.\" $NetBSD: getmntopts.3,v 1.14 2017/07/03 21:32:51 wiz Exp $ .\" .\" Copyright (c) 1994 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)getmntopts.3 8.3 (Berkeley) 3/30/95 .\" .Dd May 4, 2010 .Dt GETMNTOPTS 3 .Os .Sh NAME .Nm getmntopts , .Nm getmntoptstr , .Nm getmntoptnum , .Nm freemntopts .Nd scan mount options .Sh LIBRARY .Lb libutil .Sh SYNOPSIS .In mntopts.h .Ft mntoptparse_t .Fn getmntopts "const char *options" "const struct mntopt *mopts" "int *flagp" "int *altflagp" .Ft const char * .Fn getmntoptstr "mntoptparse_t mp" "const char *opt" .Ft long .Fn getmntoptnum "mntoptparse_t mp" "const char *opt" .Ft void .Fn freemntopts "mntoptparse_t mp" .Sh DESCRIPTION The .Fn 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. .Pp The string .Ar options is broken down into a sequence of comma separated tokens. Each token is looked up in the table described by .Ar mopts and the bits in the word referenced by either .Ar flagp or .Ar altflagp (depending on the .Dv m_altloc field of the option's table entry) are updated. The flag words are not initialized by .Fn getmntopts . The table, .Ar mopts , has the following format: .Bd -literal 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 */ }; .Ed .Pp The members of this structure are: .Bl -tag -width m_inverse .It Fa m_option the option name, for example .Dq suid . .It Fa m_inverse tells .Fn getmntopts that the name has the inverse meaning of the bit. For example, .Dq suid is the string, whereas the mount flag is .Dv MNT_NOSUID . In this case, the sense of the string and the flag are inverted, so the .Fa m_inverse flag should be set. .It Fa 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 .Dq no . The .Fa m_inverse flag causes these two operations to be reversed. .It Fa m_altloc the bit should be set or cleared in .Ar altflagp rather than .Ar flagp . .El .Pp Each of the user visible .Dv MNT_ flags has a corresponding .Dv MOPT_ macro which defines an appropriate .Li "struct mntopt" entry. To simplify the program interface and ensure consistency across all programs, a general purpose macro, .Dv MOPT_STDOPTS , is defined which contains an entry for all the generic VFS options. In addition, the macros .Dv MOPT_FORCE and .Dv MOPT_UPDATE exist to enable the .Dv MNT_FORCE and .Dv MNT_UPDATE flags to be set. Finally, the table must be terminated by an entry with a .Dv NULL first element. .Pp .Fn getmntopts returns a .Li "mntoptparse_t" handle that can be used in subsequent .Fn getmntoptstr and .Fn getmntoptnum calls to fetch a value for an option and that must be freed with a call to .Fn freemntopts . If an error occurred, then if the external integer value .Va getmnt_silent is zero then .Fn getmntopts prints an error message and exits; if .Va getmnt_silent is non-zero then .Fn getmntopts returns .Dv NULL . .Pp The .Fn 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 .Va getmnt_silent is zero then .Fn getmntoptstr prints an error message and exits; if .Va getmnt_silent is non-zero then .Fn getmntoptstr returns .Dv NULL . .Pp The .Fn 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 .Va getmnt_silent is zero then .Fn getmntoptnum prints an error message and exits; if .Va getmnt_silent is non-zero then .Fn getmntoptnum returns \-1. .Pp The .Fn freemntopts function frees the storage used by .Fn getmntopts . .Sh RETURN VALUES .Fn getmntopts returns .Dv NULL if an error occurred. Note that some bits may already have been set in .Va flagp and .Va altflagp even if .Dv NULL is returned. .Fn getmntoptstr returns .Dv NULL if an error occurred. .Fn getmntoptnum returns \-1 if an error occurred. .Sh EXAMPLES Most commands will use the standard option set. Local filesystems which support the .Dv MNT_UPDATE flag, would also have an .Dv MOPT_UPDATE entry. This can be declared and used as follows: .Bd -literal -offset indent #include 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); .Ed .Sh DIAGNOSTICS If the external integer variable .Va getmnt_silent is zero then the .Fn getmntopts , .Fn getmntoptstr , and .Fn getmntoptnum functions display an error message and exit if an error occurred. By default .Va getmnt_silent is zero. .Sh SEE ALSO .Xr err 3 , .Xr mount 8 .Sh HISTORY The .Fn getmntopts function appeared in .Bx 4.4 . It was moved to the utilities library and enhanced to retrieve option values in .Nx 2.0 .