ContentTypeDetector.java
/*******************************************************************************
* Copyright (c) 2009, 2024 Mountainminds GmbH & Co. KG and Contributors
* This program and the accompanying materials are made available under
* the terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* Marc R. Hoffmann - initial API and implementation
*
*******************************************************************************/
package org.jacoco.core.internal;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* Detector for content types of binary streams based on a magic headers.
*/
public class ContentTypeDetector {
/** Unknown file type */
public static final int UNKNOWN = -1;
/** File type Java class */
public static final int CLASSFILE = 0xcafebabe;
/** File type ZIP archive */
public static final int ZIPFILE = 0x504b0304;
/** File type GZIP compressed Data */
public static final int GZFILE = 0x1f8b0000;
/** File type Pack200 archive */
public static final int PACK200FILE = 0xcafed00d;
private static final int BUFFER_SIZE = 8;
private final InputStream in;
private final int type;
/**
* Creates a new detector based on the given input. To process the complete
* original input afterwards use the stream returned by
* {@link #getInputStream()}.
*
* @param in
* input to read the header from
* @throws IOException
* if the stream can't be read
*/
public ContentTypeDetector(final InputStream in) throws IOException {
if (in.markSupported()) {
this.in = in;
} else {
this.in = new BufferedInputStream(in, BUFFER_SIZE);
}
this.in.mark(BUFFER_SIZE);
this.type = determineType(this.in);
this.in.reset();
}
private static int determineType(final InputStream in) throws IOException {
final int header = readInt(in);
switch (header) {
case ZIPFILE:
return ZIPFILE;
case PACK200FILE:
return PACK200FILE;
case CLASSFILE:
// Mach-O fat/universal binaries have the same magic header as Java
// class files, number of architectures is stored in unsigned 4
// bytes in the same place and in the same big-endian order as major
// and minor version of class file. Hopefully on practice number of
// architectures in single executable is less than 45, which is
// major version of Java 1.1 class files:
final int majorVersion = readInt(in) & 0xFFFF;
if (majorVersion >= 45) {
return CLASSFILE;
}
}
if ((header & 0xffff0000) == GZFILE) {
return GZFILE;
}
return UNKNOWN;
}
private static int readInt(final InputStream in) throws IOException {
return in.read() << 24 | in.read() << 16 | in.read() << 8 | in.read();
}
/**
* Returns an input stream instance to read the complete content (including
* the header) of the underlying stream.
*
* @return input stream containing the complete content
*/
public InputStream getInputStream() {
return in;
}
/**
* Returns the detected file type.
*
* @return file type
*/
public int getType() {
return type;
}
}