MultiMC5/libraries/pack200/src/unpack200.cpp

/*
 * Copyright (c) 2003, 2008, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <errno.h>
#include <assert.h>
#include <limits.h>
#include <time.h>
#include <stdint.h>

#include "constants.h"
#include "utils.h"
#include "defines.h"
#include "bytes.h"
#include "coding.h"
#include "unpack200.h"
#include "unpack.h"
#include "zip.h"

// Callback for fetching data, Unix style.
static int64_t read_input_via_stdio(unpacker *u, void *buf, int64_t minlen, int64_t maxlen)
{
    assert(u->infileptr != nullptr);
    assert(minlen <= maxlen); // don't talk nonsense
    int64_t numread = 0;
    char *bufptr = (char *)buf;
    while (numread < minlen)
    {
        // read available input, up to buf.length or maxlen
        int readlen = (1 << 16);
        if (readlen > (maxlen - numread))
            readlen = (int)(maxlen - numread);
        int nr = 0;

        nr = (int)fread(bufptr, 1, readlen, u->infileptr);
        if (nr <= 0)
        {
            if (errno != EINTR)
                break;
            nr = 0;
        }
        numread += nr;
        bufptr += nr;
        assert(numread <= maxlen);
    }
    return numread;
}

enum
{
    EOF_MAGIC = 0,
    BAD_MAGIC = -1
};

static int read_magic(unpacker *u, char peek[], int peeklen)
{
    assert(peeklen == 4); // magic numbers are always 4 bytes
    int64_t nr = (u->read_input_fn)(u, peek, peeklen, peeklen);
    if (nr != peeklen)
    {
        return (nr == 0) ? EOF_MAGIC : BAD_MAGIC;
    }
    int magic = 0;
    for (int i = 0; i < peeklen; i++)
    {
        magic <<= 8;
        magic += peek[i] & 0xFF;
    }
    return magic;
}

void unpack_200(FILE *input, FILE *output)
{
    unpacker u;
    u.init(read_input_via_stdio);

    // initialize jar output
    // the output takes ownership of the file handle
    jar jarout;
    jarout.init(&u);
    jarout.jarfp = output;

    // the input doesn't
    u.infileptr = input;

    // read the magic!
    char peek[4];
    int magic;
    magic = read_magic(&u, peek, (int)sizeof(peek));

    // if it is a gzip encoded file, we need an extra gzip input filter
    if ((magic & GZIP_MAGIC_MASK) == GZIP_MAGIC)
    {
        gunzip *gzin = NEW(gunzip, 1);
        gzin->init(&u);
        // FIXME: why the side effects? WHY?
        u.gzin->start(magic);
        u.start();
    }
    else
    {
        // otherwise, feed the bytes to the unpacker directly
        u.start(peek, sizeof(peek));
    }

    // Note:  The checks to u.aborting() are necessary to gracefully
    // terminate processing when the first segment throws an error.
    for (;;)
    {
        // Each trip through this loop unpacks one segment
        // and then resets the unpacker.
        for (unpacker::file *filep; (filep = u.get_next_file()) != nullptr;)
        {
            u.write_file_to_jar(filep);
        }

        // Peek ahead for more data.
        magic = read_magic(&u, peek, (int)sizeof(peek));
        if (magic != (int)JAVA_PACKAGE_MAGIC)
        {
            // we do not feel strongly about this kind of thing...
            /*
            if (magic != EOF_MAGIC)
                unpack_abort("garbage after end of pack archive");
            */
            break; // all done
        }

        // Release all storage from parsing the old segment.
        u.reset();
        // Restart, beginning with the peek-ahead.
        u.start(peek, sizeof(peek));
    }
    u.finish();
    u.free(); // tidy up malloc blocks
    fclose(input);
}