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702f62fb48
POSIX permits but does not require checking access on the current and parent directories. Because various programs do not like it if getcwd(3) fails, it seems best to avoid checking access as much as possible. There are various reports in GNATS about this (search for getcwd). Our getcwd(3) implementation first queries the kernel for the pathname directly, which does not check any permissions but sometimes fails, and then falls back to reading all parent directories for the names. PR: standards/44425 MFC after: 2 weeks
163 lines
4.1 KiB
Groff
163 lines
4.1 KiB
Groff
.\" Copyright (c) 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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.\" 4. 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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.\" @(#)getcwd.3 8.2 (Berkeley) 12/11/93
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.\" $FreeBSD$
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.\"
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.Dd April 17, 2010
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.Dt GETCWD 3
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.Os
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.Sh NAME
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.Nm getcwd ,
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.Nm getwd
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.Nd get working directory pathname
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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 char *
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.Fn getcwd "char *buf" "size_t size"
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.Ft char *
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.Fn getwd "char *buf"
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.Sh DESCRIPTION
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The
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.Fn getcwd
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function copies the absolute pathname of the current working directory
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into the memory referenced by
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.Fa buf
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and returns a pointer to
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.Fa buf .
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The
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.Fa size
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argument is the size, in bytes, of the array referenced by
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.Fa buf .
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.Pp
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If
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.Fa buf
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is
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.Dv NULL ,
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space is allocated as necessary to store the pathname.
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This space may later be
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.Xr free 3 Ns 'd .
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.Pp
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The function
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.Fn getwd
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is a compatibility routine which calls
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.Fn getcwd
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with its
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.Fa buf
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argument and a size of
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.Dv MAXPATHLEN
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(as defined in the include
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file
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.In sys/param.h ) .
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Obviously,
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.Fa buf
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should be at least
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.Dv MAXPATHLEN
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bytes in length.
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.Pp
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These routines have traditionally been used by programs to save the
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name of a working directory for the purpose of returning to it.
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A much faster and less error-prone method of accomplishing this is to
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open the current directory
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.Pq Ql .\&
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and use the
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.Xr fchdir 2
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function to return.
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.Sh RETURN VALUES
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Upon successful completion, a pointer to the pathname is returned.
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Otherwise a
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.Dv NULL
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pointer is returned and the global variable
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.Va errno
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is set to indicate the error.
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In addition,
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.Fn getwd
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copies the error message associated with
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.Va errno
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into the memory referenced by
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.Fa buf .
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.Sh ERRORS
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The
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.Fn getcwd
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function
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa size
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argument is zero.
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.It Bq Er ENOENT
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A component of the pathname no longer exists.
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.It Bq Er ENOMEM
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Insufficient memory is available.
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.It Bq Er ERANGE
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The
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.Fa size
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argument is greater than zero but smaller than the length of the pathname
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plus 1.
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.El
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.Pp
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The
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.Fn getcwd
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function
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may fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Read or search permission was denied for a component of the pathname.
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This is only checked in limited cases, depending on implementation details.
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.El
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.Sh SEE ALSO
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.Xr chdir 2 ,
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.Xr fchdir 2 ,
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.Xr malloc 3 ,
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.Xr strerror 3
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.Sh STANDARDS
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The
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.Fn getcwd
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function
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conforms to
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.St -p1003.1-90 .
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The ability to specify a
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.Dv NULL
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pointer and have
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.Fn getcwd
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allocate memory as necessary is an extension.
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.Sh HISTORY
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The
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.Fn getwd
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function appeared in
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.Bx 4.0 .
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.Sh BUGS
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The
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.Fn getwd
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function
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does not do sufficient error checking and is not able to return very
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long, but valid, paths.
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It is provided for compatibility.
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