GETMNTOPTS(3) BSD Library Functions Manual GETMNTOPTS(3)NAMEgetmntopts — scan mount options
SYNOPSIS
#include <mntopts.h>
void
getmntopts(char *options, struct mntopt *mopts, int *flagp,
int *altflagp);
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 either flagp or altflagp (depending on the
m_altloc field of the option's table entry) are updated. The flag words
are 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 */
int m_altloc; /* non-zero to use altflagp rather than flagp */
};
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 discovered, but cleared if the option name was preceded by
the letters “no”. The m_inverse flag causes these two opera‐
tions to be reversed.
m_altloc the bit should be set or cleared in altflagp rather than
flagp.
Each of the user visible MNT_ flags has a corresponding MOPT_ macro which
defines an appropriate struct mntopt entry. To simplify the program
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 = mntaltflags = 0;
...
getmntopts(options, mopts, &mntflags, &mntaltflags);
...
DIAGNOSTICS
If the external integer variable getmnt_silent is non-zero then the
getmntopts function displays an error message and exits if an unrecog‐
nized option is encountered. By default getmnt_silent is zero.
SEE ALSOerr(3), mount(8)HISTORY
The getmntopts() function appeared in 4.4BSD.
4.4BSD March 30, 1995 4.4BSD