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mmap_t: Factorize per-OS constructor and simplify helpers
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@amyspark @dragonmux
amyspark authored and dragonmux committed Jun 3, 2023
1 parent 2161dd0 commit eb4cc6b
Showing 1 changed file with 69 additions and 59 deletions.
128 changes: 69 additions & 59 deletions substrate/mmap
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Original file line number Diff line number Diff line change
Expand Up @@ -102,27 +102,52 @@ namespace substrate
int32_t _fd{-1};

#ifdef _WIN32
mmap_t(const mmap_t &map, const std::size_t len, const int32_t prot, const int32_t = 0,
void * = nullptr) noexcept : _len{len}, _mapping{[&]() noexcept -> HANDLE
// NOLINTNEXTLINE(bugprone-easily-swappable-parameters)
SUBSTRATE_NO_DISCARD(static inline HANDLE
createMapping(const int32_t _fd, const std::size_t len, const int32_t prot) noexcept)
{
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast,performance-no-int-to-ptr)
auto *const file{reinterpret_cast<HANDLE>(_get_osfhandle(map._fd))};
return CreateFileMappingA(file, nullptr, internal::cleanProt(static_cast<DWORD>(prot)), DWORD(len >> 32U),
DWORD(len), nullptr);
}()}, _addr{[&]() noexcept -> void *
auto *const file{reinterpret_cast<HANDLE>(_get_osfhandle(_fd))};
return CreateFileMappingA(file, nullptr, internal::cleanProt(static_cast<DWORD>(prot)),
DWORD(len >> 32U), DWORD(len), nullptr);
}

SUBSTRATE_NO_DISCARD(static inline LPVOID
mapAddressWithOffset(HANDLE _mapping, const int32_t prot, const off_t offset, const size_t length) noexcept)
{
if (!_mapping)
return nullptr;
if (length > std::numeric_limits<uint32_t>::max())
return nullptr;
return MapViewOfFile(_mapping, mmap_internal::protToAccess(static_cast<DWORD>(prot)), DWORD(offset >> 32U),
DWORD(offset), SIZE_T(length));
}

SUBSTRATE_NO_DISCARD(static inline LPVOID mapAddress(HANDLE _mapping, const int32_t prot) noexcept)
{
if (!_mapping)
return nullptr;
return MapViewOfFile(_mapping, internal::protToAccess(static_cast<DWORD>(prot)), 0, 0, 0);
}()} { }
}
#else
mmap_t(const mmap_t &map, const std::size_t len, const int32_t prot, const int32_t flags = MAP_SHARED,
void *addr = nullptr) noexcept : _len{len}, _addr{[&]() noexcept -> void *
{
const auto ptr = ::mmap(addr, len, prot, flags, map._fd, 0);
return ptr == MAP_FAILED ? nullptr : ptr;
}()}, _fd{-1} { }
SUBSTRATE_NO_DISCARD(static inline void *
mapAddress(void *addr, const std::size_t len, const int32_t prot, const int32_t flags, int32_t _fd) noexcept)
{
const auto ptr = ::mmap(addr, len, prot, flags, _fd, 0);
return ptr == MAP_FAILED ? nullptr : ptr;
}
#endif

// NOLINTNEXTLINE(bugprone-easily-swappable-parameters)
mmap_t(const mmap_t &map, const std::size_t len, const int32_t prot,
SUBSTRATE_NOWARN_UNUSED(const int32_t flags = MAP_SHARED),
SUBSTRATE_NOWARN_UNUSED(void *addr = nullptr)) noexcept : _len{len},
#ifdef _WIN32
_mapping{createMapping(map._fd, len, prot)}, _addr{mapAddress(_mapping, prot)}
#else
_addr{mapAddress(addr, len, prot, flags, map._fd)}
#endif
{ }

template<typename T> SUBSTRATE_NO_DISCARD(substrate::enable_if_t<
substrate::is_pod<T>::value && !has_nullable_ctor<T>::value && !std::is_same<T, void *>::value, T *>
Expand Down Expand Up @@ -168,66 +193,50 @@ namespace substrate

public:
constexpr mmap_t() noexcept = default;
#ifndef _WIN32
mmap_t(const int32_t fd, const std::size_t len, const int32_t prot, const int32_t flags = MAP_SHARED,
void *addr = nullptr) noexcept : _len{len}, _addr{[&]() noexcept -> void *
{
const auto ptr = ::mmap(addr, len, prot, flags, fd, 0);
return ptr == MAP_FAILED ? nullptr : ptr;
}()}, _fd{fd} { }

~mmap_t() noexcept
{
if (_addr)
unmap(_addr, _len);
if (_fd != -1)
::close(_fd);
}

SUBSTRATE_NO_DISCARD(SUBSTRATE_CXX14_CONSTEXPR bool valid() const noexcept) { return _addr; }
#else
// NOLINTNEXTLINE(bugprone-easily-swappable-parameters,readability-identifier-length)
mmap_t(const int32_t fd, const std::size_t len, const int32_t prot, const int32_t = 0,
void * = nullptr) noexcept : _len{len}, _mapping{[&]() noexcept -> HANDLE
{
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast,performance-no-int-to-ptr)
auto *const file{reinterpret_cast<HANDLE>(_get_osfhandle(fd))};
return CreateFileMappingA(file, nullptr, mmap_internal::cleanProt(static_cast<DWORD>(prot)),
DWORD(len >> 32U), DWORD(len), nullptr);
}()}, _addr{[&]() noexcept -> void *
{
if (!_mapping)
return nullptr;
return MapViewOfFile(_mapping, mmap_internal::protToAccess(static_cast<DWORD>(prot)), 0, 0, 0);
}()} { }
mmap_t(const int32_t fd, const std::size_t len, const int32_t prot,
SUBSTRATE_NOWARN_UNUSED(const int32_t flags = MAP_SHARED),
SUBSTRATE_NOWARN_UNUSED(void *addr = nullptr)) noexcept :
_len{len},
#ifdef _WIN32
_mapping{createMapping(fd, len, prot)}, _addr{mapAddress(_mapping, prot)},
#else
_addr{mapAddress(addr, len, prot, flags, fd)},
#endif
_fd{fd}
{ }

#ifdef _WIN32
// NOLINTNEXTLINE(bugprone-easily-swappable-parameters,readability-identifier-length)
mmap_t(const int32_t fd, const off_t offset, const std::size_t length, const int32_t prot,
const int32_t = 0, void * = nullptr) noexcept : _len{length},
_mapping{[&]() noexcept -> HANDLE
{
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast,performance-no-int-to-ptr)
auto *const file{reinterpret_cast<HANDLE>(_get_osfhandle(fd))};
return CreateFileMappingA(file, nullptr, mmap_internal::cleanProt(static_cast<DWORD>(prot)), 0, 0, nullptr);
}()}, _addr{[&]() noexcept -> void *
{
if (!_mapping)
return nullptr;
if (length > std::numeric_limits<uint32_t>::max())
return nullptr;
return MapViewOfFile(_mapping, mmap_internal::protToAccess(static_cast<DWORD>(prot)), DWORD(offset >> 32U), DWORD(offset), SIZE_T(length));
}()} { }
const int32_t = 0, void * = nullptr) noexcept :
_len{length},
_mapping{createMapping(fd, 0, prot)}, _addr{mapAddressWithOffset(_mapping, prot, offset, length)},
_fd{fd}
{ }
#endif

~mmap_t() noexcept
{
if (_addr)
internal::unmap(_addr, _len);
#ifdef _WIN32
if (_mapping)
CloseHandle(_mapping);
#else
if (_fd != -1)
::close(_fd);
#endif
}

SUBSTRATE_NO_DISCARD(SUBSTRATE_CXX14_CONSTEXPR bool valid() const noexcept) { return _mapping && _addr; }
SUBSTRATE_NO_DISCARD(SUBSTRATE_CXX14_CONSTEXPR bool valid() const noexcept)
#ifdef _WIN32
{ return _mapping && _addr; }
#else
{ return _addr; }
#endif

mmap_t(const mmap_t &) = delete;
mmap_t &operator=(const mmap_t &) = delete;
mmap_t(mmap_t &&other) noexcept : mmap_t{} { *this = std::move(other); }
Expand All @@ -251,7 +260,8 @@ namespace substrate
return {*this, len, prot, flags, addr};
}

SUBSTRATE_NO_DISCARD(bool chperm(const int32_t prot) noexcept)
template<typename T>
SUBSTRATE_NO_DISCARD(bool chperm(const T prot) noexcept)
#ifdef _WIN32
{ return VirtualProtect(_addr, _len, prot, nullptr) == 0; }
#else
Expand Down

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