FileBasedConfig.java
/*
* Copyright (C) 2009, Constantine Plotnikov <constantine.plotnikov@gmail.com>
* Copyright (C) 2007, Dave Watson <dwatson@mimvista.com>
* Copyright (C) 2009, Google Inc.
* Copyright (C) 2009, JetBrains s.r.o.
* Copyright (C) 2008-2009, Robin Rosenberg <robin.rosenberg@dewire.com>
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
* Copyright (C) 2008, Thad Hughes <thadh@thad.corp.google.com>
* 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,
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.eclipse.jgit.storage.file;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.MessageFormat;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.errors.LockFailedException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.internal.storage.file.FileSnapshot;
import org.eclipse.jgit.internal.storage.file.LockFile;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.StoredConfig;
import org.eclipse.jgit.util.FS;
import org.eclipse.jgit.util.FileUtils;
import org.eclipse.jgit.util.IO;
import org.eclipse.jgit.util.RawParseUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The configuration file that is stored in the file of the file system.
*/
public class FileBasedConfig extends StoredConfig {
private final static Logger LOG = LoggerFactory
.getLogger(FileBasedConfig.class);
private final File configFile;
private final FS fs;
private boolean utf8Bom;
private volatile FileSnapshot snapshot;
private volatile ObjectId hash;
/**
* Create a configuration with no default fallback.
*
* @param cfgLocation
* the location of the configuration file on the file system
* @param fs
* the file system abstraction which will be necessary to perform
* certain file system operations.
*/
public FileBasedConfig(File cfgLocation, FS fs) {
this(null, cfgLocation, fs);
}
/**
* The constructor
*
* @param base
* the base configuration file
* @param cfgLocation
* the location of the configuration file on the file system
* @param fs
* the file system abstraction which will be necessary to perform
* certain file system operations.
*/
public FileBasedConfig(Config base, File cfgLocation, FS fs) {
super(base);
configFile = cfgLocation;
this.fs = fs;
this.snapshot = FileSnapshot.DIRTY;
this.hash = ObjectId.zeroId();
}
/** {@inheritDoc} */
@Override
protected boolean notifyUponTransientChanges() {
// we will notify listeners upon save()
return false;
}
/**
* Get location of the configuration file on disk
*
* @return location of the configuration file on disk
*/
public final File getFile() {
return configFile;
}
/**
* {@inheritDoc}
* <p>
* Load the configuration as a Git text style configuration file.
* <p>
* If the file does not exist, this configuration is cleared, and thus
* behaves the same as though the file exists, but is empty.
*/
@Override
public void load() throws IOException, ConfigInvalidException {
final int maxRetries = 5;
int retryDelayMillis = 20;
int retries = 0;
while (true) {
final FileSnapshot oldSnapshot = snapshot;
final FileSnapshot newSnapshot;
// don't use config in this snapshot to avoid endless recursion
newSnapshot = FileSnapshot.saveNoConfig(getFile());
try {
final byte[] in = IO.readFully(getFile());
final ObjectId newHash = hash(in);
if (hash.equals(newHash)) {
if (oldSnapshot.equals(newSnapshot)) {
oldSnapshot.setClean(newSnapshot);
} else {
snapshot = newSnapshot;
}
} else {
final String decoded;
if (isUtf8(in)) {
decoded = RawParseUtils.decode(UTF_8,
in, 3, in.length);
utf8Bom = true;
} else {
decoded = RawParseUtils.decode(in);
}
fromText(decoded);
snapshot = newSnapshot;
hash = newHash;
}
return;
} catch (FileNotFoundException noFile) {
// might be locked by another process (see exception Javadoc)
if (retries < maxRetries && configFile.exists()) {
if (LOG.isDebugEnabled()) {
LOG.debug(MessageFormat.format(
JGitText.get().configHandleMayBeLocked,
Integer.valueOf(retries)), noFile);
}
try {
Thread.sleep(retryDelayMillis);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
retries++;
retryDelayMillis *= 2; // max wait 1260 ms
continue;
}
if (configFile.exists()) {
throw noFile;
}
clear();
snapshot = newSnapshot;
return;
} catch (IOException e) {
if (FileUtils.isStaleFileHandle(e)
&& retries < maxRetries) {
if (LOG.isDebugEnabled()) {
LOG.debug(MessageFormat.format(
JGitText.get().configHandleIsStale,
Integer.valueOf(retries)), e);
}
retries++;
continue;
}
throw new IOException(MessageFormat
.format(JGitText.get().cannotReadFile, getFile()), e);
} catch (ConfigInvalidException e) {
throw new ConfigInvalidException(MessageFormat
.format(JGitText.get().cannotReadFile, getFile()), e);
}
}
}
/**
* {@inheritDoc}
* <p>
* Save the configuration as a Git text style configuration file.
* <p>
* <b>Warning:</b> Although this method uses the traditional Git file
* locking approach to protect against concurrent writes of the
* configuration file, it does not ensure that the file has not been
* modified since the last read, which means updates performed by other
* objects accessing the same backing file may be lost.
*/
@Override
public void save() throws IOException {
final byte[] out;
final String text = toText();
if (utf8Bom) {
final ByteArrayOutputStream bos = new ByteArrayOutputStream();
bos.write(0xEF);
bos.write(0xBB);
bos.write(0xBF);
bos.write(text.getBytes(UTF_8));
out = bos.toByteArray();
} else {
out = Constants.encode(text);
}
final LockFile lf = new LockFile(getFile());
if (!lf.lock())
throw new LockFailedException(getFile());
try {
lf.setNeedSnapshot(true);
lf.write(out);
if (!lf.commit())
throw new IOException(MessageFormat.format(JGitText.get().cannotCommitWriteTo, getFile()));
} finally {
lf.unlock();
}
snapshot = lf.getCommitSnapshot();
hash = hash(out);
// notify the listeners
fireConfigChangedEvent();
}
/** {@inheritDoc} */
@Override
public void clear() {
hash = hash(new byte[0]);
super.clear();
}
private static ObjectId hash(byte[] rawText) {
return ObjectId.fromRaw(Constants.newMessageDigest().digest(rawText));
}
/** {@inheritDoc} */
@SuppressWarnings("nls")
@Override
public String toString() {
return getClass().getSimpleName() + "[" + getFile().getPath() + "]";
}
/**
* Whether the currently loaded configuration file is outdated
*
* @return returns true if the currently loaded configuration file is older
* than the file on disk
*/
public boolean isOutdated() {
return snapshot.isModified(getFile());
}
/**
* {@inheritDoc}
*
* @since 4.10
*/
@Override
protected byte[] readIncludedConfig(String relPath)
throws ConfigInvalidException {
final File file;
if (relPath.startsWith("~/")) { //$NON-NLS-1$
file = fs.resolve(fs.userHome(), relPath.substring(2));
} else {
file = fs.resolve(configFile.getParentFile(), relPath);
}
if (!file.exists()) {
return null;
}
try {
return IO.readFully(file);
} catch (IOException ioe) {
throw new ConfigInvalidException(MessageFormat
.format(JGitText.get().cannotReadFile, relPath), ioe);
}
}
}