cosmopolitan/libc/calls/sync_file_range.c

45 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 │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#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);
}
}