glibc/libio/memstream.c

/* Copyright (C) 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "libioP.h"
#include "strfile.h"
#include <stdio.h>
#include <stdlib.h>


struct _IO_FILE_memstream
{
  _IO_strfile _sf;
  char **bufloc;
  _IO_size_t *sizeloc;
};


static int _IO_mem_sync __P ((_IO_FILE* fp));
static void _IO_mem_finish __P ((_IO_FILE* fp));


static const struct _IO_jump_t _IO_mem_jumps =
{
  JUMP_INIT_DUMMY,
  JUMP_INIT (finish, _IO_mem_finish),
  JUMP_INIT (overflow, _IO_str_overflow),
  JUMP_INIT (underflow, _IO_str_underflow),
  JUMP_INIT (uflow, _IO_default_uflow),
  JUMP_INIT (pbackfail, _IO_str_pbackfail),
  JUMP_INIT (xsputn, _IO_default_xsputn),
  JUMP_INIT (xsgetn, _IO_default_xsgetn),
  JUMP_INIT (seekoff, _IO_str_seekoff),
  JUMP_INIT (seekpos, _IO_default_seekpos),
  JUMP_INIT (setbuf, _IO_default_setbuf),
  JUMP_INIT (sync, _IO_mem_sync),
  JUMP_INIT (doallocate, _IO_default_doallocate),
  JUMP_INIT (read, _IO_default_read),
  JUMP_INIT (write, _IO_default_write),
  JUMP_INIT (seek, _IO_default_seek),
  JUMP_INIT (close, _IO_default_close),
  JUMP_INIT (stat, _IO_default_stat)
};

/* Open a stream that writes into a malloc'd buffer that is expanded as
   necessary.  *BUFLOC and *SIZELOC are updated with the buffer's location
   and the number of characters written on fflush or fclose.  */
_IO_FILE *
open_memstream (bufloc, sizeloc)
     char **bufloc;
     _IO_size_t *sizeloc;
{
  struct locked_FILE
  {
    struct _IO_FILE_memstream fp;
#ifdef _IO_MTSAFE_IO
    _IO_lock_t lock;
#endif
  } *new_f;
  char *buf;

  new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
  if (new_f == NULL)
    return NULL;
#ifdef _IO_MTSAFE_IO
  new_f->fp._sf._f._lock = &new_f->lock;
#endif

  buf = ALLOC_BUF (_IO_BUFSIZ);
  _IO_init (&new_f->fp._sf._f, 0);
  _IO_JUMPS (&new_f->fp._sf._f) = &_IO_mem_jumps;
  _IO_str_init_static (&new_f->fp._sf._f, buf, _IO_BUFSIZ, buf);
  new_f->fp._sf._f._flags &= ~_IO_USER_BUF;
  new_f->fp._sf._s._allocate_buffer = (_IO_alloc_type) malloc;
  new_f->fp._sf._s._free_buffer = (_IO_free_type) free;

  new_f->fp.bufloc = bufloc;
  new_f->fp.sizeloc = sizeloc;

  return &new_f->fp._sf._f;
}


static int
_IO_mem_sync (fp)
     _IO_FILE* fp;
{
  struct _IO_FILE_memstream *mp = (struct _IO_FILE_memstream *) fp;
  int res;

  res = _IO_default_sync (fp);
  if (res < 0)
    return res;

  if (fp->_IO_write_ptr == fp->_IO_write_end)
    {
      _IO_str_overflow (fp, '\0');
      --fp->_IO_write_ptr;
    }
  else
    *fp->_IO_write_ptr = '\0';

  *mp->bufloc = fp->_IO_write_base;
  *mp->sizeloc = fp->_IO_write_ptr - fp->_IO_write_base;

  return 0;
}


static void
_IO_mem_finish (fp)
     _IO_FILE* fp;
{
  struct _IO_FILE_memstream *mp = (struct _IO_FILE_memstream *) fp;

  *mp->bufloc = (char *) realloc (fp->_IO_write_base,
				  fp->_IO_write_ptr - fp->_IO_write_base + 1);
  if (*mp->bufloc != NULL)
    {
      (*mp->bufloc)[fp->_IO_write_ptr - fp->_IO_write_base] = '\0';
      *mp->sizeloc = fp->_IO_write_ptr - fp->_IO_write_base;
    }

  fp->_IO_buf_base = NULL;

  _IO_default_finish (fp);
}