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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.objc;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.actions.ActionExecutionContext;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.actions.EnvironmentalExecException;
import com.google.devtools.build.lib.actions.ExecException;
import com.google.devtools.build.lib.actions.UserExecException;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.rules.cpp.CppCompileAction;
import com.google.devtools.build.lib.rules.cpp.IncludeProcessing;
import com.google.devtools.build.lib.rules.cpp.IncludeScanner.IncludeScannerSupplier;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
/**
* Returns all inclusions that were discovered by the header scanner tool to implement the header
* thinning feature.
*
* <p>Reads the .headers_list output file if one was generated for the actions source file and
* returns the Artifact objects associated with the headers that were found.
*/
@AutoCodec
public class HeaderThinning implements IncludeProcessing {
private final Iterable<Artifact> potentialInputs;
public HeaderThinning(Iterable<Artifact> potentialInputs) {
// Just store this, don't create map of potential inputs at construction so that it is done
// later at execution time rather than analysis time when this is instantiated.
this.potentialInputs = potentialInputs;
}
private Map<PathFragment, Artifact> getAllowedInputsMap() {
Map<PathFragment, Artifact> allowedInputsMap = new HashMap<>();
for (Artifact input : potentialInputs) {
allowedInputsMap.put(input.getExecPath(), input);
}
return allowedInputsMap;
}
@Nullable
private static Artifact findHeadersListFile(NestedSet<Artifact> artifacts) {
for (Artifact artifact : artifacts) {
if (artifact.getExtension().equals("headers_list")) {
return artifact;
}
}
return null;
}
@Override
public Iterable<Artifact> determineAdditionalInputs(
@Nullable IncludeScannerSupplier includeScannerSupplier,
CppCompileAction action,
ActionExecutionContext actionExecutionContext)
throws ExecException {
Artifact headersListFile = findHeadersListFile(action.getMandatoryInputs());
if (headersListFile == null) {
return null;
}
return findRequiredHeaderInputs(action.getSourceFile(), headersListFile, getAllowedInputsMap());
}
/**
* Reads the header scanning output file and discovers all of those headers as input artifacts.
*
* @param sourceFile the source that requires these headers
* @param headersListFile .headers_list file output from header_scanner tool to be read
* @param inputArtifactsMap map of PathFragment to Artifact of possible headers
* @return collection of header artifacts that are required for {@code action} to compile
* @throws ExecException on environmental (IO) or user errors
*/
public static Iterable<Artifact> findRequiredHeaderInputs(
Artifact sourceFile, Artifact headersListFile, Map<PathFragment, Artifact> inputArtifactsMap)
throws ExecException {
try {
ImmutableList.Builder<Artifact> includeBuilder = ImmutableList.builder();
List<PathFragment> missing = new ArrayList<>();
for (String line :
FileSystemUtils.readLines(headersListFile.getPath(), StandardCharsets.UTF_8)) {
if (line.isEmpty()) {
continue;
}
PathFragment headerPath = PathFragment.create(line);
Artifact header = inputArtifactsMap.get(headerPath);
if (header == null) {
missing.add(headerPath);
} else {
includeBuilder.add(header);
}
}
if (!missing.isEmpty()) {
includeBuilder.addAll(
findRequiredHeaderInputsInTreeArtifacts(sourceFile, inputArtifactsMap, missing));
}
return includeBuilder.build();
} catch (IOException ex) {
throw new EnvironmentalExecException(
String.format("Error reading headers file %s", headersListFile.getExecPathString()), ex);
}
}
/**
* Headers inside a TreeArtifact will not have their ExecPath as a key in the map as they do not
* have their own Artifact object. These headers must be mapped to their containing TreeArtifact.
* We are unable to select individual files from within a TreeArtifact so must discover the entire
* TreeArtifact as an input.
*/
private static Iterable<Artifact> findRequiredHeaderInputsInTreeArtifacts(
Artifact sourceFile,
Map<PathFragment, Artifact> inputArtifactsMap,
List<PathFragment> missing)
throws ExecException {
ImmutableList.Builder<Artifact> includeBuilder = ImmutableList.builder();
ImmutableList.Builder<PathFragment> treeArtifactPathsBuilder = ImmutableList.builder();
for (Map.Entry<PathFragment, Artifact> inputEntry : inputArtifactsMap.entrySet()) {
if (inputEntry.getValue().isTreeArtifact()) {
treeArtifactPathsBuilder.add(inputEntry.getKey());
}
}
ImmutableList<PathFragment> treeArtifactPaths = treeArtifactPathsBuilder.build();
for (PathFragment missingPath : missing) {
includeBuilder.add(
findRequiredHeaderInputInTreeArtifacts(
sourceFile, treeArtifactPaths, inputArtifactsMap, missingPath));
}
return includeBuilder.build();
}
private static Artifact findRequiredHeaderInputInTreeArtifacts(
Artifact sourceFile,
List<PathFragment> treeArtifactPaths,
Map<PathFragment, Artifact> inputArtifactsMap,
PathFragment missingPath)
throws ExecException {
for (PathFragment treeArtifactPath : treeArtifactPaths) {
if (missingPath.startsWith(treeArtifactPath)) {
return inputArtifactsMap.get(treeArtifactPath);
}
}
throw new UserExecException(
String.format(
"Unable to map header file (%s) found during header scanning of %s."
+ " This is usually the result of a case mismatch",
missingPath, sourceFile.getExecPathString()));
}
}
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