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sortix--sortix/libc/fsetdefaultbuf.cpp

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/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
fsetdefaultbuf.cpp
Sets up default buffering semantics for a FILE.
*******************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
extern "C" int fsetdefaultbuf(FILE* fp)
{
char* buf = (char*) malloc(sizeof(char) * BUFSIZ);
if ( !buf )
{
// TODO: Determine whether this is truly what we would want and whether
// a buffer should be pre-allocated when the FILE is created such that
// this situation _cannot_ occur.
// Alright, we're in a bit of a situation here. Normally, we'd go
// buffered but we are out of memory. We could either fail, but that
// would mean subsequent calls such as fgetc and fputc would also fail -
// however that we are out of memory doesn't mean that IO would also
// fail. Therefore we'll revert to unbuffered semantics and hope that's
// good enough.
return setvbuf(fp, NULL, _IONBF, 0);
}
// Determine the buffering semantics depending on whether the destination is
// an interactive device or not.
#ifdef SORTIX_KERNEL
int mode = _IOLBF; // TODO: Detect this?
#else
int mode = fp->buffer_mode != -1 ? fp->buffer_mode
: isatty(fileno(fp)) ? _IOLBF : _IOFBF;
#endif
int ret = setvbuf(fp, buf, mode, BUFSIZ);
if ( ret )
{
free(buf);
return -1;
}
// The buffer now belongs to the FILE.
fp->flags |= _FILE_BUFFER_OWNED;
return ret;
}