/*
* Copyright 2014-present Facebook, Inc.
*
* 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.facebook.buck.cxx;
import com.facebook.buck.io.FileScrubber;
import com.facebook.buck.model.BuildTarget;
import com.facebook.buck.model.BuildTargets;
import com.facebook.buck.rules.AbstractBuildRule;
import com.facebook.buck.rules.AddToRuleKey;
import com.facebook.buck.rules.BuildContext;
import com.facebook.buck.rules.BuildRule;
import com.facebook.buck.rules.BuildRuleParams;
import com.facebook.buck.rules.BuildRuleResolver;
import com.facebook.buck.rules.BuildableContext;
import com.facebook.buck.rules.ExplicitBuildTargetSourcePath;
import com.facebook.buck.rules.RuleKeyObjectSink;
import com.facebook.buck.rules.SourcePath;
import com.facebook.buck.rules.SourcePathResolver;
import com.facebook.buck.rules.SourcePathRuleFinder;
import com.facebook.buck.rules.Tool;
import com.facebook.buck.rules.args.Arg;
import com.facebook.buck.rules.args.SourcePathArg;
import com.facebook.buck.rules.args.StringArg;
import com.facebook.buck.step.Step;
import com.facebook.buck.step.fs.MkdirStep;
import com.facebook.buck.step.fs.WriteFileStep;
import com.google.common.base.Charsets;
import com.google.common.base.Joiner;
import com.google.common.base.Suppliers;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSortedSet;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
/** A specialization of {@link Linker} containing information specific to the GNU implementation. */
public class GnuLinker implements Linker {
private final Tool tool;
public GnuLinker(Tool tool) {
this.tool = tool;
}
@Override
public ImmutableCollection<BuildRule> getDeps(SourcePathRuleFinder ruleFinder) {
return tool.getDeps(ruleFinder);
}
@Override
public ImmutableCollection<SourcePath> getInputs() {
return tool.getInputs();
}
@Override
public ImmutableList<String> getCommandPrefix(SourcePathResolver resolver) {
return tool.getCommandPrefix(resolver);
}
@Override
public ImmutableMap<String, String> getEnvironment(SourcePathResolver resolver) {
return tool.getEnvironment(resolver);
}
@Override
public ImmutableList<FileScrubber> getScrubbers(ImmutableCollection<Path> cellRoots) {
return ImmutableList.of();
}
@Override
public Iterable<Arg> linkWhole(Arg input) {
return ImmutableList.of(
StringArg.of("-Wl,--whole-archive"), input, StringArg.of("-Wl,--no-whole-archive"));
}
@Override
public Iterable<String> soname(String arg) {
return Linkers.iXlinker("-soname", arg);
}
@Override
public Iterable<Arg> fileList(Path fileListPath) {
return ImmutableList.of();
}
@Override
public String origin() {
return "$ORIGIN";
}
@Override
public String libOrigin() {
return "$ORIGIN";
}
@Override
public String searchPathEnvVar() {
return "LD_LIBRARY_PATH";
}
@Override
public String preloadEnvVar() {
return "LD_PRELOAD";
}
/**
* Write all undefined symbols given in {@code symbolFiles} into a linker script wrapped in
* `EXTERN` commands.
*
* @param target the name given to the {@link BuildRule} which creates the linker script.
* @return the list of arguments which pass the linker script containing the undefined symbols to
* link.
*/
@Override
public ImmutableList<Arg> createUndefinedSymbolsLinkerArgs(
BuildRuleParams baseParams,
BuildRuleResolver ruleResolver,
SourcePathRuleFinder ruleFinder,
BuildTarget target,
Iterable<? extends SourcePath> symbolFiles) {
UndefinedSymbolsLinkerScript rule =
ruleResolver.addToIndex(
new UndefinedSymbolsLinkerScript(
baseParams
.withBuildTarget(target)
.copyReplacingDeclaredAndExtraDeps(
Suppliers.ofInstance(
ImmutableSortedSet.copyOf(
ruleFinder.filterBuildRuleInputs(symbolFiles))),
Suppliers.ofInstance(ImmutableSortedSet.of())),
symbolFiles));
return ImmutableList.of(SourcePathArg.of(rule.getSourcePathToOutput()));
}
@Override
public Iterable<String> getNoAsNeededSharedLibsFlags() {
return Linkers.iXlinker("--no-as-needed");
}
@Override
public Iterable<String> getIgnoreUndefinedSymbolsFlags() {
return Linkers.iXlinker(
// ld.gold doesn't appear to fully implement `--unresolved-symbols=ignore-all` for shared
// libraries, so also always set `--allow-shlib-undefined`.
"--allow-shlib-undefined", "--unresolved-symbols=ignore-all");
}
@Override
public Iterable<Arg> getSharedLibFlag() {
return ImmutableList.of(StringArg.of("-shared"));
}
@Override
public Iterable<String> outputArgs(String path) {
return ImmutableList.of("-o", path);
}
@Override
public boolean hasFilePathSizeLimitations() {
return false;
}
@Override
public void appendToRuleKey(RuleKeyObjectSink sink) {
sink.setReflectively("tool", tool).setReflectively("type", getClass().getSimpleName());
}
// Write all symbols to a linker script, using the `EXTERN` command to mark them as undefined
// symbols.
private static class UndefinedSymbolsLinkerScript extends AbstractBuildRule {
@AddToRuleKey private final Iterable<? extends SourcePath> symbolFiles;
public UndefinedSymbolsLinkerScript(
BuildRuleParams buildRuleParams, Iterable<? extends SourcePath> symbolFiles) {
super(buildRuleParams);
this.symbolFiles = symbolFiles;
}
private Path getLinkerScript() {
return BuildTargets.getGenPath(
getProjectFilesystem(), getBuildTarget(), "%s/linker_script.txt");
}
@Override
public ImmutableList<Step> getBuildSteps(
BuildContext context, BuildableContext buildableContext) {
final Path linkerScript = getLinkerScript();
buildableContext.recordArtifact(linkerScript);
return ImmutableList.of(
MkdirStep.of(getProjectFilesystem(), linkerScript.getParent()),
new WriteFileStep(
getProjectFilesystem(),
() -> {
Set<String> symbols = new LinkedHashSet<>();
for (SourcePath path : symbolFiles) {
try {
symbols.addAll(
Files.readAllLines(
context.getSourcePathResolver().getAbsolutePath(path), Charsets.UTF_8));
} catch (IOException e) {
throw new RuntimeException(e);
}
}
List<String> lines = new ArrayList<>();
for (String symbol : symbols) {
lines.add(String.format("EXTERN(\"%s\")", symbol));
}
return Joiner.on(System.lineSeparator()).join(lines);
},
linkerScript,
/* executable */ false));
}
@Override
public SourcePath getSourcePathToOutput() {
return new ExplicitBuildTargetSourcePath(getBuildTarget(), getLinkerScript());
}
}
}