/* Copyright (C) 1993-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Written by Per Bothner <bothner@cygnus.com>.

   The GNU C Library 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.

   The GNU C Library 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 the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.

   As a special exception, if you link the code in this file with

   files compiled with a GNU compiler to produce an executable,

   that does not cause the resulting executable to be covered by

   the GNU Lesser General Public License.  This exception does not

   however invalidate any other reasons why the executable file

   might be covered by the GNU Lesser General Public License.

   This exception applies to code released by its copyright holders

   in files containing the exception.  */

#include "libioP.h"

#include <assert.h>

#include <fcntl.h>

#include <sys/mman.h>

#include <sys/param.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <stdlib.h>

#include "../wcsmbs/wcsmbsload.h"

#include "../iconv/gconv_charset.h"

#include "../iconv/gconv_int.h"

#include <shlib-compat.h>

#include <not-cancel.h>

#include <kernel-features.h>

extern struct __gconv_trans_data __libio_translit attribute_hidden;

/* An fstream can be in at most one of put mode, get mode, or putback mode.

   Putback mode is a variant of get mode.

   In a filebuf, there is only one current position, instead of two

   separate get and put pointers.  In get mode, the current position

   is that of gptr(); in put mode that of pptr().

   The position in the buffer that corresponds to the position

   in external file system is normally _IO_read_end, except in putback

   mode, when it is _IO_save_end and also when the file is in append mode,

   since switching from read to write mode automatically sends the position in

   the external file system to the end of file.

   If the field _fb._offset is >= 0, it gives the offset in

   the file as a whole corresponding to eGptr(). (?)

   PUT MODE:

   If a filebuf is in put mode, then all of _IO_read_ptr, _IO_read_end,

   and _IO_read_base are equal to each other.  These are usually equal

   to _IO_buf_base, though not necessarily if we have switched from

   get mode to put mode.  (The reason is to maintain the invariant

   that _IO_read_end corresponds to the external file position.)

   _IO_write_base is non-NULL and usually equal to _IO_buf_base.

   We also have _IO_write_end == _IO_buf_end, but only in fully buffered mode.

   The un-flushed character are those between _IO_write_base and _IO_write_ptr.

   GET MODE:

   If a filebuf is in get or putback mode, eback() != egptr().

   In get mode, the unread characters are between gptr() and egptr().

   The OS file position corresponds to that of egptr().

   PUTBACK MODE:

   Putback mode is used to remember "excess" characters that have

   been sputbackc'd in a separate putback buffer.

   In putback mode, the get buffer points to the special putback buffer.

   The unread characters are the characters between gptr() and egptr()

   in the putback buffer, as well as the area between save_gptr()

   and save_egptr(), which point into the original reserve buffer.

   (The pointers save_gptr() and save_egptr() are the values

   of gptr() and egptr() at the time putback mode was entered.)

   The OS position corresponds to that of save_egptr().

   LINE BUFFERED OUTPUT:

   During line buffered output, _IO_write_base==base() && epptr()==base().

   However, ptr() may be anywhere between base() and ebuf().

   This forces a call to filebuf::overflow(int C) on every put.

   If there is more space in the buffer, and C is not a '\n',

   then C is inserted, and pptr() incremented.

   UNBUFFERED STREAMS:

   If a filebuf is unbuffered(), the _shortbuf[1] is used as the buffer.

*/

#define CLOSED_FILEBUF_FLAGS \

  (_IO_IS_FILEBUF+_IO_NO_READS+_IO_NO_WRITES+_IO_TIED_PUT_GET)

void

_IO_new_file_init_internal (struct _IO_FILE_plus *fp)

{

  /* POSIX.1 allows another file handle to be used to change the position

     of our file descriptor.  Hence we actually don't know the actual

     position before we do the first fseek (and until a following fflush). */

  fp->file._offset = _IO_pos_BAD;

  fp->file._flags |= CLOSED_FILEBUF_FLAGS;

  _IO_link_in (fp);

  fp->file._fileno = -1;

}

/* External version of _IO_new_file_init_internal which switches off

   vtable validation.  */

void

_IO_new_file_init (struct _IO_FILE_plus *fp)

{

  IO_set_accept_foreign_vtables (&_IO_vtable_check);

  _IO_new_file_init_internal (fp);

}

int

_IO_new_file_close_it (FILE *fp)

{

  int write_status;

  if (!_IO_file_is_open (fp))

    return EOF;

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

      && (fp->_flags & _IO_CURRENTLY_PUTTING) != 0)

    write_status = _IO_do_flush (fp);

  else

    write_status = 0;

  _IO_unsave_markers (fp);

  int close_status = ((fp->_flags2 & _IO_FLAGS2_NOCLOSE) == 0

		      ? _IO_SYSCLOSE (fp) : 0);

  /* Free buffer. */

  if (fp->_mode > 0)

    {

      if (_IO_have_wbackup (fp))

	_IO_free_wbackup_area (fp);

      _IO_wsetb (fp, NULL, NULL, 0);

      _IO_wsetg (fp, NULL, NULL, NULL);

      _IO_wsetp (fp, NULL, NULL);

    }

  _IO_setb (fp, NULL, NULL, 0);

  _IO_setg (fp, NULL, NULL, NULL);

  _IO_setp (fp, NULL, NULL);

  _IO_un_link ((struct _IO_FILE_plus *) fp);

  fp->_flags = _IO_MAGIC|CLOSED_FILEBUF_FLAGS;

  fp->_fileno = -1;

  fp->_offset = _IO_pos_BAD;

  return close_status ? close_status : write_status;

}

libc_hidden_ver (_IO_new_file_close_it, _IO_file_close_it)

void

_IO_new_file_finish (FILE *fp, int dummy)

{

  if (_IO_file_is_open (fp))

    {

      _IO_do_flush (fp);

      if (!(fp->_flags & _IO_DELETE_DONT_CLOSE))

	_IO_SYSCLOSE (fp);

    }

  _IO_default_finish (fp, 0);

}

libc_hidden_ver (_IO_new_file_finish, _IO_file_finish)

FILE *

_IO_file_open (FILE *fp, const char *filename, int posix_mode, int prot,

	       int read_write, int is32not64)

{

  int fdesc;

  if (__glibc_unlikely (fp->_flags2 & _IO_FLAGS2_NOTCANCEL))

    fdesc = __open_nocancel (filename,

			     posix_mode | (is32not64 ? 0 : O_LARGEFILE), prot);

  else

    fdesc = __open (filename, posix_mode | (is32not64 ? 0 : O_LARGEFILE), prot);

  if (fdesc < 0)

    return NULL;

  fp->_fileno = fdesc;

  _IO_mask_flags (fp, read_write,_IO_NO_READS+_IO_NO_WRITES+_IO_IS_APPENDING);

  /* For append mode, send the file offset to the end of the file.  Don't

     update the offset cache though, since the file handle is not active.  */

  if ((read_write & (_IO_IS_APPENDING | _IO_NO_READS))

      == (_IO_IS_APPENDING | _IO_NO_READS))

    {

      off64_t new_pos = _IO_SYSSEEK (fp, 0, _IO_seek_end);

      if (new_pos == _IO_pos_BAD && errno != ESPIPE)

	{

	  __close_nocancel (fdesc);

	  return NULL;

	}

    }

  _IO_link_in ((struct _IO_FILE_plus *) fp);

  return fp;

}

libc_hidden_def (_IO_file_open)

FILE *

_IO_new_file_fopen (FILE *fp, const char *filename, const char *mode,

		    int is32not64)

{

  int oflags = 0, omode;

  int read_write;

  int oprot = 0666;

  int i;

  FILE *result;

  const char *cs;

  const char *last_recognized;

  if (_IO_file_is_open (fp))

    return 0;

  switch (*mode)

    {

    case 'r':

      omode = O_RDONLY;

      read_write = _IO_NO_WRITES;

      break;

    case 'w':

      omode = O_WRONLY;

      oflags = O_CREAT|O_TRUNC;

      read_write = _IO_NO_READS;

      break;

    case 'a':

      omode = O_WRONLY;

      oflags = O_CREAT|O_APPEND;

      read_write = _IO_NO_READS|_IO_IS_APPENDING;

      break;

    default:

      __set_errno (EINVAL);

      return NULL;

    }

  last_recognized = mode;

  for (i = 1; i < 7; ++i)

    {

      switch (*++mode)

	{

	case '\0':

	  break;

	case '+':

	  omode = O_RDWR;

	  read_write &= _IO_IS_APPENDING;

	  last_recognized = mode;

	  continue;

	case 'x':

	  oflags |= O_EXCL;

	  last_recognized = mode;

	  continue;

	case 'b':

	  last_recognized = mode;

	  continue;

	case 'm':

	  fp->_flags2 |= _IO_FLAGS2_MMAP;

	  continue;

	case 'c':

	  fp->_flags2 |= _IO_FLAGS2_NOTCANCEL;

	  continue;

	case 'e':

	  oflags |= O_CLOEXEC;

	  fp->_flags2 |= _IO_FLAGS2_CLOEXEC;

	  continue;

	default:

	  /* Ignore.  */

	  continue;

	}

      break;

    }

  result = _IO_file_open (fp, filename, omode|oflags, oprot, read_write,

			  is32not64);

  if (result != NULL)

    {

      /* Test whether the mode string specifies the conversion.  */

      cs = strstr (last_recognized + 1, ",ccs=");

      if (cs != NULL)

	{

	  /* Yep.  Load the appropriate conversions and set the orientation

	     to wide.  */

	  struct gconv_fcts fcts;

	  struct _IO_codecvt *cc;

	  char *endp = __strchrnul (cs + 5, ',');

	  char *ccs = malloc (endp - (cs + 5) + 3);

	  if (ccs == NULL)

	    {

	      int malloc_err = errno;  /* Whatever malloc failed with.  */

	      (void) _IO_file_close_it (fp);

	      __set_errno (malloc_err);

	      return NULL;

	    }

	  *((char *) __mempcpy (ccs, cs + 5, endp - (cs + 5))) = '\0';

	  strip (ccs, ccs);

	  if (__wcsmbs_named_conv (&fcts, ccs[2] == '\0'

				   ? upstr (ccs, cs + 5) : ccs) != 0)

	    {

	      /* Something went wrong, we cannot load the conversion modules.

		 This means we cannot proceed since the user explicitly asked

		 for these.  */

	      (void) _IO_file_close_it (fp);

	      free (ccs);

	      __set_errno (EINVAL);

	      return NULL;

	    }

	  free (ccs);

	  assert (fcts.towc_nsteps == 1);

	  assert (fcts.tomb_nsteps == 1);

	  fp->_wide_data->_IO_read_ptr = fp->_wide_data->_IO_read_end;

	  fp->_wide_data->_IO_write_ptr = fp->_wide_data->_IO_write_base;

	  /* Clear the state.  We start all over again.  */

	  memset (&fp->_wide_data->_IO_state, '\0', sizeof (__mbstate_t));

	  memset (&fp->_wide_data->_IO_last_state, '\0', sizeof (__mbstate_t));

	  cc = fp->_codecvt = &fp->_wide_data->_codecvt;

	  /* The functions are always the same.  */

	  *cc = __libio_codecvt;

	  cc->__cd_in.__cd.__nsteps = fcts.towc_nsteps;

	  cc->__cd_in.__cd.__steps = fcts.towc;

	  cc->__cd_in.__cd.__data[0].__invocation_counter = 0;

	  cc->__cd_in.__cd.__data[0].__internal_use = 1;

	  cc->__cd_in.__cd.__data[0].__flags = __GCONV_IS_LAST;

	  cc->__cd_in.__cd.__data[0].__statep = &result->_wide_data->_IO_state;

	  cc->__cd_out.__cd.__nsteps = fcts.tomb_nsteps;

	  cc->__cd_out.__cd.__steps = fcts.tomb;

	  cc->__cd_out.__cd.__data[0].__invocation_counter = 0;

	  cc->__cd_out.__cd.__data[0].__internal_use = 1;

	  cc->__cd_out.__cd.__data[0].__flags

	    = __GCONV_IS_LAST | __GCONV_TRANSLIT;

	  cc->__cd_out.__cd.__data[0].__statep =

	    &result->_wide_data->_IO_state;

	  /* From now on use the wide character callback functions.  */

	  _IO_JUMPS_FILE_plus (fp) = fp->_wide_data->_wide_vtable;

	  /* Set the mode now.  */

	  result->_mode = 1;

	}

    }

  return result;

}

libc_hidden_ver (_IO_new_file_fopen, _IO_file_fopen)

FILE *

_IO_new_file_attach (FILE *fp, int fd)

{

  if (_IO_file_is_open (fp))

    return NULL;

  fp->_fileno = fd;

  fp->_flags &= ~(_IO_NO_READS+_IO_NO_WRITES);

  fp->_flags |= _IO_DELETE_DONT_CLOSE;

  /* Get the current position of the file. */

  /* We have to do that since that may be junk. */

  fp->_offset = _IO_pos_BAD;

  int save_errno = errno;

  if (_IO_SEEKOFF (fp, (off64_t)0, _IO_seek_cur, _IOS_INPUT|_IOS_OUTPUT)

      == _IO_pos_BAD && errno != ESPIPE)

    return NULL;

  __set_errno (save_errno);

  return fp;

}

libc_hidden_ver (_IO_new_file_attach, _IO_file_attach)

FILE *

_IO_new_file_setbuf (FILE *fp, char *p, ssize_t len)

{

  if (_IO_default_setbuf (fp, p, len) == NULL)

    return NULL;

  fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end

    = fp->_IO_buf_base;

  _IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base, fp->_IO_buf_base);

  return fp;

}

libc_hidden_ver (_IO_new_file_setbuf, _IO_file_setbuf)

FILE *

_IO_file_setbuf_mmap (FILE *fp, char *p, ssize_t len)

{

  FILE *result;

  /* Change the function table.  */

  _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;

  fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;

  /* And perform the normal operation.  */

  result = _IO_new_file_setbuf (fp, p, len);

  /* If the call failed, restore to using mmap.  */

  if (result == NULL)

    {

      _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps_mmap;

      fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_mmap;

    }

  return result;

}

static size_t new_do_write (FILE *, const char *, size_t);

/* Write TO_DO bytes from DATA to FP.

   Then mark FP as having empty buffers. */

int

_IO_new_do_write (FILE *fp, const char *data, size_t to_do)

{

  return (to_do == 0

	  || (size_t) new_do_write (fp, data, to_do) == to_do) ? 0 : EOF;

}

libc_hidden_ver (_IO_new_do_write, _IO_do_write)

static size_t

new_do_write (FILE *fp, const char *data, size_t to_do)

{

  size_t count;

  if (fp->_flags & _IO_IS_APPENDING)

    /* On a system without a proper O_APPEND implementation,

       you would need to sys_seek(0, SEEK_END) here, but is

       not needed nor desirable for Unix- or Posix-like systems.

       Instead, just indicate that offset (before and after) is

       unpredictable. */

    fp->_offset = _IO_pos_BAD;

  else if (fp->_IO_read_end != fp->_IO_write_base)

    {

      off64_t new_pos

	= _IO_SYSSEEK (fp, fp->_IO_write_base - fp->_IO_read_end, 1);

      if (new_pos == _IO_pos_BAD)

	return 0;

      fp->_offset = new_pos;

    }

  count = _IO_SYSWRITE (fp, data, to_do);

  if (fp->_cur_column && count)

    fp->_cur_column = _IO_adjust_column (fp->_cur_column - 1, data, count) + 1;

  _IO_setg (fp, fp->_IO_buf_base, fp->_IO_buf_base, fp->_IO_buf_base);

  fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_buf_base;

  fp->_IO_write_end = (fp->_mode <= 0

		       && (fp->_flags & (_IO_LINE_BUF | _IO_UNBUFFERED))

		       ? fp->_IO_buf_base : fp->_IO_buf_end);

  return count;

}

int

_IO_new_file_underflow (FILE *fp)

{

  ssize_t count;

  /* C99 requires EOF to be "sticky".  */

  if (fp->_flags & _IO_EOF_SEEN)

    return EOF;

  if (fp->_flags & _IO_NO_READS)

    {

      fp->_flags |= _IO_ERR_SEEN;

      __set_errno (EBADF);

      return EOF;

    }

  if (fp->_IO_read_ptr < fp->_IO_read_end)

    return *(unsigned char *) fp->_IO_read_ptr;

  if (fp->_IO_buf_base == NULL)

    {

      /* Maybe we already have a push back pointer.  */

      if (fp->_IO_save_base != NULL)

	{

	  free (fp->_IO_save_base);

	  fp->_flags &= ~_IO_IN_BACKUP;

	}

      _IO_doallocbuf (fp);

    }

  /* FIXME This can/should be moved to genops ?? */

  if (fp->_flags & (_IO_LINE_BUF|_IO_UNBUFFERED))

    {

      /* We used to flush all line-buffered stream.  This really isn't

	 required by any standard.  My recollection is that

	 traditional Unix systems did this for stdout.  stderr better

	 not be line buffered.  So we do just that here

	 explicitly.  --drepper */

      _IO_acquire_lock (_IO_stdout);

      if ((_IO_stdout->_flags & (_IO_LINKED | _IO_NO_WRITES | _IO_LINE_BUF))

	  == (_IO_LINKED | _IO_LINE_BUF))

	_IO_OVERFLOW (_IO_stdout, EOF);

      _IO_release_lock (_IO_stdout);

    }

  _IO_switch_to_get_mode (fp);

  /* This is very tricky. We have to adjust those

     pointers before we call _IO_SYSREAD () since

     we may longjump () out while waiting for

     input. Those pointers may be screwed up. H.J. */

  fp->_IO_read_base = fp->_IO_read_ptr = fp->_IO_buf_base;

  fp->_IO_read_end = fp->_IO_buf_base;

  fp->_IO_write_base = fp->_IO_write_ptr = fp->_IO_write_end

    = fp->_IO_buf_base;

  count = _IO_SYSREAD (fp, fp->_IO_buf_base,

		       fp->_IO_buf_end - fp->_IO_buf_base);

  if (count <= 0)

    {

      if (count == 0)

	fp->_flags |= _IO_EOF_SEEN;

      else

	fp->_flags |= _IO_ERR_SEEN, count = 0;

  }

  fp->_IO_read_end += count;

  if (count == 0)

    {

      /* If a stream is read to EOF, the calling application may switch active

	 handles.  As a result, our offset cache would no longer be valid, so

	 unset it.  */

      fp->_offset = _IO_pos_BAD;

      return EOF;

    }

  if (fp->_offset != _IO_pos_BAD)

    _IO_pos_adjust (fp->_offset, count);

  return *(unsigned char *) fp->_IO_read_ptr;

}

libc_hidden_ver (_IO_new_file_underflow, _IO_file_underflow)

/* Guts of underflow callback if we mmap the file.  This stats the file and

   updates the stream state to match.  In the normal case we return zero.

   If the file is no longer eligible for mmap, its jump tables are reset to

   the vanilla ones and we return nonzero.  */

static int

mmap_remap_check (FILE *fp)

{

  struct stat64 st;

  if (_IO_SYSSTAT (fp, &st) == 0

      && S_ISREG (st.st_mode) && st.st_size != 0

      /* Limit the file size to 1MB for 32-bit machines.  */

      && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024))

    {

      const size_t pagesize = __getpagesize ();

# define ROUNDED(x)	(((x) + pagesize - 1) & ~(pagesize - 1))

      if (ROUNDED (st.st_size) < ROUNDED (fp->_IO_buf_end

					  - fp->_IO_buf_base))

	{

	  /* We can trim off some pages past the end of the file.  */

	  (void) __munmap (fp->_IO_buf_base + ROUNDED (st.st_size),

			   ROUNDED (fp->_IO_buf_end - fp->_IO_buf_base)

			   - ROUNDED (st.st_size));

	  fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;

	}

      else if (ROUNDED (st.st_size) > ROUNDED (fp->_IO_buf_end

					       - fp->_IO_buf_base))

	{

	  /* The file added some pages.  We need to remap it.  */

	  void *p;

#if _G_HAVE_MREMAP

	  p = __mremap (fp->_IO_buf_base, ROUNDED (fp->_IO_buf_end

						   - fp->_IO_buf_base),

			ROUNDED (st.st_size), MREMAP_MAYMOVE);

	  if (p == MAP_FAILED)

	    {

	      (void) __munmap (fp->_IO_buf_base,

			       fp->_IO_buf_end - fp->_IO_buf_base);

	      goto punt;

	    }

#else

	  (void) __munmap (fp->_IO_buf_base,

			   fp->_IO_buf_end - fp->_IO_buf_base);

	  p = __mmap64 (NULL, st.st_size, PROT_READ, MAP_SHARED,

			fp->_fileno, 0);

	  if (p == MAP_FAILED)

	    goto punt;

#endif

	  fp->_IO_buf_base = p;

	  fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;

	}

      else

	{

	  /* The number of pages didn't change.  */

	  fp->_IO_buf_end = fp->_IO_buf_base + st.st_size;

	}

# undef ROUNDED

      fp->_offset -= fp->_IO_read_end - fp->_IO_read_ptr;

      _IO_setg (fp, fp->_IO_buf_base,

		fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base

		? fp->_IO_buf_base + fp->_offset : fp->_IO_buf_end,

		fp->_IO_buf_end);

      /* If we are already positioned at or past the end of the file, don't

	 change the current offset.  If not, seek past what we have mapped,

	 mimicking the position left by a normal underflow reading into its

	 buffer until EOF.  */

      if (fp->_offset < fp->_IO_buf_end - fp->_IO_buf_base)

	{

	  if (__lseek64 (fp->_fileno, fp->_IO_buf_end - fp->_IO_buf_base,

			 SEEK_SET)

	      != fp->_IO_buf_end - fp->_IO_buf_base)

	    fp->_flags |= _IO_ERR_SEEN;

	  else

	    fp->_offset = fp->_IO_buf_end - fp->_IO_buf_base;

	}

      return 0;

    }

  else

    {

      /* Life is no longer good for mmap.  Punt it.  */

      (void) __munmap (fp->_IO_buf_base,

		       fp->_IO_buf_end - fp->_IO_buf_base);

    punt:

      fp->_IO_buf_base = fp->_IO_buf_end = NULL;

      _IO_setg (fp, NULL, NULL, NULL);

      if (fp->_mode <= 0)

	_IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;

      else

	_IO_JUMPS_FILE_plus (fp) = &_IO_wfile_jumps;

      fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;

      return 1;

    }

}

/* Special callback replacing the underflow callbacks if we mmap the file.  */

int

_IO_file_underflow_mmap (FILE *fp)

{

  if (fp->_IO_read_ptr < fp->_IO_read_end)

    return *(unsigned char *) fp->_IO_read_ptr;

  if (__glibc_unlikely (mmap_remap_check (fp)))

    /* We punted to the regular file functions.  */

    return _IO_UNDERFLOW (fp);

  if (fp->_IO_read_ptr < fp->_IO_read_end)

    return *(unsigned char *) fp->_IO_read_ptr;

  fp->_flags |= _IO_EOF_SEEN;

  return EOF;

}

static void

decide_maybe_mmap (FILE *fp)

{

  /* We use the file in read-only mode.  This could mean we can

     mmap the file and use it without any copying.  But not all

     file descriptors are for mmap-able objects and on 32-bit

     machines we don't want to map files which are too large since

     this would require too much virtual memory.  */

  struct stat64 st;

  if (_IO_SYSSTAT (fp, &st) == 0

      && S_ISREG (st.st_mode) && st.st_size != 0

      /* Limit the file size to 1MB for 32-bit machines.  */

      && (sizeof (ptrdiff_t) > 4 || st.st_size < 1*1024*1024)

      /* Sanity check.  */

      && (fp->_offset == _IO_pos_BAD || fp->_offset <= st.st_size))

    {

      /* Try to map the file.  */

      void *p;

      p = __mmap64 (NULL, st.st_size, PROT_READ, MAP_SHARED, fp->_fileno, 0);

      if (p != MAP_FAILED)

	{

	  /* OK, we managed to map the file.  Set the buffer up and use a

	     special jump table with simplified underflow functions which

	     never tries to read anything from the file.  */

	  if (__lseek64 (fp->_fileno, st.st_size, SEEK_SET) != st.st_size)

	    {

	      (void) __munmap (p, st.st_size);

	      fp->_offset = _IO_pos_BAD;

	    }

	  else

	    {

	      _IO_setb (fp, p, (char *) p + st.st_size, 0);

	      if (fp->_offset == _IO_pos_BAD)

		fp->_offset = 0;

	      _IO_setg (fp, p, p + fp->_offset, p + st.st_size);

	      fp->_offset = st.st_size;

	      if (fp->_mode <= 0)

		_IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps_mmap;

	      else

		_IO_JUMPS_FILE_plus (fp) = &_IO_wfile_jumps_mmap;

	      fp->_wide_data->_wide_vtable = &_IO_wfile_jumps_mmap;

	      return;

	    }

	}

    }

  /* We couldn't use mmap, so revert to the vanilla file operations.  */

  if (fp->_mode <= 0)

    _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;

  else

    _IO_JUMPS_FILE_plus (fp) = &_IO_wfile_jumps;

  fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;

}

int

_IO_file_underflow_maybe_mmap (FILE *fp)

{

  /* This is the first read attempt.  Choose mmap or vanilla operations

     and then punt to the chosen underflow routine.  */

  decide_maybe_mmap (fp);

  return _IO_UNDERFLOW (fp);

}

int

_IO_new_file_overflow (FILE *f, int ch)

{

  if (f->_flags & _IO_NO_WRITES) /* SET ERROR */

    {

      f->_flags |= _IO_ERR_SEEN;

      __set_errno (EBADF);

      return EOF;

    }

  /* If currently reading or no buffer allocated. */

  if ((f->_flags & _IO_CURRENTLY_PUTTING) == 0 || f->_IO_write_base == NULL)

    {

      /* Allocate a buffer if needed. */

      if (f->_IO_write_base == NULL)

	{

	  _IO_doallocbuf (f);

	  _IO_setg (f, f->_IO_buf_base, f->_IO_buf_base, f->_IO_buf_base);

	}

      /* Otherwise must be currently reading.

	 If _IO_read_ptr (and hence also _IO_read_end) is at the buffer end,

	 logically slide the buffer forwards one block (by setting the

	 read pointers to all point at the beginning of the block).  This

	 makes room for subsequent output.

	 Otherwise, set the read pointers to _IO_read_end (leaving that

	 alone, so it can continue to correspond to the external position). */

      if (__glibc_unlikely (_IO_in_backup (f)))

	{

	  size_t nbackup = f->_IO_read_end - f->_IO_read_ptr;

	  _IO_free_backup_area (f);

	  f->_IO_read_base -= MIN (nbackup,

				   f->_IO_read_base - f->_IO_buf_base);

	  f->_IO_read_ptr = f->_IO_read_base;

	}

      if (f->_IO_read_ptr == f->_IO_buf_end)

	f->_IO_read_end = f->_IO_read_ptr = f->_IO_buf_base;

      f->_IO_write_ptr = f->_IO_read_ptr;

      f->_IO_write_base = f->_IO_write_ptr;

      f->_IO_write_end = f->_IO_buf_end;

      f->_IO_read_base = f->_IO_read_ptr = f->_IO_read_end;

      f->_flags |= _IO_CURRENTLY_PUTTING;

      if (f->_mode <= 0 && f->_flags & (_IO_LINE_BUF | _IO_UNBUFFERED))

	f->_IO_write_end = f->_IO_write_ptr;

    }

  if (ch == EOF)

    return _IO_do_write (f, f->_IO_write_base,

			 f->_IO_write_ptr - f->_IO_write_base);

  if (f->_IO_write_ptr == f->_IO_buf_end ) /* Buffer is really full */

    if (_IO_do_flush (f) == EOF)

      return EOF;

  *f->_IO_write_ptr++ = ch;

  if ((f->_flags & _IO_UNBUFFERED)

      || ((f->_flags & _IO_LINE_BUF) && ch == '\n'))

    if (_IO_do_write (f, f->_IO_write_base,

		      f->_IO_write_ptr - f->_IO_write_base) == EOF)

      return EOF;

  return (unsigned char) ch;

}

libc_hidden_ver (_IO_new_file_overflow, _IO_file_overflow)

int

_IO_new_file_sync (FILE *fp)

{

  ssize_t delta;

  int retval = 0;

  /*    char* ptr = cur_ptr(); */

  if (fp->_IO_write_ptr > fp->_IO_write_base)

    if (_IO_do_flush(fp)) return EOF;

  delta = fp->_IO_read_ptr - fp->_IO_read_end;

  if (delta != 0)

    {

      off64_t new_pos = _IO_SYSSEEK (fp, delta, 1);

      if (new_pos != (off64_t) EOF)

	fp->_IO_read_end = fp->_IO_read_ptr;

      else if (errno == ESPIPE)

	; /* Ignore error from unseekable devices. */

      else

	retval = EOF;

    }

  if (retval != EOF)

    fp->_offset = _IO_pos_BAD;

  /* FIXME: Cleanup - can this be shared? */

  /*    setg(base(), ptr, ptr); */

  return retval;

}

libc_hidden_ver (_IO_new_file_sync, _IO_file_sync)

static int

_IO_file_sync_mmap (FILE *fp)

{

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

    {

      if (__lseek64 (fp->_fileno, fp->_IO_read_ptr - fp->_IO_buf_base,

		     SEEK_SET)

	  != fp->_IO_read_ptr - fp->_IO_buf_base)

	{

	  fp->_flags |= _IO_ERR_SEEN;

	  return EOF;

	}

    }

  fp->_offset = fp->_IO_read_ptr - fp->_IO_buf_base;

  fp->_IO_read_end = fp->_IO_read_ptr = fp->_IO_read_base;

  return 0;

}

/* ftell{,o} implementation.  The only time we modify the state of the stream

   is when we have unflushed writes.  In that case we seek to the end and

   record that offset in the stream object.  */

static off64_t

do_ftell (FILE *fp)

{

  off64_t result, offset = 0;

  /* No point looking at unflushed data if we haven't allocated buffers

     yet.  */

  if (fp->_IO_buf_base != NULL)

    {

      bool unflushed_writes = fp->_IO_write_ptr > fp->_IO_write_base;

      bool append_mode = (fp->_flags & _IO_IS_APPENDING) == _IO_IS_APPENDING;

      /* When we have unflushed writes in append mode, seek to the end of the

	 file and record that offset.  This is the only time we change the file

	 stream state and it is safe since the file handle is active.  */

      if (unflushed_writes && append_mode)

	{

	  result = _IO_SYSSEEK (fp, 0, _IO_seek_end);

	  if (result == _IO_pos_BAD)

	    return EOF;

	  else

	    fp->_offset = result;

	}

      /* Adjust for unflushed data.  */

      if (!unflushed_writes)

	offset -= fp->_IO_read_end - fp->_IO_read_ptr;

      /* We don't trust _IO_read_end to represent the current file offset when

	 writing in append mode because the value would have to be shifted to

	 the end of the file during a flush.  Use the write base instead, along

	 with the new offset we got above when we did a seek to the end of the

	 file.  */

      else if (append_mode)