/*	$NetBSD: fvwrite.c,v 1.25 2012/03/27 15:05:42 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 <stddef.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "reentrant.h"
#include "local.h"
#include "fvwrite.h"

/*
 * Write some memory regions.  Return zero on success, EOF on error.
 *
 * This routine is large and unsightly, but most of the ugliness due
 * to the three different kinds of output buffering is handled here.
 */
int __sfvwrite(FILE *fp, struct __suio *uio) {
  size_t len;
  char *p;
  struct __siov *iov;
  int s;
  ssize_t w;
  char *nl;
  size_t nlknown, nldist;

  _DIAGASSERT(fp != NULL);
  _DIAGASSERT(uio != NULL);

  if ((ssize_t)uio->uio_resid < 0) {
    errno = EINVAL;
    return EOF;
  }
  if (uio->uio_resid == 0)
    return 0;
  /* make sure we can write */
  if (cantwrite(fp)) {
    errno = EBADF;
    return EOF;
  }

#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define COPY(n) (void)memcpy(fp->_p, p, (size_t)(n))

  iov = uio->uio_iov;
  p = iov->iov_base;
  len = iov->iov_len;
  iov++;
#define GETIOV(extra_work)                                                     \
  while (len == 0) {                                                           \
    extra_work;                                                                \
    p = iov->iov_base;                                                         \
    len = iov->iov_len;                                                        \
    iov++;                                                                     \
  }
  if (fp->_flags & __SNBF) {
    /*
     * Unbuffered: write up to BUFSIZ bytes at a time.
     */
    do {
      GETIOV(;);
      w = (*fp->_write)(fp->_cookie, p, MIN(len, BUFSIZ));
      if (w <= 0)
        goto err;
      p += w;
      len -= w;
    } while ((uio->uio_resid -= w) != 0);
  } else if ((fp->_flags & __SLBF) == 0) {
    /*
     * Fully buffered: fill partially full buffer, if any,
     * and then flush.  If there is no partial buffer, write
     * one _bf._size byte chunk directly (without copying).
     *
     * String output is a special case: write as many bytes
     * as fit, but pretend we wrote everything.  This makes
     * snprintf() return the number of bytes needed, rather
     * than the number used, and avoids its write function
     * (so that the write function can be invalid).
     */
    do {
      GETIOV(;);
      if ((fp->_flags & (__SALC | __SSTR)) == (__SALC | __SSTR) &&
          (size_t)fp->_w < len) {
        ptrdiff_t blen = fp->_p - fp->_bf._base;
        unsigned char *_base;
        int _size;

        /* Allocate space exponentially. */
        _size = fp->_bf._size;
        do {
          _size = (_size << 1) + 1;
        } while ((size_t)_size < blen + len);
        _base = realloc(fp->_bf._base, (size_t)(_size + 1));
        if (_base == NULL)
          goto err;
        fp->_w += _size - fp->_bf._size;
        fp->_bf._base = _base;
        fp->_bf._size = _size;
        fp->_p = _base + blen;
      }
      w = fp->_w;
      if (fp->_flags & __SSTR) {
        if (len < (size_t)w)
          w = len;
        COPY(w); /* copy MIN(fp->_w,len), */
        fp->_w -= (int)w;
        fp->_p += w;
        w = len; /* but pretend copied all */
      } else if (fp->_p > fp->_bf._base && len > (size_t)w) {
        /* fill and flush */
        COPY(w);
        /* fp->_w -= w; */ /* unneeded */
        fp->_p += w;
        if (fflush(fp))
          goto err;
      } else if (len >= (size_t)(w = fp->_bf._size)) {
        /* write directly */
        w = (*fp->_write)(fp->_cookie, p, (size_t)w);
        if (w <= 0)
          goto err;
      } else {
        /* fill and done */
        w = len;
        COPY(w);
        fp->_w -= (int)w;
        fp->_p += w;
      }
      p += w;
      len -= w;
    } while ((uio->uio_resid -= w) != 0);
  } else {
    /*
     * Line buffered: like fully buffered, but we
     * must check for newlines.  Compute the distance
     * to the first newline (including the newline),
     * or `infinity' if there is none, then pretend
     * that the amount to write is MIN(len,nldist).
     */
    nlknown = 0;
    nldist = 0; /* XXX just to keep gcc happy */
    do {
      GETIOV(nlknown = 0);
      if (!nlknown) {
        nl = memchr(p, '\n', len);
        nldist = nl ? (size_t)(nl + 1 - p) : len + 1;
        nlknown = 1;
      }
      s = (int)MIN(len, nldist);
      w = fp->_w + fp->_bf._size;
      if (fp->_p > fp->_bf._base && s > w) {
        COPY(w);
        /* fp->_w -= w; */
        fp->_p += w;
        if (fflush(fp))
          goto err;
      } else if (s >= (w = fp->_bf._size)) {
        w = (*fp->_write)(fp->_cookie, p, (size_t)w);
        if (w <= 0)
          goto err;
      } else {
        w = s;
        COPY(w);
        fp->_w -= (int)w;
        fp->_p += w;
      }
      if ((nldist -= w) == 0) {
        /* copied the newline: flush and forget */
        if (fflush(fp))
          goto err;
        nlknown = 0;
      }
      p += w;
      len -= w;
    } while ((uio->uio_resid -= w) != 0);
  }
  return 0;

err:
  fp->_flags |= __SERR;
  return EOF;
}
