__write.c

一个C源代码分析器

/* Copyright (C) 1994 Free Software Foundation, Inc.
   Ported to standalone by Joel Sherrill [e-mail],
     On-Line Applications Research Corporation.

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., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <ansidecl.h>
#include <sysdep.h>
#include <errno.h>
#include <unistd.h>
#include <stddef.h>

#include "filedesc.h"
#include <fcntl.h>
#include <standalone.h>

/* Write NBYTES of BUF to FD.  Return the number written, or -1.  */
ssize_t
DEFUN(__write, (fd, buf, nbytes),
      int fd AND CONST PTR buf AND size_t nbytes)
{
  int count;
  CONST char *data = buf;

  if (nbytes == 0)
    return 0;
  if ( !__FD_Is_valid( fd ) || !__FD_Table[ fd ].in_use )
    {
      errno = EBADF;
      return -1;
    }
  if (buf == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  if ( !(__FD_Table[ fd ].flags & (O_WRONLY|O_RDWR)) )  /* is it writeable? */
    {
      errno = EBADF;
      return -1;
    }

  /*
   *  All open file descriptors are mapped to the console.
   */

  for ( count=0 ; count != nbytes ; count++ ) {
    if ( _Console_Putc(data[ count ]) == -1 )
      return -1;
    if ( data[count] == '\n' && _Console_Putc('\r') == -1 )
      return -1;
  }

  return count;
}