cosmopolitan/libc/calls/splice.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"
#include "libc/errno.h"
#include "libc/sysv/errfuns.h"
static ssize_t splicer(int infd, int64_t *inoffset, int outfd,
int64_t *outoffset, size_t uptobytes, uint32_t flags,
int64_t impl(int infd, int64_t *inoffset, int outfd,
int64_t *outoffset, size_t uptobytes,
uint32_t flags)) {
int olderr;
ssize_t transferred;
if (!uptobytes || flags == -1) return einval();
if (IsModeDbg() && uptobytes > 1) uptobytes >>= 1;
olderr = errno;
if ((transferred =
impl(infd, inoffset, outfd, outoffset, uptobytes, flags)) == -1 &&
errno == ENOSYS) {
errno = olderr;
transferred = copyfd(infd, inoffset, outfd, outoffset, uptobytes, flags);
}
return transferred;
}
/**
* Transfers data to/from pipe.
*
* @param flags can have SPLICE_F_{MOVE,NONBLOCK,MORE,GIFT}
* @return number of bytes transferred, 0 on input end, or -1 w/ errno
* @see copy_file_range() for file file
* @see sendfile() for seekable socket
*/
ssize_t splice(int infd, int64_t *inopt_out_inoffset, int outfd,
int64_t *inopt_out_outoffset, size_t uptobytes, uint32_t flags) {
return splicer(infd, inopt_out_inoffset, outfd, inopt_out_outoffset,
uptobytes, flags, splice$sysv);
}
/**
* Transfers data between files.
*
* @param outfd should be a writable file, but not O_APPEND
* @param flags is reserved for future use
* @return number of bytes actually copied, or -1 w/ errno
* @see sendfile() for seekable socket
* @see splice() for fd pipe
*/
ssize_t copy_file_range(int infd, int64_t *inopt_out_inoffset, int outfd,
int64_t *inopt_out_outoffset, size_t uptobytes,
uint32_t flags) {
return splicer(infd, inopt_out_inoffset, outfd, inopt_out_outoffset,
uptobytes, flags, copy_file_range$sysv);
}