cosmopolitan/libc/calls/sync_file_range.c

46 lines
2.6 KiB
C

/*-*- 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/errno.h"
/**
* Flushes subset of file to disk.
*
* @param offset is page rounded
* @param bytes is page rounded; 0 means until EOF
* @param flags can have SYNC_FILE_RANGE_{WAIT_BEFORE,WRITE,WAIT_AFTER}
* @note Linux documentation says this call is "dangerous"; for highest
* assurance of data recovery after crash, consider fsync() on both
* file and directory
* @see fsync(), fdatasync(), PAGESIZE
*/
int sync_file_range(int fd, int64_t offset, int64_t bytes, unsigned flags) {
int rc, olderr;
olderr = errno;
if ((rc = sync_file_range$sysv(fd, offset, bytes, flags)) != -1 ||
errno != ENOSYS) {
return rc;
} else {
errno = olderr;
return fdatasync(fd);
}
}