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Update fcntl(2) after r352695

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This commit is contained in:
Kyle Evans 2019-09-25 17:33:12 +00:00
parent af755d3e48
commit f17221ee7a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=352696
1 changed files with 62 additions and 1 deletions
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63
lib/libc/sys/fcntl.2
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@ -28,7 +28,7 @@
.\" @(#)fcntl.2 8.2 (Berkeley) 1/12/94
.\" $FreeBSD$
.\"
.Dd Nov 15, 2018
.Dd September 4, 2019
.Dt FCNTL 2
.Os
.Sh NAME
@ -180,6 +180,11 @@ is non-zero.
A zero value in
.Fa arg
turns off read ahead.
.It Dv F_ADD_SEALS
Add seals to the file as described below, if the underlying filesystem supports
seals.
.It Dv F_GET_SEALS
Get seals associated with the file, if the underlying filesystem supports seals.
.El
.Pp
The flags for the
@ -217,6 +222,37 @@ when I/O is possible, e.g.,
upon availability of data to be read.
.El
.Pp
The seals that may be applied with
.Dv F_ADD_SEALS
are as follows:
.Bl -tag -width F_SEAL_SHRINK
.It Dv F_SEAL_SEAL
Prevent any further seals from being applied to the file.
.It Dv F_SEAL_SHRINK
Prevent the file from being shrunk with
.Xr ftruncate 2 .
.It Dv F_SEAL_GROW
Prevent the file from being enlarged with
.Xr ftruncate 2 .
.It Dv F_SEAL_WRITE
Prevent any further
.Xr write 2
calls to the file.
Any writes in progress will finish before
.Fn fcntl
returns.
If any writeable mappings exist, F_ADD_SEALS will fail and return
.Dv EBUSY .
.El
.Pp
Seals are on a per-inode basis and require support by the underlying filesystem.
If the underlying filesystem does not support seals,
.Dv F_ADD_SEALS
and
.Dv F_GET_SEALS
will fail and return
.Dv EINVAL .
.Pp
Several commands are available for doing advisory file locking;
they all operate on the following structure:
.Bd -literal
@ -528,6 +564,14 @@ is an exclusive lock
and
.Fa fd
is not a valid file descriptor open for writing.
.It Bq Er EBUSY
The argument
.Fa cmd
is
.Dv F_ADD_SEALS ,
attempting to set
.Dv F_SEAL_WRITE ,
and writeable mappings of the file exist.
.It Bq Er EDEADLK
The argument
.Fa cmd
@ -565,6 +609,14 @@ points is not valid.
.Pp
The argument
.Fa cmd
is
.Dv F_ADD_SEALS
or
.Dv F_GET_SEALS ,
and the underlying filesystem does not support sealing.
.Pp
The argument
.Fa cmd
is invalid.
.It Bq Er EMFILE
The argument
@ -624,6 +676,15 @@ is
and
the process ID or process group given as an argument is in a
different session than the caller.
.Pp
The
.Fa cmd
argument
is
.Dv F_ADD_SEALS
and the
.Dv F_SEAL_SEAL
seal has already been set.
.It Bq Er ESRCH
The
.Fa cmd