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
152 lines
4.3 KiB
Groff
152 lines
4.3 KiB
Groff
.\" $NetBSD: truncate.2,v 1.26 2010/05/31 12:16:20 njoly Exp $
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.\"
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.\" Copyright (c) 1983, 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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.\" @(#)truncate.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd March 16, 2008
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.Dt TRUNCATE 2
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.Os
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.Sh NAME
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.Nm truncate ,
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.Nm ftruncate
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.Nd truncate a file to a specified length
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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 int
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.Fn truncate "const char *path" "off_t length"
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.Ft int
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.Fn ftruncate "int fd" "off_t length"
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.Sh DESCRIPTION
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.Fn truncate
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causes the file named by
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.Fa path
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or referenced by
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.Fa fd
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to have a size of
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.Fa length
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bytes.
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If the file previously was larger than this size, the extra data is discarded.
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If it was previously shorter than
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.Fa length ,
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its size is increased to the specified value and
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the extended area appears as if it were zero-filled.
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.Pp
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With
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.Fn ftruncate ,
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the file must be open for writing; for
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.Fn truncate ,
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the process must have write permissions for the file.
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.Sh RETURN VALUES
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A value of 0 is returned if the call succeeds.
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If the call fails a \-1 is returned, and the global variable
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.Va errno
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specifies the error.
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.Sh ERRORS
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Error return codes common to
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.Fn truncate
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and
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.Fn ftruncate
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are:
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.Bl -tag -width Er
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.It Bq Er EISDIR
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The named file is a directory.
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.It Bq Er EROFS
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The named file resides on a read-only file system.
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.It Bq Er ETXTBSY
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The file is a pure procedure (shared text) file that is being executed.
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.It Bq Er EIO
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An I/O error occurred updating the inode.
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.It Bq Er ENOSPC
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There was no space in the filesystem to complete the operation.
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.El
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.Pp
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Error codes specific to
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.Fn truncate
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are:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Brq Dv NAME_MAX
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characters, or an entire path name exceeded
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.Brq Dv PATH_MAX
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characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix, or
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the named file is not writable by the user.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EFAULT
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.Fa path
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points outside the process's allocated address space.
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.El
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.Pp
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Error codes specific to
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.Fn ftruncate
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are:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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is not a valid descriptor.
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.It Bq Er EINVAL
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The
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.Fa fd
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references a socket, not a file, or
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the
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.Fa fd
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is not open for writing.
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.El
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.Sh SEE ALSO
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.Xr open 2
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.Sh STANDARDS
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Use of
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.Fn truncate
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to extend a file is an
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.St -p1003.1-2004
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extension, and is thus not portable.
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Files can be extended in a portable way seeking (using
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.Xr lseek 2 )
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to the required size and writing a single character with
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.Xr write 2 .
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.Sh HISTORY
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The
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.Fn truncate
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and
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.Fn ftruncate
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function calls appeared in
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.Bx 4.2 .
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.Sh BUGS
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These calls should be generalized to allow ranges
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of bytes in a file to be discarded.
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