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.\" Copyright (c) 2019 Rick Macklem
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.Dd March 30, 2020
.Dt VOP_COPY_FILE_RANGE 9
.Os
.Sh NAME
.Nm VOP_COPY_FILE_RANGE
.Nd copy a byte range from one file to another or within one file
in a single file system
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft int
.Fo VOP_COPY_FILE_RANGE
.Fa "struct vnode *invp"
.Fa "off_t *inoff"
.Fa "struct vnode *outvp"
.Fa "off_t *outoff"
.Fa "size_t *len"
.Fa "unsigned int flags"
.Fa "struct ucred *incred"
.Fa "struct ucred *outcred"
.Fa "struct thread *fsize_td"
.Sh DESCRIPTION
This entry point copies a byte range from one regular file to another
or within one file in a single file system.
.Fa invp
and
.Fa outvp
can refer to the same file.
For this case, the byte ranges defined by
.Fa *inoff ,
.Fa *outoff and
.Fa *len
will not overlap.
.Pp
The arguments are:
.Bl -tag -width ioflag
.It Fa invp
The vnode of the input file.
.It Fa inoff
A pointer to the file offset for the input file.
.It Fa outvp
The vnode of the output file.
.It Fa outoff
A pointer to the file offset for the output file.
.It Fa len
A pointer to the byte count for the copy.
.It Fa flags
Flags, should be set to 0 for now.
.It Fa incred
The credentials used to read
.Fa invp .
.It Fa outcred
The credentials used to write
.Fa outvp .
.It Fa fsize_td
The thread pointer to be passed to vn_rlimit_fsize().
This will be
.Dv NULL
for a server thread without limits, such as for the NFS
server or
.Dv curthread
otherwise.
.El
.Pp
On entry and on return, the
.Fa inoff
and
.Fa outoff
arguments point to the locations of the file offsets.
These file offsets should be updated by the number of bytes copied.
The
.Fa len
argument points to the location that stores the number of bytes
to be copied.
Upon a successful return
.Fa len
will be updated to the number of bytes actually copied.
Normally, this will be the number of bytes requested to be copied,
however a copy of fewer bytes than requested is permitted.
This does not necessarily indicate that the copy reached EOF on the input file.
However, if the value pointed to by the
.Fa len
argument is zero upon a successful return,
it indicates that the offset pointed to by
.Fa inoff
is at or beyond EOF on the input file.
.Sh LOCKS
The vnode are unlocked on entry and must be unlocked on return.
The byte ranges for both
.Fa invp
and
.Fa outvp
should be range locked when this call is done.
.Sh RETURN VALUES
Zero is returned on success, otherwise an error code is returned.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EFBIG
If the copy exceeds the process's file size limit or the maximum file size
for the file system
.Fa invp
and
.Fa outvp
reside on.
.It Bq Er EINTR
A signal interrupted the VOP call before it could be completed.
.It Bq Er EIO
An I/O error occurred while reading/writing the files.
.It Bq Er EINTEGRITY
Corrupted data was detected while reading/writing the files.
.It Bq Er ENOSPC
The file system is full.
.El
.Sh SEE ALSO
.Xr vn_rdwr 9 ,
.Xr vnode 9