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sortix--sortix/libc/stdio/fsetdefaultbuf_unlocked.cpp
2014-12-01 18:45:11 +01:00

72 lines
2.4 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.
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/>.
stdio/fsetdefaultbuf_unlocked.cpp
Sets up default buffering semantics for a FILE.
*******************************************************************************/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
extern "C" int fsetdefaultbuf_unlocked(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_unlocked(fp, NULL, _IONBF, 0);
}
// Determine the buffering semantics depending on whether the destination is
// an interactive device or not.
int mode = fp->buffer_mode;
if ( mode == -1 )
{
#if defined(__is_sortix_kernel)
mode = _IOLBF;
#else
mode = _IOFBF;
int saved_errno = errno;
if ( isatty(fileno_unlocked(fp)) )
mode = _IOLBF;
errno = saved_errno;
#endif
}
if ( setvbuf_unlocked(fp, buf, mode, BUFSIZ) )
return fp->flags |= _FILE_STATUS_ERROR, free(buf), -1;
// The buffer now belongs to the FILE.
fp->flags |= _FILE_BUFFER_OWNED;
fp->buffer_free_indirect = free;
return 0;
}