/*-------------------------------------------------------------------------
 *
 * win32ntdll.c
 *   Dynamically loaded Windows NT functions.
 *
 * Portions Copyright (c) 2021-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *   src/port/win32ntdll.c
 *
 *-------------------------------------------------------------------------
 */

#include "c.h"

#include "port/win32ntdll.h"

RtlGetLastNtStatus_t pg_RtlGetLastNtStatus;
RtlNtStatusToDosError_t pg_RtlNtStatusToDosError;
NtFlushBuffersFileEx_t pg_NtFlushBuffersFileEx;

typedef struct NtDllRoutine
{
 const char *name;
 pg_funcptr_t *address;
} NtDllRoutine;

static const NtDllRoutine routines[] = {
 {"RtlGetLastNtStatus", (pg_funcptr_t *) &pg_RtlGetLastNtStatus},
 {"RtlNtStatusToDosError", (pg_funcptr_t *) &pg_RtlNtStatusToDosError},
 {"NtFlushBuffersFileEx", (pg_funcptr_t *) &pg_NtFlushBuffersFileEx}
};

static bool initialized;

int
initialize_ntdll(void)
{
 HMODULE  module;

 if (initialized)
  return 0;

 if (!(module = LoadLibraryEx("ntdll.dll", NULL, 0)))
 {
  _dosmaperr(GetLastError());
  return -1;
 }

 for (int i = 0; i < lengthof(routines); ++i)
 {
  pg_funcptr_t address;

  address = (pg_funcptr_t) GetProcAddress(module, routines[i].name);
  if (!address)
  {
   _dosmaperr(GetLastError());
   FreeLibrary(module);

   return -1;
  }

  *(pg_funcptr_t *) routines[i].address = address;
 }

 initialized = true;

 return 0;
}