org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/LfsPointer.java - jgit - Git at Google

 /*
  * Copyright (C) 2016, 2021 Christian Halstrick <christian.halstrick@sap.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.lfs;

 import static java.nio.charset.StandardCharsets.UTF_8;

 import java.io.BufferedInputStream;
 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.PrintStream;
 import java.io.UnsupportedEncodingException;
 import java.util.Locale;
 import java.util.Objects;

 import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
 import org.eclipse.jgit.lfs.lib.Constants;
 import org.eclipse.jgit.lfs.lib.LongObjectId;
 import org.eclipse.jgit.util.IO;

 /**
  * Represents an LFS pointer file
  *
  * @since 4.6
  */
 public class LfsPointer implements Comparable<LfsPointer> {
 	/**
 	 * The version of the LfsPointer file format
 	 */
 	public static final String VERSION = "https://git-lfs.github.com/spec/v1"; //$NON-NLS-1$

 	/**
 	 * The version of the LfsPointer file format using legacy URL
 	 * @since 4.7
 	 */
 	public static final String VERSION_LEGACY = "https://hawser.github.com/spec/v1"; //$NON-NLS-1$

 	/**
 	 * Don't inspect files that are larger than this threshold to avoid
 	 * excessive reading. No pointer file should be larger than this.
 	 * @since 4.11
 	 */
 	public static final int SIZE_THRESHOLD = 200;

 	/**
 	 * The name of the hash function as used in the pointer files. This will
 	 * evaluate to "sha256"
 	 */
 	public static final String HASH_FUNCTION_NAME = Constants.LONG_HASH_FUNCTION
 			.toLowerCase(Locale.ROOT).replace("-", ""); //$NON-NLS-1$ //$NON-NLS-2$

 	/**
 	 * {@link #SIZE_THRESHOLD} is too low; with lfs extensions a LFS pointer can
 	 * be larger. But 8kB should be more than enough.
 	 */
 	static final int FULL_SIZE_THRESHOLD = 8 * 1024;

 	private final AnyLongObjectId oid;

 	private final long size;

 	/**
 	 * <p>Constructor for LfsPointer.</p>
 	 *
 	 * @param oid
 	 *            the id of the content
 	 * @param size
 	 *            the size of the content
 	 */
 	public LfsPointer(AnyLongObjectId oid, long size) {
 		this.oid = oid;
 		this.size = size;
 	}

 	/**
 	 * <p>Getter for the field <code>oid</code>.</p>
 	 *
 	 * @return the id of the content
 	 */
 	public AnyLongObjectId getOid() {
 		return oid;
 	}

 	/**
 	 * <p>Getter for the field <code>size</code>.</p>
 	 *
 	 * @return the size of the content
 	 */
 	public long getSize() {
 		return size;
 	}

 	/**
 	 * Encode this object into the LFS format defined by {@link #VERSION}
 	 *
 	 * @param out
 	 *            the {@link java.io.OutputStream} into which the encoded data should be
 	 *            written
 	 */
 	public void encode(OutputStream out) {
 		try (PrintStream ps = new PrintStream(out, false,
 				UTF_8.name())) {
 			ps.print("version "); //$NON-NLS-1$
 			ps.print(VERSION + "\n"); //$NON-NLS-1$
 			ps.print("oid " + HASH_FUNCTION_NAME + ":"); //$NON-NLS-1$ //$NON-NLS-2$
 			ps.print(oid.name() + "\n"); //$NON-NLS-1$
 			ps.print("size "); //$NON-NLS-1$
 			ps.print(size + "\n"); //$NON-NLS-1$
 		} catch (UnsupportedEncodingException e) {
 			// should not happen, we are using a standard charset
 		}
 	}

 	/**
 	 * Try to parse the data provided by an InputStream to the format defined by
 	 * {@link #VERSION}. If the given stream supports mark and reset as
 	 * indicated by {@link InputStream#markSupported()}, its input position will
 	 * be reset if the stream content is not actually a LFS pointer (i.e., when
 	 * {@code null} is returned). If the stream content is an invalid LFS
 	 * pointer or the given stream does not support mark/reset, the input
 	 * position may not be reset.
 	 *
 	 * @param in
 	 *            the {@link java.io.InputStream} from where to read the data
 	 * @return an {@link org.eclipse.jgit.lfs.LfsPointer} or {@code null} if the
 	 *         stream was not parseable as LfsPointer
 	 * @throws java.io.IOException
 	 */
 	@Nullable
 	public static LfsPointer parseLfsPointer(InputStream in)
 			throws IOException {
 		if (in.markSupported()) {
 			return parse(in);
 		}
 		// Fallback; note that while parse() resets its input stream, that won't
 		// reset "in".
 		return parse(new BufferedInputStream(in));
 	}

 	@Nullable
 	private static LfsPointer parse(InputStream in)
 			throws IOException {
 		if (!in.markSupported()) {
 			// No translation; internal error
 			throw new IllegalArgumentException(
 					"LFS pointer parsing needs InputStream.markSupported() == true"); //$NON-NLS-1$
 		}
 		// Try reading only a short block first.
 		in.mark(SIZE_THRESHOLD);
 		byte[] preamble = new byte[SIZE_THRESHOLD];
 		int length = IO.readFully(in, preamble, 0);
 		if (length < preamble.length || in.read() < 0) {
 			// We have the whole file. Try to parse a pointer from it.
 			try (BufferedReader r = new BufferedReader(new InputStreamReader(
 					new ByteArrayInputStream(preamble, 0, length), UTF_8))) {
 				LfsPointer ptr = parse(r);
 				if (ptr == null) {
 					in.reset();
 				}
 				return ptr;
 			}
 		}
 		// Longer than SIZE_THRESHOLD: expect "version" to be the first line.
 		boolean hasVersion = checkVersion(preamble);
 		in.reset();
 		if (!hasVersion) {
 			return null;
 		}
 		in.mark(FULL_SIZE_THRESHOLD);
 		byte[] fullPointer = new byte[FULL_SIZE_THRESHOLD];
 		length = IO.readFully(in, fullPointer, 0);
 		if (length == fullPointer.length && in.read() >= 0) {
 			in.reset();
 			return null; // Too long.
 		}
 		try (BufferedReader r = new BufferedReader(new InputStreamReader(
 				new ByteArrayInputStream(fullPointer, 0, length), UTF_8))) {
 			LfsPointer ptr = parse(r);
 			if (ptr == null) {
 				in.reset();
 			}
 			return ptr;
 		}
 	}

 	private static LfsPointer parse(BufferedReader r) throws IOException {
 		boolean versionLine = false;
 		LongObjectId id = null;
 		long sz = -1;
 		// This parsing is a bit too general if we go by the spec at
 		// https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
 		// Comment lines are not mentioned in the spec, the "version" line
 		// MUST be the first, and keys are ordered alphabetically.
 		for (String s = r.readLine(); s != null; s = r.readLine()) {
 			if (s.startsWith("#") || s.length() == 0) { //$NON-NLS-1$
 				continue;
 			} else if (s.startsWith("version")) { //$NON-NLS-1$
 				if (versionLine || !checkVersionLine(s)) {
 					return null; // Not a LFS pointer
 				}
 				versionLine = true;
 			} else {
 				try {
 					if (s.startsWith("oid sha256:")) { //$NON-NLS-1$
 						if (id != null) {
 							return null; // Not a LFS pointer
 						}
 						id = LongObjectId.fromString(s.substring(11).trim());
 					} else if (s.startsWith("size")) { //$NON-NLS-1$
 						if (sz > 0 || s.length() < 5 || s.charAt(4) != ' ') {
 							return null; // Not a LFS pointer
 						}
 						sz = Long.parseLong(s.substring(5).trim());
 					}
 				} catch (RuntimeException e) {
 					// We could not parse the line. If we have a version
 					// already, this is a corrupt LFS pointer. Otherwise it
 					// is just not an LFS pointer.
 					if (versionLine) {
 						throw e;
 					}
 					return null;
 				}
 			}
 			if (versionLine && id != null && sz > -1) {
 				return new LfsPointer(id, sz);
 			}
 		}
 		return null;
 	}

 	private static boolean checkVersion(byte[] data) {
 		// According to the spec at
 		// https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
 		// it MUST always be the first line.
 		try (BufferedReader r = new BufferedReader(
 				new InputStreamReader(new ByteArrayInputStream(data), UTF_8))) {
 			String s = r.readLine();
 			if (s != null && s.startsWith("version")) { //$NON-NLS-1$
 				return checkVersionLine(s);
 			}
 		} catch (IOException e) {
 			// Doesn't occur, we're reading from a byte array!
 		}
 		return false;
 	}

 	private static boolean checkVersionLine(String s) {
 		if (s.length() < 8 || s.charAt(7) != ' ') {
 			return false; // Not a valid LFS pointer version line
 		}
 		String rest = s.substring(8).trim();
 		return VERSION.equals(rest) || VERSION_LEGACY.equals(rest);
 	}

 	/** {@inheritDoc} */
 	@Override
 	public String toString() {
 		return "LfsPointer: oid=" + oid.name() + ", size=" //$NON-NLS-1$ //$NON-NLS-2$
 				+ size;
 	}

 	/**
 	 * @since 4.11
 	 */
 	@Override
 	public int compareTo(LfsPointer o) {
 		int x = getOid().compareTo(o.getOid());
 		if (x != 0) {
 			return x;
 		}

 		return Long.compare(getSize(), o.getSize());
 	}

 	@Override
 	public int hashCode() {
 		return Objects.hash(getOid()) * 31 + Long.hashCode(getSize());
 	}

 	@Override
 	public boolean equals(Object obj) {
 		if (this == obj) {
 			return true;
 		}
 		if (obj == null || getClass() != obj.getClass()) {
 			return false;
 		}
 		LfsPointer other = (LfsPointer) obj;
 		return Objects.equals(getOid(), other.getOid())
 				&& getSize() == other.getSize();
 	}
 }
	/*
	* Copyright (C) 2016, 2021 Christian Halstrick <christian.halstrick@sap.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.lfs;

	import static java.nio.charset.StandardCharsets.UTF_8;

	import java.io.BufferedInputStream;
	import java.io.BufferedReader;
	import java.io.ByteArrayInputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.io.OutputStream;
	import java.io.PrintStream;
	import java.io.UnsupportedEncodingException;
	import java.util.Locale;
	import java.util.Objects;

	import org.eclipse.jgit.annotations.Nullable;
	import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
	import org.eclipse.jgit.lfs.lib.Constants;
	import org.eclipse.jgit.lfs.lib.LongObjectId;
	import org.eclipse.jgit.util.IO;

	/**
	* Represents an LFS pointer file
	*
	* @since 4.6
	*/
	public class LfsPointer implements Comparable<LfsPointer> {
	/**
	* The version of the LfsPointer file format
	*/
	public static final String VERSION = "https://git-lfs.github.com/spec/v1"; //$NON-NLS-1$

	/**
	* The version of the LfsPointer file format using legacy URL
	* @since 4.7
	*/
	public static final String VERSION_LEGACY = "https://hawser.github.com/spec/v1"; //$NON-NLS-1$

	/**
	* Don't inspect files that are larger than this threshold to avoid
	* excessive reading. No pointer file should be larger than this.
	* @since 4.11
	*/
	public static final int SIZE_THRESHOLD = 200;

	/**
	* The name of the hash function as used in the pointer files. This will
	* evaluate to "sha256"
	*/
	public static final String HASH_FUNCTION_NAME = Constants.LONG_HASH_FUNCTION
	.toLowerCase(Locale.ROOT).replace("-", ""); //$NON-NLS-1$ //$NON-NLS-2$

	/**
	* {@link #SIZE_THRESHOLD} is too low; with lfs extensions a LFS pointer can
	* be larger. But 8kB should be more than enough.
	*/
	static final int FULL_SIZE_THRESHOLD = 8 * 1024;

	private final AnyLongObjectId oid;

	private final long size;

	/**
	* <p>Constructor for LfsPointer.</p>
	*
	* @param oid
	* the id of the content
	* @param size
	* the size of the content
	*/
	public LfsPointer(AnyLongObjectId oid, long size) {
	this.oid = oid;
	this.size = size;
	}

	/**
	* <p>Getter for the field <code>oid</code>.</p>
	*
	* @return the id of the content
	*/
	public AnyLongObjectId getOid() {
	return oid;
	}

	/**
	* <p>Getter for the field <code>size</code>.</p>
	*
	* @return the size of the content
	*/
	public long getSize() {
	return size;
	}

	/**
	* Encode this object into the LFS format defined by {@link #VERSION}
	*
	* @param out
	* the {@link java.io.OutputStream} into which the encoded data should be
	* written
	*/
	public void encode(OutputStream out) {
	try (PrintStream ps = new PrintStream(out, false,
	UTF_8.name())) {
	ps.print("version "); //$NON-NLS-1$
	ps.print(VERSION + "\n"); //$NON-NLS-1$
	ps.print("oid " + HASH_FUNCTION_NAME + ":"); //$NON-NLS-1$ //$NON-NLS-2$
	ps.print(oid.name() + "\n"); //$NON-NLS-1$
	ps.print("size "); //$NON-NLS-1$
	ps.print(size + "\n"); //$NON-NLS-1$
	} catch (UnsupportedEncodingException e) {
	// should not happen, we are using a standard charset
	}
	}

	/**
	* Try to parse the data provided by an InputStream to the format defined by
	* {@link #VERSION}. If the given stream supports mark and reset as
	* indicated by {@link InputStream#markSupported()}, its input position will
	* be reset if the stream content is not actually a LFS pointer (i.e., when
	* {@code null} is returned). If the stream content is an invalid LFS
	* pointer or the given stream does not support mark/reset, the input
	* position may not be reset.
	*
	* @param in
	* the {@link java.io.InputStream} from where to read the data
	* @return an {@link org.eclipse.jgit.lfs.LfsPointer} or {@code null} if the
	* stream was not parseable as LfsPointer
	* @throws java.io.IOException
	*/
	@Nullable
	public static LfsPointer parseLfsPointer(InputStream in)
	throws IOException {
	if (in.markSupported()) {
	return parse(in);
	}
	// Fallback; note that while parse() resets its input stream, that won't
	// reset "in".
	return parse(new BufferedInputStream(in));
	}

	@Nullable
	private static LfsPointer parse(InputStream in)
	throws IOException {
	if (!in.markSupported()) {
	// No translation; internal error
	throw new IllegalArgumentException(
	"LFS pointer parsing needs InputStream.markSupported() == true"); //$NON-NLS-1$
	}
	// Try reading only a short block first.
	in.mark(SIZE_THRESHOLD);
	byte[] preamble = new byte[SIZE_THRESHOLD];
	int length = IO.readFully(in, preamble, 0);
	if (length < preamble.length \|\| in.read() < 0) {
	// We have the whole file. Try to parse a pointer from it.
	try (BufferedReader r = new BufferedReader(new InputStreamReader(
	new ByteArrayInputStream(preamble, 0, length), UTF_8))) {
	LfsPointer ptr = parse(r);
	if (ptr == null) {
	in.reset();
	}
	return ptr;
	}
	}
	// Longer than SIZE_THRESHOLD: expect "version" to be the first line.
	boolean hasVersion = checkVersion(preamble);
	in.reset();
	if (!hasVersion) {
	return null;
	}
	in.mark(FULL_SIZE_THRESHOLD);
	byte[] fullPointer = new byte[FULL_SIZE_THRESHOLD];
	length = IO.readFully(in, fullPointer, 0);
	if (length == fullPointer.length && in.read() >= 0) {
	in.reset();
	return null; // Too long.
	}
	try (BufferedReader r = new BufferedReader(new InputStreamReader(
	new ByteArrayInputStream(fullPointer, 0, length), UTF_8))) {
	LfsPointer ptr = parse(r);
	if (ptr == null) {
	in.reset();
	}
	return ptr;
	}
	}

	private static LfsPointer parse(BufferedReader r) throws IOException {
	boolean versionLine = false;
	LongObjectId id = null;
	long sz = -1;
	// This parsing is a bit too general if we go by the spec at
	// https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
	// Comment lines are not mentioned in the spec, the "version" line
	// MUST be the first, and keys are ordered alphabetically.
	for (String s = r.readLine(); s != null; s = r.readLine()) {
	if (s.startsWith("#") \|\| s.length() == 0) { //$NON-NLS-1$
	continue;
	} else if (s.startsWith("version")) { //$NON-NLS-1$
	if (versionLine \|\| !checkVersionLine(s)) {
	return null; // Not a LFS pointer
	}
	versionLine = true;
	} else {
	try {
	if (s.startsWith("oid sha256:")) { //$NON-NLS-1$
	if (id != null) {
	return null; // Not a LFS pointer
	}
	id = LongObjectId.fromString(s.substring(11).trim());
	} else if (s.startsWith("size")) { //$NON-NLS-1$
	if (sz > 0 \|\| s.length() < 5 \|\| s.charAt(4) != ' ') {
	return null; // Not a LFS pointer
	}
	sz = Long.parseLong(s.substring(5).trim());
	}
	} catch (RuntimeException e) {
	// We could not parse the line. If we have a version
	// already, this is a corrupt LFS pointer. Otherwise it
	// is just not an LFS pointer.
	if (versionLine) {
	throw e;
	}
	return null;
	}
	}
	if (versionLine && id != null && sz > -1) {
	return new LfsPointer(id, sz);
	}
	}
	return null;
	}

	private static boolean checkVersion(byte[] data) {
	// According to the spec at
	// https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
	// it MUST always be the first line.
	try (BufferedReader r = new BufferedReader(
	new InputStreamReader(new ByteArrayInputStream(data), UTF_8))) {
	String s = r.readLine();
	if (s != null && s.startsWith("version")) { //$NON-NLS-1$
	return checkVersionLine(s);
	}
	} catch (IOException e) {
	// Doesn't occur, we're reading from a byte array!
	}
	return false;
	}

	private static boolean checkVersionLine(String s) {
	if (s.length() < 8 \|\| s.charAt(7) != ' ') {
	return false; // Not a valid LFS pointer version line
	}
	String rest = s.substring(8).trim();
	return VERSION.equals(rest) \|\| VERSION_LEGACY.equals(rest);
	}

	/** {@inheritDoc} */
	@Override
	public String toString() {
	return "LfsPointer: oid=" + oid.name() + ", size=" //$NON-NLS-1$ //$NON-NLS-2$
	+ size;
	}

	/**
	* @since 4.11
	*/
	@Override
	public int compareTo(LfsPointer o) {
	int x = getOid().compareTo(o.getOid());
	if (x != 0) {
	return x;
	}

	return Long.compare(getSize(), o.getSize());
	}

	@Override
	public int hashCode() {
	return Objects.hash(getOid()) * 31 + Long.hashCode(getSize());
	}

	@Override
	public boolean equals(Object obj) {
	if (this == obj) {
	return true;
	}
	if (obj == null \|\| getClass() != obj.getClass()) {
	return false;
	}
	LfsPointer other = (LfsPointer) obj;
	return Objects.equals(getOid(), other.getOid())
	&& getSize() == other.getSize();
	}
	}