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/*
 * Copyright (c) 2017-2021 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */


#ifndef mach_o_Misc_h
#define mach_o_Misc_h

#include <stdint.h>

#include <span>
#include <string_view>

#include "MachODefines.h"
#include "Error.h"

namespace mach_o {

struct Header;

/// Returns true if (addLHS + addRHS) > b, or if the add overflowed
template<typename T>
VIS_HIDDEN inline bool greaterThanAddOrOverflow(uint32_t addLHS, uint32_t addRHS, T b) {
    uint32_t sum;
    if (__builtin_add_overflow(addLHS, addRHS, &sum) )
        return true;
    return (sum > b);
}

/// Returns true if (addLHS + addRHS) > b, or if the add overflowed
template<typename T>
VIS_HIDDEN inline bool greaterThanAddOrOverflow(uint64_t addLHS, uint64_t addRHS, T b) {
    uint64_t sum;
    if (__builtin_add_overflow(addLHS, addRHS, &sum) )
        return true;
    return (sum > b);
}


uint64_t    read_uleb128(const uint8_t*& p, const uint8_t* end, bool& malformed) VIS_HIDDEN;
uint64_t    read_uleb128(std::span<const uint8_t>& buffer, bool& malformed) VIS_HIDDEN;
int64_t     read_sleb128(const uint8_t*& p, const uint8_t* end, bool& malformed) VIS_HIDDEN;
uint32_t	uleb128_size(uint64_t value) VIS_HIDDEN;

inline void pageAlign4K(uint64_t& value)
{
    value = ((value + 0xFFF) & (-0x1000));
}

inline void pageAlign16K(uint64_t& value)
{
    value = ((value + 0x3FFF) & (-0x4000));
}

// magic way to tell compiler that 32-bit instruction may not be 32-bit aligned
struct __attribute__((__packed__)) Unaligned32
{
    uint32_t value;
};
struct __attribute__((__packed__)) Unaligned64
{
    uint64_t value;
};

inline uint32_t readUnaligned32(const uint8_t* ptr)
{
    return ((Unaligned32*)ptr)->value;
}

inline uint64_t readUnaligned64(const uint8_t* ptr)
{
    return ((Unaligned64*)ptr)->value;
}

// used to walk fat/thin files and get all mach-o headers
Error forEachHeader(std::span<const uint8_t> buffer, std::string_view path,
                    void (^callback)(const Header* sliceHeader, size_t sliceLength, bool& stop)) VIS_HIDDEN;

} // namespace mach_o

#endif /* mach_o_Misc_h */