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 attempting 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 contain
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.