FS_POSIX.java
/*
* Copyright (C) 2010, Robin Rosenberg
* 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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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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package org.eclipse.jgit.util;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.nio.charset.Charset;
import java.nio.file.AccessDeniedException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.PosixFilePermission;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.UUID;
import org.eclipse.jgit.annotations.Nullable;
import org.eclipse.jgit.api.errors.JGitInternalException;
import org.eclipse.jgit.errors.CommandFailedException;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.ConfigConstants;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.storage.file.FileBasedConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Base FS for POSIX based systems
*
* @since 3.0
*/
public class FS_POSIX extends FS {
private final static Logger LOG = LoggerFactory.getLogger(FS_POSIX.class);
private static final int DEFAULT_UMASK = 0022;
private volatile int umask = -1;
private volatile boolean supportsUnixNLink = true;
private volatile AtomicFileCreation supportsAtomicCreateNewFile = AtomicFileCreation.UNDEFINED;
private enum AtomicFileCreation {
SUPPORTED, NOT_SUPPORTED, UNDEFINED
}
/**
* Default constructor.
*/
protected FS_POSIX() {
}
/**
* Constructor
*
* @param src
* FS to copy some settings from
*/
protected FS_POSIX(FS src) {
super(src);
if (src instanceof FS_POSIX) {
umask = ((FS_POSIX) src).umask;
}
}
private void determineAtomicFileCreationSupport() {
// @TODO: enhance SystemReader to support this without copying code
AtomicFileCreation ret = getAtomicFileCreationSupportOption(
SystemReader.getInstance().openUserConfig(null, this));
if (ret == AtomicFileCreation.UNDEFINED
&& StringUtils.isEmptyOrNull(SystemReader.getInstance()
.getenv(Constants.GIT_CONFIG_NOSYSTEM_KEY))) {
ret = getAtomicFileCreationSupportOption(
SystemReader.getInstance().openSystemConfig(null, this));
}
supportsAtomicCreateNewFile = ret;
}
private AtomicFileCreation getAtomicFileCreationSupportOption(
FileBasedConfig config) {
try {
config.load();
String value = config.getString(ConfigConstants.CONFIG_CORE_SECTION,
null,
ConfigConstants.CONFIG_KEY_SUPPORTSATOMICFILECREATION);
if (value == null) {
return AtomicFileCreation.UNDEFINED;
}
return StringUtils.toBoolean(value)
? AtomicFileCreation.SUPPORTED
: AtomicFileCreation.NOT_SUPPORTED;
} catch (IOException | ConfigInvalidException e) {
return AtomicFileCreation.SUPPORTED;
}
}
/** {@inheritDoc} */
@Override
public FS newInstance() {
return new FS_POSIX(this);
}
/**
* Set the umask, overriding any value observed from the shell.
*
* @param umask
* mask to apply when creating files.
* @since 4.0
*/
public void setUmask(int umask) {
this.umask = umask;
}
private int umask() {
int u = umask;
if (u == -1) {
u = readUmask();
umask = u;
}
return u;
}
/** @return mask returned from running {@code umask} command in shell. */
private static int readUmask() {
try {
Process p = Runtime.getRuntime().exec(
new String[] { "sh", "-c", "umask" }, //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
null, null);
try (BufferedReader lineRead = new BufferedReader(
new InputStreamReader(p.getInputStream(), Charset
.defaultCharset().name()))) {
if (p.waitFor() == 0) {
String s = lineRead.readLine();
if (s != null && s.matches("0?\\d{3}")) { //$NON-NLS-1$
return Integer.parseInt(s, 8);
}
}
return DEFAULT_UMASK;
}
} catch (Exception e) {
return DEFAULT_UMASK;
}
}
/** {@inheritDoc} */
@Override
protected File discoverGitExe() {
String path = SystemReader.getInstance().getenv("PATH"); //$NON-NLS-1$
File gitExe = searchPath(path, "git"); //$NON-NLS-1$
if (gitExe == null) {
if (SystemReader.getInstance().isMacOS()) {
if (searchPath(path, "bash") != null) { //$NON-NLS-1$
// On MacOSX, PATH is shorter when Eclipse is launched from the
// Finder than from a terminal. Therefore try to launch bash as a
// login shell and search using that.
String w;
try {
w = readPipe(userHome(),
new String[]{"bash", "--login", "-c", "which git"}, // //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
Charset.defaultCharset().name());
} catch (CommandFailedException e) {
LOG.warn(e.getMessage());
return null;
}
if (!StringUtils.isEmptyOrNull(w)) {
gitExe = new File(w);
}
}
}
}
return gitExe;
}
/** {@inheritDoc} */
@Override
public boolean isCaseSensitive() {
return !SystemReader.getInstance().isMacOS();
}
/** {@inheritDoc} */
@Override
public boolean supportsExecute() {
return true;
}
/** {@inheritDoc} */
@Override
public boolean canExecute(File f) {
return FileUtils.canExecute(f);
}
/** {@inheritDoc} */
@Override
public boolean setExecute(File f, boolean canExecute) {
if (!isFile(f))
return false;
if (!canExecute)
return f.setExecutable(false, false);
try {
Path path = FileUtils.toPath(f);
Set<PosixFilePermission> pset = Files.getPosixFilePermissions(path);
// owner (user) is always allowed to execute.
pset.add(PosixFilePermission.OWNER_EXECUTE);
int mask = umask();
apply(pset, mask, PosixFilePermission.GROUP_EXECUTE, 1 << 3);
apply(pset, mask, PosixFilePermission.OTHERS_EXECUTE, 1);
Files.setPosixFilePermissions(path, pset);
return true;
} catch (IOException e) {
// The interface doesn't allow to throw IOException
final boolean debug = Boolean.parseBoolean(SystemReader
.getInstance().getProperty("jgit.fs.debug")); //$NON-NLS-1$
if (debug)
System.err.println(e);
return false;
}
}
private static void apply(Set<PosixFilePermission> set,
int umask, PosixFilePermission perm, int test) {
if ((umask & test) == 0) {
// If bit is clear in umask, permission is allowed.
set.add(perm);
} else {
// If bit is set in umask, permission is denied.
set.remove(perm);
}
}
/** {@inheritDoc} */
@Override
public ProcessBuilder runInShell(String cmd, String[] args) {
List<String> argv = new ArrayList<>(4 + args.length);
argv.add("sh"); //$NON-NLS-1$
argv.add("-c"); //$NON-NLS-1$
argv.add(cmd + " \"$@\""); //$NON-NLS-1$
argv.add(cmd);
argv.addAll(Arrays.asList(args));
ProcessBuilder proc = new ProcessBuilder();
proc.command(argv);
return proc;
}
/** {@inheritDoc} */
@Override
public ProcessResult runHookIfPresent(Repository repository, String hookName,
String[] args, PrintStream outRedirect, PrintStream errRedirect,
String stdinArgs) throws JGitInternalException {
return internalRunHookIfPresent(repository, hookName, args, outRedirect,
errRedirect, stdinArgs);
}
/** {@inheritDoc} */
@Override
public boolean retryFailedLockFileCommit() {
return false;
}
/** {@inheritDoc} */
@Override
public boolean supportsSymlinks() {
return true;
}
/** {@inheritDoc} */
@Override
public void setHidden(File path, boolean hidden) throws IOException {
// no action on POSIX
}
/** {@inheritDoc} */
@Override
public Attributes getAttributes(File path) {
return FileUtils.getFileAttributesPosix(this, path);
}
/** {@inheritDoc} */
@Override
public File normalize(File file) {
return FileUtils.normalize(file);
}
/** {@inheritDoc} */
@Override
public String normalize(String name) {
return FileUtils.normalize(name);
}
/** {@inheritDoc} */
@Override
public File findHook(Repository repository, String hookName) {
final File gitdir = repository.getDirectory();
if (gitdir == null) {
return null;
}
final Path hookPath = gitdir.toPath().resolve(Constants.HOOKS)
.resolve(hookName);
if (Files.isExecutable(hookPath))
return hookPath.toFile();
return null;
}
/** {@inheritDoc} */
@Override
public boolean supportsAtomicCreateNewFile() {
if (supportsAtomicCreateNewFile == AtomicFileCreation.UNDEFINED) {
determineAtomicFileCreationSupport();
}
return supportsAtomicCreateNewFile == AtomicFileCreation.SUPPORTED;
}
@Override
@SuppressWarnings("boxing")
/**
* {@inheritDoc}
* <p>
* An implementation of the File#createNewFile() semantics which works also
* on NFS. If the config option
* {@code core.supportsAtomicCreateNewFile = true} (which is the default)
* then simply File#createNewFile() is called.
*
* But if {@code core.supportsAtomicCreateNewFile = false} then after
* successful creation of the lock file a hard link to that lock file is
* created and the attribute nlink of the lock file is checked to be 2. If
* multiple clients manage to create the same lock file nlink would be
* greater than 2 showing the error.
*
* @see "https://www.time-travellers.org/shane/papers/NFS_considered_harmful.html"
*
* @deprecated use {@link FS_POSIX#createNewFileAtomic(File)} instead
* @since 4.5
*/
@Deprecated
public boolean createNewFile(File lock) throws IOException {
if (!lock.createNewFile()) {
return false;
}
if (supportsAtomicCreateNewFile() || !supportsUnixNLink) {
return true;
}
Path lockPath = lock.toPath();
Path link = null;
try {
link = Files.createLink(
Paths.get(lock.getAbsolutePath() + ".lnk"), //$NON-NLS-1$
lockPath);
Integer nlink = (Integer) (Files.getAttribute(lockPath,
"unix:nlink")); //$NON-NLS-1$
if (nlink > 2) {
LOG.warn(MessageFormat.format(
JGitText.get().failedAtomicFileCreation, lockPath,
nlink));
return false;
} else if (nlink < 2) {
supportsUnixNLink = false;
}
return true;
} catch (UnsupportedOperationException | IllegalArgumentException e) {
supportsUnixNLink = false;
return true;
} finally {
if (link != null) {
Files.delete(link);
}
}
}
/**
* {@inheritDoc}
* <p>
* An implementation of the File#createNewFile() semantics which can create
* a unique file atomically also on NFS. If the config option
* {@code core.supportsAtomicCreateNewFile = true} (which is the default)
* then simply File#createNewFile() is called.
*
* But if {@code core.supportsAtomicCreateNewFile = false} then after
* successful creation of the lock file a hard link to that lock file is
* created and the attribute nlink of the lock file is checked to be 2. If
* multiple clients manage to create the same lock file nlink would be
* greater than 2 showing the error. The hard link needs to be retained
* until the corresponding file is no longer needed in order to prevent that
* another process can create the same file concurrently using another NFS
* client which might not yet see the file due to caching.
*
* @see "https://www.time-travellers.org/shane/papers/NFS_considered_harmful.html"
* @param file
* the unique file to be created atomically
* @return LockToken this lock token must be held until the file is no
* longer needed
* @throws IOException
* @since 5.0
*/
@Override
public LockToken createNewFileAtomic(File file) throws IOException {
if (!file.createNewFile()) {
return token(false, null);
}
if (supportsAtomicCreateNewFile() || !supportsUnixNLink) {
return token(true, null);
}
Path link = null;
Path path = file.toPath();
try {
link = Files.createLink(Paths.get(uniqueLinkPath(file)), path);
Integer nlink = (Integer) (Files.getAttribute(path,
"unix:nlink")); //$NON-NLS-1$
if (nlink.intValue() > 2) {
LOG.warn(MessageFormat.format(
JGitText.get().failedAtomicFileCreation, path, nlink));
return token(false, link);
} else if (nlink.intValue() < 2) {
supportsUnixNLink = false;
}
return token(true, link);
} catch (UnsupportedOperationException | IllegalArgumentException
| AccessDeniedException | SecurityException e) {
supportsUnixNLink = false;
return token(true, link);
}
}
private static LockToken token(boolean created, @Nullable Path p) {
return ((p != null) && Files.exists(p))
? new LockToken(created, Optional.of(p))
: new LockToken(created, Optional.empty());
}
private static String uniqueLinkPath(File file) {
UUID id = UUID.randomUUID();
return file.getAbsolutePath() + "." //$NON-NLS-1$
+ Long.toHexString(id.getMostSignificantBits())
+ Long.toHexString(id.getLeastSignificantBits());
}
}