Annotation of src/lib/libutil/getmntopts.3, Revision 1.14
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1.11 jruoho 32: .Dd May 4, 2010
1.1 jdolecek 33: .Dt GETMNTOPTS 3
34: .Os
35: .Sh NAME
1.13 abhinav 36: .Nm getmntopts ,
37: .Nm getmntoptstr ,
38: .Nm getmntoptnum ,
39: .Nm freemntopts
1.1 jdolecek 40: .Nd scan mount options
41: .Sh LIBRARY
42: .Lb libutil
43: .Sh SYNOPSIS
1.5 wiz 44: .In mntopts.h
1.3 christos 45: .Ft mntoptparse_t
46: .Fn getmntopts "const char *options" "const struct mntopt *mopts" "int *flagp" "int *altflagp"
47: .Ft const char *
48: .Fn getmntoptstr "mntoptparse_t mp" "const char *opt"
49: .Ft long
50: .Fn getmntoptnum "mntoptparse_t mp" "const char *opt"
1.1 jdolecek 51: .Ft void
1.3 christos 52: .Fn freemntopts "mntoptparse_t mp"
1.1 jdolecek 53: .Sh DESCRIPTION
54: The
1.2 wiz 55: .Fn getmntopts
1.1 jdolecek 56: function takes a comma separated option list and a list
1.12 christos 57: of valid option names, and computes the bitmasks
1.1 jdolecek 58: corresponding to the requested set of options.
59: .Pp
60: The string
1.2 wiz 61: .Ar options
1.1 jdolecek 62: is broken down into a sequence of comma separated tokens.
63: Each token is looked up in the table described by
1.2 wiz 64: .Ar mopts
1.1 jdolecek 65: and the bits in
66: the word referenced by either
1.2 wiz 67: .Ar flagp
1.1 jdolecek 68: or
1.2 wiz 69: .Ar altflagp
1.1 jdolecek 70: (depending on the
71: .Dv m_altloc
72: field of the option's table entry)
73: are updated.
74: The flag words are not initialized by
1.4 wiz 75: .Fn getmntopts .
1.1 jdolecek 76: The table,
1.2 wiz 77: .Ar mopts ,
1.1 jdolecek 78: has the following format:
79: .Bd -literal
80: struct mntopt {
81: const char *m_option; /* option name */
1.8 pooka 82: int m_inverse; /* negative option, e.g., "dev" */
1.4 wiz 83: int m_flag; /* bit to set, e.g., MNT_RDONLY */
1.8 pooka 84: int m_altloc; /* use altflagp rather than flagp */
1.1 jdolecek 85: };
86: .Ed
87: .Pp
88: The members of this structure are:
89: .Bl -tag -width m_inverse
90: .It Fa m_option
91: the option name,
92: for example
93: .Dq suid .
94: .It Fa m_inverse
95: tells
1.2 wiz 96: .Fn getmntopts
97: that the name has the inverse meaning of the bit.
1.1 jdolecek 98: For example,
99: .Dq suid
1.2 wiz 100: is the string, whereas the mount flag is
1.1 jdolecek 101: .Dv MNT_NOSUID .
102: In this case, the sense of the string and the flag
103: are inverted, so the
1.2 wiz 104: .Fa m_inverse
1.1 jdolecek 105: flag should be set.
106: .It Fa m_flag
107: the value of the bit to be set or cleared in
108: the flag word when the option is recognized.
109: The bit is set when the option is discovered,
110: but cleared if the option name was preceded
111: by the letters
112: .Dq no .
113: The
1.2 wiz 114: .Fa m_inverse
1.1 jdolecek 115: flag causes these two operations to be reversed.
116: .It Fa m_altloc
117: the bit should be set or cleared in
1.2 wiz 118: .Ar altflagp
1.1 jdolecek 119: rather than
1.2 wiz 120: .Ar flagp .
1.1 jdolecek 121: .El
122: .Pp
123: Each of the user visible
124: .Dv MNT_
125: flags has a corresponding
126: .Dv MOPT_
127: macro which defines an appropriate
128: .Li "struct mntopt"
129: entry.
130: To simplify the program interface and ensure consistency across all
131: programs, a general purpose macro,
132: .Dv MOPT_STDOPTS ,
1.2 wiz 133: is defined which contains an entry for all the generic VFS options.
1.1 jdolecek 134: In addition, the macros
135: .Dv MOPT_FORCE
136: and
137: .Dv MOPT_UPDATE
138: exist to enable the
139: .Dv MNT_FORCE
140: and
141: .Dv MNT_UPDATE
142: flags to be set.
1.2 wiz 143: Finally, the table must be terminated by an entry with a
144: .Dv NULL
1.1 jdolecek 145: first element.
1.3 christos 146: .Pp
1.12 christos 147: .Fn getmntopts
148: returns a
149: .Li "mntoptparse_t"
150: handle that can be used in subsequent
151: .Fn getmntoptstr
152: and
153: .Fn getmntoptnum
154: calls to fetch a value for an option and that must be freed with a call
155: to
156: .Fn freemntopts .
157: If an error occurred, then if the external integer value
158: .Va getmnt_silent
159: is zero then
160: .Fn getmntopts
161: prints an error message and exits;
162: if
163: .Va getmnt_silent
164: is non-zero then
165: .Fn getmntopts
166: returns
167: .Dv NULL .
168: .Pp
1.3 christos 169: The
170: .Fn getmntoptstr
171: function returns the string value of the named option, if such a value
1.12 christos 172: was set in the option string.
173: If the value was not set, then if the external integer value
174: .Va getmnt_silent
175: is zero then
176: .Fn getmntoptstr
177: prints an error message and exits;
178: if
179: .Va getmnt_silent
180: is non-zero then
181: .Fn getmntoptstr
182: returns
183: .Dv NULL .
1.3 christos 184: .Pp
185: The
186: .Fn getmntoptnum
1.13 abhinav 187: function returns the long value of the named option, if such a value was set in the
1.4 wiz 188: option string.
1.12 christos 189: If the value was not set, or could not be converted from a string to a
190: long, then if the external integer value
191: .Va getmnt_silent
192: is zero then
193: .Fn getmntoptnum
194: prints an error message and exits;
195: if
196: .Va getmnt_silent
197: is non-zero then
198: .Fn getmntoptnum
199: returns \-1.
1.3 christos 200: .Pp
201: The
202: .Fn freemntopts
1.13 abhinav 203: function frees the storage used by
1.3 christos 204: .Fn getmntopts .
1.9 wiz 205: .Sh RETURN VALUES
206: .Fn getmntopts
207: returns
208: .Dv NULL
209: if an error occurred.
210: Note that some bits may already have been set in
211: .Va flagp
212: and
213: .Va altflagp
214: even if
215: .Dv NULL
216: is returned.
217: .Fn getmntoptstr
218: returns
219: .Dv NULL
1.12 christos 220: if an error occurred.
1.9 wiz 221: .Fn getmntoptnum
222: returns \-1 if an error occurred.
1.1 jdolecek 223: .Sh EXAMPLES
224: Most commands will use the standard option set.
225: Local filesystems which support the
226: .Dv MNT_UPDATE
227: flag, would also have an
228: .Dv MOPT_UPDATE
229: entry.
230: This can be declared and used as follows:
1.11 jruoho 231: .Bd -literal -offset indent
1.14 ! wiz 232: #include <mntopts.h>
1.1 jdolecek 233:
234: static const struct mntopt mopts[] = {
235: MOPT_STDOPTS,
236: MOPT_UPDATE,
237: { NULL }
238: };
239:
1.10 joerg 240: \&...
1.11 jruoho 241:
1.3 christos 242: long val;
1.11 jruoho 243: mntoptparse_t mp;
1.3 christos 244: mntflags = mntaltflags = 0;
1.11 jruoho 245:
1.10 joerg 246: \&...
1.11 jruoho 247:
1.14 ! wiz 248: mp = getmntopts(options, mopts, &mntflags, &mntaltflags);
1.11 jruoho 249:
250: if (mp == NULL)
251: err(EXIT_FAILURE, "getmntopts");
252:
1.10 joerg 253: \&...
1.11 jruoho 254:
1.3 christos 255: val = getmntoptnum(mp, "rsize");
256: freemntopts(mp);
1.1 jdolecek 257: .Ed
258: .Sh DIAGNOSTICS
259: If the external integer variable
1.4 wiz 260: .Va getmnt_silent
1.8 pooka 261: is zero then the
1.12 christos 262: .Fn getmntopts ,
263: .Fn getmntoptstr ,
264: and
265: .Fn getmntoptnum
266: functions display an error message and exit if an error occurred.
1.1 jdolecek 267: By default
1.4 wiz 268: .Va getmnt_silent
1.1 jdolecek 269: is zero.
270: .Sh SEE ALSO
271: .Xr err 3 ,
272: .Xr mount 8
273: .Sh HISTORY
274: The
275: .Fn getmntopts
276: function appeared in
277: .Bx 4.4 .
1.3 christos 278: It was moved to the utilities library and enhanced to retrieve option
279: values in
1.1 jdolecek 280: .Nx 2.0 .
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