BREAD(3)

NAME
bread, bwrite - read and write blocks of a UFS file system

LIBRARY
libufs

SYNOPSIS
#include <sys/param.h>
#include <sys/mount.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/dinode.h>
#include <ufs/ffs/fs.h>
#include <libufs.h>
ssize_t
bread(struct uufsd *disk, ufs2_daddr_t blockno, void *data, size_t size);
ssize_t
bwrite(struct uufsd *disk, ufs2_daddr_t blockno, const void *data, size_t size);

DESCRIPTION
The bread() and bwrite() functions provide a block read and write API for 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 d_bsize value of the structure.

RETURN VALUES
The bread() and bwrite() functions return the amount read or written, or -1 in case of any error, including short read.

ERRORS
The function bread() may fail and set errno for any of the errors specified for the library functions ufs_disk_write(3) or pread(2). Additionally, it may follow the libufs(3) error methodologies in situations where the amount of data read is not equal to the amount requested, or in case of device error.

The function bwrite() may fail and set errno for any of the errors specified for the library function pwrite(2). Additionally, it may follow the 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.

SEE ALSO
libufs(3), ufs_disk_write(3)

HISTORY
These functions first appeared as part of libufs(3) in FreeBSD 5.0.

AUTHORS
Juli Mallett <jmallett@FreeBSD.org>