void
_IO_doallocbuf (_IO_FILE *fp)
{
if (fp->_IO_buf_base)
return;
if (!(fp->_flags & _IO_UNBUFFERED) || fp->_mode > 0)
if (_IO_DOALLOCATE (fp) != EOF)
return;
_IO_setb (fp, fp->_shortbuf, fp->_shortbuf+1, 0);
}
int
_IO_setvbuf (_IO_FILE *fp, char *buf, int mode, _IO_size_t size)
{
int result;
CHECK_FILE (fp, EOF);
_IO_acquire_lock (fp);
switch (mode)
{
case _IOFBF:
fp->_IO_file_flags &= ~(_IO_LINE_BUF|_IO_UNBUFFERED);
if (buf == NULL)
{
if (fp->_IO_buf_base == NULL)
{
/* There is no flag to distinguish between "fully buffered
mode has been explicitly set" as opposed to "line
buffering has not been explicitly set". In both
cases, _IO_LINE_BUF is off. If this is a tty, and
_IO_filedoalloc later gets called, it cannot know if
it should set the _IO_LINE_BUF flag (because that is
the default), or not (because we have explicitly asked
for fully buffered mode). So we make sure a buffer
gets allocated now, and explicitly turn off line
buffering.
A possibly cleaner alternative would be to add an
extra flag, but then flags are a finite resource. */
if (_IO_DOALLOCATE (fp) < 0)
{
result = EOF;
goto unlock_return;
}
fp->_IO_file_flags &= ~_IO_LINE_BUF;
}
result = 0;
goto unlock_return;
}
break;
case _IOLBF:
fp->_IO_file_flags &= ~_IO_UNBUFFERED;
fp->_IO_file_flags |= _IO_LINE_BUF;
if (buf == NULL)
{
result = 0;
goto unlock_return;
}
break;
case _IONBF:
fp->_IO_file_flags &= ~_IO_LINE_BUF;
fp->_IO_file_flags |= _IO_UNBUFFERED;
buf = NULL;
size = 0;
break;
default:
result = EOF;
goto unlock_return;
}
result = _IO_SETBUF (fp, buf, size) == NULL ? EOF : 0;
unlock_return:
_IO_release_lock (fp);
return result;
}
