#418

Committed 23 Jul 2026 12:50PM UTC coverage: 81.28% (+0.5%) from 80.829%

Build # #418

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97.53

/jsign-core/src/main/java/net/jsign/ChannelUtils.java

/*
 * Copyright 2021 Emmanuel Bourg
 *
 * Licensed 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 net.jsign;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ByteChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.FileSystemException;
import java.nio.file.Files;
import java.nio.file.StandardOpenOption;
import java.security.MessageDigest;

/**
 * Helper class for Channel operations.
 *
 * @since 4.0
 */
public class ChannelUtils {

    /**
     * Opens a channel for the specified file with read/write access, falling back to read-only access
     * if the file is not writable or locked.
     *
     * @since 8.0
     */
    public static SeekableByteChannel openReadWriteOrReadOnly(File file) throws IOException {
        try {
            return Files.newByteChannel(file.toPath(), StandardOpenOption.READ, StandardOpenOption.WRITE);
        } catch (FileSystemException e) {
            return Files.newByteChannel(file.toPath(), StandardOpenOption.READ);
        }
    }

    public static void copy(SeekableByteChannel src, WritableByteChannel dest) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(1024 * 1024);
        src.position(0);

        while (src.position() < src.size()) {
            buffer.clear();
            src.read(buffer);
            buffer.flip();
            dest.write(buffer);
        }
    }

    public static void copy(SeekableByteChannel src, SeekableByteChannel dest, long length) throws IOException {
        ByteBuffer buffer = ByteBuffer.allocate(1024 * 1024);
        long remaining = length;
        long destOffset = dest.position();
        long srcOffset = src.position();
        while (remaining > 0) {
            int avail = (int) Math.min(remaining, buffer.capacity());
            buffer.clear();
            buffer.limit(avail);

            src.position(srcOffset);
            src.read(buffer);
            buffer.flip();

            dest.position(destOffset);
            dest.write(buffer);
            remaining -= buffer.position();
            srcOffset += buffer.position();
            destOffset += buffer.position();
        }
    }

    /**
     * Insert data into a SeekableByteChannel at the specified position,
     * shifting the data after the insertion point.
     */
    public static void insert(SeekableByteChannel channel, long position, byte[] data) throws IOException {
        if (position > channel.size()) {
            throw new IOException("Cannot insert data after the end of the file");
        }

        File backupFile = File.createTempFile("jsign", ".tmp");
        try (SeekableByteChannel backupChannel = Files.newByteChannel(backupFile.toPath(), StandardOpenOption.READ, StandardOpenOption.WRITE)) {
            copy(channel, backupChannel);

            channel.position(position);
            channel.write(ByteBuffer.wrap(data));

            backupChannel.position(position);
            copy(backupChannel, channel, backupChannel.size() - position);
        } finally {
            backupFile.delete();
        }
    }

    /**
     * Remove data from a SeekableByteChannel, shifting the data after the deletion point.
     */
    public static void delete(SeekableByteChannel channel, long position, long length) throws IOException {
        delete(channel, position, length, 1024 * 1024);
    }

    public static void delete(SeekableByteChannel channel, long position, long length, int bufferSize) throws IOException {
        if (position + length > channel.size()) {
            throw new IOException("Cannot delete data after the end of the file");
        }

        ByteBuffer buffer = ByteBuffer.allocate(bufferSize);
        long remaining = channel.size() - position - length;
        while (remaining > 0) {
            buffer.clear();
            buffer.limit((int) Math.min(remaining, buffer.capacity()));

            channel.position(position + length);
            channel.read(buffer);
            buffer.flip();

            channel.position(position);
            channel.write(buffer);
            remaining -= buffer.position();
            position += buffer.position();
        }
        
        channel.truncate(channel.size() - length);
    }

    /**
     * Update the specified digest by reading the SeekableByteChannel
     * from the start offset included to the end offset excluded.
     *
     * @param digest      the message digest to update
     * @param startOffset the start offset
     * @param endOffset   the end offset
     * @throws IOException if an I/O error occurs
     */
    public static void updateDigest(SeekableByteChannel channel, MessageDigest digest, long startOffset, long endOffset) throws IOException {
        channel.position(startOffset);

        ByteBuffer buffer = ByteBuffer.allocate(65536);

        long position = startOffset;
        while (position < endOffset) {
            buffer.clear();
            buffer.limit((int) Math.min(buffer.capacity(), endOffset - position));
            channel.read(buffer);
            buffer.rewind();

            digest.update(buffer);

            position += buffer.limit();
        }
    }

    /**
     * Read a null terminated string from the specified channel.
     */
    public static byte[] readNullTerminatedString(ByteChannel channel) throws IOException {
        try (ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
            byte singleChar;
            ByteBuffer buffer = ByteBuffer.allocate(1);
            do {
                buffer.clear();
                buffer.limit(1);
                if (channel.read(buffer) < 0) {
                    throw new IOException("End of file reached, cannot read null terminated string");
                }
                buffer.flip();
                singleChar = buffer.array()[0];
                bos.write(singleChar);
            } while (singleChar != 0);
            return bos.toByteArray();
        }
    }
}

1	/*
2	* Copyright 2021 Emmanuel Bourg
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16
17	package net.jsign;
18
19	import java.io.ByteArrayOutputStream;
20	import java.io.File;
21	import java.io.IOException;
22	import java.nio.ByteBuffer;
23	import java.nio.channels.ByteChannel;
24	import java.nio.channels.SeekableByteChannel;
25	import java.nio.channels.WritableByteChannel;
26	import java.nio.file.FileSystemException;
27	import java.nio.file.Files;
28	import java.nio.file.StandardOpenOption;
29	import java.security.MessageDigest;
30
31	/**
32	* Helper class for Channel operations.
33	*
34	* @since 4.0
35	*/
36	public class ChannelUtils {	×
37
38	/**
39	* Opens a channel for the specified file with read/write access, falling back to read-only access
40	* if the file is not writable or locked.
41	*
42	* @since 8.0
43	*/
44	public static SeekableByteChannel openReadWriteOrReadOnly(File file) throws IOException {
45	try {
46	return Files.newByteChannel(file.toPath(), StandardOpenOption.READ, StandardOpenOption.WRITE);	1✔
47	} catch (FileSystemException e) {	1✔
48	return Files.newByteChannel(file.toPath(), StandardOpenOption.READ);	1✔
49	}
50	}
51
52	public static void copy(SeekableByteChannel src, WritableByteChannel dest) throws IOException {
53	ByteBuffer buffer = ByteBuffer.allocate(1024 * 1024);	1✔
54	src.position(0);	1✔
55
56	while (src.position() < src.size()) {	1✔
57	buffer.clear();	1✔
58	src.read(buffer);	1✔
59	buffer.flip();	1✔
60	dest.write(buffer);	1✔
61	}
62	}	1✔
63
64	public static void copy(SeekableByteChannel src, SeekableByteChannel dest, long length) throws IOException {
65	ByteBuffer buffer = ByteBuffer.allocate(1024 * 1024);	1✔
66	long remaining = length;	1✔
67	long destOffset = dest.position();	1✔
68	long srcOffset = src.position();	1✔
69	while (remaining > 0) {	1✔
70	int avail = (int) Math.min(remaining, buffer.capacity());	1✔
71	buffer.clear();	1✔
72	buffer.limit(avail);	1✔
73
74	src.position(srcOffset);	1✔
75	src.read(buffer);	1✔
76	buffer.flip();	1✔
77
78	dest.position(destOffset);	1✔
79	dest.write(buffer);	1✔
80	remaining -= buffer.position();	1✔
81	srcOffset += buffer.position();	1✔
82	destOffset += buffer.position();	1✔
83	}	1✔
84	}	1✔
85
86	/**
87	* Insert data into a SeekableByteChannel at the specified position,
88	* shifting the data after the insertion point.
89	*/
90	public static void insert(SeekableByteChannel channel, long position, byte[] data) throws IOException {
91	if (position > channel.size()) {	1✔
92	throw new IOException("Cannot insert data after the end of the file");	×
93	}
94
95	File backupFile = File.createTempFile("jsign", ".tmp");	1✔
96	try (SeekableByteChannel backupChannel = Files.newByteChannel(backupFile.toPath(), StandardOpenOption.READ, StandardOpenOption.WRITE)) {	1✔
97	copy(channel, backupChannel);	1✔
98
99	channel.position(position);	1✔
100	channel.write(ByteBuffer.wrap(data));	1✔
101
102	backupChannel.position(position);	1✔
103	copy(backupChannel, channel, backupChannel.size() - position);	1✔
104	} finally {
105	backupFile.delete();	1✔
106	}
107	}	1✔
108
109	/**
110	* Remove data from a SeekableByteChannel, shifting the data after the deletion point.
111	*/
112	public static void delete(SeekableByteChannel channel, long position, long length) throws IOException {
113	delete(channel, position, length, 1024 * 1024);	1✔
114	}	1✔
115
116	public static void delete(SeekableByteChannel channel, long position, long length, int bufferSize) throws IOException {
117	if (position + length > channel.size()) {	1✔
118	throw new IOException("Cannot delete data after the end of the file");	1✔
119	}
120
121	ByteBuffer buffer = ByteBuffer.allocate(bufferSize);	1✔
122	long remaining = channel.size() - position - length;	1✔
123	while (remaining > 0) {	1✔
124	buffer.clear();	1✔
125	buffer.limit((int) Math.min(remaining, buffer.capacity()));	1✔
126
127	channel.position(position + length);	1✔
128	channel.read(buffer);	1✔
129	buffer.flip();	1✔
130
131	channel.position(position);	1✔
132	channel.write(buffer);	1✔
133	remaining -= buffer.position();	1✔
134	position += buffer.position();	1✔
135	}
136
137	channel.truncate(channel.size() - length);	1✔
138	}	1✔
139
140	/**
141	* Update the specified digest by reading the SeekableByteChannel
142	* from the start offset included to the end offset excluded.
143	*
144	* @param digest the message digest to update
145	* @param startOffset the start offset
146	* @param endOffset the end offset
147	* @throws IOException if an I/O error occurs
148	*/
149	public static void updateDigest(SeekableByteChannel channel, MessageDigest digest, long startOffset, long endOffset) throws IOException {
150	channel.position(startOffset);	1✔
151
152	ByteBuffer buffer = ByteBuffer.allocate(65536);	1✔
153
154	long position = startOffset;	1✔
155	while (position < endOffset) {	1✔
156	buffer.clear();	1✔
157	buffer.limit((int) Math.min(buffer.capacity(), endOffset - position));	1✔
158	channel.read(buffer);	1✔
159	buffer.rewind();	1✔
160
161	digest.update(buffer);	1✔
162
163	position += buffer.limit();	1✔
164	}
165	}	1✔
166
167	/**
168	* Read a null terminated string from the specified channel.
169	*/
170	public static byte[] readNullTerminatedString(ByteChannel channel) throws IOException {
171	try (ByteArrayOutputStream bos = new ByteArrayOutputStream()) {	1✔
172	byte singleChar;
173	ByteBuffer buffer = ByteBuffer.allocate(1);	1✔
174	do {
175	buffer.clear();	1✔
176	buffer.limit(1);	1✔
177	if (channel.read(buffer) < 0) {	1✔
178	throw new IOException("End of file reached, cannot read null terminated string");	1✔
179	}
180	buffer.flip();	1✔
181	singleChar = buffer.array()[0];	1✔
182	bos.write(singleChar);	1✔
183	} while (singleChar != 0);	1✔
184	return bos.toByteArray();	1✔
185	}
186	}
187	}

ebourg / jsign / #418

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