119 lines
4.4 KiB
Groff
119 lines
4.4 KiB
Groff
.\" $NetBSD: errno.9,v 1.2 2004/12/03 21:34:01 christos Exp $
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.\"
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.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Andrew Brown.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd December 3, 2004
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.Dt ERRNO 9
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.Os
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.Sh NAME
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.Nm errno
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.Nd kernel internal error numbers
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.Sh SYNOPSIS
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.In sys/errno.h
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.Sh DESCRIPTION
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This section provides an overview of the error numbers used internally
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by the kernel and indicate neither success nor failure.
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These error numbers are not returned to userland code.
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.Sh DIAGNOSTICS
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Kernel functions that indicate success or failure by means of either 0
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or an
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.Xr errno 2
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value sometimes have a need to indicate that
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.Dq special
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handling is required at an upper layer or, in the case of
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.Xr ioctl 2
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processing, that
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.Dq nothing was wrong but the request was not handled .
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To handle these cases, some negative
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.Xr errno 2
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values are defined which are handled by the kernel before returning a
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different
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.Xr errno 2
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value to userland or simply zero.
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.Pp
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The following is a list of the defined names and their meanings as
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given in
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.Aq Pa errno.h .
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It is important to note that the value \-1 is
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.Em not
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used, since it is commonly used to indicate generic failure and leaves
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it up to the caller to determine the action to take.
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.Bl -hang -width Ds
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.It Er \-2 EJUSTRETURN Em "Modify regs, just return" .
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No more work is required and the function should just return.
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.It Er \-3 ERESTART Em "Restart syscall" .
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The system call should be restarted.
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This typically means that the machine dependent system call trap code
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will reposition the process's instruction pointer or program counter
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to re-execute the current system call with no other work required.
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.It Er \-4 EPASSTHROUGH Em "Operation not handled by this layer" .
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The operation was not handled and should be passed through to another
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layer.
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This often occurs when processing
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.Xr ioctl 2
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requests since lower layer processing may not handle something that
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subsequent code at a higher level will.
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.It Er \-5 EDUPFD Em "Duplicate file descriptor."
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This error is returned from the device open routine indicating that
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the
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.Ar l_dupfd
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field contains the file descriptor information to be returned to the caller,
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instead of the file descriptor that has been opened already.
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This error is used by cloning device multiplexors.
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Cloning device multiplexors open a new file descriptor and associate that
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file descriptor with the appropriate cloned device. They set
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.Ar l_dupfd
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to that new file descriptor
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and return
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.Er EDUPFD .
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.Xr vn_open 9
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takes the file descriptor pointed to by
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.Ar l_dupfd
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and copies it to the file descriptor that the open call will return.
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.It Er \-6 EMOVEFD Em "Move file descriptor."
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This error is similar to
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.Er EDUPFD
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except that the file descriptor in
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.Ar l_dupfd
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is closed after it has been copied.
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.Sh SEE ALSO
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.Xr errno 2 ,
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.Xr ioctl 9
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.Sh HISTORY
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An
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.Nm
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manual page appeared in
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.At v6 .
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This
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.Nm
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manual page appeared in
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.Nx 3.0 .
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