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VFS_GETOPT(9)		    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_getopts(struct vfsoptlist *opts, const char *name, int *error);

     int
     vfs_flagopt(struct vfsoptlist *opts, const char *name, uint64_t *flags,
	 uint64_t 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  re-
     moved 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 consid-
     ered valid.

     The vfs_setopt() and vfs_setopt_part() functions copy new data into the op-
     tion'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_getopts() function returns the specified option if it is found, and
     is NUL terminated.  If the option was found, but  is  not	NUL  terminated,
     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; therefore, 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  suc-
     cessful,  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>.

FreeBSD 15.1			  May 19, 2024			   VFS_GETOPT(9)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=vfs_getopt&sektion=9&manpath=FreeBSD+15.1-RELEASE+and+Ports.quarterly>

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