.TH LLAPI_OPEN_BY_FID 3 2024-08-27 "Lustre User API" "Lustre Library Functions"
.SH NAME
llapi_open_by_fid, llapi_open_by_fid_at \- open a file descriptor from a File Identifier
.SH SYNOPSIS
.nf
.B #include <lustre/lustreapi.h>
.PP
.BI "int llapi_open_by_fid(const char *" mntpath ", struct lu_fid *" fid ", int " oflag ");"
.BI "int llapi_open_by_fid_at(int " dir_fd ", struct lu_fid *" fid ", int " oflag ");"
.fi
.SH DESCRIPTION
.BR llapi_open_by_fid()
opens a file descriptor in the filesystem mountpoint referenced by
.I path
for the file identified by
.IR fid  ,
using the open file flags in
.IR oflag
(as with the normal
.BR open (2)
call).
.PP
.BR llapi_open_by_fid_at()
opens a file descriptor on
.I fid
in the filesystem referenced by the open file descriptor
.IR dir_fd .
This is similar to the
.IR open_by_handle_at (3)
system call that can open files by their NFS file handle.  If
.I dir_fd
is
.B AT_CWD
then the open is performed against the local working directory.
.SH RETURN VALUES
returns file descriptor number or a negative errno value on failure.
.SH ERRORS
.TP 15
.B -EINVAL
An invalid argument was specified.
.TP 15
.B -ENOMEM
No memory was available during operation.
.SH AVAILABILITY
.B llapi_open_by_fid()
and
.B llapi_open_by_fid_at()
is part of the
.BR lustre (7)
user application interface library since release 2.4.0
.\" Added in commit 2.3.53-7-gf715e4e298
.SH SEE ALSO
.BR llapi_fd2fid (3),
.BR llapi_fid_parse (3),
.BR llapi_fid2path (3),
.BR llapi_path2fid (3),
.BR open_by_handle_at (3),
.BR lustreapi (7)