MultipartInput.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.fileupload2.core;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import org.apache.commons.fileupload2.core.FileItemInput.ItemSkippedException;
import org.apache.commons.io.Charsets;
import org.apache.commons.io.IOUtils;
import org.apache.commons.io.build.AbstractOrigin;
import org.apache.commons.io.build.AbstractStreamBuilder;
import org.apache.commons.io.output.NullOutputStream;
/**
* Low-level API for processing file uploads.
*
* <p>
* This class can be used to process data streams conforming to MIME 'multipart' format as defined in <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC
* 1867</a>. Arbitrarily large amounts of data in the stream can be processed under constant memory usage.
* </p>
* <p>
* The format of the stream is defined in the following way:
* </p>
* <pre>
* multipart-body := preamble 1*encapsulation close-delimiter epilogue<br>
* encapsulation := delimiter body CRLF<br>
* delimiter := "--" boundary CRLF<br>
* close-delimiter := "--" boundary "--"<br>
* preamble := <ignore><br>
* epilogue := <ignore><br>
* body := header-part CRLF body-part<br>
* header-part := 1*header CRLF<br>
* header := header-name ":" header-value<br>
* header-name := <printable ASCII characters except ":"><br>
* header-value := <any ASCII characters except CR & LF><br>
* body-data := <arbitrary data><br>
* </pre>
*
* <p>
* Note that body-data can contain another mulipart entity. There is limited support for single pass processing of such nested streams. The nested stream is
* <strong>required</strong> to have a boundary token of the same length as the parent stream (see {@link #setBoundary(byte[])}).
* </p>
* <p>
* Here is an example of usage of this class:
* </p>
*
* <pre>
* try {
* MultipartInput multipartStream = MultipartInput.builder()
* .setBoundary(boundary)
* .setInputStream(input)
* .get();
* boolean nextPart = multipartStream.skipPreamble();
* OutputStream output;
* while (nextPart) {
* String header = multipartStream.readHeaders();
* // process headers
* // create some output stream
* multipartStream.readBodyData(output);
* nextPart = multipartStream.readBoundary();
* }
* } catch (MultipartInput.MalformedStreamException e) {
* // the stream failed to follow required syntax
* } catch (IOException e) {
* // a read or write error occurred
* }
* </pre>
*/
public final class MultipartInput {
/**
* Builds a new {@link MultipartInput} instance.
* <p>
* For example:
* </p>
*
* <pre>{@code
* MultipartInput factory = MultipartInput.builder().setPath(path).setBufferSize(DEFAULT_THRESHOLD).get();
* }
* </pre>
*/
public static class Builder extends AbstractStreamBuilder<MultipartInput, Builder> {
/**
* Boundary.
*/
private byte[] boundary;
/**
* Progress notifier.
*/
private ProgressNotifier progressNotifier;
/** The per part size limit for headers.
*/
private int partHeaderSizeMax = DEFAULT_PART_HEADER_SIZE_MAX;
/**
* Constructs a new instance.
*/
public Builder() {
setBufferSizeDefault(DEFAULT_BUFSIZE);
}
/**
* Constructs a new instance.
* <p>
* This builder uses the InputStream, buffer size, boundary and progress notifier aspects.
* </p>
* <p>
* You must provide an origin that can be converted to a Reader by this builder, otherwise, this call will throw an
* {@link UnsupportedOperationException}.
* </p>
*
* @return a new instance.
* @throws IOException if an I/O error occurs.
* @throws UnsupportedOperationException if the origin cannot provide a Path.
* @see AbstractOrigin#getReader(Charset)
*/
@Override
public MultipartInput get() throws IOException {
return new MultipartInput(getInputStream(), boundary, getBufferSize(), getPartHeaderSizeMax(), progressNotifier);
}
/** Returns the per part size limit for headers.
* @return The maximum size of the headers in bytes.
* @since 2.0.0-M4
*/
public int getPartHeaderSizeMax() {
return partHeaderSizeMax;
}
/**
* Sets the boundary.
*
* @param boundary the boundary.
* @return {@code this} instance.
*/
public Builder setBoundary(final byte[] boundary) {
this.boundary = boundary;
return this;
}
/** Sets the per part size limit for headers.
* @param partHeaderSizeMax The maximum size of the headers in bytes.
* @return This builder.
* @since 2.0.0-M4
*/
public Builder setPartHeaderSizeMax(final int partHeaderSizeMax) {
this.partHeaderSizeMax = partHeaderSizeMax;
return this;
}
/**
* Sets the progress notifier.
*
* @param progressNotifier progress notifier.
* @return {@code this} instance.
*/
public Builder setProgressNotifier(final ProgressNotifier progressNotifier) {
this.progressNotifier = progressNotifier;
return this;
}
}
/**
* Signals an attempt to set an invalid boundary token.
*/
public static class FileUploadBoundaryException extends FileUploadException {
/**
* The UID to use when serializing this instance.
*/
private static final long serialVersionUID = 2;
/**
* Constructs an instance with the specified detail message.
*
* @param message The detail message (which is saved for later retrieval by the {@link #getMessage()} method)
*/
public FileUploadBoundaryException(final String message) {
super(message);
}
}
/**
* An {@link InputStream} for reading an items contents.
*/
public class ItemInputStream extends InputStream {
/**
* Offset when converting negative bytes to integers.
*/
private static final int BYTE_POSITIVE_OFFSET = 256;
/**
* The number of bytes, which have been read so far.
*/
private long total;
/**
* The number of bytes, which must be hold, because they might be a part of the boundary.
*/
private int pad;
/**
* The current offset in the buffer.
*/
private int pos;
/**
* Whether the stream is already closed.
*/
private boolean closed;
/**
* Creates a new instance.
*/
ItemInputStream() {
findSeparator();
}
/**
* Returns the number of bytes, which are currently available, without blocking.
*
* @throws IOException An I/O error occurs.
* @return Number of bytes in the buffer.
*/
@Override
public int available() throws IOException {
if (pos == -1) {
return tail - head - pad;
}
return pos - head;
}
private void checkOpen() throws ItemSkippedException {
if (closed) {
throw new FileItemInput.ItemSkippedException("checkOpen()");
}
}
/**
* Closes the input stream.
*
* @throws IOException An I/O error occurred.
*/
@Override
public void close() throws IOException {
close(false);
}
/**
* Closes the input stream.
*
* @param closeUnderlying Whether to close the underlying stream (hard close)
* @throws IOException An I/O error occurred.
*/
public void close(final boolean closeUnderlying) throws IOException {
if (closed) {
return;
}
if (closeUnderlying) {
closed = true;
input.close();
} else {
for (;;) {
var avail = available();
if (avail == 0) {
avail = makeAvailable();
if (avail == 0) {
break;
}
}
if (skip(avail) != avail) {
// TODO What to do?
}
}
}
closed = true;
}
/**
* Called for finding the separator.
*/
private void findSeparator() {
pos = MultipartInput.this.findSeparator();
if (pos == -1) {
if (tail - head > keepRegion) {
pad = keepRegion;
} else {
pad = tail - head;
}
}
}
/**
* Gets the number of bytes, which have been read by the stream.
*
* @return Number of bytes, which have been read so far.
*/
public long getBytesRead() {
return total;
}
/**
* Tests whether this instance is closed.
*
* @return whether this instance is closed.
*/
public boolean isClosed() {
return closed;
}
/**
* Attempts to read more data.
*
* @return Number of available bytes
* @throws IOException An I/O error occurred.
*/
private int makeAvailable() throws IOException {
if (pos != -1) {
return 0;
}
// Move the data to the beginning of the buffer.
total += tail - head - pad;
System.arraycopy(buffer, tail - pad, buffer, 0, pad);
// Refill buffer with new data.
head = 0;
tail = pad;
for (;;) {
final var bytesRead = input.read(buffer, tail, bufSize - tail);
if (bytesRead == -1) {
// The last pad amount is left in the buffer.
// Boundary can't be in there so signal an error
// condition.
final var msg = "Stream ended unexpectedly";
throw new MalformedStreamException(msg);
}
if (notifier != null) {
notifier.noteBytesRead(bytesRead);
}
tail += bytesRead;
findSeparator();
final var av = available();
if (av > 0 || pos != -1) {
return av;
}
}
}
/**
* Reads the next byte in the stream.
*
* @return The next byte in the stream, as a non-negative integer, or -1 for EOF.
* @throws IOException An I/O error occurred.
*/
@Override
public int read() throws IOException {
checkOpen();
if (available() == 0 && makeAvailable() == 0) {
return -1;
}
++total;
final int b = buffer[head++];
if (b >= 0) {
return b;
}
return b + BYTE_POSITIVE_OFFSET;
}
/**
* Reads bytes into the given buffer.
*
* @param b The destination buffer, where to write to.
* @param off Offset of the first byte in the buffer.
* @param len Maximum number of bytes to read.
* @return Number of bytes, which have been actually read, or -1 for EOF.
* @throws IOException An I/O error occurred.
*/
@Override
public int read(final byte[] b, final int off, final int len) throws IOException {
checkOpen();
if (len == 0) {
return 0;
}
var res = available();
if (res == 0) {
res = makeAvailable();
if (res == 0) {
return -1;
}
}
res = Math.min(res, len);
System.arraycopy(buffer, head, b, off, res);
head += res;
total += res;
return res;
}
/**
* Skips the given number of bytes.
*
* @param bytes Number of bytes to skip.
* @return The number of bytes, which have actually been skipped.
* @throws IOException An I/O error occurred.
*/
@Override
public long skip(final long bytes) throws IOException {
checkOpen();
var available = available();
if (available == 0) {
available = makeAvailable();
if (available == 0) {
return 0;
}
}
// Fix "Implicit narrowing conversion in compound assignment"
// https://github.com/apache/commons-fileupload/security/code-scanning/118
// Math.min always returns an int because available is an int.
final var res = Math.toIntExact(Math.min(available, bytes));
head += res;
return res;
}
}
/**
* Signals that the input stream fails to follow the required syntax.
*/
public static class MalformedStreamException extends FileUploadException {
/**
* The UID to use when serializing this instance.
*/
private static final long serialVersionUID = 2;
/**
* Constructs an {@code MalformedStreamException} with the specified detail message.
*
* @param message The detail message.
*/
public MalformedStreamException(final String message) {
super(message);
}
/**
* Constructs an {@code MalformedStreamException} with the specified detail message.
*
* @param message The detail message.
* @param cause The cause (which is saved for later retrieval by the {@link #getCause()} method). (A null value is permitted, and indicates that the
* cause is nonexistent or unknown.)
*/
public MalformedStreamException(final String message, final Throwable cause) {
super(message, cause);
}
}
/**
* Internal class, which is used to invoke the {@link ProgressListener}.
*/
public static class ProgressNotifier {
/**
* The listener to invoke.
*/
private final ProgressListener progressListener;
/**
* Number of expected bytes, if known, or -1.
*/
private final long contentLength;
/**
* Number of bytes, which have been read so far.
*/
private long bytesRead;
/**
* Number of items, which have been read so far.
*/
private int items;
/**
* Creates a new instance with the given listener and content length.
*
* @param progressListener The listener to invoke.
* @param contentLength The expected content length.
*/
public ProgressNotifier(final ProgressListener progressListener, final long contentLength) {
this.progressListener = progressListener != null ? progressListener : ProgressListener.NOP;
this.contentLength = contentLength;
}
/**
* Called to indicate that bytes have been read.
*
* @param byteCount Number of bytes, which have been read.
*/
void noteBytesRead(final int byteCount) {
//
// Indicates, that the given number of bytes have been read from the input stream.
//
bytesRead += byteCount;
notifyListener();
}
/**
* Called to indicate, that a new file item has been detected.
*/
public void noteItem() {
++items;
notifyListener();
}
/**
* Called for notifying the listener.
*/
private void notifyListener() {
progressListener.update(bytesRead, contentLength, items);
}
}
/**
* The Carriage Return ASCII character value.
*/
public static final byte CR = 0x0D;
/**
* The Line Feed ASCII character value.
*/
public static final byte LF = 0x0A;
/**
* The dash (-) ASCII character value.
*/
public static final byte DASH = 0x2D;
/**
* The default length of the buffer used for processing a request.
*/
static final int DEFAULT_BUFSIZE = 4096;
/**
* Default per part header size limit in bytes.
* @since 2.0.0-M4
*/
public static final int DEFAULT_PART_HEADER_SIZE_MAX = 512;
/**
* A byte sequence that marks the end of {@code header-part} ({@code CRLFCRLF}).
*/
static final byte[] HEADER_SEPARATOR = { CR, LF, CR, LF };
/**
* A byte sequence that that follows a delimiter that will be followed by an encapsulation ({@code CRLF}).
*/
static final byte[] FIELD_SEPARATOR = { CR, LF };
/**
* A byte sequence that that follows a delimiter of the last encapsulation in the stream ({@code --}).
*/
static final byte[] STREAM_TERMINATOR = { DASH, DASH };
/**
* A byte sequence that precedes a boundary ({@code CRLF--}).
*/
static final byte[] BOUNDARY_PREFIX = { CR, LF, DASH, DASH };
/**
* Compares {@code count} first bytes in the arrays {@code a} and {@code b}.
*
* @param a The first array to compare.
* @param b The second array to compare.
* @param count How many bytes should be compared.
* @return {@code true} if {@code count} first bytes in arrays {@code a} and {@code b} are equal.
*/
static boolean arrayEquals(final byte[] a, final byte[] b, final int count) {
for (var i = 0; i < count; i++) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
/**
* Constructs a new {@link Builder}.
*
* @return a new {@link Builder}.
*/
public static Builder builder() {
return new Builder();
}
/**
* The input stream from which data is read.
*/
private final InputStream input;
/**
* The length of the boundary token plus the leading {@code CRLF--}.
*/
private int boundaryLength;
/**
* The amount of data, in bytes, that must be kept in the buffer in order to detect delimiters reliably.
*/
private final int keepRegion;
/**
* The byte sequence that partitions the stream.
*/
private final byte[] boundary;
/**
* The table for Knuth-Morris-Pratt search algorithm.
*/
private final int[] boundaryTable;
/**
* The length of the buffer used for processing the request.
*/
private final int bufSize;
/**
* The buffer used for processing the request.
*/
private final byte[] buffer;
/**
* The index of first valid character in the buffer. <br>
* 0 <= head < bufSize
*/
private int head;
/**
* The index of last valid character in the buffer + 1. <br>
* 0 <= tail <= bufSize
*/
private int tail;
/**
* The content encoding to use when reading headers.
*/
private Charset headerCharset;
/**
* The progress notifier, if any, or null.
*/
private final ProgressNotifier notifier;
/**
* The maximum size of the headers in bytes.
*/
private final int partHeaderSizeMax;
/**
* Constructs a {@code MultipartInput} with a custom size buffer.
* <p>
* Note that the buffer must be at least big enough to contain the boundary string, plus 4 characters for CR/LF and double dash, plus at least one byte of
* data. Too small a buffer size setting will degrade performance.
* </p>
*
* @param input The {@code InputStream} to serve as a data source.
* @param boundary The token used for dividing the stream into {@code encapsulations}.
* @param bufferSize The size of the buffer to be used, in bytes.
* @param notifier The notifier, which is used for calling the progress listener, if any.
* @throws IllegalArgumentException If the buffer size is too small.
*/
private MultipartInput(final InputStream input, final byte[] boundary, final int bufferSize, final int partHeaderSizeMax, final ProgressNotifier notifier) {
if (boundary == null) {
throw new IllegalArgumentException("boundary may not be null");
}
// We prepend CR/LF to the boundary to chop trailing CR/LF from
// body-data tokens.
this.boundaryLength = boundary.length + BOUNDARY_PREFIX.length;
if (bufferSize < this.boundaryLength + 1) {
throw new IllegalArgumentException("The buffer size specified for the MultipartInput is too small");
}
this.input = input;
this.bufSize = Math.max(bufferSize, boundaryLength * 2);
this.buffer = new byte[this.bufSize];
this.notifier = notifier;
this.partHeaderSizeMax = partHeaderSizeMax;
this.boundary = new byte[this.boundaryLength];
this.boundaryTable = new int[this.boundaryLength + 1];
this.keepRegion = this.boundary.length;
System.arraycopy(BOUNDARY_PREFIX, 0, this.boundary, 0, BOUNDARY_PREFIX.length);
System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length, boundary.length);
computeBoundaryTable();
head = 0;
tail = 0;
}
/**
* Computes the table used for Knuth-Morris-Pratt search algorithm.
*/
private void computeBoundaryTable() {
var position = 2;
var candidate = 0;
boundaryTable[0] = -1;
boundaryTable[1] = 0;
while (position <= boundaryLength) {
if (boundary[position - 1] == boundary[candidate]) {
boundaryTable[position] = candidate + 1;
candidate++;
position++;
} else if (candidate > 0) {
candidate = boundaryTable[candidate];
} else {
boundaryTable[position] = 0;
position++;
}
}
}
/**
* Reads {@code body-data} from the current {@code encapsulation} and discards it.
* <p>
* Use this method to skip encapsulations you don't need or don't understand.
* </p>
*
* @return The amount of data discarded.
* @throws MalformedStreamException if the stream ends unexpectedly.
* @throws IOException if an i/o error occurs.
*/
public long discardBodyData() throws MalformedStreamException, IOException {
return readBodyData(NullOutputStream.INSTANCE);
}
/**
* Searches for a byte of specified value in the {@code buffer}, starting at the specified {@code position}.
*
* @param value The value to find.
* @param pos The starting position for searching.
* @return The position of byte found, counting from beginning of the {@code buffer}, or {@code -1} if not found.
*/
protected int findByte(final byte value, final int pos) {
for (var i = pos; i < tail; i++) {
if (buffer[i] == value) {
return i;
}
}
return -1;
}
/**
* Searches for the {@code boundary} in the {@code buffer} region delimited by {@code head} and {@code tail}.
*
* @return The position of the boundary found, counting from the beginning of the {@code buffer}, or {@code -1} if not found.
*/
protected int findSeparator() {
var bufferPos = this.head;
var tablePos = 0;
while (bufferPos < this.tail) {
while (tablePos >= 0 && buffer[bufferPos] != boundary[tablePos]) {
tablePos = boundaryTable[tablePos];
}
bufferPos++;
tablePos++;
if (tablePos == boundaryLength) {
return bufferPos - boundaryLength;
}
}
return -1;
}
/**
* Gets the character encoding used when reading the headers of an individual part. When not specified, or {@code null}, the platform default encoding is
* used.
*
* @return The encoding used to read part headers.
*/
public Charset getHeaderCharset() {
return headerCharset;
}
/** Returns the per part size limit for headers.
*
* @return The maximum size of the headers in bytes.
* @since 2.0.0-M4
*/
public int getPartHeaderSizeMax() {
return partHeaderSizeMax;
}
/**
* Creates a new {@link ItemInputStream}.
*
* @return A new instance of {@link ItemInputStream}.
*/
public ItemInputStream newInputStream() {
return new ItemInputStream();
}
/**
* Reads {@code body-data} from the current {@code encapsulation} and writes its contents into the output {@code Stream}.
* <p>
* Arbitrary large amounts of data can be processed by this method using a constant size buffer. (see {@link MultipartInput#builder()}).
* </p>
*
* @param output The {@code Stream} to write data into. May be null, in which case this method is equivalent to {@link #discardBodyData()}.
* @return the amount of data written.
* @throws MalformedStreamException if the stream ends unexpectedly.
* @throws IOException if an i/o error occurs.
*/
public long readBodyData(final OutputStream output) throws MalformedStreamException, IOException {
try (var inputStream = newInputStream()) {
return IOUtils.copyLarge(inputStream, output);
}
}
/**
* Skips a {@code boundary} token, and checks whether more {@code encapsulations} are contained in the stream.
*
* @return {@code true} if there are more encapsulations in this stream; {@code false} otherwise.
* @throws FileUploadSizeException if the bytes read from the stream exceeded the size limits
* @throws MalformedStreamException if the stream ends unexpectedly or fails to follow required syntax.
*/
public boolean readBoundary() throws FileUploadSizeException, MalformedStreamException {
final var marker = new byte[2];
final boolean nextChunk;
head += boundaryLength;
try {
marker[0] = readByte();
if (marker[0] == LF) {
// Work around IE5 Mac bug with input type=image.
// Because the boundary delimiter, not including the trailing
// CRLF, must not appear within any file (RFC 2046, section
// 5.1.1), we know the missing CR is due to a buggy browser
// rather than a file containing something similar to a
// boundary.
return true;
}
marker[1] = readByte();
if (arrayEquals(marker, STREAM_TERMINATOR, 2)) {
nextChunk = false;
} else if (arrayEquals(marker, FIELD_SEPARATOR, 2)) {
nextChunk = true;
} else {
throw new MalformedStreamException("Unexpected characters follow a boundary");
}
} catch (final FileUploadSizeException e) {
throw e;
} catch (final IOException e) {
throw new MalformedStreamException("Stream ended unexpectedly", e);
}
return nextChunk;
}
/**
* Reads a byte from the {@code buffer}, and refills it as necessary.
*
* @return The next byte from the input stream.
* @throws IOException if there is no more data available.
*/
public byte readByte() throws IOException {
// Buffer depleted ?
if (head == tail) {
head = 0;
// Refill.
tail = input.read(buffer, head, bufSize);
if (tail == -1) {
// No more data available.
throw new IOException("No more data is available");
}
if (notifier != null) {
notifier.noteBytesRead(tail);
}
}
return buffer[head++];
}
/**
* Reads the {@code header-part} of the current {@code encapsulation}.
* <p>
* Headers are returned verbatim to the input stream, including the trailing {@code CRLF} marker. Parsing is left to the application.
* </p>
* <p>
* <strong>TODO</strong> allow limiting maximum header size to protect against abuse.
* </p>
*
* @return The {@code header-part} of the current encapsulation.
* @throws FileUploadSizeException if the bytes read from the stream exceeded the size limits.
* @throws MalformedStreamException if the stream ends unexpectedly.
*/
public String readHeaders() throws FileUploadSizeException, MalformedStreamException {
var i = 0;
byte b;
// to support multi-byte characters
final var baos = new ByteArrayOutputStream();
var size = 0;
while (i < HEADER_SEPARATOR.length) {
try {
b = readByte();
} catch (final FileUploadSizeException e) {
// wraps a FileUploadSizeException, re-throw as it will be unwrapped later
throw e;
} catch (final IOException e) {
throw new MalformedStreamException("Stream ended unexpectedly", e);
}
final int phsm = getPartHeaderSizeMax();
if (phsm != -1 && ++size > phsm) {
throw new FileUploadSizeException(
String.format("Header section has more than %s bytes (maybe it is not properly terminated)", Integer.valueOf(phsm)), phsm, size);
}
if (b == HEADER_SEPARATOR[i]) {
i++;
} else {
i = 0;
}
baos.write(b);
}
try {
return baos.toString(Charsets.toCharset(headerCharset, Charset.defaultCharset()).name());
} catch (final UnsupportedEncodingException e) {
// not possible
throw new IllegalStateException(e);
}
}
/**
* Changes the boundary token used for partitioning the stream.
* <p>
* This method allows single pass processing of nested multipart streams.
* </p>
* <p>
* The boundary token of the nested stream is {@code required} to be of the same length as the boundary token in parent stream.
* </p>
* <p>
* Restoring the parent stream boundary token after processing of a nested stream is left to the application.
* </p>
*
* @param boundary The boundary to be used for parsing of the nested stream.
* @throws FileUploadBoundaryException if the {@code boundary} has a different length than the one being currently parsed.
*/
public void setBoundary(final byte[] boundary) throws FileUploadBoundaryException {
if (boundary.length != boundaryLength - BOUNDARY_PREFIX.length) {
throw new FileUploadBoundaryException("The length of a boundary token cannot be changed");
}
System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length, boundary.length);
computeBoundaryTable();
}
/**
* Sets the character encoding to be used when reading the headers of individual parts. When not specified, or {@code null}, the platform default encoding
* is used.
*
* @param headerCharset The encoding used to read part headers.
*/
public void setHeaderCharset(final Charset headerCharset) {
this.headerCharset = headerCharset;
}
/**
* Finds the beginning of the first {@code encapsulation}.
*
* @return {@code true} if an {@code encapsulation} was found in the stream.
* @throws IOException if an i/o error occurs.
*/
public boolean skipPreamble() throws IOException {
// First delimiter may be not preceded with a CRLF.
System.arraycopy(boundary, 2, boundary, 0, boundary.length - 2);
boundaryLength = boundary.length - 2;
computeBoundaryTable();
try {
// Discard all data up to the delimiter.
discardBodyData();
// Read boundary - if succeeded, the stream contains an
// encapsulation.
return readBoundary();
} catch (final MalformedStreamException e) {
return false;
} finally {
// Restore delimiter.
System.arraycopy(boundary, 0, boundary, 2, boundary.length - 2);
boundaryLength = boundary.length;
boundary[0] = CR;
boundary[1] = LF;
computeBoundaryTable();
}
}
}