/* ftruncate emulations for native Windows.

   Copyright (C) 1992-2020 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3, 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; if not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <unistd.h>

#if HAVE_CHSIZE

/* A native Windows platform.  */

# include <errno.h>

# if _GL_WINDOWS_64_BIT_OFF_T

/* Large File Support: off_t is 64-bit, but chsize() takes only a 32-bit

   argument.  So, define a 64-bit safe SetFileSize function ourselves.  */

/* Ensure that <windows.h> declares GetFileSizeEx.  */

#  if !defined _WIN32_WINNT || (_WIN32_WINNT < _WIN32_WINNT_WIN2K)

#   undef _WIN32_WINNT

#   define _WIN32_WINNT _WIN32_WINNT_WIN2K

#  endif

/* Get declarations of the native Windows API functions.  */

#  define WIN32_LEAN_AND_MEAN

#  include <windows.h>

/* Get _get_osfhandle.  */

#  if GNULIB_MSVC_NOTHROW

#   include "msvc-nothrow.h"

#  else

#   include <io.h>

#  endif

static BOOL

SetFileSize (HANDLE h, LONGLONG size)

{

  LARGE_INTEGER old_size;

  if (!GetFileSizeEx (h, &old_size))

    return FALSE;

  if (size != old_size.QuadPart)

    {

      /* Duplicate the handle, so we are free to modify its file position.  */

      HANDLE curr_process = GetCurrentProcess ();

      HANDLE tmph;

      if (!DuplicateHandle (curr_process,           /* SourceProcessHandle */

                            h,                      /* SourceHandle */

                            curr_process,           /* TargetProcessHandle */

                            (PHANDLE) &tmph,        /* TargetHandle */

                            (DWORD) 0,              /* DesiredAccess */

                            FALSE,                  /* InheritHandle */

                            DUPLICATE_SAME_ACCESS)) /* Options */

        return FALSE;

      if (size < old_size.QuadPart)

        {

          /* Reduce the size.  */

          LONG size_hi = (LONG) (size >> 32);

          if (SetFilePointer (tmph, (LONG) size, &size_hi, FILE_BEGIN)

              == INVALID_SET_FILE_POINTER

              && GetLastError() != NO_ERROR)

            {

              CloseHandle (tmph);

              return FALSE;

            }

          if (!SetEndOfFile (tmph))

            {

              CloseHandle (tmph);

              return FALSE;

            }

        }

      else

        {

          /* Increase the size by adding zero bytes at the end.  */

          static char zero_bytes[1024];

          LONG pos_hi = 0;

          LONG pos_lo = SetFilePointer (tmph, (LONG) 0, &pos_hi, FILE_END);

          LONGLONG pos;

          if (pos_lo == INVALID_SET_FILE_POINTER

              && GetLastError() != NO_ERROR)

            {

              CloseHandle (tmph);

              return FALSE;

            }

          pos = ((LONGLONG) pos_hi << 32) | (ULONGLONG) (ULONG) pos_lo;

          while (pos < size)

            {

              DWORD written;

              LONGLONG count = size - pos;

              if (count > sizeof (zero_bytes))

                count = sizeof (zero_bytes);

              if (!WriteFile (tmph, zero_bytes, (DWORD) count, &written, NULL)

                  || written == 0)

                {

                  CloseHandle (tmph);

                  return FALSE;

                }

              pos += (ULONGLONG) (ULONG) written;

            }

        }

      /* Close the handle.  */

      CloseHandle (tmph);

    }

  return TRUE;

}

int

ftruncate (int fd, off_t length)

{

  HANDLE handle = (HANDLE) _get_osfhandle (fd);

  if (handle == INVALID_HANDLE_VALUE)

    {

      errno = EBADF;

      return -1;

    }

  if (length < 0)

    {

      errno = EINVAL;

      return -1;

    }

  if (!SetFileSize (handle, length))

    {

      switch (GetLastError ())

        {

        case ERROR_ACCESS_DENIED:

          errno = EACCES;

          break;

        case ERROR_HANDLE_DISK_FULL:

        case ERROR_DISK_FULL:

        case ERROR_DISK_TOO_FRAGMENTED:

          errno = ENOSPC;

          break;

        default:

          errno = EIO;

          break;

        }

      return -1;

    }

  return 0;

}

# else

#  include <io.h>

#  if HAVE_MSVC_INVALID_PARAMETER_HANDLER

#   include "msvc-inval.h"

static int

chsize_nothrow (int fd, long length)

{

  int result;

  TRY_MSVC_INVAL

    {

      result = chsize (fd, length);

    }

  CATCH_MSVC_INVAL

    {

      result = -1;

      errno = EBADF;

    }

  DONE_MSVC_INVAL;

  return result;

}

#  else

#   define chsize_nothrow chsize

#  endif

int

ftruncate (int fd, off_t length)

{

  return chsize_nothrow (fd, length);

}

# endif

#endif