated on
// separately so don't handle them here.
if (target_->output_type() == Target::ACTION) {
for (const auto& source : target_->sources())
// ----------
// Collect all target input dependencies of this target as was done for the
// files above.
std::vector<const Target*> input_deps_targets;
// Hard dependencies that are direct or indirect dependencies.
// These are large (up to 100s), hence why we check other
const TargetSet& hard_deps(target_->recursive_hard_deps());
for (const Target* target : hard_deps) {
// BUNDLE_DATA should normally be treated as a data-only dependency
// (see Target::IsDataOnly()). Only the CREATE_BUNDLE target, that actually
// consumes this data, needs to have the BUNDLE_DATA as an input dependency.
if (target->output_type() != Target::BUNDLE_DATA ||
target_->output_type() == Target::CREATE_BUNDLE)
// Additional hard dependencies passed in. These are usually empty or small,
// and we don't want to duplicate the explicit hard deps of the target.
for (const Target* target : additional_hard_deps) {
if (!hard_deps.count(target))
// Toolchain dependencies. These must be resolved before doing anything.
// This just writes all toolchain deps for simplicity. If we find that
// toolchains often have more than one dependency, we could consider writing
// a toolchain-specific stamp file and only include the stamp here.
// Note that these are usually empty/small.
const LabelTargetVector& toolchain_deps = target_->toolchain()->deps();
for (const auto& toolchain_dep : toolchain_deps) {
// This could theoretically duplicate dependencies already in the list,
// but it shouldn't happen in practice, is inconvenient to check for,
// and only results in harmless redundant dependencies listed.
// ---------
// Write the outputs.
if (input_deps_sources.size() + input_deps_targets.size() == 0)
return std::vector<OutputFile>(); // No input dependencies.
// If we're only generating one input dependency, return it directly instead
// of writing a stamp file for it.
if (input_deps_sources.size() == 1 && input_deps_targets.size() == 0)
return std::vector<OutputFile>{
OutputFile(settings_->build_settings(), *input_deps_sources[0])};
if (input_deps_sources.size() == 0 && input_deps_targets.size() == 1) {
const OutputFile& dep = input_deps_targets[0]->dependency_output_file();
return std::vector<OutputFile>{dep};
std::vector<OutputFile> outs;
// File input deps.
for (const SourceFile* source : input_deps_sources)
outs.push_back(OutputFile(settings_->build_settings(), *source));
// Target input deps. Sort by label so the output is deterministic (otherwise
// some of the targets will have gone through std::sets which will have
// sorted them by pointer).
input_deps_targets.begin(), input_deps_targets.end(),
[](const Target* a, const Target* b) { return a->label() < b->label(); });
for (auto* dep : input_deps_targets) {
// If there are multiple inputs, but the stamp file would be referenced only
// once, don't write it but depend on the inputs directly.
if (num_stamp_uses == 1u)
return outs;
// Make a stamp file.
OutputFile input_stamp_file =
GetBuildDirForTargetAsOutputFile(target_, BuildDirType::OBJ);
out_ << "build ";
path_output_.WriteFile(out_, input_stamp_file);
out_ << ": " << GetNinjaRulePrefixForToolchain(settings_)
<< GeneralTool::kGeneralToolStamp;
path_output_.WriteFiles(out_, outs);
out_ << "\n";
return std::vector<OutputFile>{input_stamp_file};
void NinjaTargetWriter::WriteStampForTarget(
const std::vector<OutputFile>& files,
const std::vector<OutputFile>& order_only_deps) {
const OutputFile& stamp_file = target_->dependency_output_file();
// First validate that the target's dependency is a stamp file. Otherwise,
// we shouldn't have gotten here!
CHECK(base::EndsWith(stamp_file.value(), ".stamp",
<< "Output should end in \".stamp\" for stamp file output. Instead got: "
<< "\"" << stamp_file.value() << "\"";
out_ << "build ";
path_output_.WriteFile(out_, stamp_file);
out_ << ": " << GetNinjaRulePrefixForToolchain(settings_)
<< GeneralTool::kGeneralToolStamp;
path_output_.WriteFiles(out_, files);
if (!order_only_deps.empty()) {
out_ << " ||";
path_output_.WriteFiles(out_, order_only_deps);
out_ << std::endl;