/* An fseeko() function that, together with fflush(), is POSIX compliant.

   Copyright (C) 2007-2025 Free Software Foundation, Inc.

   This file is free software: you can redistribute it and/or modify

   it under the terms of the GNU Lesser General Public License as

   published by the Free Software Foundation; either version 2.1 of the

   License, or (at your option) any later version.

   This file 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 Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <stdio.h>

/* Get off_t, lseek, _POSIX_VERSION.  */

#include <unistd.h>

#include "stdio-impl.h"

int

fseeko (FILE *fp, off_t offset, int whence)

#undef fseeko

#if !HAVE_FSEEKO

# undef fseek

# define fseeko fseek

#endif

#if _GL_WINDOWS_64_BIT_OFF_T

# undef fseeko

# if HAVE__FSEEKI64 && HAVE_DECL__FSEEKI64 /* msvc, mingw since msvcrt8.0, mingw64 */

#  define fseeko _fseeki64

# else /* mingw before msvcrt8.0 */

#  define fseeko fseeko64

# endif

#endif

{

#if LSEEK_PIPE_BROKEN

  /* mingw gives bogus answers rather than failure on non-seekable files.  */

  if (lseek (fileno (fp), 0, SEEK_CUR) == -1)

    return EOF;

#endif

  /* These tests are based on fpurge.c.  */

#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1

  /* GNU libc, BeOS, Haiku, Linux libc5 */

  if (fp->_IO_read_end == fp->_IO_read_ptr

      && fp->_IO_write_ptr == fp->_IO_write_base

      && fp->_IO_save_base == NULL)

#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__

  /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

# if defined __SL64 && defined __SCLE /* Cygwin */

  if ((fp->_flags & __SL64) == 0)

    {

      /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit

         mode; but has an fseeko that requires 64-bit mode.  */

      FILE *tmp = fopen ("/dev/null", "r");

      if (!tmp)

        return -1;

      fp->_flags |= __SL64;

      fp->_seek64 = tmp->_seek64;

      fclose (tmp);

    }

# endif

  if (fp_->_p == fp_->_bf._base

      && fp_->_r == 0

      && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */

                     ? fp_->_bf._size

                     : 0)

      && fp_ub._base == NULL)

#elif defined __EMX__               /* emx+gcc */

  if (fp->_ptr == fp->_buffer

      && fp->_rcount == 0

      && fp->_wcount == 0

      && fp->_ungetc_count == 0)

#elif defined __minix               /* Minix */

  if (fp_->_ptr == fp_->_buf

      && (fp_->_ptr == NULL || fp_->_count == 0))

#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */

  if (fp_->_ptr == fp_->_base

      && (fp_->_ptr == NULL || fp_->_cnt == 0))

#elif defined __UCLIBC__            /* uClibc */

  if (((fp->__modeflags & __FLAG_WRITING) == 0

       || fp->__bufpos == fp->__bufstart)

      && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0

          || fp->__bufpos == fp->__bufread))

#elif defined __QNX__               /* QNX */

  if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)

      && fp->_Rback == fp->_Back + sizeof (fp->_Back)

      && fp->_Rsave == NULL)

#elif defined __MINT__              /* Atari FreeMiNT */

  if (fp->__bufp == fp->__buffer

      && fp->__get_limit == fp->__bufp

      && fp->__put_limit == fp->__bufp

      && !fp->__pushed_back)

#elif defined EPLAN9                /* Plan9 */

  if (fp->rp == fp->buf

      && fp->wp == fp->buf)

#elif FUNC_FFLUSH_STDIN < 0 && 200809 <= _POSIX_VERSION

  /* Cross-compiling to some other system advertising conformance to

     POSIX.1-2008 or later.  Assume fseeko and fflush work as advertised.

     If this assumption is incorrect, please report the bug to

     bug-gnulib.  */

  if (0)

#else

  #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."

#endif

    {

      /* We get here when an fflush() call immediately preceded this one (or

         if ftell() has created buffers but no I/O has occurred on a

         newly-opened stream).  We know there are no buffers.  */

      off_t pos = lseek (fileno (fp), offset, whence);

      if (pos == -1)

        {

#if defined __sferror || defined __DragonFly__ || defined __ANDROID__

          /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

          fp_->_flags &= ~__SOFF;

#endif

          return -1;

        }

#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1

      /* GNU libc, BeOS, Haiku, Linux libc5 */

      fp->_flags &= ~_IO_EOF_SEEN;

      fp->_offset = pos;

#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__

      /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */

# if defined __CYGWIN__ || (defined __NetBSD__ && __NetBSD_Version__ >= 600000000) || defined __minix

      /* fp_->_offset is typed as an integer.  */

      fp_->_offset = pos;

# else

      /* fp_->_offset is an fpos_t.  */

      {

        /* Use a union, since on NetBSD, the compilation flags

           determine whether fpos_t is typedef'd to off_t or a struct

           containing a single off_t member.  */

        union

          {

            fpos_t f;

            off_t o;

          } u;

        u.o = pos;

        fp_->_offset = u.f;

      }

# endif

      fp_->_flags |= __SOFF;

      fp_->_flags &= ~__SEOF;

#elif defined __EMX__               /* emx+gcc */

      fp->_flags &= ~_IOEOF;

#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */

      fp_->_flag &= ~_IOEOF;

#elif defined __MINT__              /* Atari FreeMiNT */

      fp->__offset = pos;

      fp->__eof = 0;

#endif

      return 0;

    }

  return fseeko (fp, offset, whence);

}