Java tutorial
/* * Copyright (C) 2008, Google Inc. * Copyright (C) 2008, Robin Rosenberg <robin.rosenberg@dewire.com> * Copyright (C) 2006-2017, Shawn O. Pearce <spearce@spearce.org> * and other copyright owners as documented in the project's IP log. * * This program and the accompanying materials are made available * under the terms of the Eclipse Distribution License v1.0 which * accompanies this distribution, is reproduced below, and is * available at http://www.eclipse.org/org/documents/edl-v10.php * * All rights reserved. * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * - Neither the name of the Eclipse Foundation, Inc. nor the * names of its contributors may be used to endorse or promote * products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.eclipse.jgit.lib; import static java.nio.charset.StandardCharsets.UTF_8; import java.nio.ByteBuffer; import java.nio.charset.Charset; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.text.MessageFormat; import org.eclipse.jgit.errors.CorruptObjectException; import org.eclipse.jgit.internal.JGitText; import org.eclipse.jgit.util.MutableInteger; /** * Misc. constants and helpers used throughout JGit. */ @SuppressWarnings("nls") public final class Constants { /** Hash function used natively by Git for all objects. */ private static final String HASH_FUNCTION = "SHA-1"; /** * A Git object hash is 160 bits, i.e. 20 bytes. * <p> * Changing this assumption is not going to be as easy as changing this * declaration. */ public static final int OBJECT_ID_LENGTH = 20; /** * A Git object can be expressed as a 40 character string of hexadecimal * digits. * * @see #OBJECT_ID_LENGTH */ public static final int OBJECT_ID_STRING_LENGTH = OBJECT_ID_LENGTH * 2; /** Special name for the "HEAD" symbolic-ref. */ public static final String HEAD = "HEAD"; /** Special name for the "FETCH_HEAD" symbolic-ref. */ public static final String FETCH_HEAD = "FETCH_HEAD"; /** * Text string that identifies an object as a commit. * <p> * Commits connect trees into a string of project histories, where each * commit is an assertion that the best way to continue is to use this other * tree (set of files). */ public static final String TYPE_COMMIT = "commit"; /** * Text string that identifies an object as a blob. * <p> * Blobs store whole file revisions. They are used for any user file, as * well as for symlinks. Blobs form the bulk of any project's storage space. */ public static final String TYPE_BLOB = "blob"; /** * Text string that identifies an object as a tree. * <p> * Trees attach object ids (hashes) to names and file modes. The normal use * for a tree is to store a version of a directory and its contents. */ public static final String TYPE_TREE = "tree"; /** * Text string that identifies an object as an annotated tag. * <p> * Annotated tags store a pointer to any other object, and an additional * message. It is most commonly used to record a stable release of the * project. */ public static final String TYPE_TAG = "tag"; private static final byte[] ENCODED_TYPE_COMMIT = encodeASCII(TYPE_COMMIT); private static final byte[] ENCODED_TYPE_BLOB = encodeASCII(TYPE_BLOB); private static final byte[] ENCODED_TYPE_TREE = encodeASCII(TYPE_TREE); private static final byte[] ENCODED_TYPE_TAG = encodeASCII(TYPE_TAG); /** An unknown or invalid object type code. */ public static final int OBJ_BAD = -1; /** * In-pack object type: extended types. * <p> * This header code is reserved for future expansion. It is currently * undefined/unsupported. */ public static final int OBJ_EXT = 0; /** * In-pack object type: commit. * <p> * Indicates the associated object is a commit. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> * * @see #TYPE_COMMIT */ public static final int OBJ_COMMIT = 1; /** * In-pack object type: tree. * <p> * Indicates the associated object is a tree. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> * * @see #TYPE_BLOB */ public static final int OBJ_TREE = 2; /** * In-pack object type: blob. * <p> * Indicates the associated object is a blob. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> * * @see #TYPE_BLOB */ public static final int OBJ_BLOB = 3; /** * In-pack object type: annotated tag. * <p> * Indicates the associated object is an annotated tag. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> * * @see #TYPE_TAG */ public static final int OBJ_TAG = 4; /** In-pack object type: reserved for future use. */ public static final int OBJ_TYPE_5 = 5; /** * In-pack object type: offset delta * <p> * Objects stored with this type actually have a different type which must * be obtained from their delta base object. Delta objects store only the * changes needed to apply to the base object in order to recover the * original object. * <p> * An offset delta uses a negative offset from the start of this object to * refer to its delta base. The base object must exist in this packfile * (even in the case of a thin pack). * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> */ public static final int OBJ_OFS_DELTA = 6; /** * In-pack object type: reference delta * <p> * Objects stored with this type actually have a different type which must * be obtained from their delta base object. Delta objects store only the * changes needed to apply to the base object in order to recover the * original object. * <p> * A reference delta uses a full object id (hash) to reference the delta * base. The base object is allowed to be omitted from the packfile, but * only in the case of a thin pack being transferred over the network. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> */ public static final int OBJ_REF_DELTA = 7; /** * Pack file signature that occurs at file header - identifies file as Git * packfile formatted. * <p> * <b>This constant is fixed and is defined by the Git packfile format.</b> */ public static final byte[] PACK_SIGNATURE = { 'P', 'A', 'C', 'K' }; /** * Native character encoding for commit messages, file names... * * @deprecated Use {@link java.nio.charset.StandardCharsets#UTF_8} directly * instead. */ @Deprecated public static final Charset CHARSET; /** * Native character encoding for commit messages, file names... * * @deprecated Use {@link java.nio.charset.StandardCharsets#UTF_8} directly * instead. */ @Deprecated public static final String CHARACTER_ENCODING; /** Default main branch name */ public static final String MASTER = "master"; /** Default stash branch name */ public static final String STASH = "stash"; /** Prefix for branch refs */ public static final String R_HEADS = "refs/heads/"; /** Prefix for remotes refs */ public static final String R_REMOTES = "refs/remotes/"; /** Prefix for tag refs */ public static final String R_TAGS = "refs/tags/"; /** Prefix for notes refs */ public static final String R_NOTES = "refs/notes/"; /** Standard notes ref */ public static final String R_NOTES_COMMITS = R_NOTES + "commits"; /** Prefix for any ref */ public static final String R_REFS = "refs/"; /** Standard stash ref */ public static final String R_STASH = R_REFS + STASH; /** Logs folder name */ public static final String LOGS = "logs"; /** * Objects folder name * @since 5.5 */ public static final String OBJECTS = "objects"; /** * Reftable folder name * @since 5.6 */ public static final String REFTABLE = "reftable"; /** Info refs folder */ public static final String INFO_REFS = "info/refs"; /** * Info alternates file (goes under OBJECTS) * @since 5.5 */ public static final String INFO_ALTERNATES = "info/alternates"; /** * HTTP alternates file (goes under OBJECTS) * @since 5.5 */ public static final String INFO_HTTP_ALTERNATES = "info/http-alternates"; /** Packed refs file */ public static final String PACKED_REFS = "packed-refs"; /** * Excludes-file * * @since 3.0 */ public static final String INFO_EXCLUDE = "info/exclude"; /** * Attributes-override-file * * @since 4.2 */ public static final String INFO_ATTRIBUTES = "info/attributes"; /** * The system property that contains the system user name * * @since 3.6 */ public static final String OS_USER_DIR = "user.dir"; /** The system property that contains the system user name */ public static final String OS_USER_NAME_KEY = "user.name"; /** The environment variable that contains the author's name */ public static final String GIT_AUTHOR_NAME_KEY = "GIT_AUTHOR_NAME"; /** The environment variable that contains the author's email */ public static final String GIT_AUTHOR_EMAIL_KEY = "GIT_AUTHOR_EMAIL"; /** The environment variable that contains the commiter's name */ public static final String GIT_COMMITTER_NAME_KEY = "GIT_COMMITTER_NAME"; /** The environment variable that contains the commiter's email */ public static final String GIT_COMMITTER_EMAIL_KEY = "GIT_COMMITTER_EMAIL"; /** * The environment variable that blocks use of the system config file * * @since 3.3 */ public static final String GIT_CONFIG_NOSYSTEM_KEY = "GIT_CONFIG_NOSYSTEM"; /** * The key of the XDG_CONFIG_HOME directory defined in the XDG base * directory specification, see * {@link "https://wiki.archlinux.org/index.php/XDG_Base_Directory"} * * @since 5.5.2 */ public static final String XDG_CONFIG_HOME = "XDG_CONFIG_HOME"; /** * The environment variable that limits how close to the root of the file * systems JGit will traverse when looking for a repository root. */ public static final String GIT_CEILING_DIRECTORIES_KEY = "GIT_CEILING_DIRECTORIES"; /** * The environment variable that tells us which directory is the ".git" * directory */ public static final String GIT_DIR_KEY = "GIT_DIR"; /** * The environment variable that tells us which directory is the working * directory. */ public static final String GIT_WORK_TREE_KEY = "GIT_WORK_TREE"; /** * The environment variable that tells us which file holds the Git index. */ public static final String GIT_INDEX_FILE_KEY = "GIT_INDEX_FILE"; /** * The environment variable that tells us where objects are stored */ public static final String GIT_OBJECT_DIRECTORY_KEY = "GIT_OBJECT_DIRECTORY"; /** * The environment variable that tells us where to look for objects, besides * the default objects directory. */ public static final String GIT_ALTERNATE_OBJECT_DIRECTORIES_KEY = "GIT_ALTERNATE_OBJECT_DIRECTORIES"; /** Default value for the user name if no other information is available */ public static final String UNKNOWN_USER_DEFAULT = "unknown-user"; /** Beginning of the common "Signed-off-by: " commit message line */ public static final String SIGNED_OFF_BY_TAG = "Signed-off-by: "; /** A gitignore file name */ public static final String GITIGNORE_FILENAME = ".gitignore"; /** Default remote name used by clone, push and fetch operations */ public static final String DEFAULT_REMOTE_NAME = "origin"; /** Default name for the Git repository directory */ public static final String DOT_GIT = ".git"; /** Default name for the Git repository configuration */ public static final String CONFIG = "config"; /** A bare repository typically ends with this string */ public static final String DOT_GIT_EXT = ".git"; /** * Name of the attributes file * * @since 3.7 */ public static final String DOT_GIT_ATTRIBUTES = ".gitattributes"; /** * Key for filters in .gitattributes * * @since 4.2 */ public static final String ATTR_FILTER = "filter"; /** * clean command name, used to call filter driver * * @since 4.2 */ public static final String ATTR_FILTER_TYPE_CLEAN = "clean"; /** * smudge command name, used to call filter driver * * @since 4.2 */ public static final String ATTR_FILTER_TYPE_SMUDGE = "smudge"; /** * Builtin filter commands start with this prefix * * @since 4.6 */ public static final String BUILTIN_FILTER_PREFIX = "jgit://builtin/"; /** Name of the ignore file */ public static final String DOT_GIT_IGNORE = ".gitignore"; /** Name of the submodules file */ public static final String DOT_GIT_MODULES = ".gitmodules"; /** Name of the .git/shallow file */ public static final String SHALLOW = "shallow"; /** * Prefix of the first line in a ".git" file * * @since 3.6 */ public static final String GITDIR = "gitdir: "; /** * Name of the folder (inside gitDir) where submodules are stored * * @since 3.6 */ public static final String MODULES = "modules"; /** * Name of the folder (inside gitDir) where the hooks are stored. * * @since 3.7 */ public static final String HOOKS = "hooks"; /** * Merge attribute. * * @since 4.9 */ public static final String ATTR_MERGE = "merge"; //$NON-NLS-1$ /** * Diff attribute. * * @since 4.11 */ public static final String ATTR_DIFF = "diff"; //$NON-NLS-1$ /** * Binary value for custom merger. * * @since 4.9 */ public static final String ATTR_BUILTIN_BINARY_MERGER = "binary"; //$NON-NLS-1$ /** * Create a new digest function for objects. * * @return a new digest object. * @throws java.lang.RuntimeException * this Java virtual machine does not support the required hash * function. Very unlikely given that JGit uses a hash function * that is in the Java reference specification. */ public static MessageDigest newMessageDigest() { try { return MessageDigest.getInstance(HASH_FUNCTION); } catch (NoSuchAlgorithmException nsae) { throw new RuntimeException( MessageFormat.format(JGitText.get().requiredHashFunctionNotAvailable, HASH_FUNCTION), nsae); } } /** * Convert an OBJ_* type constant to a TYPE_* type constant. * * @param typeCode the type code, from a pack representation. * @return the canonical string name of this type. */ public static String typeString(int typeCode) { switch (typeCode) { case OBJ_COMMIT: return TYPE_COMMIT; case OBJ_TREE: return TYPE_TREE; case OBJ_BLOB: return TYPE_BLOB; case OBJ_TAG: return TYPE_TAG; default: throw new IllegalArgumentException( MessageFormat.format(JGitText.get().badObjectType, Integer.valueOf(typeCode))); } } /** * Convert an OBJ_* type constant to an ASCII encoded string constant. * <p> * The ASCII encoded string is often the canonical representation of * the type within a loose object header, or within a tag header. * * @param typeCode the type code, from a pack representation. * @return the canonical ASCII encoded name of this type. */ public static byte[] encodedTypeString(int typeCode) { switch (typeCode) { case OBJ_COMMIT: return ENCODED_TYPE_COMMIT; case OBJ_TREE: return ENCODED_TYPE_TREE; case OBJ_BLOB: return ENCODED_TYPE_BLOB; case OBJ_TAG: return ENCODED_TYPE_TAG; default: throw new IllegalArgumentException( MessageFormat.format(JGitText.get().badObjectType, Integer.valueOf(typeCode))); } } /** * Parse an encoded type string into a type constant. * * @param id * object id this type string came from; may be null if that is * not known at the time the parse is occurring. * @param typeString * string version of the type code. * @param endMark * character immediately following the type string. Usually ' ' * (space) or '\n' (line feed). * @param offset * position within <code>typeString</code> where the parse * should start. Updated with the new position (just past * <code>endMark</code> when the parse is successful. * @return a type code constant (one of {@link #OBJ_BLOB}, * {@link #OBJ_COMMIT}, {@link #OBJ_TAG}, {@link #OBJ_TREE}. * @throws org.eclipse.jgit.errors.CorruptObjectException * there is no valid type identified by <code>typeString</code>. */ public static int decodeTypeString(final AnyObjectId id, final byte[] typeString, final byte endMark, final MutableInteger offset) throws CorruptObjectException { try { int position = offset.value; switch (typeString[position]) { case 'b': if (typeString[position + 1] != 'l' || typeString[position + 2] != 'o' || typeString[position + 3] != 'b' || typeString[position + 4] != endMark) throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); offset.value = position + 5; return Constants.OBJ_BLOB; case 'c': if (typeString[position + 1] != 'o' || typeString[position + 2] != 'm' || typeString[position + 3] != 'm' || typeString[position + 4] != 'i' || typeString[position + 5] != 't' || typeString[position + 6] != endMark) throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); offset.value = position + 7; return Constants.OBJ_COMMIT; case 't': switch (typeString[position + 1]) { case 'a': if (typeString[position + 2] != 'g' || typeString[position + 3] != endMark) throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); offset.value = position + 4; return Constants.OBJ_TAG; case 'r': if (typeString[position + 2] != 'e' || typeString[position + 3] != 'e' || typeString[position + 4] != endMark) throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); offset.value = position + 5; return Constants.OBJ_TREE; default: throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); } default: throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); } } catch (ArrayIndexOutOfBoundsException bad) { throw new CorruptObjectException(id, JGitText.get().corruptObjectInvalidType); } } /** * Convert an integer into its decimal representation. * * @param s * the integer to convert. * @return a decimal representation of the input integer. The returned array * is the smallest array that will hold the value. */ public static byte[] encodeASCII(long s) { return encodeASCII(Long.toString(s)); } /** * Convert a string to US-ASCII encoding. * * @param s * the string to convert. Must not contain any characters over * 127 (outside of 7-bit ASCII). * @return a byte array of the same length as the input string, holding the * same characters, in the same order. * @throws java.lang.IllegalArgumentException * the input string contains one or more characters outside of * the 7-bit ASCII character space. */ public static byte[] encodeASCII(String s) { final byte[] r = new byte[s.length()]; for (int k = r.length - 1; k >= 0; k--) { final char c = s.charAt(k); if (c > 127) throw new IllegalArgumentException(MessageFormat.format(JGitText.get().notASCIIString, s)); r[k] = (byte) c; } return r; } /** * Convert a string to a byte array in the standard character encoding. * * @param str * the string to convert. May contain any Unicode characters. * @return a byte array representing the requested string, encoded using the * default character encoding (UTF-8). * @see #CHARACTER_ENCODING */ public static byte[] encode(String str) { final ByteBuffer bb = UTF_8.encode(str); final int len = bb.limit(); if (bb.hasArray() && bb.arrayOffset() == 0) { final byte[] arr = bb.array(); if (arr.length == len) return arr; } final byte[] arr = new byte[len]; bb.get(arr); return arr; } static { if (OBJECT_ID_LENGTH != newMessageDigest().getDigestLength()) throw new LinkageError(JGitText.get().incorrectOBJECT_ID_LENGTH); CHARSET = UTF_8; CHARACTER_ENCODING = UTF_8.name(); } /** name of the file containing the commit msg for a merge commit */ public static final String MERGE_MSG = "MERGE_MSG"; /** name of the file containing the IDs of the parents of a merge commit */ public static final String MERGE_HEAD = "MERGE_HEAD"; /** name of the file containing the ID of a cherry pick commit in case of conflicts */ public static final String CHERRY_PICK_HEAD = "CHERRY_PICK_HEAD"; /** name of the file containing the commit msg for a squash commit */ public static final String SQUASH_MSG = "SQUASH_MSG"; /** name of the file containing the ID of a revert commit in case of conflicts */ public static final String REVERT_HEAD = "REVERT_HEAD"; /** * name of the ref ORIG_HEAD used by certain commands to store the original * value of HEAD */ public static final String ORIG_HEAD = "ORIG_HEAD"; /** * Name of the file in which git commands and hooks store and read the * message prepared for the upcoming commit. * * @since 4.0 */ public static final String COMMIT_EDITMSG = "COMMIT_EDITMSG"; /** * Well-known object ID for the empty blob. * * @since 0.9.1 */ public static final ObjectId EMPTY_BLOB_ID = ObjectId.fromString("e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"); /** * Well-known object ID for the empty tree. * * @since 5.1 */ public static final ObjectId EMPTY_TREE_ID = ObjectId.fromString("4b825dc642cb6eb9a060e54bf8d69288fbee4904"); /** * Suffix of lock file name * * @since 4.7 */ public static final String LOCK_SUFFIX = ".lock"; //$NON-NLS-1$ private Constants() { // Hide the default constructor } }