2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
149 lines
3.7 KiB
Groff
149 lines
3.7 KiB
Groff
.\" $NetBSD: lseek.2,v 1.24 2010/04/05 07:53:47 wiz Exp $
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.\"
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.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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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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.\" @(#)lseek.2 8.3 (Berkeley) 4/19/94
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.\"
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.Dd April 3, 2010
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.Dt LSEEK 2
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.Os
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.Sh NAME
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.Nm lseek ,
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.Nm seek
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.Nd reposition read/write file offset
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft off_t
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.Fn lseek "int fildes" "off_t offset" "int whence"
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.Sh DESCRIPTION
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The
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.Fn lseek
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function repositions the offset of the file descriptor
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.Fa fildes
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to the
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argument
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.Fa offset
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according to the directive
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.Fa whence .
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The argument
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.Fa fildes
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must be an open
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file descriptor.
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.Fn lseek
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repositions the file pointer
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.Fa fildes
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as follows:
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.Bl -item -offset indent
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.It
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If
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.Fa whence
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is
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.Dv SEEK_SET ,
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the offset is set to
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.Fa offset
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bytes.
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.It
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If
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.Fa whence
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is
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.Dv SEEK_CUR ,
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the offset is set to its current location plus
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.Fa offset
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bytes.
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.It
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If
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.Fa whence
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is
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.Dv SEEK_END ,
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the offset is set to the size of the
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file plus
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.Fa offset
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bytes.
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.El
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.Pp
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The
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.Fn lseek
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function allows the file offset to be set beyond the end
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of the existing end-of-file of the file.
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If data is later written
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at this point, subsequent reads of the data in the gap return
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bytes of zeros (until data is actually written into the gap).
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.Pp
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Some devices are incapable of seeking.
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The value of the pointer associated with such a device is undefined.
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.Sh RETURN VALUES
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Upon successful completion,
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.Fn lseek
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returns the resulting offset location as measured in bytes from the
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beginning of the file.
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Otherwise,
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a value of \-1 is returned and
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.Va errno
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is set to indicate
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the error.
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.Sh ERRORS
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.Fn lseek
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will fail and the file pointer will remain unchanged if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa fildes
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is not an open file descriptor.
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.It Bq Er EINVAL
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.Fa whence
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is not a proper value, or the resulting file offset would be invalid.
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.It Bq Er ESPIPE
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.Fa fildes
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is associated with a pipe, socket, or FIFO.
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.El
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.Sh SEE ALSO
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.Xr dup 2 ,
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.Xr open 2
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.Sh STANDARDS
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The
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.Fn lseek
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function conforms to
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.St -p1003.1-90 .
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.Sh HISTORY
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A
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.Fn seek
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function appeared in
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.At v2 ,
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later renamed into
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.Fn lseek
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for
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.Dq long seek
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due to a larger
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.Fa offset
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argument type.
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.Sh BUGS
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This document's use of
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.Fa whence
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is incorrect English, but is maintained for historical reasons.
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