bsd man page for getmntopts

GETMNTOPTS(3)						     Library Functions Manual						     GETMNTOPTS(3)

NAME
       getmntopts - scan mount options

SYNOPSIS
       #include <mntopts.h>

       void
       getmntopts(options, mopts, flagp)
       char *options;
       struct mntopt *mopts;
       int *flagp

DESCRIPTION
       The  getmntopts()  function takes a comma separated option list and a list of valid option names, and computes the bitmask corresponding to
       the requested set of options.

       The string options is broken down into a sequence of comma separated tokens.  Each token is looked up in the table described by	mopts  and
       the  bits in the word referenced by flagp are updated.  The flag word is not initialized by getmntopt.  The table, mopts, has the following
       format:

       struct mntopt {
	    char *m_option;	     /* option name */
	    int m_inverse;	/* is this a negative option, eg "dev" */
	    int m_flag; 	/* bit to set, eg MNT_RDONLY */
       };

       The members of this structure are:

       m_option  the option name, for example ``suid''.

       m_inverse tells getmntopts that the name has the inverse meaning of the bit.  For example, ``suid'' is the string, whereas the  mount  flag
		 is MNT_NOSUID.  In this case, the sense of the string and the flag are inverted, so the m_inverse flag should be set.

       m_flag	 the value of the bit to be set or cleared in the flag word when the option is recognized.  The bit is set when the option is dis-
		 covered, but cleared if the option name was preceded by the letters ``no''.  The m_inverse flag causes these two operations to be
		 reversed.

       Each of the user visible MNT_ flags has a corresponding MOPT_ macro which defines an appropriate struct mntopt entry.  To simplify the pro-
       gram interface and ensure consistency across all programs, a general purpose macro, MOPT_STDOPTS, is defined which contains  an	entry  for
       all  the  generic VFS options.  In addition, the macros MOPT_FORCE and MOPT_UPDATE exist to enable the MNT_FORCE and MNT_UPDATE flags to be
       set.  Finally, the table must be terminated by an entry with a NULL first element.

EXAMPLES
       Most commands will use the standard option set.	Local filesystems which support the MNT_UPDATE flag, would also have an MOPT_UPDATE entry.
       This can be declared and used as follows:

       #include "mntopts.h"

       struct mntopt mopts[] = {
	    MOPT_STDOPTS,
	    MOPT_UPDATE,
	    { NULL }
       };

	    ...
	    mntflags = 0;
	    ...
	    getmntopts(options, mopts, &mntflags)
	    ...

DIAGNOSTICS
       The getmntopts function displays an error message and exits if an unrecognized option is encountered.

SEE ALSO
       err(3), mount(8)

HISTORY
       The getmntopts function appeared in 4.4BSD.

4.4 Berkeley Distribution					 January 16, 1996						     GETMNTOPTS(3)