VFS_GETOPT(9) BSD Kernel Developer's Manual VFS_GETOPT(9)NAME
vfs_getopt, vfs_getopts, vfs_flagopt, vfs_scanopt, vfs_copyopt,
vfs_filteropt, vfs_setopt, vfs_setopt_part, vfs_setopts — manipulate
mount options and their values
SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
int
vfs_getopt(struct vfsoptlist *opts, const char *name, void **buf,
int *len);
char *
vfs_getops(struct vfsoptlist *opts, const char *name, int *error);
int
vfs_flagopt(struct vfsoptlist *opts, const char *name, u_int *flags,
u_int flag);
int
vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt,
...);
int
vfs_copyopt(struct vfsoptlist *opts, const char *name, void *dest,
int len);
int
vfs_filteropt(struct vfsoptlist *opts, const char **legal);
int
vfs_setopt(struct vfsoptlist *opts, const char *name, void *value,
int len);
int
vfs_setopt_part(struct vfsoptlist *opts, const char *name, void *value,
int len);
int
vfs_setopts(struct vfsoptlist *opts, const char *name,
const char *value);
DESCRIPTION
The vfs_getopt() function sets buf to point to the value of the named
mount option, and sets len to the length of the value if it is not NULL.
The buf argument will point to the actual value, and does not need to be
freed or released (and probably should not be modified).
The vfs_getopts() function returns the value of the specified option if
it is a string (i.e., NUL terminated).
The vfs_flagopt() function determines if an option exists. If the option
does exist, and flags is not NULL, flag is added to those already set in
flags. If the option does not exist, and flags is not NULL, flag is
removed from those already set in flags. An example of typical usage is:
if (vfs_flagopt(mp->mnt_optnew, "wormlike", NULL, 0))
vfs_flagopt(mp->mnt_optnew, "appendok", &(mp->flags), F_APPENDOK);
The vfs_scanopt() function performs a vsscanf(3) with the option's value,
using the given format, into the specified variable arguments. The value
must be a string (i.e., NUL terminated).
The vfs_copyopt() function creates a copy of the option's value. The len
argument must match the length of the option's value exactly (i.e., a
larger buffer will still cause vfs_copyout() to fail with EINVAL).
The vfs_filteropt() function ensures that no unknown options were speci‐
fied. A option is valid if its name matches one of the names in the list
of legal names. An option may be prefixed with 'no', and still be con‐
sidered valid.
The vfs_setopt() and vfs_setopt_part() functions copy new data into the
option's value. In vfs_setopt(), the len argument must match the length
of the option's value exactly (i.e., a larger buffer will still cause
vfs_copyout() to fail with EINVAL).
The vfs_setopts() function copies a new string into the option's value.
The string, including NUL byte, must be no longer than the option's
length.
RETURN VALUES
The vfs_getopt() function returns 0 if the option was found; otherwise,
ENOENT is returned.
The vfs_getops() function returns the specified option if it is found,
and is NUL terminated. If the option was found, but is not NUL termi‐
nated, error is set to EINVAL and NULL is returned. If the option was
not found, error is set to 0, and NULL is returned.
The vfs_flagopt() function returns 1 if the option was found, and 0 if it
was not.
The vfs_scanopt() function returns 0 if the option was not found, or was
not NUL terminated; otherwise, the return value of vsscanf(3) is
returned. If vsscanf(3) returns 0, it will be returned unchanged; there‐
fore, a return value of 0 does not always mean the option does not exist,
or is not a valid string.
The vfs_copyopt() and vfs_setopt() functions return 0 if the copy was
successful, EINVAL if the option was found but the lengths did not match,
and ENOENT if the option was not found.
The vfs_filteropt() function returns 0 if all of the options are legal;
otherwise, EINVAL is returned.
The vfs_setopts() function returns 0 if the copy was successful, EINVAL
if the option was found but the string was too long, and ENOENT if the
option was not found.
AUTHORS
This manual page was written by Chad David ⟨davidc@FreeBSD.org⟩ and
Ruslan Ermilov ⟨ru@FreeBSD.org⟩.
BSD March 2, 2009 BSD
