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// Copyright 2015 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.bazel.repository;
import static com.google.devtools.build.lib.bazel.repository.StripPrefixedPath.maybeDeprefixSymlink;
import com.google.common.base.Optional;
import com.google.common.io.ByteStreams;
import com.google.devtools.build.lib.bazel.repository.DecompressorValue.Decompressor;
import com.google.devtools.build.lib.vfs.FileSystemUtils;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
/**
* Common code for unarchiving a compressed TAR file.
*/
public abstract class CompressedTarFunction implements Decompressor {
protected abstract InputStream getDecompressorStream(DecompressorDescriptor descriptor)
throws IOException;
@Override
public Path decompress(DecompressorDescriptor descriptor)
throws InterruptedException, IOException {
if (Thread.interrupted()) {
throw new InterruptedException();
}
Optional<String> prefix = descriptor.prefix();
Map<String, String> renameFiles = descriptor.renameFiles();
boolean foundPrefix = false;
Set<String> availablePrefixes = new HashSet<>();
// Store link, target info of symlinks, we create them after regular files are extracted.
Map<Path, PathFragment> symlinks = new HashMap<>();
try (InputStream decompressorStream = getDecompressorStream(descriptor)) {
TarArchiveInputStream tarStream = new TarArchiveInputStream(decompressorStream);
TarArchiveEntry entry;
while ((entry = tarStream.getNextTarEntry()) != null) {
String entryName = entry.getName();
entryName = renameFiles.getOrDefault(entryName, entryName);
StripPrefixedPath entryPath = StripPrefixedPath.maybeDeprefix(entryName, prefix);
foundPrefix = foundPrefix || entryPath.foundPrefix();
if (prefix.isPresent() && !foundPrefix) {
Optional<String> suggestion =
CouldNotFindPrefixException.maybeMakePrefixSuggestion(entryPath.getPathFragment());
if (suggestion.isPresent()) {
availablePrefixes.add(suggestion.get());
}
}
if (entryPath.skip()) {
continue;
}
Path filePath = descriptor.destinationPath().getRelative(entryPath.getPathFragment());
filePath.getParentDirectory().createDirectoryAndParents();
if (entry.isDirectory()) {
filePath.createDirectoryAndParents();
} else {
if (entry.isSymbolicLink() || entry.isLink()) {
PathFragment targetName = PathFragment.create(entry.getLinkName());
targetName = maybeDeprefixSymlink(targetName, prefix, descriptor.destinationPath());
if (entry.isSymbolicLink()) {
symlinks.put(filePath, targetName);
} else {
Path targetPath = descriptor.destinationPath().getRelative(targetName);
if (filePath.equals(targetPath)) {
// The behavior here is semantically different, depending on whether the underlying
// filesystem is case-sensitive or case-insensitive. However, it is effectively the
// same: we drop the link entry.
// * On a case-sensitive filesystem, this is a hardlink to itself, such as GNU tar
// creates when given repeated files. We do nothing since the link already exists.
// * On a case-insensitive filesystem, we may be extracting a differently-cased
// hardlink to the same file (such as when extracting an archive created on a
// case-sensitive filesystem). GNU tar, for example, will drop the new link entry.
// BSD tar on MacOS X (by default case-insensitive) errors and aborts extraction.
} else {
if (filePath.exists()) {
filePath.delete();
}
FileSystemUtils.createHardLink(filePath, targetPath);
}
}
} else {
try (OutputStream out = filePath.getOutputStream()) {
ByteStreams.copy(tarStream, out);
}
filePath.chmod(entry.getMode());
// This can only be done on real files, not links, or it will skip the reader to
// the next "real" file to try to find the mod time info.
Date lastModified = entry.getLastModifiedDate();
filePath.setLastModifiedTime(lastModified.getTime());
}
}
if (Thread.interrupted()) {
throw new InterruptedException();
}
}
for (Map.Entry<Path, PathFragment> symlink : symlinks.entrySet()) {
Path linkPath = symlink.getKey();
if (linkPath.exists()) {
linkPath.delete();
}
FileSystemUtils.ensureSymbolicLink(linkPath, symlink.getValue());
}
if (prefix.isPresent() && !foundPrefix) {
throw new CouldNotFindPrefixException(prefix.get(), availablePrefixes);
}
}
return descriptor.destinationPath();
}
}