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
125 lines
3.6 KiB
Groff
125 lines
3.6 KiB
Groff
.\" $NetBSD: readlink.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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.\" @(#)readlink.2 8.1 (Berkeley) 6/4/93
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.\"
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.Dd May 11, 2004
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.Dt READLINK 2
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.Os
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.Sh NAME
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.Nm readlink
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.Nd read value of a symbolic link
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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 ssize_t
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.Fn readlink "const char * restrict path" "char * restrict buf" "size_t bufsiz"
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.Sh DESCRIPTION
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.Fn readlink
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places the contents of the symbolic link
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.Fa path
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in the buffer
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.Fa buf ,
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which has size
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.Fa bufsiz .
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.Fn readlink
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does not append a
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.Dv NUL
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character to
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.Fa buf .
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.Sh RETURN VALUES
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The call returns the count of characters placed in the buffer
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if it succeeds, or a \-1 if an error occurs, placing the error
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code in the global variable
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.Va errno .
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.Sh EXAMPLES
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A typical use is illustrated in the following piece of code
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which reads the contents of a symbolic link named
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.Pa /symbolic/link
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and stores them as null-terminated string:
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.Bd -literal -offset indent
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#include \*[Lt]limits.h\*[Gt]
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#include \*[Lt]unistd.h\*[Gt]
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char buf[PATH_MAX];
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ssize_t len;
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if ((len = readlink("/symbolic/link", buf, sizeof(buf)-1)) == -1)
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error handling;
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buf[len] = '\e0';
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.Ed
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.Sh ERRORS
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.Fn readlink
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will fail if:
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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.
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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 EINVAL
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The named file is not a symbolic link.
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.It Bq Er EIO
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An I/O error occurred while reading from the file system.
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.It Bq Er EFAULT
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.Fa buf
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extends outside the process's allocated address space.
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.El
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.Sh SEE ALSO
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.Xr lstat 2 ,
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.Xr stat 2 ,
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.Xr symlink 2 ,
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.Xr symlink 7
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.Sh STANDARDS
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The
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.Fn readlink
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function conforms to
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.St -p1003.1-2001 .
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.Sh HISTORY
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The
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.Fn readlink
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function appeared in
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.Bx 4.2 .
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The type returned was changed from
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.Ft int
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to
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.Ft ssize_t
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in
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.Nx 2.1 .
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