xref: /freebsd/lib/libufs/getinode.3 (revision cd0d51baaa4509a1db83251a601d34404d20c990)
1.\" Author:	Marshall Kirk McKusick <mckusick@freebsd.org>
2.\" Date:	January 19, 2018
3.\" Description:
4.\" 	Manual page for libufs functions:
5.\"		getinode(3)
6.\"		putinode(3)
7.\"
8.\" This file is in the public domain.
9.\"
10.\" $FreeBSD$
11.\"
12.Dd November 10, 2018
13.Dt GETINODE 3
14.Os
15.Sh NAME
16.Nm getinode , putinode
17.Nd fetch and store inodes on a UFS file system
18.Sh LIBRARY
19.Lb libufs
20.Sh SYNOPSIS
21.In ufs/ufs/dinode.h
22.In ufs/ffs/fs.h
23.In libufs.h
24.Ft int
25.Fn getinode "struct uufsd *disk" "union dinodep *dp" "ino_t inumber"
26.Ft int
27.Fn putinode "struct uufsd *disk"
28.Sh DESCRIPTION
29The
30.Fn getinode
31and
32.Fn putinode
33functions provide an inode fetch and store API for
34.Xr libufs 3
35consumers.
36They operate on a userland UFS disk structure.
37The
38.Fn getinode
39function fetches the specified inode from the filesystem.
40The
41.Fn putinode
42function stores the most recently fetched inode to the filesystem.
43.Pp
44The
45.Va dinodep
46union is defined as:
47.Bd -literal -offset indent
48union dinodep {
49	struct ufs1_dinode *dp1;
50	struct ufs2_dinode *dp2;
51};
52.Ed
53.Pp
54Sample code to clear write permissions for inode number
55.Fa inumber
56stored on the filesystem described by
57.Fa diskp .
58.Bd -literal -offset indent
59#include <sys/stat.h>
60#include <err.h>
61
62#include <ufs/ufs/dinode.h>
63#include <ufs/ffs/fs.h>
64#include <libufs.h>
65
66void
67clearwrite(struct uufsd *diskp, ino_t inumber)
68{
69	union dinodep dp;
70
71	if (getinode(diskp, &dp, inumber) == -1)
72		err(1, "getinode: %s", diskp->d_error);
73	switch (diskp->d_ufs) {
74	case 1: /* UFS 1 filesystem */
75		dp.dp1->di_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
76		break;
77	case 2: /* UFS 2 filesystem */
78		dp.dp2->di_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
79		break;
80	default:
81		errx(1, "unknown filesystem type");
82	}
83	if (putinode(diskp) == -1)
84		err(1, "putinode: %s", diskp->d_error);
85}
86.Ed
87.Sh RETURN VALUES
88The
89.Fn getinode
90and
91.Fn putinode
92functions return 0 on success, or \-1 in case of any error.
93A string describing the error is stored in
94.Fa diskp->d_error .
95The global
96.Fa errno
97often provides additional information.
98.Sh ERRORS
99The function
100.Fn getinode
101may fail and set
102.Va errno
103for any of the errors specified for the library function
104.Xr pread 2 .
105It can also fail if the inode number is out of the range of inodes
106in the filesystem.
107.Pp
108The function
109.Fn putinode
110may fail and set
111.Va errno
112for any of the errors specified for the library functions
113.Xr ufs_disk_write 3
114or
115.Xr pwrite 2 .
116.Pp
117Additionally both functions may follow the
118.Xr libufs 3
119error methodologies in case of a device error.
120.Sh SEE ALSO
121.Xr pread 2 ,
122.Xr pwrite 2 ,
123.Xr libufs 3 ,
124.Xr ufs_disk_write 3
125.Sh HISTORY
126These functions first appeared as part of
127.Xr libufs 3
128in
129.Fx 13.0 .
130.Sh AUTHORS
131.An Marshall Kirk McKusick Aq Mt mckusick@freebsd.org
132