/*
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
*
* 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 Git Development Community 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.spearce.jgit.treewalk;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharacterCodingException;
import java.nio.charset.CharsetEncoder;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.Comparator;
import org.spearce.jgit.errors.CorruptObjectException;
import org.spearce.jgit.lib.Constants;
import org.spearce.jgit.lib.FileMode;
/**
* Walks a working directory tree as part of a {@link TreeWalk}.
* <p>
* Most applications will want to use the standard implementation of this
* iterator, {@link FileTreeIterator}, as that does all IO through the standard
* <code>java.io</code> package. Plugins for a Java based IDE may however wish
* to create their own implementations of this class to allow traversal of the
* IDE's project space, as well as benefit from any caching the IDE may have.
*
* @see FileTreeIterator
*/
public abstract class WorkingTreeIterator extends AbstractTreeIterator {
/** An empty entry array, suitable for {@link #init(Entry[])}. */
protected static final Entry[] EOF = {};
/** Size we perform file IO in if we have to read and hash a file. */
private static final int BUFFER_SIZE = 2048;
/** The {@link #idBuffer()} for the current entry. */
private byte[] contentId;
/** Index within {@link #entries} that {@link #contentId} came from. */
private int contentIdFromPtr;
/** Buffer used to perform {@link #contentId} computations. */
private byte[] contentReadBuffer;
/** Digest computer for {@link #contentId} computations. */
private MessageDigest contentDigest;
/** File name character encoder. */
private final CharsetEncoder nameEncoder;
/** List of entries obtained from the subclass. */
private Entry[] entries;
/** Total number of entries in {@link #entries} that are valid. */
private int entryCnt;
/** Current position within {@link #entries}. */
private int ptr;
/** Create a new iterator with no parent. */
protected WorkingTreeIterator() {
super();
nameEncoder = Constants.CHARSET.newEncoder();
}
/**
* Create a new iterator with no parent and a prefix.
* <p>
* The prefix path supplied is inserted in front of all paths generated by
* this iterator. It is intended to be used when an iterator is being
* created for a subsection of an overall repository and needs to be
* combined with other iterators that are created to run over the entire
* repository namespace.
*
* @param prefix
* position of this iterator in the repository tree. The value
* may be null or the empty string to indicate the prefix is the
* root of the repository. A trailing slash ('/') is
* automatically appended if the prefix does not end in '/'.
*/
protected WorkingTreeIterator(final String prefix) {
super(prefix);
nameEncoder = Constants.CHARSET.newEncoder();
}
/**
* Create an iterator for a subtree of an existing iterator.
*
* @param p
* parent tree iterator.
*/
protected WorkingTreeIterator(final WorkingTreeIterator p) {
super(p);
nameEncoder = p.nameEncoder;
}
@Override
public byte[] idBuffer() {
if (contentIdFromPtr == ptr)
return contentId;
switch (mode & FileMode.TYPE_MASK) {
case FileMode.TYPE_FILE:
contentIdFromPtr = ptr;
return contentId = idBufferBlob(entries[ptr]);
case FileMode.TYPE_SYMLINK:
// Java does not support symbolic links, so we should not
// have reached this particular part of the walk code.
//
return zeroid;
case FileMode.TYPE_GITLINK:
// TODO: Support obtaining current HEAD SHA-1 from nested repository
//
return zeroid;
}
return zeroid;
}
private void initializeDigest() {
if (contentDigest != null)
return;
if (parent == null) {
contentReadBuffer = new byte[BUFFER_SIZE];
contentDigest = Constants.newMessageDigest();
} else {
final WorkingTreeIterator p = (WorkingTreeIterator) parent;
p.initializeDigest();
contentReadBuffer = p.contentReadBuffer;
contentDigest = p.contentDigest;
}
}
private static final byte[] digits = { '0', '1', '2', '3', '4', '5', '6',
'7', '8', '9' };
private static final byte[] hblob = Constants
.encodedTypeString(Constants.OBJ_BLOB);
private byte[] idBufferBlob(final Entry e) {
try {
final InputStream is = e.openInputStream();
if (is == null)
return zeroid;
try {
initializeDigest();
contentDigest.reset();
contentDigest.update(hblob);
contentDigest.update((byte) ' ');
final long blobLength = e.getLength();
long sz = blobLength;
if (sz == 0) {
contentDigest.update((byte) '0');
} else {
final int bufn = contentReadBuffer.length;
int p = bufn;
do {
contentReadBuffer[--p] = digits[(int) (sz % 10)];
sz /= 10;
} while (sz > 0);
contentDigest.update(contentReadBuffer, p, bufn - p);
}
contentDigest.update((byte) 0);
for (;;) {
final int r = is.read(contentReadBuffer);
if (r <= 0)
break;
contentDigest.update(contentReadBuffer, 0, r);
sz += r;
}
if (sz != blobLength)
return zeroid;
return contentDigest.digest();
} finally {
try {
is.close();
} catch (IOException err2) {
// Suppress any error related to closing an input
// stream. We don't care, we should not have any
// outstanding data to flush or anything like that.
}
}
} catch (IOException err) {
// Can't read the file? Don't report the failure either.
//
return zeroid;
}
}
@Override
public int idOffset() {
return 0;
}
@Override
public boolean first() {
return ptr == 0;
}
@Override
public boolean eof() {
return ptr == entryCnt;
}
@Override
public void next(final int delta) throws CorruptObjectException {
ptr += delta;
if (!eof())
parseEntry();
}
@Override
public void back(final int delta) throws CorruptObjectException {
ptr -= delta;
parseEntry();
}
private void parseEntry() {
final Entry e = entries[ptr];
mode = e.getMode().getBits();
final int nameLen = e.encodedNameLen;
ensurePathCapacity(pathOffset + nameLen, pathOffset);
System.arraycopy(e.encodedName, 0, path, pathOffset, nameLen);
pathLen = pathOffset + nameLen;
}
/**
* Get the byte length of this entry.
*
* @return size of this file, in bytes.
*/
public long getEntryLength() {
return current().getLength();
}
/**
* Get the last modified time of this entry.
*
* @return last modified time of this file, in milliseconds since the epoch
* (Jan 1, 1970 UTC).
*/
public long getEntryLastModified() {
return current().getLastModified();
}
private static final Comparator<Entry> ENTRY_CMP = new Comparator<Entry>() {
public int compare(final Entry o1, final Entry o2) {
final byte[] a = o1.encodedName;
final byte[] b = o2.encodedName;
final int aLen = o1.encodedNameLen;
final int bLen = o2.encodedNameLen;
int cPos;
for (cPos = 0; cPos < aLen && cPos < bLen; cPos++) {
final int cmp = (a[cPos] & 0xff) - (b[cPos] & 0xff);
if (cmp != 0)
return cmp;
}
if (cPos < aLen)
return (a[cPos] & 0xff) - lastPathChar(o2);
if (cPos < bLen)
return lastPathChar(o1) - (b[cPos] & 0xff);
return lastPathChar(o1) - lastPathChar(o2);
}
};
static int lastPathChar(final Entry e) {
return e.getMode() == FileMode.TREE ? '/' : '\0';
}
/**
* Constructor helper.
*
* @param list
* files in the subtree of the work tree this iterator operates
* on
*/
protected void init(final Entry[] list) {
// Filter out nulls, . and .. as these are not valid tree entries,
// also cache the encoded forms of the path names for efficient use
// later on during sorting and iteration.
//
entries = list;
int i, o;
for (i = 0, o = 0; i < entries.length; i++) {
final Entry e = entries[i];
if (e == null)
continue;
final String name = e.getName();
if (".".equals(name) || "..".equals(name))
continue;
if (".git".equals(name))
continue;
if (i != o)
entries[o] = e;
e.encodeName(nameEncoder);
o++;
}
entryCnt = o;
Arrays.sort(entries, 0, entryCnt, ENTRY_CMP);
contentIdFromPtr = -1;
ptr = 0;
if (!eof())
parseEntry();
}
/**
* Obtain the current entry from this iterator.
*
* @return the currently selected entry.
*/
protected Entry current() {
return entries[ptr];
}
/** A single entry within a working directory tree. */
protected static abstract class Entry {
byte[] encodedName;
int encodedNameLen;
void encodeName(final CharsetEncoder enc) {
final ByteBuffer b;
try {
b = enc.encode(CharBuffer.wrap(getName()));
} catch (CharacterCodingException e) {
// This should so never happen.
throw new RuntimeException("Unencodeable file: " + getName());
}
encodedNameLen = b.limit();
if (b.hasArray() && b.arrayOffset() == 0)
encodedName = b.array();
else
b.get(encodedName = new byte[encodedNameLen]);
}
public String toString() {
return getMode().toString() + " " + getName();
}
/**
* Get the type of this entry.
* <p>
* <b>Note: Efficient implementation required.</b>
* <p>
* The implementation of this method must be efficient. If a subclass
* needs to compute the value they should cache the reference within an
* instance member instead.
*
* @return a file mode constant from {@link FileMode}.
*/
public abstract FileMode getMode();
/**
* Get the byte length of this entry.
* <p>
* <b>Note: Efficient implementation required.</b>
* <p>
* The implementation of this method must be efficient. If a subclass
* needs to compute the value they should cache the reference within an
* instance member instead.
*
* @return size of this file, in bytes.
*/
public abstract long getLength();
/**
* Get the last modified time of this entry.
* <p>
* <b>Note: Efficient implementation required.</b>
* <p>
* The implementation of this method must be efficient. If a subclass
* needs to compute the value they should cache the reference within an
* instance member instead.
*
* @return time since the epoch (in ms) of the last change.
*/
public abstract long getLastModified();
/**
* Get the name of this entry within its directory.
* <p>
* Efficient implementations are not required. The caller will obtain
* the name only once and cache it once obtained.
*
* @return name of the entry.
*/
public abstract String getName();
/**
* Obtain an input stream to read the file content.
* <p>
* Efficient implementations are not required. The caller will usually
* obtain the stream only once per entry, if at all.
* <p>
* The input stream should not use buffering if the implementation can
* avoid it. The caller will buffer as necessary to perform efficient
* block IO operations.
* <p>
* The caller will close the stream once complete.
*
* @return a stream to read from the file.
* @throws IOException
* the file could not be opened for reading.
*/
public abstract InputStream openInputStream() throws IOException;
}
}