upx/src/util/xspan_impl_common.h

/* xspan -- a minimally invasive checked memory smart pointer

   This file is part of the UPX executable compressor.

   Copyright (C) 1996-2023 Markus Franz Xaver Johannes Oberhumer
   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
   <markus@oberhumer.com>
 */

/*************************************************************************
//
**************************************************************************/

#if CLANG_FORMAT_DUMMY_CLASS
class CSelf {
#endif

public:
    typedef T element_type;
    typedef typename std::add_lvalue_reference<T>::type reference;
    typedef typename std::add_pointer<T>::type pointer;
    typedef size_t size_type;

    // befriend all
    template <class>
    friend struct PtrOrSpan;
    template <class>
    friend struct PtrOrSpanOrNull;
    template <class>
    friend struct Span;

#if XSPAN_CONFIG_ENABLE_IMPLICIT_CONVERSION
public:
    operator pointer() const noexcept { return ptr; }
#endif

private:
    pointer ptr; // current view into (base, base+size_in_bytes) iff base != nullptr
    pointer base;
    size_type size_in_bytes;

// debug - internal sanity check; also serves as pseudo-documentation
#if DEBUG
    noinline void assertInvariants() const {
        if __acc_cte (configRequirePtr)
            assert(ptr != nullptr);
        if __acc_cte (configRequireBase)
            assert(base != nullptr);
        if __acc_cte ((configRequirePtr || ptr != nullptr) &&
                      (configRequireBase || base != nullptr))
            xspan_check_range(ptr, base, size_in_bytes);
    }
#else
forceinline void assertInvariants() const noexcept {}
#endif

    static inline pointer makeNotNull(pointer p) {
        if very_unlikely (p == nullptr)
            xspan_fail_nullptr();
        return p;
    }
    // enforce config invariants at constructor time - static functions
    static inline pointer makePtr(pointer p) {
        if __acc_cte (configRequirePtr && p == nullptr)
            xspan_fail_nullptr();
        return p;
    }
    static inline pointer makeBase(pointer b) {
        if __acc_cte (configRequireBase && b == nullptr)
            xspan_fail_nullbase();
        return b;
    }
    // inverse logic for ensuring valid pointers from existing objects
    inline pointer ensurePtr() const {
        if __acc_cte (!configRequirePtr && ptr == nullptr)
            xspan_fail_nullptr();
        return ptr;
    }
    inline pointer ensureBase() const {
        if __acc_cte (!configRequireBase && base == nullptr)
            xspan_fail_nullbase();
        return base;
    }

public:
#if DEBUG
    ~CSelf() noexcept {
        try {
            invalidate();
        } catch (...) {
            std::terminate();
        }
    }
#else
forceinline ~CSelf() noexcept {}
#endif
    noinline void invalidate() {
        assertInvariants();
        // poison the pointer
        ptr = (pointer) (upx_uintptr_t) 16; // point to non-null invalid address
        // ptr = (pointer) (void *) &ptr; // point to self
        base = ptr;
        size_in_bytes = 0;
        assertInvariants();
    }
    // constructors from pointers
    CSelf(pointer first, XSpanCount count)
        : ptr(makePtr(first)), base(makeBase(first)),
          size_in_bytes(xspan_mem_size<T>(count.count)) {
        assertInvariants();
    }
    CSelf(pointer first, XSpanSizeInBytes bytes)
        : ptr(makePtr(first)), base(makeBase(first)),
          size_in_bytes(xspan_mem_size<char>(bytes.size_in_bytes)) {
        assertInvariants();
    }
    // enable this constructor only if the underlying type is char or void
    template <class U>
    CSelf(U *first, size_type count, XSPAN_REQUIRES_SIZE_1_A)
        : ptr(makePtr(first)), base(makeBase(first)), size_in_bytes(xspan_mem_size<T>(count)) {
        assertInvariants();
    }
    CSelf(pointer first, XSpanCount count, pointer base_)
        : ptr(makePtr(first)), base(makeBase(base_)),
          size_in_bytes(xspan_mem_size<T>(count.count)) {
        // check invariants
        if __acc_cte ((configRequirePtr || ptr != nullptr) &&
                      (configRequireBase || base != nullptr))
            xspan_check_range(ptr, base, size_in_bytes);
        // double sanity check
        assertInvariants();
    }
    CSelf(pointer first, XSpanSizeInBytes bytes, pointer base_)
        : ptr(makePtr(first)), base(makeBase(base_)),
          size_in_bytes(xspan_mem_size<char>(bytes.size_in_bytes)) {
        // check invariants
        if __acc_cte ((configRequirePtr || ptr != nullptr) &&
                      (configRequireBase || base != nullptr))
            xspan_check_range(ptr, base, size_in_bytes);
        // double sanity check
        assertInvariants();
    }
    // enable this constructor only if the underlying type is char or void
    template <class U>
    CSelf(pointer first, size_type count, U *base_, XSPAN_REQUIRES_SIZE_1_A)
        : ptr(makePtr(first)), base(makeBase(base_)), size_in_bytes(xspan_mem_size<T>(count)) {
        // check invariants
        if __acc_cte ((configRequirePtr || ptr != nullptr) &&
                      (configRequireBase || base != nullptr))
            xspan_check_range(ptr, base, size_in_bytes);
        // double sanity check
        assertInvariants();
    }
#ifdef UPX_VERSION_HEX
    // constructors from MemBuffer
    CSelf(MemBuffer &mb)
        : CSelf(makeNotNull((pointer) membuffer_get_void_ptr(mb)),
                XSpanSizeInBytes(membuffer_get_size(mb))) {}
    CSelf(pointer first, MemBuffer &mb)
        : CSelf(first, XSpanSizeInBytes(membuffer_get_size(mb)),
                makeNotNull((pointer) membuffer_get_void_ptr(mb))) {}
    CSelf(std::nullptr_t, MemBuffer &) XSPAN_DELETED_FUNCTION;
#endif
    // disable constructors from nullptr to catch compile-time misuse
private:
    CSelf(std::nullptr_t, XSpanCount) XSPAN_DELETED_FUNCTION;
    CSelf(std::nullptr_t, XSpanCount, std::nullptr_t) XSPAN_DELETED_FUNCTION;
    CSelf(const void *, XSpanCount, std::nullptr_t) XSPAN_DELETED_FUNCTION;
    CSelf(std::nullptr_t, XSpanSizeInBytes) XSPAN_DELETED_FUNCTION;
    CSelf(std::nullptr_t, XSpanSizeInBytes, std::nullptr_t) XSPAN_DELETED_FUNCTION;
    CSelf(const void *, XSpanSizeInBytes, std::nullptr_t) XSPAN_DELETED_FUNCTION;
    CSelf(std::nullptr_t, size_type) XSPAN_DELETED_FUNCTION;
    CSelf(std::nullptr_t, size_type, std::nullptr_t) XSPAN_DELETED_FUNCTION;
    CSelf(const void *, size_type, std::nullptr_t) XSPAN_DELETED_FUNCTION;

    // unchecked constructor
protected:
    enum ModeUnchecked { Unchecked };
    CSelf(ModeUnchecked, pointer p, size_type bytes, pointer b)
        : ptr(p), base(b), size_in_bytes(bytes) {
        assertInvariants();
    }
    // unchecked assignment
    Self &assign(ModeUnchecked, pointer p, size_type bytes, pointer b) {
        ptr = p;
        base = b;
        size_in_bytes = bytes;
        assertInvariants();
        return *this;
    }
#if 0
Self &assign(ModeUnchecked, const Self &other) {
    ptr = other.ptr;
    base = other.base;
    size_in_bytes = other.size_in_bytes;
    assertInvariants();
    return *this;
}
#endif

public:
    // assignment - here we can rely on invariants enforced at construction time by makePtr/makeBase
    // NOTE: *this remains unmodified in case of failure
    Self &assign(pointer other) {
        assertInvariants();
        other = makePtr(other);
        if __acc_cte ((configRequirePtr || other != nullptr) &&
                      (configRequireBase || base != nullptr))
            xspan_check_range(other, base, size_in_bytes);
        // ok
        ptr = other;
        assertInvariants();
        return *this;
    }
    Self &assign(const Self &other) {
        assertInvariants();
        other.assertInvariants();
        if __acc_cte (!configRequireBase && base == nullptr) {
            // magic 1: if base is unset, automatically set base/size_in_bytes from other
            if __acc_cte ((configRequirePtr || other.ptr != nullptr) &&
                          (configRequireBase || other.base != nullptr))
                xspan_check_range(other.ptr, other.base, other.size_in_bytes);
            // ok
            ptr = other.ptr;
            base = other.base;
            size_in_bytes = other.size_in_bytes;
        } else {
            // magic 2: assert same base (but ignore size_in_bytes !)
            if __acc_cte (configRequireBase || other.base != nullptr)
                if very_unlikely (base != other.base)
                    xspan_fail_not_same_base();
            if __acc_cte ((configRequirePtr || other.ptr != nullptr) &&
                          (configRequireBase || base != nullptr))
                xspan_check_range(other.ptr, base, size_in_bytes);
            // ok
            ptr = other.ptr;
        }
        assertInvariants();
        return *this;
    }

    Self &operator=(pointer other) { return assign(other); }

    Self &operator=(const Self &other) { return assign(other); }

    // FIXME: this is not called??
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(Self &)
    operator=(const CSelf<U> &other) {
        // assert(0);
        return assign(Self(other));
    }

#ifdef UPX_VERSION_HEX
    Self &operator=(MemBuffer &mb) { return assign(Self(mb)); }
#endif

    Self subspan(ptrdiff_t offset, ptrdiff_t count) {
        pointer begin = check_add(ptr, offset);
        pointer end = check_add(begin, count);
        if (begin <= end)
            return Self(Unchecked, begin, (end - begin) * sizeof(T), begin);
        else
            return Self(Unchecked, end, (begin - end) * sizeof(T), end);
    }

    bool operator==(pointer other) const { return ptr == other; }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator==(U *other) const {
        return ptr == other;
    }
    bool operator!=(pointer other) const { return ptr != other; }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator!=(U *other) const {
        return ptr != other;
    }

    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator==(const PtrOrSpan<U> &other) const {
        return ptr == other.ptr;
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator==(const PtrOrSpanOrNull<U> &other) const {
        return ptr == other.ptr;
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator==(const Span<U> &other) const {
        return ptr == other.ptr;
    }

    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator!=(const PtrOrSpan<U> &other) const {
        return !(*this == other);
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator!=(const PtrOrSpanOrNull<U> &other) const {
        return !(*this == other);
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator!=(const Span<U> &other) const {
        return !(*this == other);
    }

    // check for notNull here
    bool operator<(std::nullptr_t) const XSPAN_DELETED_FUNCTION;
    bool operator<(pointer other) const { return ensurePtr() < makeNotNull(other); }

    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator<(const PtrOrSpan<U> &other) const {
        return ensurePtr() < other.ensurePtr();
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator<(const PtrOrSpanOrNull<U> &other) const {
        return ensurePtr() < other.ensurePtr();
    }
    template <class U>
    XSPAN_REQUIRES_CONVERTIBLE_R(bool)
    operator<(const Span<U> &other) const {
        return ensurePtr() < other.ensurePtr();
    }

    // dereference
    reference operator*() const { return *check_deref(ptr); }

    // array access
    reference operator[](ptrdiff_t i) const { return *check_deref(ptr, i); }

    // arrow operator
    pointer operator->() const { return check_deref(ptr); }

    Self &operator++() {
        ptr = check_add(ptr, 1);
        return *this;
    }
    Self operator++(int) {
        Self tmp = *this;
        ++*this;
        return tmp;
    }
    Self &operator--() {
        ptr = check_add(ptr, -1);
        return *this;
    }
    Self operator--(int) {
        Self tmp = *this;
        --*this;
        return tmp;
    }

    Self &operator+=(ptrdiff_t n) {
        ptr = check_add(ptr, n);
        return *this;
    }
    Self &operator-=(ptrdiff_t n) {
        ptr = check_add(ptr, -n);
        return *this;
    }

    Self operator+(ptrdiff_t n) const {
        pointer first = check_add(ptr, n);
        return Self(Unchecked, first, size_in_bytes, base);
    }
    Self operator-(ptrdiff_t n) const {
        pointer first = check_add(ptr, -n);
        return Self(Unchecked, first, size_in_bytes, base);
    }

private:
    pointer check_deref(pointer p) const {
        if __acc_cte (!configRequirePtr && p == nullptr)
            xspan_fail_nullptr();
        if __acc_cte (configRequireBase || base != nullptr)
            xspan_check_range(p, base, size_in_bytes - sizeof(T));
        assertInvariants();
        return p;
    }
    pointer check_deref(pointer p, ptrdiff_t n) const {
        if __acc_cte (!configRequirePtr && p == nullptr)
            xspan_fail_nullptr();
        xspan_mem_size_assert_ptrdiff<T>(n);
        p += n;
        if __acc_cte (configRequireBase || base != nullptr)
            xspan_check_range(p, base, size_in_bytes - sizeof(T));
        assertInvariants();
        return p;
    }
    pointer check_add(pointer p, ptrdiff_t n) const {
        if __acc_cte (!configRequirePtr && p == nullptr)
            xspan_fail_nullptr();
        xspan_mem_size_assert_ptrdiff<T>(n);
        p += n;
        if __acc_cte (configRequireBase || base != nullptr)
            xspan_check_range(p, base, size_in_bytes);
        assertInvariants();
        return p;
    }

    // disable taking the address => force passing by reference
    // [I'm not too sure about this design decision, but we can always allow it if needed]
    Self *operator&() const XSPAN_DELETED_FUNCTION;

public: // raw access
    pointer raw_ptr() const noexcept { return ptr; }
    pointer raw_base() const noexcept { return base; }
    size_type raw_size_in_bytes() const noexcept { return size_in_bytes; }

    pointer raw_bytes(size_t bytes) const {
        assertInvariants();
        if (bytes > 0) {
            if __acc_cte (!configRequirePtr && ptr == nullptr)
                xspan_fail_nullptr();
            if __acc_cte (configRequireBase || base != nullptr) {
                xspan_check_range(ptr, base, size_in_bytes - bytes);
            }
        }
        return ptr;
    }

    // like C++ std::span
    pointer data() const noexcept { return ptr; }
    pointer data(size_t bytes) const { return raw_bytes(bytes); } // UPX extra
    // size_type size() const { return size_bytes() / sizeof(element_type); } // NOT USED
    size_type size_bytes() const {
        assertInvariants();
        if __acc_cte (!configRequirePtr && ptr == nullptr)
            return 0;
        if __acc_cte (!configRequireBase && base == nullptr)
            return 0;
        const charptr begin = (const charptr) ptr;
        const charptr end = (const charptr) base + size_in_bytes;
        return end - begin;
    }

#if CLANG_FORMAT_DUMMY_CLASS
}; // class
#endif

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