GETMNTOPTS(3) | Library Functions Manual | GETMNTOPTS(3) |
getmntopts
, getmntoptstr
,
getmntoptnum
, freemntopts
—
#include <mntopts.h>
mntoptparse_t
getmntopts
(const
char *options, const
struct mntopt *mopts, int
*flagp, int
*altflagp);
const char *
getmntoptstr
(mntoptparse_t
mp, const char
*opt);
long
getmntoptnum
(mntoptparse_t
mp, const char
*opt);
void
freemntopts
(mntoptparse_t
mp);
getmntopts
() function takes a comma separated option
list and a list of valid option names, and computes the bitmasks 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
getmntopts
(). The table,
mopts, has the following format:
struct mntopt { const char *m_option; /* option name */ int m_inverse; /* negative option, e.g., "dev" */ int m_flag; /* bit to set, e.g., MNT_RDONLY */ int m_altloc; /* use altflagp rather than flagp */ };
The members of this structure are:
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.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.
getmntopts
() returns a
mntoptparse_t
handle that can be used in subsequent
getmntoptstr
() and
getmntoptnum
() calls to fetch a value for an option
and that must be freed with a call to freemntopts
().
If an error occurred, then if the external integer value
getmnt_silent is zero then
getmntopts
() prints an error message and exits; if
getmnt_silent is non-zero then
getmntopts
() returns
NULL
.
The getmntoptstr
() function returns the
string value of the named option, if such a value was set in the option
string. If the value was not set, then if the external integer value
getmnt_silent is zero then
getmntoptstr
() prints an error message and exits; if
getmnt_silent is non-zero then
getmntoptstr
() returns
NULL
.
The getmntoptnum
() function returns the
long value of the named option, if such a value was set in the option
string. If the value was not set, or could not be converted from a string to
a long, then if the external integer value
getmnt_silent is zero then
getmntoptnum
() prints an error message and exits; if
getmnt_silent is non-zero then
getmntoptnum
() returns -1.
The freemntopts
() function frees the
storage used by getmntopts
().
getmntopts
() returns NULL
if an
error occurred. Note that some bits may already have been set in
flagp and altflagp even if
NULL
is returned.
getmntoptstr
() returns NULL
if
an error occurred. getmntoptnum
() returns -1 if an
error occurred.
MNT_UPDATE
flag, would also have an
MOPT_UPDATE
entry. This can be declared and used as
follows:
#include <mntopts.h> static const struct mntopt mopts[] = { MOPT_STDOPTS, MOPT_UPDATE, { NULL } }; ... long val; mntoptparse_t mp; mntflags = mntaltflags = 0; ... mp = getmntopts(options, mopts, &mntflags, &mntaltflags); if (mp == NULL) err(EXIT_FAILURE, "getmntopts"); ... val = getmntoptnum(mp, "rsize"); freemntopts(mp);
getmntopts
(),
getmntoptstr
(), and
getmntoptnum
() functions display an error message and
exit if an error occurred. By default getmnt_silent is
zero.
getmntopts
() function appeared in
4.4BSD. It was moved to the utilities library and
enhanced to retrieve option values in NetBSD 2.0.
May 4, 2010 | NetBSD 9.0 |