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// Copyright 2014 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.rules.cpp;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.actions.Executor;
import com.google.devtools.build.lib.analysis.BuildInfoHelper;
import com.google.devtools.build.lib.analysis.WorkspaceStatusAction;
import com.google.devtools.build.lib.analysis.actions.AbstractFileWriteAction;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.lib.util.Fingerprint;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* An action that creates a C++ header containing the build information in the
* form of #define directives.
*/
public final class WriteBuildInfoHeaderAction extends AbstractFileWriteAction {
private static final String GUID = "b0798174-1352-4a54-854a-9785aaea491b";
private final ImmutableList<Artifact> valueArtifacts;
private final boolean writeVolatileInfo;
private final boolean writeStableInfo;
/**
* Creates an action that writes a C++ header with the build information.
*
* <p>It reads the set of build info keys from an action context that is usually contributed
* to Bazel by the workspace status module, and the value associated with said keys from the
* workspace status files (stable and volatile) written by the workspace status action.
*
* <p>Without input artifacts this action uses redacted build information.
* @param inputs Artifacts that contain build information, or an empty
* collection to use redacted build information
* @param output the C++ header Artifact created by this action
* @param writeVolatileInfo whether to write the volatile part of the build
* information to the generated header
* @param writeStableInfo whether to write the non-volatile part of the
* build information to the generated header
*/
public WriteBuildInfoHeaderAction(Collection<Artifact> inputs,
Artifact output, boolean writeVolatileInfo, boolean writeStableInfo) {
super(BuildInfoHelper.BUILD_INFO_ACTION_OWNER,
inputs, output, /*makeExecutable=*/false);
valueArtifacts = ImmutableList.copyOf(inputs);
if (!inputs.isEmpty()) {
// With non-empty inputs we should not generate both volatile and non-volatile data
// in the same header file.
Preconditions.checkState(writeVolatileInfo ^ writeStableInfo);
}
Preconditions.checkState(
output.isConstantMetadata() == (writeVolatileInfo && !inputs.isEmpty()));
this.writeVolatileInfo = writeVolatileInfo;
this.writeStableInfo = writeStableInfo;
}
@Override
public DeterministicWriter newDeterministicWriter(EventHandler eventHandler, Executor executor)
throws IOException {
WorkspaceStatusAction.Context context =
executor.getContext(WorkspaceStatusAction.Context.class);
final Map<String, WorkspaceStatusAction.Key> keys = new LinkedHashMap<>();
if (writeVolatileInfo) {
keys.putAll(context.getVolatileKeys());
}
if (writeStableInfo) {
keys.putAll(context.getStableKeys());
}
final Map<String, String> values = new LinkedHashMap<>();
for (Artifact valueFile : valueArtifacts) {
values.putAll(WorkspaceStatusAction.parseValues(valueFile.getPath()));
}
final boolean redacted = valueArtifacts.isEmpty();
return new DeterministicWriter() {
@Override
public void writeOutputFile(OutputStream out) throws IOException {
Writer writer = new OutputStreamWriter(out, UTF_8);
for (Map.Entry<String, WorkspaceStatusAction.Key> key : keys.entrySet()) {
if (!key.getValue().isInLanguage("C++")) {
continue;
}
String value = redacted ? key.getValue().getRedactedValue()
: values.containsKey(key.getKey()) ? values.get(key.getKey())
: key.getValue().getDefaultValue();
switch (key.getValue().getType()) {
case VERBATIM:
case INTEGER:
break;
case STRING:
value = quote(value);
break;
default:
throw new IllegalStateException();
}
define(writer, key.getKey(), value);
}
writer.flush();
}
};
}
@Override
protected String computeKey() {
Fingerprint f = new Fingerprint();
f.addString(GUID);
f.addBoolean(writeStableInfo);
f.addBoolean(writeVolatileInfo);
return f.hexDigestAndReset();
}
@Override
public boolean executeUnconditionally() {
// Note: isVolatile must return true if executeUnconditionally can ever return true
// for this instance.
return isUnconditional();
}
@Override
public boolean isVolatile() {
return isUnconditional();
}
private boolean isUnconditional() {
// Because of special handling in the MetadataHandler, changed volatile build
// information does not trigger relinking of all libraries that have
// linkstamps. But we do want to regenerate the header in case libraries are
// relinked because of other reasons.
// Without inputs the contents of the header do not change, so there is no
// point in executing the action again in that case.
return writeVolatileInfo && !Iterables.isEmpty(getInputs());
}
/**
* Quote a string with double quotes.
*/
private String quote(String string) {
// TODO(bazel-team): This is doesn't really work if the string contains quotes. Or a newline.
// Or a backslash. Or anything unusual, really.
return "\"" + string + "\"";
}
/**
* Write a preprocessor define directive to a Writer.
*/
private void define(Writer writer, String name, String value) throws IOException {
writer.write("#define ");
writer.write(name);
writer.write(' ');
writer.write(value);
writer.write('\n');
}
@Override
protected String getRawProgressMessage() {
return null;
}
}
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