/*	$NetBSD: setvbuf.c,v 1.19 2012/03/15 18:22:30 christos Exp $	*/

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
#include "reentrant.h"
#include "local.h"

/*
 * Set one of the three kinds of buffering, optionally including
 * a buffer.
 */
int setvbuf(FILE *fp, char *buf, int mode, size_t size) {
  int ret, flags;
  size_t iosize;
  int ttyflag;

  _DIAGASSERT(fp != NULL);
  /* buf may be NULL */

  /*
   * Verify arguments.  The `int' limit on `size' is due to this
   * particular implementation.  Note, buf and size are ignored
   * when setting _IONBF.
   */
  if (mode != _IONBF)
    if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
      return -1;

  FLOCKFILE(fp);
  /*
   * Write current buffer, if any.  Discard unread input (including
   * ungetc data), cancel line buffering, and free old buffer if
   * malloc()ed.  We also clear any eof condition, as if this were
   * a seek.
   */
  ret = 0;
  (void)__sflush(fp);
  if (HASUB(fp))
    FREEUB(fp);
  WCIO_FREE(fp);
  fp->_r = fp->_lbfsize = 0;
  flags = fp->_flags;
  if (flags & __SMBF)
    free((void *)fp->_bf._base);
  flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);

  /* If setting unbuffered mode, skip all the hard work. */
  if (mode == _IONBF)
    goto nbf;

  /*
   * Find optimal I/O size for seek optimization.  This also returns
   * a `tty flag' to suggest that we check isatty(fd), but we do not
   * care since our caller told us how to buffer.
   */
  flags |= __swhatbuf(fp, &iosize, &ttyflag);
  if (size == 0) {
    buf = NULL; /* force local allocation */
    size = iosize;
  }

  /* Allocate buffer if needed. */
  if (buf == NULL) {
    if ((buf = malloc(size)) == NULL) {
      /*
       * Unable to honor user's request.  We will return
       * failure, but try again with file system size.
       */
      ret = -1;
      if (size != iosize) {
        size = iosize;
        buf = malloc(size);
      }
    }
    if (buf == NULL) {
      /* No luck; switch to unbuffered I/O. */
    nbf:
      fp->_flags = flags | __SNBF;
      fp->_w = 0;
      fp->_bf._base = fp->_p = fp->_nbuf;
      fp->_bf._size = 1;
      FUNLOCKFILE(fp);
      return ret;
    }
    flags |= __SMBF;
  }

  /*
   * Kill any seek optimization if the buffer is not the
   * right size.
   *
   * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
   */
  if (size != iosize)
    flags |= __SNPT;

  /*
   * Fix up the FILE fields, and set __cleanup for output flush on
   * exit (since we are buffered in some way).
   */
  if (mode == _IOLBF)
    flags |= __SLBF;
  fp->_flags = flags;
  fp->_bf._base = fp->_p = (unsigned char *)buf;
  _DIAGASSERT(__type_fit(int, size));
  fp->_bf._size = (int)size;
  /* fp->_lbfsize is still 0 */
  if (flags & __SWR) {
    /*
     * Begin or continue writing: see __swsetup().  Note
     * that __SNBF is impossible (it was handled earlier).
     */
    if (flags & __SLBF) {
      fp->_w = 0;
      fp->_lbfsize = -fp->_bf._size;
    } else {
      _DIAGASSERT(__type_fit(int, size));
      fp->_w = (int)size;
    }
  } else {
    /* begin/continue reading, or stay in intermediate state */
    fp->_w = 0;
  }
  __cleanup = _cleanup;

  FUNLOCKFILE(fp);
  return ret;
}
