SIMPLE SOLUTIONS

VOP_WRITE(9FREEBSD) - man page online | system kernel interfaces

Read or write a file.

Chapter
July 24, 1996
VOP_RDWR(9)                       BSD Kernel Developer's Manual                       VOP_RDWR(9)

NAME

VOP_READ, VOP_WRITE — read or write a file

SYNOPSIS

#include <sys/param.h> #include <sys/vnode.h> #include <sys/uio.h> int VOP_READ(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred); int VOP_WRITE(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred);

DESCRIPTION

These entry points read or write the contents of a file The arguments are: vp The vnode of the file. uio The location of the data to be read or written. ioflag Various flags. cnp The credentials of the caller. The ioflag argument is used to give directives and hints to the file system. When attempt‐ ing a read, the high 16 bits are used to provide a read-ahead hint (in units of file system blocks) that the file system should attempt. The low 16 bits are a bit mask which can con‐ tain the following flags: IO_UNIT Do I/O as atomic unit. IO_APPEND Append write to end. IO_SYNC Do I/O synchronously. IO_NODELOCKED Underlying node already locked. IO_NDELAY FNDELAY flag set in file table. IO_VMIO Data already in VMIO space.

LOCKS

The file should be locked on entry and will still be locked on exit.

RETURN VALUES

Zero is returned on success, otherwise an error code is returned.

ERRORS

[EFBIG] An attempt was made to write a file that exceeds the process's file size limit or the maximum file size. [ENOSPC] The file system is full. [EPERM] An append-only flag is set on the file, but the caller is attempting to write before the current end of file.

SEE ALSO

uiomove(9), vnode(9)

AUTHORS

This manual page was written by Doug Rabson.
BSD July 24, 1996 BSD
This manual Reference Other manuals
VOP_WRITE(9freebsd) referred by VOP_ALLOCATE(9freebsd) | VOP_SETEXTATTR(9freebsd)
refer to uiomove(9freebsd) | vnode(9freebsd) | VOP_RDWR(9freebsd)