BREAD(3)               FreeBSD Library Functions Manual               BREAD(3)

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

LIBRARY
     UFS File System Access Library (libufs, -lufs)

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);

     int
     berase(struct uufsd *disk, ufs2_daddr_t blockno, ufs2_daddr_t size);

DESCRIPTION
     The bread(), bwrite() and berase() functions provide a block read, write
     and erase 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.

     The berase() function returns non-zero on error.

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).

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

     The function berase() may fail and set errno for any of the errors
     specified for the library function ioctl(2).

     Additionally all three functions 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>

FreeBSD 13.1-RELEASE-p6          June 4, 2003          FreeBSD 13.1-RELEASE-p6