/*

 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.security.util;

import java.io.IOException;

import java.io.InputStream;

import java.util.Arrays;

import java.util.jar.Attributes;

import java.util.jar.Manifest;

/**

 * This class provides streaming mode reading of manifest files.

 * Used by {@link SignatureFileVerifier}.

 */

class SignatureFileManifest extends Manifest {

    /*

     * Reading a manifest into this object by calling update(byte[]) on chunks.

     * During the reading, the bytes are saved in (@code current} until a line

     * is complete and the key-value pair is saved in {@code currentAttr}. When

     * a section is complete, {@code consumeAttr} is called to merge

     * {@code currentAttr} into main attributes or a named entry.

     */

    // Internal state during update() style reading

    // 0. not in update mode

    // 1, in update mode but main attributes not completed yet

    // 2. main attributes completed, still reading the entries

    private int state = 0;

    // The partial line read

    private byte[] current;

    // Number of bytes in current

    private int currentPos = 0;

    // The current Attribute

    private Attributes currentAttr;

    /**

     * Reads a manifest in chunks.

     * <p>

     * This method must be called in a row, reading chunks from a single

     * manifest file by order. After all chunks are read, caller must call

     * {@code update(null)} to fully consume the manifest.

     * <p>

     * The entry names and attributes read will be merged in with the current

     * manifest entries. The {@link #read} method cannot be called inside a

     * row of update calls.

     * <p>

     * Along with the calls, caller can call {@link #getMainAttributes()},

     * {@link #getAttributes(java.lang.String)} or {@link #getEntries()}

     * to get already available contents. However, in order not to return

     * partial result, when the main attributes in the new manifest is not

     * consumed completely, {@link #getMainAttributes()} throws an

     * {@code IllegalStateException}. When a certain named entry is not

     * consumed completely, {@link #getAttributes(java.lang.String)}

     * returns the old {@code Attributes} for the name (if it exists).

     *

     * @param data null for last call, otherwise, feeding chunks

     * @param offset offset into data to begin read

     * @param length length of data after offset to read

     * @exception IOException if an I/O error has occurred

     * @exception IllegalStateException if {@code update(null)} is called

     * without any previous {@code update(non-null)} call

     */

    public void update(byte[] data, int offset, int length) throws IOException {

        // The last call

        if (data == null) {

            if (state == 0) {

                throw new IllegalStateException("No data to update");

            }

            // We accept manifest not ended with \n or \n\n

            if (hasLastByte()) {

                consumeCurrent();

            }

            // We accept empty lines at the end

            if (!currentAttr.isEmpty()) {

                consumeAttr();

            }

            state = 0;  // back to non-update state

            current = null;

            currentAttr = null;

            return;

        }

        // The first call

        if (state == 0) {

            current = new byte[1024];

            currentAttr = super.getMainAttributes(); // the main attribute

            state = 1;

        }

        int end = offset + length;

        while (offset < end) {

            switch (data[offset]) {

                case '\r':

                    break;  // always skip

                case '\n':

                    if (hasLastByte() && lastByte() == '\n') {  // new section

                        consumeCurrent();

                        consumeAttr();

                        if (state == 1) {

                            state = 2;

                        }

                        currentAttr = new Attributes(2);

                    } else {

                        if (hasLastByte()) {

                            // save \n into current but do not parse,

                            // there might be a continuation later

                            ensureCapacity();

                            current[currentPos++] = data[offset];

                        } else if (state == 1) {

                            // there can be multiple empty lines between

                            // sections, but cannot be at the beginning

                            throw new IOException("invalid manifest format");

                        }

                    }

                    break;

                case ' ':

                    if (!hasLastByte()) {

                        throw new IOException("invalid manifest format");

                    } else if (lastByte() == '\n') {

                        currentPos--;   // continuation, remove last \n

                    } else {    // a very normal ' '

                        ensureCapacity();

                        current[currentPos++] = data[offset];

                    }

                    break;

                default:

                    if (hasLastByte() && lastByte() == '\n') {

                        // The start of a new pair, not continuation

                        consumeCurrent();   // the last line read

                    }

                    ensureCapacity();

                    current[currentPos++] = data[offset];

                    break;

            }

            offset++;

        }

    }

    /**

     * Returns the main Attributes for the Manifest.

     * @exception IllegalStateException the main attributes is being read

     * @return the main Attributes for the Manifest

     */

    public Attributes getMainAttributes() {

        if (state == 1) {

            throw new IllegalStateException();

        }

        return super.getMainAttributes();

    }

    /**

     * Reads the Manifest from the specified InputStream. The entry

     * names and attributes read will be merged in with the current

     * manifest entries.

     *

     * @param is the input stream

     * @exception IOException if an I/O error has occurred

     * @exception IllegalStateException if called between two {@link #update}

     * calls

     */

    public void read(InputStream is) throws IOException {

        if (state != 0) {

            throw new IllegalStateException("Cannot call read between updates");

        }

        super.read(is);

    }

    /*

     * ----------  Helper methods  -----------------

     */

    private void ensureCapacity() {

        if (currentPos >= current.length-1) {

            current = Arrays.copyOf(current, current.length*2);

        }

    }

    private boolean hasLastByte() {

        return currentPos > 0;

    }

    private byte lastByte() {

        return current[currentPos-1];

    }

    // Parse current as key:value and save into currentAttr.

    // There MUST be something inside current.

    private void consumeCurrent() throws IOException {

        // current normally has a \n end, except for the last line

        if (current[currentPos-1] == '\n') currentPos--;

        for (int i=0; i<currentPos; i++) {

            if (current[i] == ':') {

                String key = new String(current, 0, 0, i);

                i++;

                while (i < currentPos && current[i] == ' ') { i++; }

                String value = new String(current, i, currentPos-i, "UTF-8");

                currentAttr.putValue(key, value);

                currentPos = 0;

                return;

            }

        }

        throw new IOException("invalid header field");

    }

    // Merge currentAttr into Manifest

    private void consumeAttr() throws IOException {

        // Only needed for named entries. For the main attribute, key/value

        // is added into attr directly, but since getMainAttributes() throws

        // an exception, the partial data is not leaked.

        if (state != 1) {

            String name = currentAttr.getValue("Name");

            if (name != null) {

                currentAttr.remove(new Attributes.Name("Name"));

                Attributes old = getAttributes(name);

                if (old != null) old.putAll(currentAttr);

                else getEntries().put(name, currentAttr);

            } else {

                throw new IOException("invalid manifest format");

            }

        }

    }

}