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ModuleHashes
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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*
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package jdk.internal.module;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
The result of hashing the contents of a number of module artifacts.
/**
* The result of hashing the contents of a number of module artifacts.
*/
public final class ModuleHashes {
A supplier of a message digest.
/**
* A supplier of a message digest.
*/
public static interface HashSupplier {
byte[] generate(String algorithm);
}
private final String algorithm;
private final Map<String, byte[]> nameToHash;
Creates a ModuleHashes. Params: - algorithm – the algorithm used to create the hashes
- nameToHash – the map of module name to hash value
/**
* Creates a {@code ModuleHashes}.
*
* @param algorithm the algorithm used to create the hashes
* @param nameToHash the map of module name to hash value
*/
public ModuleHashes(String algorithm, Map<String, byte[]> nameToHash) {
this.algorithm = algorithm;
this.nameToHash = Collections.unmodifiableMap(nameToHash);
}
Returns the algorithm used to hash the modules ("SHA-256" for example).
/**
* Returns the algorithm used to hash the modules ("SHA-256" for example).
*/
public String algorithm() {
return algorithm;
}
Returns the set of module names for which hashes are recorded.
/**
* Returns the set of module names for which hashes are recorded.
*/
public Set<String> names() {
return nameToHash.keySet();
}
Returns the hash for the given module name, null if there is no hash recorded for the module. /**
* Returns the hash for the given module name, {@code null}
* if there is no hash recorded for the module.
*/
public byte[] hashFor(String mn) {
return nameToHash.get(mn);
}
Returns unmodifiable map of module name to hash
/**
* Returns unmodifiable map of module name to hash
*/
public Map<String, byte[]> hashes() {
return nameToHash;
}
Computes the hash for the given file with the given message digest
algorithm.
Throws: - UncheckedIOException – if an I/O error occurs
- RuntimeException – if the algorithm is not available
/**
* Computes the hash for the given file with the given message digest
* algorithm.
*
* @throws UncheckedIOException if an I/O error occurs
* @throws RuntimeException if the algorithm is not available
*/
public static byte[] computeHash(Path file, String algorithm) {
try {
MessageDigest md = MessageDigest.getInstance(algorithm);
// Ideally we would just mmap the file but this consumes too much
// memory when jlink is running concurrently on very large jmods
try (FileChannel fc = FileChannel.open(file)) {
ByteBuffer bb = ByteBuffer.allocate(32*1024);
while (fc.read(bb) > 0) {
bb.flip();
md.update(bb);
assert bb.remaining() == 0;
bb.clear();
}
}
return md.digest();
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
} catch (IOException ioe) {
throw new UncheckedIOException(ioe);
}
}
Computes the hash for every entry in the given map, returning a ModuleHashes to encapsulate the result. The map key is the entry name, typically the module name. The map value is the file path to the entry (module artifact). Returns: ModuleHashes that encapsulates the hashes
/**
* Computes the hash for every entry in the given map, returning a
* {@code ModuleHashes} to encapsulate the result. The map key is
* the entry name, typically the module name. The map value is the file
* path to the entry (module artifact).
*
* @return ModuleHashes that encapsulates the hashes
*/
public static ModuleHashes generate(Map<String, Path> map, String algorithm) {
Map<String, byte[]> nameToHash = new HashMap<>();
for (Map.Entry<String, Path> entry: map.entrySet()) {
String name = entry.getKey();
Path path = entry.getValue();
nameToHash.put(name, computeHash(path, algorithm));
}
return new ModuleHashes(algorithm, nameToHash);
}
This is used by jdk.internal.module.SystemModules class
generated at link time.
/**
* This is used by jdk.internal.module.SystemModules class
* generated at link time.
*/
public static class Builder {
final String algorithm;
final Map<String, byte[]> nameToHash;
Builder(String algorithm, int initialCapacity) {
this.nameToHash = new HashMap<>(initialCapacity);
this.algorithm = Objects.requireNonNull(algorithm);
}
Sets the module hash for the given module name
/**
* Sets the module hash for the given module name
*/
public Builder hashForModule(String mn, byte[] hash) {
nameToHash.put(mn, hash);
return this;
}
Builds a ModuleHashes. /**
* Builds a {@code ModuleHashes}.
*/
public ModuleHashes build() {
if (!nameToHash.isEmpty()) {
return new ModuleHashes(algorithm, nameToHash);
} else {
return null;
}
}
}
}