1.\" 2.\" Copyright (c) 2004 Tom Rhodes 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd December 13, 2004 29.Dt KERNEL_MOUNT 9 30.Os 31.Sh NAME 32.Nm free_mntarg , 33.Nm kernel_mount , 34.Nm kernel_vmount , 35.Nm mount_arg , 36.Nm mount_argb , 37.Nm mount_argf , 38.Nm mount_argsu 39.Nd "functions provided as part of the kernel mount interface" 40.Sh SYNOPSIS 41.Ft void 42.Fn free_mntarg "struct mntarg *ma" 43.Ft int 44.Fn kernel_mount "struct mntarg *ma" "int flags" 45.Ft int 46.Fn kernel_vmount "int flags" ... 47.Ft "struct mntarg *" 48.Fo mount_arg 49.Fa "struct mntarg *ma" "const char *name" "const void *val" "int len" 50.Fc 51.Ft "struct mntarg *" 52.Fn mount_argb "struct mntarg *ma" "int flag" "const char *name" 53.Ft "struct mntarg *" 54.Fn mount_argf "struct mntarg *ma" "const char *name" "const char *fmt" ... 55.Ft "struct mntarg *" 56.Fo mount_argsu 57.Fa "struct mntarg *ma" "const char *name" "const void *val" "int len" 58.Fc 59.Sh DESCRIPTION 60The 61.Fn kernel_mount 62family of functions are provided as an API for building a list 63of mount arguments which will be used to mount file systems 64from inside the kernel. 65By accumulating a list of arguments, the API takes shape and 66provides the information necessary for the kernel to control 67the 68.Xr mount 8 69utility. 70When an error occurs, the process will stop. 71This will not cause a 72.Xr panic 9 . 73.Pp 74The header of the structure is stored in 75.Pa src/sys/kern/vfs_mount.c 76which permits automatic structure creation to 77ease the mount process. 78Memory allocation must always be freed when the entire 79process is complete, it is an error otherwise. 80.Pp 81The 82.Fn free_mntarg 83function is used to free or clear the 84.Vt mntarg 85structure. 86.Pp 87The 88.Fn kernel_mount 89function pulls information from the structure to perform 90the mount request on a given file system. 91Additionally, the 92.Fn kernel_mount 93function always calls the 94.Fn free_mntarg 95function. 96If 97.Fa ma 98contains any error code generated during the construction, 99that code will be called and the file system mount will 100not be attempted. 101.Pp 102The 103.Fn kernel_vmount 104is a function similar to 105.Xr printf 9 106which is used to mount a file system. 107.Pp 108The 109.Fn mount_arg 110function takes a plain argument and crafts parts of 111the structure with regards to various mount options. 112If the length is a value less than 0, 113.Xr strlen 3 114is used. 115This argument will be referenced until either 116.Fn free_mntarg 117or 118.Fn kernel_mount 119is called. 120.Pp 121The 122.Fn mount_argb 123function is used to add boolean arguments to 124the structure. 125The 126.Fa flag 127is the boolean value and 128.Fa name 129must start with 130.Qq Li no , 131otherwise a panic will occur. 132.Pp 133The 134.Fn mount_argf 135function adds 136.Xr printf 9 137style arguments to the current structure. 138.Pp 139The 140.Fn mount_argsu 141function will add arguments to the structure from a 142userland string. 143.Sh EXAMPLES 144An example of the 145.Fn *_cmount 146function: 147.Bd -literal 148static int 149msdosfs_cmount(struct mntarg *ma, void *data, int flags, struct thread *td) 150{ 151 struct msdosfs_args args; 152 int error; 153 154 if (data == NULL) 155 return (EINVAL); 156 error = copyin(data, &args, sizeof(args)); 157 if (error) 158 return (error); 159 160 ma = mount_argsu(ma, "from", args.fspec, MAXPATHLEN); 161 ma = mount_arg(ma, "export", &args.export, sizeof(args.export)); 162 ma = mount_argf(ma, "uid", "%d", args.uid); 163 ma = mount_argf(ma, "gid", "%d", args.gid); 164 ma = mount_argf(ma, "mask", "%d", args.mask); 165 ma = mount_argf(ma, "dirmask", "%d", args.dirmask); 166 167 ma = mount_argb(ma, args.flags & MSDOSFSMNT_SHORTNAME, "noshortname"); 168 ma = mount_argb(ma, args.flags & MSDOSFSMNT_LONGNAME, "nolongname"); 169 ma = mount_argb(ma, !(args.flags & MSDOSFSMNT_NOWIN95), "nowin95"); 170 ma = mount_argb(ma, args.flags & MSDOSFSMNT_KICONV, "nokiconv"); 171 172 ma = mount_argsu(ma, "cs_win", args.cs_win, MAXCSLEN); 173 ma = mount_argsu(ma, "cs_dos", args.cs_dos, MAXCSLEN); 174 ma = mount_argsu(ma, "cs_local", args.cs_local, MAXCSLEN); 175 176 error = kernel_mount(ma, flags); 177 178 return (error); 179} 180.Ed 181.Pp 182When working with 183.Fn kernel_vmount , 184.Fa varargs 185must come in pairs, e.g., 186.Brq Va name , value . 187.Bd -literal 188 error = kernel_vmount( 189 MNT_RDONLY, 190 "fstype", vfsname, 191 "fspath", "/", 192 "from", path, 193 NULL); 194.Ed 195.Sh SEE ALSO 196.Xr VFS 9 , 197.Xr VFS_MOUNT 9 198.Sh HISTORY 199The 200.Fn kernel_mount 201family of functions and this manual page first 202appeared in 203.Fx 6.0 . 204.Sh AUTHORS 205.An -nosplit 206The 207.Fn kernel_mount 208family of functions and API was developed by 209.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org . 210This manual page was written by 211.An Tom Rhodes Aq Mt trhodes@FreeBSD.org . 212