/* packer_r.cpp -- Packer relocation handling

   This file is part of the UPX executable compressor.

   Copyright (C) Markus Franz Xaver Johannes Oberhumer
   Copyright (C) Laszlo Molnar
   All Rights Reserved.

   UPX and the UCL library are free software; you can redistribute them
   and/or modify them under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version.

   This program 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 for more details.

   You should have received a copy of the GNU General Public License
   along with this program; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer              Laszlo Molnar
   <markus@oberhumer.com>               <ezerotven+github@gmail.com>
 */

#include "conf.h"
#include "packer.h"

/*************************************************************************
// sort and delta-compress relocations with optional bswap within image
// returns number of **bytes** written to 'out'
**************************************************************************/

/*static*/
unsigned Packer::optimizeReloc(unsigned relocnum, SPAN_P(byte) relocs, SPAN_S(byte) out,
                               SPAN_P(byte) image, unsigned image_size, int bits, bool bswap,
                               int *big) {
    assert(bits == 32 || bits == 64);
    mem_size_assert(1, image_size);
#if WITH_XSPAN >= 2
    ptr_check_no_overlap(relocs.data(), relocs.size_bytes(), image.data(image_size), image_size,
                         out.data(), out.size_bytes());
#endif
    SPAN_S_VAR(byte, fix, out);

    *big = 0;
    if (opt->exact)
        throwCantPackExact();
    if (relocnum == 0)
        return 0;
    upx_qsort(raw_bytes(relocs, 4 * relocnum), relocnum, 4, le32_compare);
    if (0) {
        printf("optimizeReloc: u_reloc %9u checksum=0x%08x\n", 4 * relocnum,
               upx_adler32(relocs, 4 * relocnum));
        printf("optimizeReloc: u_image %9u checksum=0x%08x\n", image_size,
               upx_adler32(image, image_size));
    }

    unsigned pc = (unsigned) -4;
    for (unsigned i = 0; i < relocnum; i++) {
        unsigned delta = get_le32(relocs + i * 4) - pc;
        if (delta == 0)
            continue;
        else if ((int) delta < 4)
            throwCantPack("overlapping fixups");
        else if (delta < 0xf0)
            *fix++ = (byte) delta;
        else if (delta < 0x100000) {
            *fix++ = (byte) (0xf0 + (delta >> 16));
            *fix++ = (byte) delta;
            *fix++ = (byte) (delta >> 8);
        } else {
            *big = 1;
            *fix++ = 0xf0;
            *fix++ = 0;
            *fix++ = 0;
            set_le32(fix, delta);
            fix += 4;
        }
        pc += delta;
        if (pc + 4 > image_size)
            throwCantPack("bad reloc[%#x] = %#x", i, pc);
        if (bswap) {
            if (bits == 32)
                set_be32(image + pc, get_le32(image + pc));
            else
                set_be64(image + pc, get_le64(image + pc));
        }
    }
    *fix++ = 0; // end marker
    const unsigned bytes = ptr_udiff_bytes(fix, out);
    if (0) {
        printf("optimizeReloc: c_reloc %9u checksum=0x%08x\n", bytes, upx_adler32(out, bytes));
        printf("optimizeReloc: c_image %9u checksum=0x%08x\n", image_size,
               upx_adler32(image, image_size));
    }
    return bytes;
}

/*************************************************************************
// delta-decompress relocations
// advances 'in'
// allocates 'mb_out' and returns number of **relocs** written to 'mb_out'
**************************************************************************/

/*static*/
unsigned Packer::unoptimizeReloc(SPAN_S(const byte) & in, MemBuffer &mb_out, SPAN_P(byte) image,
                                 unsigned image_size, int bits, bool bswap) {
    assert(bits == 32 || bits == 64);
    mem_size_assert(1, image_size);
#if WITH_XSPAN >= 2
    ptr_check_no_overlap(in.data(), in.size_bytes(), image.data(image_size), image_size);
#endif
    SPAN_S_VAR(const byte, fix, in);

    // count
    unsigned relocnum = 0;
    for (fix = in; *fix; fix++, relocnum++) {
        if (*fix >= 0xf0) {
            if (*fix == 0xf0 && get_le16(fix + 1) == 0)
                fix += 4;
            fix += 2;
        }
    }
    NO_fprintf(stderr, "relocnum=%x\n", relocnum);
    if (0) {
        const unsigned bytes = ptr_udiff_bytes(fix + 1, in);
        printf("unoptimizeReloc: c_reloc %9u checksum=0x%08x\n", bytes, upx_adler32(in, bytes));
        printf("unoptimizeReloc: c_image %9u checksum=0x%08x\n", image_size,
               upx_adler32(image, image_size));
    }

    mb_out.alloc(mem_size(4, relocnum + 1)); // one extra entry
    SPAN_S_VAR(LE32, relocs, mb_out);

    fix = in;
    unsigned pc = (unsigned) -4;
    for (unsigned i = 0; i < relocnum; i++) {
        unsigned delta;
        if (*fix < 0xf0)
            delta = *fix++;
        else {
            delta = (*fix & 0x0f) * 0x10000 + get_le16(fix + 1);
            fix += 3;
            if (delta == 0) {
                delta = get_le32(fix);
                fix += 4;
            }
        }
        if ((int) delta < 4)
            throwCantUnpack("overlapping fixups");
        pc += delta;
        if (pc + 4 > image_size)
            throwCantUnpack("bad reloc[%#x] = %#x", i, pc);
        *relocs++ = pc;
        if (bswap) {
            if (bits == 32)
                set_be32(image + pc, get_le32(image + pc));
            else
                set_be64(image + pc, get_le64(image + pc));
        }
    }
    in = fix + 1; // advance
    assert(relocnum == ptr_udiff_bytes(relocs, raw_bytes(mb_out, 0)) / 4);
    if (0) {
        printf("unoptimizeReloc: u_reloc %9u checksum=0x%08x\n", 4 * relocnum,
               upx_adler32(mb_out, 4 * relocnum));
        printf("unoptimizeReloc: u_image %9u checksum=0x%08x\n", image_size,
               upx_adler32(image, image_size));
    }
    return relocnum;
}

/* vim:set ts=4 sw=4 et: */
