1.\" Author: Juli Mallett <jmallett@FreeBSD.org> 2.\" Date: June 04, 2003 3.\" Description: 4.\" Manual page for libufs functions: 5.\" cgread(3) 6.\" cgread1(3) 7.\" cgwrite1(3) 8.\" 9.\" This file is in the public domain. 10.\" 11.\" $FreeBSD$ 12.\" 13.Dd June 4, 2003 14.Dt CGREAD 3 15.Os 16.Sh NAME 17.Nm cgread , cgread1, cgwrite1 18.Nd read/write cylinder groups of UFS disks 19.Sh LIBRARY 20.Lb libufs 21.Sh SYNOPSIS 22.In sys/param.h 23.In sys/mount.h 24.In ufs/ufs/ufsmount.h 25.In ufs/ufs/dinode.h 26.In ufs/ffs/fs.h 27.In libufs.h 28.Ft int 29.Fn cgread "struct uufsd *disk" 30.Ft int 31.Fn cgread1 "struct uufsd *disk" "int c" 32.Ft int 33.Fn cgwrite1 "struct uufsd *disk" "int c" 34.Sh DESCRIPTION 35The 36.Fn cgread 37and 38.Fn cgread1 39functions provide cylinder group reads for 40.Xr libufs 3 41consumers. 42The 43.Fn cgread1 44function reads from one cylinder group, specified by 45.Fa c 46into the 47.Va d_cg 48field of a userland UFS disk structure. 49It sets the 50.Va d_lcg 51field to the cylinder group number 52.Fa c . 53.Pp 54The 55.Fn cgread 56function operates on sequential cylinder groups. 57Calling the 58.Fn cgread 59function is equivalent to calling 60.Fn cgread1 61with a cylinder group specifier equivalent to the value of the current 62.Va d_ccg 63field, and then incrementing the 64.Va d_ccg 65field. 66.Pp 67The 68.Fn cgwrite1 69function stores cylinder group specified by 70.Fa c 71from 72.Va d_cg 73field of a userland UFS disk structure on disk. 74.Sh RETURN VALUES 75Both functions return 0 if there are no more cylinder groups to read, 761 if there are more cylinder groups, and \-1 on error. 77.Sh ERRORS 78The function 79.Fn cgread 80may fail and set 81.Va errno 82for any of the errors specified for the library function 83.Xr bread 3 . 84.Pp 85The function 86.Fn cgread1 87has semantically identical failure conditions to those of 88.Fn cgread . 89.Pp 90The function 91.Fn cgwrite1 92may fail and set 93.Va errno 94for any of the errors specified for the library function 95.Xr bwrite 3 . 96.Sh SEE ALSO 97.Xr bread 3 , 98.Xr bwrite 3 , 99.Xr libufs 3 100.Sh HISTORY 101These functions first appeared as part of 102.Xr libufs 3 103in 104.Fx 5.1 . 105.Sh AUTHORS 106.An Juli Mallett Aq Mt jmallett@FreeBSD.org 107