libmdbx/src/osal.h

/* https://en.wikipedia.org/wiki/Operating_system_abstraction_layer */

/*
 * Copyright 2015-2022 Leonid Yuriev <leo@yuriev.ru>
 * and other libmdbx authors: please see AUTHORS file.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */

#pragma once

/*----------------------------------------------------------------------------*/
/* C11 Atomics */

#if defined(__cplusplus) && !defined(__STDC_NO_ATOMICS__) && __has_include(<cstdatomic>)
#include <cstdatomic>
#define MDBX_HAVE_C11ATOMICS
#elif !defined(__cplusplus) &&                                                 \
    (__STDC_VERSION__ >= 201112L || __has_extension(c_atomic)) &&              \
    !defined(__STDC_NO_ATOMICS__) &&                                           \
    (__GNUC_PREREQ(4, 9) || __CLANG_PREREQ(3, 8) ||                            \
     !(defined(__GNUC__) || defined(__clang__)))
#include <stdatomic.h>
#define MDBX_HAVE_C11ATOMICS
#elif defined(__GNUC__) || defined(__clang__)
#elif defined(_MSC_VER)
#pragma warning(disable : 4163) /* 'xyz': not available as an intrinsic */
#pragma warning(disable : 4133) /* 'function': incompatible types - from       \
                                   'size_t' to 'LONGLONG' */
#pragma warning(disable : 4244) /* 'return': conversion from 'LONGLONG' to     \
                                   'std::size_t', possible loss of data */
#pragma warning(disable : 4267) /* 'function': conversion from 'size_t' to     \
                                   'long', possible loss of data */
#pragma intrinsic(_InterlockedExchangeAdd, _InterlockedCompareExchange)
#pragma intrinsic(_InterlockedExchangeAdd64, _InterlockedCompareExchange64)
#elif defined(__APPLE__)
#include <libkern/OSAtomic.h>
#else
#error FIXME atomic-ops
#endif

/*----------------------------------------------------------------------------*/
/* Memory/Compiler barriers, cache coherence */

#if __has_include(<sys/cachectl.h>)
#include <sys/cachectl.h>
#elif defined(__mips) || defined(__mips__) || defined(__mips64) ||             \
    defined(__mips64__) || defined(_M_MRX000) || defined(_MIPS_) ||            \
    defined(__MWERKS__) || defined(__sgi)
/* MIPS should have explicit cache control */
#include <sys/cachectl.h>
#endif

MDBX_MAYBE_UNUSED static __inline void mdbx_compiler_barrier(void) {
#if defined(__clang__) || defined(__GNUC__)
  __asm__ __volatile__("" ::: "memory");
#elif defined(_MSC_VER)
  _ReadWriteBarrier();
#elif defined(__INTEL_COMPILER) /* LY: Intel Compiler may mimic GCC and MSC */
  __memory_barrier();
#elif defined(__SUNPRO_C) || defined(__sun) || defined(sun)
  __compiler_barrier();
#elif (defined(_HPUX_SOURCE) || defined(__hpux) || defined(__HP_aCC)) &&       \
    (defined(HP_IA64) || defined(__ia64))
  _Asm_sched_fence(/* LY: no-arg meaning 'all expect ALU', e.g. 0x3D3D */);
#elif defined(_AIX) || defined(__ppc__) || defined(__powerpc__) ||             \
    defined(__ppc64__) || defined(__powerpc64__)
  __fence();
#else
#error "Could not guess the kind of compiler, please report to us."
#endif
}

MDBX_MAYBE_UNUSED static __inline void mdbx_memory_barrier(void) {
#ifdef MDBX_HAVE_C11ATOMICS
  atomic_thread_fence(memory_order_seq_cst);
#elif defined(__ATOMIC_SEQ_CST)
#ifdef __clang__
  __c11_atomic_thread_fence(__ATOMIC_SEQ_CST);
#else
  __atomic_thread_fence(__ATOMIC_SEQ_CST);
#endif
#elif defined(__clang__) || defined(__GNUC__)
  __sync_synchronize();
#elif defined(_WIN32) || defined(_WIN64)
  MemoryBarrier();
#elif defined(__INTEL_COMPILER) /* LY: Intel Compiler may mimic GCC and MSC */
#if defined(__ia32__)
  _mm_mfence();
#else
  __mf();
#endif
#elif defined(__SUNPRO_C) || defined(__sun) || defined(sun)
  __machine_rw_barrier();
#elif (defined(_HPUX_SOURCE) || defined(__hpux) || defined(__HP_aCC)) &&       \
    (defined(HP_IA64) || defined(__ia64))
  _Asm_mf();
#elif defined(_AIX) || defined(__ppc__) || defined(__powerpc__) ||             \
    defined(__ppc64__) || defined(__powerpc64__)
  __lwsync();
#else
#error "Could not guess the kind of compiler, please report to us."
#endif
}

/*----------------------------------------------------------------------------*/
/* system-depended definitions */

#if defined(_WIN32) || defined(_WIN64)
#define HAVE_SYS_STAT_H
#define HAVE_SYS_TYPES_H
typedef HANDLE mdbx_thread_t;
typedef unsigned mdbx_thread_key_t;
#define MAP_FAILED NULL
#define HIGH_DWORD(v) ((DWORD)((sizeof(v) > 4) ? ((uint64_t)(v) >> 32) : 0))
#define THREAD_CALL WINAPI
#define THREAD_RESULT DWORD
typedef struct {
  HANDLE mutex;
  HANDLE event[2];
} mdbx_condpair_t;
typedef CRITICAL_SECTION mdbx_fastmutex_t;

#if !defined(_MSC_VER) && !defined(__try)
/* *INDENT-OFF* */
/* clang-format off */
#define __try
#define __except(COND) if (false)
/* *INDENT-ON* */
/* clang-format on */
#endif /* stub for MSVC's __try/__except */

#if MDBX_WITHOUT_MSVC_CRT

#ifndef mdbx_malloc
static inline void *mdbx_malloc(size_t bytes) {
  return HeapAlloc(GetProcessHeap(), 0, bytes);
}
#endif /* mdbx_malloc */

#ifndef mdbx_calloc
static inline void *mdbx_calloc(size_t nelem, size_t size) {
  return HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, nelem * size);
}
#endif /* mdbx_calloc */

#ifndef mdbx_realloc
static inline void *mdbx_realloc(void *ptr, size_t bytes) {
  return ptr ? HeapReAlloc(GetProcessHeap(), 0, ptr, bytes)
             : HeapAlloc(GetProcessHeap(), 0, bytes);
}
#endif /* mdbx_realloc */

#ifndef mdbx_free
static inline void mdbx_free(void *ptr) { HeapFree(GetProcessHeap(), 0, ptr); }
#endif /* mdbx_free */

#else /* MDBX_WITHOUT_MSVC_CRT */

#define mdbx_malloc malloc
#define mdbx_calloc calloc
#define mdbx_realloc realloc
#define mdbx_free free
#define mdbx_strdup _strdup

#endif /* MDBX_WITHOUT_MSVC_CRT */

#ifndef snprintf
#define snprintf _snprintf /* ntdll */
#endif

#ifndef vsnprintf
#define vsnprintf _vsnprintf /* ntdll */
#endif

#else /*----------------------------------------------------------------------*/

typedef pthread_t mdbx_thread_t;
typedef pthread_key_t mdbx_thread_key_t;
#define INVALID_HANDLE_VALUE (-1)
#define THREAD_CALL
#define THREAD_RESULT void *
typedef struct {
  pthread_mutex_t mutex;
  pthread_cond_t cond[2];
} mdbx_condpair_t;
typedef pthread_mutex_t mdbx_fastmutex_t;
#define mdbx_malloc malloc
#define mdbx_calloc calloc
#define mdbx_realloc realloc
#define mdbx_free free
#define mdbx_strdup strdup
#endif /* Platform */

#if __GLIBC_PREREQ(2, 12) || defined(__FreeBSD__) || defined(malloc_usable_size)
/* malloc_usable_size() already provided */
#elif defined(__APPLE__)
#define malloc_usable_size(ptr) malloc_size(ptr)
#elif defined(_MSC_VER) && !MDBX_WITHOUT_MSVC_CRT
#define malloc_usable_size(ptr) _msize(ptr)
#endif /* malloc_usable_size */

/*----------------------------------------------------------------------------*/
/* OS abstraction layer stuff */

/* Get the size of a memory page for the system.
 * This is the basic size that the platform's memory manager uses, and is
 * fundamental to the use of memory-mapped files. */
MDBX_MAYBE_UNUSED MDBX_NOTHROW_CONST_FUNCTION static __inline size_t
mdbx_syspagesize(void) {
#if defined(_WIN32) || defined(_WIN64)
  SYSTEM_INFO si;
  GetSystemInfo(&si);
  return si.dwPageSize;
#else
  return sysconf(_SC_PAGE_SIZE);
#endif
}

typedef struct mdbx_mmap_param {
  union {
    void *address;
    uint8_t *dxb;
    struct MDBX_lockinfo *lck;
  };
  mdbx_filehandle_t fd;
  size_t limit;   /* mapping length, but NOT a size of file nor DB */
  size_t current; /* mapped region size, i.e. the size of file and DB */
  uint64_t filesize /* in-process cache of a file size */;
#if defined(_WIN32) || defined(_WIN64)
  HANDLE section; /* memory-mapped section handle */
#endif
} mdbx_mmap_t;

typedef union bin128 {
  __anonymous_struct_extension__ struct { uint64_t x, y; };
  __anonymous_struct_extension__ struct { uint32_t a, b, c, d; };
} bin128_t;

#if defined(_WIN32) || defined(_WIN64)
typedef union MDBX_srwlock {
  __anonymous_struct_extension__ struct {
    long volatile readerCount;
    long volatile writerCount;
  };
  RTL_SRWLOCK native;
} MDBX_srwlock;
#endif /* Windows */

#ifndef __cplusplus

/*----------------------------------------------------------------------------*/
/* libc compatibility stuff */

#if (!defined(__GLIBC__) && __GLIBC_PREREQ(2, 1)) &&                           \
    (defined(_GNU_SOURCE) || defined(_BSD_SOURCE))
#define mdbx_asprintf asprintf
#define mdbx_vasprintf vasprintf
#else
MDBX_MAYBE_UNUSED MDBX_INTERNAL_FUNC
    MDBX_PRINTF_ARGS(2, 3) int mdbx_asprintf(char **strp, const char *fmt, ...);
MDBX_INTERNAL_FUNC int mdbx_vasprintf(char **strp, const char *fmt, va_list ap);
#endif

#if !defined(MADV_DODUMP) && defined(MADV_CORE)
#define MADV_DODUMP MADV_CORE
#endif /* MADV_CORE -> MADV_DODUMP */

#if !defined(MADV_DONTDUMP) && defined(MADV_NOCORE)
#define MADV_DONTDUMP MADV_NOCORE
#endif /* MADV_NOCORE -> MADV_DONTDUMP */

MDBX_MAYBE_UNUSED MDBX_INTERNAL_FUNC void mdbx_osal_jitter(bool tiny);
MDBX_MAYBE_UNUSED static __inline void mdbx_jitter4testing(bool tiny);

/* max bytes to write in one call */
#if defined(_WIN32) || defined(_WIN64)
#define MAX_WRITE UINT32_C(0x01000000)
#else
#define MAX_WRITE UINT32_C(0x3fff0000)
#endif

#if defined(__linux__) || defined(__gnu_linux__)
MDBX_INTERNAL_VAR uint32_t mdbx_linux_kernel_version;
MDBX_INTERNAL_VAR bool mdbx_RunningOnWSL1 /* Windows Subsystem 1 for Linux */;
#endif /* Linux */

#ifndef mdbx_strdup
LIBMDBX_API char *mdbx_strdup(const char *str);
#endif

MDBX_MAYBE_UNUSED static __inline int mdbx_get_errno(void) {
#if defined(_WIN32) || defined(_WIN64)
  DWORD rc = GetLastError();
#else
  int rc = errno;
#endif
  return rc;
}

#ifndef mdbx_memalign_alloc
MDBX_INTERNAL_FUNC int mdbx_memalign_alloc(size_t alignment, size_t bytes,
                                           void **result);
#endif
#ifndef mdbx_memalign_free
MDBX_INTERNAL_FUNC void mdbx_memalign_free(void *ptr);
#endif

MDBX_INTERNAL_FUNC int mdbx_condpair_init(mdbx_condpair_t *condpair);
MDBX_INTERNAL_FUNC int mdbx_condpair_lock(mdbx_condpair_t *condpair);
MDBX_INTERNAL_FUNC int mdbx_condpair_unlock(mdbx_condpair_t *condpair);
MDBX_INTERNAL_FUNC int mdbx_condpair_signal(mdbx_condpair_t *condpair,
                                            bool part);
MDBX_INTERNAL_FUNC int mdbx_condpair_wait(mdbx_condpair_t *condpair, bool part);
MDBX_INTERNAL_FUNC int mdbx_condpair_destroy(mdbx_condpair_t *condpair);

MDBX_INTERNAL_FUNC int mdbx_fastmutex_init(mdbx_fastmutex_t *fastmutex);
MDBX_INTERNAL_FUNC int mdbx_fastmutex_acquire(mdbx_fastmutex_t *fastmutex);
MDBX_INTERNAL_FUNC int mdbx_fastmutex_release(mdbx_fastmutex_t *fastmutex);
MDBX_INTERNAL_FUNC int mdbx_fastmutex_destroy(mdbx_fastmutex_t *fastmutex);

MDBX_INTERNAL_FUNC int mdbx_pwritev(mdbx_filehandle_t fd, struct iovec *iov,
                                    int iovcnt, uint64_t offset,
                                    size_t expected_written);
MDBX_INTERNAL_FUNC int mdbx_pread(mdbx_filehandle_t fd, void *buf, size_t count,
                                  uint64_t offset);
MDBX_INTERNAL_FUNC int mdbx_pwrite(mdbx_filehandle_t fd, const void *buf,
                                   size_t count, uint64_t offset);
MDBX_INTERNAL_FUNC int mdbx_write(mdbx_filehandle_t fd, const void *buf,
                                  size_t count);

MDBX_INTERNAL_FUNC int
mdbx_thread_create(mdbx_thread_t *thread,
                   THREAD_RESULT(THREAD_CALL *start_routine)(void *),
                   void *arg);
MDBX_INTERNAL_FUNC int mdbx_thread_join(mdbx_thread_t thread);

enum mdbx_syncmode_bits {
  MDBX_SYNC_NONE = 0,
  MDBX_SYNC_DATA = 1,
  MDBX_SYNC_SIZE = 2,
  MDBX_SYNC_IODQ = 4
};

MDBX_INTERNAL_FUNC int mdbx_fsync(mdbx_filehandle_t fd,
                                  const enum mdbx_syncmode_bits mode_bits);
MDBX_INTERNAL_FUNC int mdbx_ftruncate(mdbx_filehandle_t fd, uint64_t length);
MDBX_INTERNAL_FUNC int mdbx_fseek(mdbx_filehandle_t fd, uint64_t pos);
MDBX_INTERNAL_FUNC int mdbx_filesize(mdbx_filehandle_t fd, uint64_t *length);

enum mdbx_openfile_purpose {
  MDBX_OPEN_DXB_READ = 0,
  MDBX_OPEN_DXB_LAZY = 1,
  MDBX_OPEN_DXB_DSYNC = 2,
  MDBX_OPEN_LCK = 3,
  MDBX_OPEN_COPY = 4,
  MDBX_OPEN_DELETE = 5
};

MDBX_INTERNAL_FUNC int mdbx_openfile(const enum mdbx_openfile_purpose purpose,
                                     const MDBX_env *env, const char *pathname,
                                     mdbx_filehandle_t *fd,
                                     mdbx_mode_t unix_mode_bits);
MDBX_INTERNAL_FUNC int mdbx_closefile(mdbx_filehandle_t fd);
MDBX_INTERNAL_FUNC int mdbx_removefile(const char *pathname);
MDBX_INTERNAL_FUNC int mdbx_removedirectory(const char *pathname);
MDBX_INTERNAL_FUNC int mdbx_is_pipe(mdbx_filehandle_t fd);
MDBX_INTERNAL_FUNC int mdbx_lockfile(mdbx_filehandle_t fd, bool wait);

#define MMAP_OPTION_TRUNCATE 1
#define MMAP_OPTION_SEMAPHORE 2
MDBX_INTERNAL_FUNC int mdbx_mmap(const int flags, mdbx_mmap_t *map,
                                 const size_t must, const size_t limit,
                                 const unsigned options);
MDBX_INTERNAL_FUNC int mdbx_munmap(mdbx_mmap_t *map);
#define MDBX_MRESIZE_MAY_MOVE 0x00000100
#define MDBX_MRESIZE_MAY_UNMAP 0x00000200
MDBX_INTERNAL_FUNC int mdbx_mresize(const int flags, mdbx_mmap_t *map,
                                    size_t size, size_t limit);
#if defined(_WIN32) || defined(_WIN64)
typedef struct {
  unsigned limit, count;
  HANDLE handles[31];
} mdbx_handle_array_t;
MDBX_INTERNAL_FUNC int
mdbx_suspend_threads_before_remap(MDBX_env *env, mdbx_handle_array_t **array);
MDBX_INTERNAL_FUNC int
mdbx_resume_threads_after_remap(mdbx_handle_array_t *array);
#endif /* Windows */
MDBX_INTERNAL_FUNC int mdbx_msync(mdbx_mmap_t *map, size_t offset,
                                  size_t length,
                                  enum mdbx_syncmode_bits mode_bits);
MDBX_INTERNAL_FUNC int mdbx_check_fs_rdonly(mdbx_filehandle_t handle,
                                            const char *pathname, int err);

MDBX_MAYBE_UNUSED static __inline uint32_t mdbx_getpid(void) {
  STATIC_ASSERT(sizeof(mdbx_pid_t) <= sizeof(uint32_t));
#if defined(_WIN32) || defined(_WIN64)
  return GetCurrentProcessId();
#else
  STATIC_ASSERT(sizeof(pid_t) <= sizeof(uint32_t));
  return getpid();
#endif
}

MDBX_MAYBE_UNUSED static __inline uintptr_t mdbx_thread_self(void) {
  mdbx_tid_t thunk;
  STATIC_ASSERT(sizeof(uintptr_t) >= sizeof(thunk));
#if defined(_WIN32) || defined(_WIN64)
  thunk = GetCurrentThreadId();
#else
  thunk = pthread_self();
#endif
  return (uintptr_t)thunk;
}

#if !defined(_WIN32) && !defined(_WIN64)
#if defined(__ANDROID_API__) || defined(ANDROID) || defined(BIONIC)
MDBX_INTERNAL_FUNC int mdbx_check_tid4bionic(void);
#else
static __inline int mdbx_check_tid4bionic(void) { return 0; }
#endif /* __ANDROID_API__ || ANDROID) || BIONIC */

MDBX_MAYBE_UNUSED static __inline int
mdbx_pthread_mutex_lock(pthread_mutex_t *mutex) {
  int err = mdbx_check_tid4bionic();
  return unlikely(err) ? err : pthread_mutex_lock(mutex);
}
#endif /* !Windows */

MDBX_INTERNAL_FUNC uint64_t mdbx_osal_monotime(void);
MDBX_INTERNAL_FUNC uint64_t
mdbx_osal_16dot16_to_monotime(uint32_t seconds_16dot16);
MDBX_INTERNAL_FUNC uint32_t mdbx_osal_monotime_to_16dot16(uint64_t monotime);

MDBX_INTERNAL_FUNC bin128_t mdbx_osal_bootid(void);
/*----------------------------------------------------------------------------*/
/* lck stuff */

/// \brief Initialization of synchronization primitives linked with MDBX_env
///   instance both in LCK-file and within the current process.
/// \param
///   global_uniqueness_flag = true - denotes that there are no other processes
///     working with DB and LCK-file. Thus the function MUST initialize
///     shared synchronization objects in memory-mapped LCK-file.
///   global_uniqueness_flag = false - denotes that at least one process is
///     already working with DB and LCK-file, including the case when DB
///     has already been opened in the current process. Thus the function
///     MUST NOT initialize shared synchronization objects in memory-mapped
///     LCK-file that are already in use.
/// \return Error code or zero on success.
MDBX_INTERNAL_FUNC int mdbx_lck_init(MDBX_env *env,
                                     MDBX_env *inprocess_neighbor,
                                     int global_uniqueness_flag);

/// \brief Disconnects from shared interprocess objects and destructs
///   synchronization objects linked with MDBX_env instance
///   within the current process.
/// \param
///   inprocess_neighbor = NULL - if the current process does not have other
///     instances of MDBX_env linked with the DB being closed.
///     Thus the function MUST check for other processes working with DB or
///     LCK-file, and keep or destroy shared synchronization objects in
///     memory-mapped LCK-file depending on the result.
///   inprocess_neighbor = not-NULL - pointer to another instance of MDBX_env
///     (anyone of there is several) working with DB or LCK-file within the
///     current process. Thus the function MUST NOT try to acquire exclusive
///     lock and/or try to destruct shared synchronization objects linked with
///     DB or LCK-file. Moreover, the implementation MUST ensure correct work
///     of other instances of MDBX_env within the current process, e.g.
///     restore POSIX-fcntl locks after the closing of file descriptors.
/// \return Error code (MDBX_PANIC) or zero on success.
MDBX_INTERNAL_FUNC int mdbx_lck_destroy(MDBX_env *env,
                                        MDBX_env *inprocess_neighbor);

/// \brief Connects to shared interprocess locking objects and tries to acquire
///   the maximum lock level (shared if exclusive is not available)
///   Depending on implementation or/and platform (Windows) this function may
///   acquire the non-OS super-level lock (e.g. for shared synchronization
///   objects initialization), which will be downgraded to OS-exclusive or
///   shared via explicit calling of mdbx_lck_downgrade().
/// \return
///   MDBX_RESULT_TRUE (-1) - if an exclusive lock was acquired and thus
///     the current process is the first and only after the last use of DB.
///   MDBX_RESULT_FALSE (0) - if a shared lock was acquired and thus
///     DB has already been opened and now is used by other processes.
///   Otherwise (not 0 and not -1) - error code.
MDBX_INTERNAL_FUNC int mdbx_lck_seize(MDBX_env *env);

/// \brief Downgrades the level of initially acquired lock to
///   operational level specified by argument. The reson for such downgrade:
///    - unblocking of other processes that are waiting for access, i.e.
///      if (env->me_flags & MDBX_EXCLUSIVE) != 0, then other processes
///      should be made aware that access is unavailable rather than
///      wait for it.
///    - freeing locks that interfere file operation (especially for Windows)
///   (env->me_flags & MDBX_EXCLUSIVE) == 0 - downgrade to shared lock.
///   (env->me_flags & MDBX_EXCLUSIVE) != 0 - downgrade to exclusive
///   operational lock.
/// \return Error code or zero on success
MDBX_INTERNAL_FUNC int mdbx_lck_downgrade(MDBX_env *env);

/// \brief Locks LCK-file or/and table of readers for (de)registering.
/// \return Error code or zero on success
MDBX_INTERNAL_FUNC int mdbx_rdt_lock(MDBX_env *env);

/// \brief Unlocks LCK-file or/and table of readers after (de)registering.
MDBX_INTERNAL_FUNC void mdbx_rdt_unlock(MDBX_env *env);

/// \brief Acquires lock for DB change (on writing transaction start)
///   Reading transactions will not be blocked.
///   Declared as LIBMDBX_API because it is used in mdbx_chk.
/// \return Error code or zero on success
LIBMDBX_API int mdbx_txn_lock(MDBX_env *env, bool dont_wait);

/// \brief Releases lock once DB changes is made (after writing transaction
///   has finished).
///   Declared as LIBMDBX_API because it is used in mdbx_chk.
LIBMDBX_API void mdbx_txn_unlock(MDBX_env *env);

/// \brief Sets alive-flag of reader presence (indicative lock) for PID of
///   the current process. The function does no more than needed for
///   the correct working of mdbx_rpid_check() in other processes.
/// \return Error code or zero on success
MDBX_INTERNAL_FUNC int mdbx_rpid_set(MDBX_env *env);

/// \brief Resets alive-flag of reader presence (indicative lock)
///   for PID of the current process. The function does no more than needed
///   for the correct working of mdbx_rpid_check() in other processes.
/// \return Error code or zero on success
MDBX_INTERNAL_FUNC int mdbx_rpid_clear(MDBX_env *env);

/// \brief Checks for reading process status with the given pid with help of
///   alive-flag of presence (indicative lock) or using another way.
/// \return
///   MDBX_RESULT_TRUE (-1) - if the reader process with the given PID is alive
///     and working with DB (indicative lock is present).
///   MDBX_RESULT_FALSE (0) - if the reader process with the given PID is absent
///     or not working with DB (indicative lock is not present).
///   Otherwise (not 0 and not -1) - error code.
MDBX_INTERNAL_FUNC int mdbx_rpid_check(MDBX_env *env, uint32_t pid);

#if defined(_WIN32) || defined(_WIN64)

typedef void(WINAPI *MDBX_srwlock_function)(MDBX_srwlock *);
MDBX_INTERNAL_VAR MDBX_srwlock_function mdbx_srwlock_Init,
    mdbx_srwlock_AcquireShared, mdbx_srwlock_ReleaseShared,
    mdbx_srwlock_AcquireExclusive, mdbx_srwlock_ReleaseExclusive;

#if _WIN32_WINNT < 0x0600 /* prior to Windows Vista */
typedef enum _FILE_INFO_BY_HANDLE_CLASS {
  FileBasicInfo,
  FileStandardInfo,
  FileNameInfo,
  FileRenameInfo,
  FileDispositionInfo,
  FileAllocationInfo,
  FileEndOfFileInfo,
  FileStreamInfo,
  FileCompressionInfo,
  FileAttributeTagInfo,
  FileIdBothDirectoryInfo,
  FileIdBothDirectoryRestartInfo,
  FileIoPriorityHintInfo,
  FileRemoteProtocolInfo,
  MaximumFileInfoByHandleClass
} FILE_INFO_BY_HANDLE_CLASS,
    *PFILE_INFO_BY_HANDLE_CLASS;

typedef struct _FILE_END_OF_FILE_INFO {
  LARGE_INTEGER EndOfFile;
} FILE_END_OF_FILE_INFO, *PFILE_END_OF_FILE_INFO;

#define REMOTE_PROTOCOL_INFO_FLAG_LOOPBACK 0x00000001
#define REMOTE_PROTOCOL_INFO_FLAG_OFFLINE 0x00000002

typedef struct _FILE_REMOTE_PROTOCOL_INFO {
  USHORT StructureVersion;
  USHORT StructureSize;
  DWORD Protocol;
  USHORT ProtocolMajorVersion;
  USHORT ProtocolMinorVersion;
  USHORT ProtocolRevision;
  USHORT Reserved;
  DWORD Flags;
  struct {
    DWORD Reserved[8];
  } GenericReserved;
  struct {
    DWORD Reserved[16];
  } ProtocolSpecificReserved;
} FILE_REMOTE_PROTOCOL_INFO, *PFILE_REMOTE_PROTOCOL_INFO;

#endif /* _WIN32_WINNT < 0x0600 (prior to Windows Vista) */

typedef BOOL(WINAPI *MDBX_GetFileInformationByHandleEx)(
    _In_ HANDLE hFile, _In_ FILE_INFO_BY_HANDLE_CLASS FileInformationClass,
    _Out_ LPVOID lpFileInformation, _In_ DWORD dwBufferSize);
MDBX_INTERNAL_VAR MDBX_GetFileInformationByHandleEx
    mdbx_GetFileInformationByHandleEx;

typedef BOOL(WINAPI *MDBX_GetVolumeInformationByHandleW)(
    _In_ HANDLE hFile, _Out_opt_ LPWSTR lpVolumeNameBuffer,
    _In_ DWORD nVolumeNameSize, _Out_opt_ LPDWORD lpVolumeSerialNumber,
    _Out_opt_ LPDWORD lpMaximumComponentLength,
    _Out_opt_ LPDWORD lpFileSystemFlags,
    _Out_opt_ LPWSTR lpFileSystemNameBuffer, _In_ DWORD nFileSystemNameSize);
MDBX_INTERNAL_VAR MDBX_GetVolumeInformationByHandleW
    mdbx_GetVolumeInformationByHandleW;

typedef DWORD(WINAPI *MDBX_GetFinalPathNameByHandleW)(_In_ HANDLE hFile,
                                                      _Out_ LPWSTR lpszFilePath,
                                                      _In_ DWORD cchFilePath,
                                                      _In_ DWORD dwFlags);
MDBX_INTERNAL_VAR MDBX_GetFinalPathNameByHandleW mdbx_GetFinalPathNameByHandleW;

typedef BOOL(WINAPI *MDBX_SetFileInformationByHandle)(
    _In_ HANDLE hFile, _In_ FILE_INFO_BY_HANDLE_CLASS FileInformationClass,
    _Out_ LPVOID lpFileInformation, _In_ DWORD dwBufferSize);
MDBX_INTERNAL_VAR MDBX_SetFileInformationByHandle
    mdbx_SetFileInformationByHandle;

typedef NTSTATUS(NTAPI *MDBX_NtFsControlFile)(
    IN HANDLE FileHandle, IN OUT HANDLE Event,
    IN OUT PVOID /* PIO_APC_ROUTINE */ ApcRoutine, IN OUT PVOID ApcContext,
    OUT PIO_STATUS_BLOCK IoStatusBlock, IN ULONG FsControlCode,
    IN OUT PVOID InputBuffer, IN ULONG InputBufferLength,
    OUT OPTIONAL PVOID OutputBuffer, IN ULONG OutputBufferLength);
MDBX_INTERNAL_VAR MDBX_NtFsControlFile mdbx_NtFsControlFile;

typedef uint64_t(WINAPI *MDBX_GetTickCount64)(void);
MDBX_INTERNAL_VAR MDBX_GetTickCount64 mdbx_GetTickCount64;

#if !defined(_WIN32_WINNT_WIN8) || _WIN32_WINNT < _WIN32_WINNT_WIN8
typedef struct _WIN32_MEMORY_RANGE_ENTRY {
  PVOID VirtualAddress;
  SIZE_T NumberOfBytes;
} WIN32_MEMORY_RANGE_ENTRY, *PWIN32_MEMORY_RANGE_ENTRY;
#endif /* Windows 8.x */

typedef BOOL(WINAPI *MDBX_PrefetchVirtualMemory)(
    HANDLE hProcess, ULONG_PTR NumberOfEntries,
    PWIN32_MEMORY_RANGE_ENTRY VirtualAddresses, ULONG Flags);
MDBX_INTERNAL_VAR MDBX_PrefetchVirtualMemory mdbx_PrefetchVirtualMemory;

typedef enum _SECTION_INHERIT { ViewShare = 1, ViewUnmap = 2 } SECTION_INHERIT;

typedef NTSTATUS(NTAPI *MDBX_NtExtendSection)(IN HANDLE SectionHandle,
                                              IN PLARGE_INTEGER NewSectionSize);
MDBX_INTERNAL_VAR MDBX_NtExtendSection mdbx_NtExtendSection;

static __inline bool mdbx_RunningUnderWine(void) {
  return !mdbx_NtExtendSection;
}

typedef LSTATUS(WINAPI *MDBX_RegGetValueA)(HKEY hkey, LPCSTR lpSubKey,
                                           LPCSTR lpValue, DWORD dwFlags,
                                           LPDWORD pdwType, PVOID pvData,
                                           LPDWORD pcbData);
MDBX_INTERNAL_VAR MDBX_RegGetValueA mdbx_RegGetValueA;

NTSYSAPI ULONG RtlRandomEx(PULONG Seed);

#endif /* Windows */

#endif /* !__cplusplus */

/*----------------------------------------------------------------------------*/

#if defined(_MSC_VER) && _MSC_VER >= 1900
/* LY: MSVC 2015/2017/2019 has buggy/inconsistent PRIuPTR/PRIxPTR macros
 * for internal format-args checker. */
#undef PRIuPTR
#undef PRIiPTR
#undef PRIdPTR
#undef PRIxPTR
#define PRIuPTR "Iu"
#define PRIiPTR "Ii"
#define PRIdPTR "Id"
#define PRIxPTR "Ix"
#define PRIuSIZE "zu"
#define PRIiSIZE "zi"
#define PRIdSIZE "zd"
#define PRIxSIZE "zx"
#endif /* fix PRI*PTR for _MSC_VER */

#ifndef PRIuSIZE
#define PRIuSIZE PRIuPTR
#define PRIiSIZE PRIiPTR
#define PRIdSIZE PRIdPTR
#define PRIxSIZE PRIxPTR
#endif /* PRI*SIZE macros for MSVC */

#ifdef _MSC_VER
#pragma warning(pop)
#endif