LfsFactory.java
/*
* Copyright (C) 2018, Markus Duft <markus.duft@ssi-schaefer.com> and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.util;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.text.MessageFormat;
import java.util.concurrent.Callable;
import org.eclipse.jgit.annotations.Nullable;
import org.eclipse.jgit.attributes.Attribute;
import org.eclipse.jgit.attributes.Attributes;
import org.eclipse.jgit.hooks.PrePushHook;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.treewalk.FileTreeIterator;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.treewalk.filter.PathFilter;
/**
* Represents an optionally present LFS support implementation
*
* @since 4.11
*/
public class LfsFactory {
private static LfsFactory instance = new LfsFactory();
/**
* Constructor
*/
protected LfsFactory() {
}
/**
* @return the current LFS implementation
*/
public static LfsFactory getInstance() {
return instance;
}
/**
* @param instance
* register a {@link LfsFactory} instance as the
* {@link LfsFactory} implementation to use.
*/
public static void setInstance(LfsFactory instance) {
LfsFactory.instance = instance;
}
/**
* @return whether LFS support is available
*/
public boolean isAvailable() {
return false;
}
/**
* Apply clean filtering to the given stream, writing the file content to
* the LFS storage if required and returning a stream to the LFS pointer
* instead.
*
* @param db
* the repository
* @param input
* the original input
* @param length
* the expected input stream length
* @param attribute
* the attribute used to check for LFS enablement (i.e. "merge",
* "diff", "filter" from .gitattributes).
* @return a stream to the content that should be written to the object
* store along with the expected length of the stream. the original
* stream is not applicable.
* @throws IOException
* in case of an error
*/
public LfsInputStream applyCleanFilter(Repository db,
InputStream input, long length, Attribute attribute)
throws IOException {
return new LfsInputStream(input, length);
}
/**
* Apply smudge filtering to a given loader, potentially redirecting it to a
* LFS blob which is downloaded on demand.
*
* @param db
* the repository
* @param loader
* the loader for the blob
* @param attribute
* the attribute used to check for LFS enablement (i.e. "merge",
* "diff", "filter" from .gitattributes).
* @return a loader for the actual data of a blob, or the original loader in
* case LFS is not applicable.
* @throws IOException
*/
public ObjectLoader applySmudgeFilter(Repository db,
ObjectLoader loader, Attribute attribute) throws IOException {
return loader;
}
/**
* Retrieve a pre-push hook to be applied using the default error stream.
*
* @param repo
* the {@link Repository} the hook is applied to.
* @param outputStream
* @return a {@link PrePushHook} implementation or <code>null</code>
*/
@Nullable
public PrePushHook getPrePushHook(Repository repo,
PrintStream outputStream) {
return null;
}
/**
* Retrieve a pre-push hook to be applied.
*
* @param repo
* the {@link Repository} the hook is applied to.
* @param outputStream
* @param errorStream
* @return a {@link PrePushHook} implementation or <code>null</code>
* @since 5.6
*/
@Nullable
public PrePushHook getPrePushHook(Repository repo, PrintStream outputStream,
PrintStream errorStream) {
return getPrePushHook(repo, outputStream);
}
/**
* Retrieve an {@link LfsInstallCommand} which can be used to enable LFS
* support (if available) either per repository or for the user.
*
* @return a command to install LFS support.
*/
@Nullable
public LfsInstallCommand getInstallCommand() {
return null;
}
/**
* @param db
* the repository to check
* @return whether LFS is enabled for the given repository locally or
* globally.
*/
public boolean isEnabled(Repository db) {
return false;
}
/**
* @param db
* the repository
* @param path
* the path to find attributes for
* @return the {@link Attributes} for the given path.
* @throws IOException
* in case of an error
*/
public static Attributes getAttributesForPath(Repository db, String path)
throws IOException {
try (TreeWalk walk = new TreeWalk(db)) {
walk.addTree(new FileTreeIterator(db));
PathFilter f = PathFilter.create(path);
walk.setFilter(f);
walk.setRecursive(false);
Attributes attr = null;
while (walk.next()) {
if (f.isDone(walk)) {
attr = walk.getAttributes();
break;
} else if (walk.isSubtree()) {
walk.enterSubtree();
}
}
if (attr == null) {
throw new IOException(MessageFormat
.format(JGitText.get().noPathAttributesFound, path));
}
return attr;
}
}
/**
* Get attributes for given path and commit
*
* @param db
* the repository
* @param path
* the path to find attributes for
* @param commit
* the commit to inspect.
* @return the {@link Attributes} for the given path.
* @throws IOException
* in case of an error
*/
public static Attributes getAttributesForPath(Repository db, String path,
RevCommit commit) throws IOException {
if (commit == null) {
return getAttributesForPath(db, path);
}
try (TreeWalk walk = TreeWalk.forPath(db, path, commit.getTree())) {
Attributes attr = walk == null ? null : walk.getAttributes();
if (attr == null) {
throw new IOException(MessageFormat
.format(JGitText.get().noPathAttributesFound, path));
}
return attr;
}
}
/**
* Encapsulate a potentially exchanged {@link InputStream} along with the
* expected stream content length.
*/
public static final class LfsInputStream extends InputStream {
/**
* The actual stream.
*/
private InputStream stream;
/**
* The expected stream content length.
*/
private long length;
/**
* Create a new wrapper around a certain stream
*
* @param stream
* the stream to wrap. the stream will be closed on
* {@link #close()}.
* @param length
* the expected length of the stream
*/
public LfsInputStream(InputStream stream, long length) {
this.stream = stream;
this.length = length;
}
/**
* Create a new wrapper around a temporary buffer.
*
* @param buffer
* the buffer to initialize stream and length from. The
* buffer will be destroyed on {@link #close()}
* @throws IOException
* in case of an error opening the stream to the buffer.
*/
public LfsInputStream(TemporaryBuffer buffer) throws IOException {
this.stream = buffer.openInputStreamWithAutoDestroy();
this.length = buffer.length();
}
@Override
public void close() throws IOException {
stream.close();
}
@Override
public int read() throws IOException {
return stream.read();
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
return stream.read(b, off, len);
}
/**
* @return the length of the stream
*/
public long getLength() {
return length;
}
}
/**
* A command to enable LFS. Optionally set a {@link Repository} to enable
* locally on the repository only.
*/
public interface LfsInstallCommand extends Callable<Void> {
/**
* @param repo
* the repository to enable support for.
* @return The {@link LfsInstallCommand} for chaining.
*/
public LfsInstallCommand setRepository(Repository repo);
}
}