blob: 0a9b862c0edef0236658dc3b86e0c62868421755 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
.\" Author: Juli Mallett <jmallett@FreeBSD.org>
.\" Date: June 04, 2003
.\" Description:
.\" Manual page for libufs functions:
.\" bread(3)
.\" bwrite(3)
.\"
.\" This file is in the public domain.
.\"
.\" $FreeBSD$
.\"
.Dd June 4, 2003
.Dt BREAD 3
.Os
.Sh NAME
.Nm bread , bwrite
.Nd read and write blocks of a UFS file system
.Sh LIBRARY
.Lb libufs
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.In ufs/ufs/ufsmount.h
.In ufs/ufs/dinode.h
.In ufs/ffs/fs.h
.In libufs.h
.Ft ssize_t
.Fn bread "struct uufsd *disk" "ufs2_daddr_t blockno" "void *data" "size_t size"
.Ft ssize_t
.Fo bwrite
.Fa "struct uufsd *disk" "ufs2_daddr_t blockno"
.Fa "const void *data" "size_t size"
.Fc
.Ft int
.Fo berase
.Fa "struct uufsd *disk" "ufs2_daddr_t blockno" "ufs2_daddr_t size"
.Fc
.Sh DESCRIPTION
The
.Fn bread ,
.Fn bwrite
and
.Fn berase
functions provide a block read, write and erase API for
.Xr libufs 3
consumers.
They operate on a userland UFS disk structure, and perform the read
and write at a given block address, which uses the current
.Va d_bsize
value of the structure.
.Sh RETURN VALUES
The
.Fn bread
and
.Fn bwrite
functions return the amount read or written, or \-1 in case of any error,
including short read.
.Pp
The
.Fn berase
function returns non-zero on error.
.Sh ERRORS
The function
.Fn bread
may fail and set
.Va errno
for any of the errors specified for the library functions
.Xr ufs_disk_write 3
or
.Xr pread 2 .
.Pp
The function
.Fn bwrite
may fail and set
.Va errno
for any of the errors specified for the library function
.Xr pwrite 2 .
.Pp
The function
.Fn berase
may fail and set
.Va errno
for any of the errors specified for the library function
.Xr ioctl 2 .
.Pp
Additionally all three functions may follow the
.Xr libufs 3
error methodologies in situations where the amount of data written
is not equal to the amount requested, or in case of a device error.
.Sh SEE ALSO
.Xr libufs 3 ,
.Xr ufs_disk_write 3
.Sh HISTORY
These functions first appeared as part of
.Xr libufs 3
in
.Fx 5.0 .
.Sh AUTHORS
.An Juli Mallett Aq jmallett@FreeBSD.org
|
