f86bce5ed0
vfsopt and the vfs_buildopts function public, and add some new fields to struct vfsopt (pos and seen), and new functions vfs_getopt_pos and vfs_opterror. Further extend the interface to allow reading options from the kernel in addition to sending them to the kernel, with vfs_setopt and related functions. While this allows the "name=value" option interface to be used for more than just FS mounts (planned use is for jails), it retains the current "vfsopt" name and <sys/mount.h> requirement. Approved by: bz (mentor)
246 lines
6.0 KiB
Groff
246 lines
6.0 KiB
Groff
.\"
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.\" Copyright (C) 2007 Chad David <davidc@acns.ab.ca>. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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.\" DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 2, 2009
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.Dt VFS_GETOPT 9
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.Os
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.Sh NAME
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.Nm vfs_getopt ,
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.Nm vfs_getopts ,
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.Nm vfs_flagopt ,
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.Nm vfs_scanopt ,
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.Nm vfs_copyopt ,
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.Nm vfs_filteropt ,
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.Nm vfs_setopt ,
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.Nm vfs_setopt_part ,
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.Nm vfs_setopts
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.Nd "manipulate mount options and their values"
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/mount.h
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.Ft int
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.Fo vfs_getopt
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.Fa "struct vfsoptlist *opts" "const char *name" "void **buf" "int *len"
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.Fc
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.Ft "char *"
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.Fn vfs_getops "struct vfsoptlist *opts" "const char *name" "int *error"
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.Ft int
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.Fo vfs_flagopt
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.Fa "struct vfsoptlist *opts" "const char *name" "u_int *flags" "u_int flag"
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.Fc
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.Ft int
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.Fo vfs_scanopt
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.Fa "struct vfsoptlist *opts" "const char *name" "const char *fmt" ...
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.Fc
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.Ft int
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.Fo vfs_copyopt
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.Fa "struct vfsoptlist *opts" "const char *name" "void *dest" "int len"
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.Fc
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.Ft int
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.Fo vfs_filteropt
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.Fa "struct vfsoptlist *opts" "const char **legal"
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.Fc
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.Ft int
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.Fo vfs_setopt
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.Fa "struct vfsoptlist *opts" "const char *name" "void *value" "int len"
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.Fc
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.Ft int
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.Fo vfs_setopt_part
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.Fa "struct vfsoptlist *opts" "const char *name" "void *value" "int len"
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.Fc
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.Ft int
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.Fo vfs_setopts
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.Fa "struct vfsoptlist *opts" "const char *name" "const char *value"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn vfs_getopt
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function sets
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.Fa buf
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to point to the value of the named mount option, and sets
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.Fa len
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to the length of the value if it is not
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.Dv NULL .
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The
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.Fa buf
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argument
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will point to the actual value, and does not need to be freed or released
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(and probably should not be modified).
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.Pp
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The
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.Fn vfs_getopts
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function
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returns the value of the specified option if it is a string (i.e.,
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.Dv NUL
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terminated).
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.Pp
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The
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.Fn vfs_flagopt
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function determines if an option exists.
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If the option does exist, and
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.Fa flags
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is not
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.Dv NULL ,
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.Fa flag
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is added to those already set in
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.Fa flags .
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If the option does not exist, and
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.Fa flags
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is not
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.Dv NULL ,
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.Fa flag
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is removed from those already set in
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.Fa flags .
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An example of typical usage is:
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.Bd -literal
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if (vfs_flagopt(mp->mnt_optnew, "wormlike", NULL, 0))
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vfs_flagopt(mp->mnt_optnew, "appendok", &(mp->flags), F_APPENDOK);
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.Ed
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.Pp
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The
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.Fn vfs_scanopt
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function performs a
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.Xr vsscanf 3
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with the option's value, using the given format,
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into the specified variable arguments.
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The value must be a string (i.e.,
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.Dv NUL
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terminated).
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.Pp
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The
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.Fn vfs_copyopt
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function creates a copy of the option's value.
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The
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.Fa len
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argument must match the length of the option's value exactly
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(i.e., a larger buffer will still cause
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.Fn vfs_copyout
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to fail with
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.Er EINVAL ) .
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.Pp
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The
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.Fn vfs_filteropt
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function ensures that no unknown options were specified.
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A option is valid if its name matches one of the names in the
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list of legal names.
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An option may be prefixed with 'no', and still be considered valid.
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.Pp
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The
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.Fn vfs_setopt
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and
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.Fn vfs_setopt_part
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functions copy new data into the option's value.
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In
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.Fn vfs_setopt ,
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the
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.Fa len
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argument must match the length of the option's value exactly
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(i.e., a larger buffer will still cause
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.Fn vfs_copyout
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to fail with
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.Er EINVAL ) .
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.Pp
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The
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.Fn vfs_setopts
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function copies a new string into the option's value.
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The string, including
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.Dv NUL
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byte, must be no longer than the option's length.
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.Sh RETURN VALUES
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The
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.Fn vfs_getopt
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function returns 0 if the option was found; otherwise,
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.Er ENOENT
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is returned.
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.Pp
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The
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.Fn vfs_getops
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function returns the specified option if it is found, and is
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.Dv NUL
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terminated.
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If the option was found, but is not
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.Dv NUL
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terminated,
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.Fa error
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is set to
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.Er EINVAL
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and
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.Dv NULL
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is returned.
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If the option was not found,
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.Fa error
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is set to 0, and
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.Dv NULL
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is returned.
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.Pp
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The
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.Fn vfs_flagopt
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function returns 1 if the option was found, and 0 if it was not.
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.Pp
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The
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.Fn vfs_scanopt
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function returns 0 if the option was not found, or was not
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.Dv NUL
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terminated; otherwise, the return value of
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.Xr vsscanf 3
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is returned.
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If
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.Xr vsscanf 3
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returns 0, it will be returned unchanged; therefore, a return value of 0 does
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not always mean the option does not exist, or is not a valid string.
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.Pp
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The
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.Fn vfs_copyopt
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and
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.Fn vfs_setopt
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functions return 0 if the copy was successful,
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.Er EINVAL
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if the option was found but the lengths did not match, and
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.Er ENOENT
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if the option was not found.
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.Pp
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The
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.Fn vfs_filteropt
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function returns 0 if all of the options are legal; otherwise,
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.Er EINVAL
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is returned.
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.Pp
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The
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.Fn vfs_setopts
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function returns 0 if the copy was successful,
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.Er EINVAL
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if the option was found but the string was too long, and
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.Er ENOENT
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if the option was not found.
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.Sh AUTHORS
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.An -nosplit
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This manual page was written by
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.An Chad David Aq davidc@FreeBSD.org
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and
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.An Ruslan Ermilov Aq ru@FreeBSD.org .
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