NAME
errno
- kernel internal error numbers
SYNOPSIS
DESCRIPTION
This section provides an overview of the error numbers used internally
by the kernel and indicate neither success nor failure.
These error numbers are not returned to userland code.
DIAGNOSTICS
Kernel functions that indicate success or failure by means of either 0
or an
errno(2)
value sometimes have a need to indicate that
``special''
handling is required at an upper layer or, in the case of
ioctl(2)
processing, that
``nothing was wrong but the request was not handled''.
To handle these cases, some negative
errno(2)
values are defined which are handled by the kernel before returning a
different
errno(2)
value to userland or simply zero.
The following is a list of the defined names and their meanings as
given in
<
errno.h
>.
It is important to note that the value -1 is
not
used, since it is commonly used to indicate generic failure and leaves
it up to the caller to determine the action to take.
-2
EJUSTRETURN
Modify regs, just return- .
No more work is required and the function should just return.
-3
ERESTART
Restart syscall- .
The system call should be restarted.
This typically means that the machine dependent system call trap code
will reposition the process's instruction pointer or program counter
to re-execute the current system call with no other work required.
-4
EPASSTHROUGH
Operation not handled by this layer- .
The operation was not handled and should be passed through to another
layer.
This often occurs when processing
ioctl(2)
requests since lower layer processing may not handle something that
subsequent code at a higher level will.
-5
EDUPFD
Duplicate file descriptor.-
This error is returned from the device open routine indicating that
the
l_dupfd
field contains the file descriptor information to be returned to the caller,
instead of the file descriptor that has been opened already.
This error is used by cloning device multiplexors.
Cloning device multiplexors open a new file descriptor and associate that
file descriptor with the appropriate cloned device.
They set
l_dupfd
to that new file descriptor and return
EDUPFD
.
vn_open(9)
takes the file descriptor pointed to by
l_dupfd
and copies it to the file descriptor that the open call will return.
-6
EMOVEFD
Move file descriptor.-
This error is similar to
EDUPFD
except that the file descriptor in
l_dupfd
is closed after it has been copied.
SEE ALSO
errno(2),
ioctl(9)
HISTORY
An
errno
manual page appeared in
Version 6 AT&T UNIX
.
This
errno
manual page appeared in
NetBSD3.0.