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- /*
- * 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();
- }
- }
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