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package jdk.nio.zipfs;
import java.io.IOException;
import java.io.InputStream;
import java.lang.Runtime.Version;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.jar.Attributes;
import java.util.jar.Manifest;
Adds aliasing to ZipFileSystem to support multi-release jar files. An alias map is created by createVersionedLinks(int). The map is then consulted when an entry is looked up in ZipFileSystem.getEntry(byte[]) to determine if the entry has a corresponding versioned entry. If so, the versioned entry is returned. Author: Steve Drach
/**
* Adds aliasing to ZipFileSystem to support multi-release jar files. An alias map
* is created by {@link JarFileSystem#createVersionedLinks(int)}. The map is then
* consulted when an entry is looked up in {@link JarFileSystem#getEntry(byte[])}
* to determine if the entry has a corresponding versioned entry. If so, the
* versioned entry is returned.
*
* @author Steve Drach
*/
class JarFileSystem extends ZipFileSystem {
private Function<byte[],byte[]> lookup;
@Override
IndexNode getInode(byte[] path) {
// check for an alias to a versioned entry
byte[] versionedPath = lookup.apply(path);
return versionedPath == null ? super.getInode(path) : super.getInode(versionedPath);
}
JarFileSystem(ZipFileSystemProvider provider, Path zfpath, Map<String,?> env)
throws IOException {
super(provider, zfpath, env);
lookup = path -> path; // lookup needs to be set before isMultiReleaseJar is called
// because it eventually calls getEntry
if (isMultiReleaseJar()) {
int version;
Object o = env.get("multi-release");
if (o instanceof String) {
String s = (String)o;
if (s.equals("runtime")) {
version = Runtime.version().feature();
} else {
version = Integer.parseInt(s);
}
} else if (o instanceof Integer) {
version = (Integer)o;
} else if (o instanceof Version) {
version = ((Version)o).feature();
} else {
throw new IllegalArgumentException("env parameter must be String, Integer, "
+ "or Version");
}
lookup = createVersionedLinks(version < 0 ? 0 : version);
setReadOnly();
}
}
private boolean isMultiReleaseJar() throws IOException {
try (InputStream is = newInputStream(getBytes("/META-INF/MANIFEST.MF"))) {
String multiRelease = new Manifest(is).getMainAttributes()
.getValue(Attributes.Name.MULTI_RELEASE);
return "true".equalsIgnoreCase(multiRelease);
} catch (NoSuchFileException x) {
return false;
}
}
create a map of aliases for versioned entries, for example:
version/PackagePrivate.class -> META-INF/versions/9/version/PackagePrivate.class
version/PackagePrivate.java -> META-INF/versions/9/version/PackagePrivate.java
version/Version.class -> META-INF/versions/10/version/Version.class
version/Version.java -> META-INF/versions/10/version/Version.java
then wrap the map in a function that getEntry can use to override root
entry lookup for entries that have corresponding versioned entries
/**
* create a map of aliases for versioned entries, for example:
* version/PackagePrivate.class -> META-INF/versions/9/version/PackagePrivate.class
* version/PackagePrivate.java -> META-INF/versions/9/version/PackagePrivate.java
* version/Version.class -> META-INF/versions/10/version/Version.class
* version/Version.java -> META-INF/versions/10/version/Version.java
*
* then wrap the map in a function that getEntry can use to override root
* entry lookup for entries that have corresponding versioned entries
*/
private Function<byte[],byte[]> createVersionedLinks(int version) {
HashMap<IndexNode,byte[]> aliasMap = new HashMap<>();
IndexNode verdir = getInode(getBytes("/META-INF/versions"));
if (verdir != null) {
getVersionMap(version, verdir).values()
.forEach(versionNode -> { // for each META-INF/versions/{n} directory
// put all the leaf inodes, i.e. entries, into the alias map
// possibly shadowing lower versioned entries
walk(versionNode, entryNode -> {
byte[] rootName = getRootName(versionNode, entryNode);
if (rootName != null) {
IndexNode rootNode = getInode(rootName);
if (rootNode == null) { // no matching root node, make a virtual one
rootNode = IndexNode.keyOf(rootName);
}
aliasMap.put(rootNode, entryNode.name);
}
});
});
}
return path -> aliasMap.get(IndexNode.keyOf(path));
}
create a sorted version map of version -> inode, for inodes <= max version
9 -> META-INF/versions/9
10 -> META-INF/versions/10
/**
* create a sorted version map of version -> inode, for inodes <= max version
* 9 -> META-INF/versions/9
* 10 -> META-INF/versions/10
*/
private TreeMap<Integer, IndexNode> getVersionMap(int version, IndexNode metaInfVersions) {
TreeMap<Integer,IndexNode> map = new TreeMap<>();
IndexNode child = metaInfVersions.child;
while (child != null) {
Integer key = getVersion(child.name, metaInfVersions.name.length + 1);
if (key != null && key <= version) {
map.put(key, child);
}
child = child.sibling;
}
return map;
}
extract the integer version number -- META-INF/versions/9 returns 9
/**
* extract the integer version number -- META-INF/versions/9 returns 9
*/
private Integer getVersion(byte[] name, int offset) {
try {
return Integer.parseInt(getString(Arrays.copyOfRange(name, offset, name.length)));
} catch (NumberFormatException x) {
// ignore this even though it might indicate issues with the JAR structure
return null;
}
}
walk the IndexNode tree processing all leaf nodes
/**
* walk the IndexNode tree processing all leaf nodes
*/
private void walk(IndexNode inode, Consumer<IndexNode> process) {
if (inode == null) return;
if (inode.isDir()) {
walk(inode.child, process);
} else {
process.accept(inode);
}
walk(inode.sibling, process);
}
extract the root name from a versioned entry name
given inode for META-INF/versions/9/foo/bar.class
and prefix META-INF/versions/9/
returns foo/bar.class
/**
* extract the root name from a versioned entry name
* given inode for META-INF/versions/9/foo/bar.class
* and prefix META-INF/versions/9/
* returns foo/bar.class
*/
private byte[] getRootName(IndexNode prefix, IndexNode inode) {
int offset = prefix.name.length;
byte[] fullName = inode.name;
return Arrays.copyOfRange(fullName, offset, fullName.length);
}
}