cosmopolitan/libc/calls/fadvise.c

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2020-06-15 14:18:57 +00:00
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/dce.h"
/**
* Drops hints to O/S about intended I/O behavior.
*
* It makes a huge difference. For example, when copying a large file,
* it can stop the system from persisting GBs of useless memory content.
*
* @param len 0 means til end of file
* @param advice can be MADV_SEQUENTIAL, MADV_RANDOM, etc.
* @return -1 on error
* @syscall
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*/
int fadvise(int fd, uint64_t offset, uint64_t len, int advice) {
if (!IsWindows()) {
return fadvise$sysv(fd, offset, len, advice); /* linux & freebsd */
} else {
return fadvise$nt(fd, offset, len, advice);
}
}