BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / sys / access.2

diff --git a/usr/src/lib/libc/sys/access.2 b/usr/src/lib/libc/sys/access.2
index 87164d7..9a0f180 100644 (file)
--- a/usr/src/lib/libc/sys/access.2
+++ b/usr/src/lib/libc/sys/access.2
@@ -1,88 +1,110 @@
-.\" Copyright (c) 1980 Regents of the University of California.
-.\" All rights reserved.  The Berkeley software License Agreement
-.\" specifies the terms and conditions for redistribution.
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.

 .\"
 .\"

-.\"    @(#)access.2    6.6 (Berkeley) 5/13/90
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.

 .\"
 .\"

-.TH ACCESS 2 "May 13, 1990"
-.UC 4
-.SH NAME
-access \- determine accessibility of file
-.SH SYNOPSIS
-.nf
-.ft B
-#include <unistd.h>
-
-accessible = access(path, mode)
-int accessible;
-char *path;
-int mode;
-.ft R
-.fi
-.SH DESCRIPTION
-.I Access
-checks the given
-file
-.I path
-for accessibility according to
-.IR mode ,
-which is the bitwise inclusive OR of the access permissions to be
-checked (R_OK for read permission, W_OK for write permission and X_OK
-for execute/search permission) or the existence test, F_OK.
-Specifying
-.I mode
-as F_OK tests whether the directories leading to the file can be
-searched and the file exists.
-.PP
-The real user ID and the group access list
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)access.2   6.7 (Berkeley) 3/10/91
+.\"
+.Dd March 10, 1991
+.Dt ACCESS 2
+.Os BSD 4
+.Sh NAME
+.Nm access
+.Nd check access permissions of a file or pathname
+.Sh SYNOPSIS
+.Fd #include <unistd.h>
+.Ft int
+.Fn access "const char *path" "int mode"
+.Sh DESCRIPTION
+The
+.Fn access
+function checks the accessibility of the
+file named by
+.Fa path
+for the access permissions indicated by
+.Fa mode .
+The value of
+.Fa mode
+is the bitwise inclusive OR of the access permissions to be
+checked
+.Pf ( Dv R_OK
+for read permission,
+.Dv W_OK
+for write permission and
+.Dv X_OK
+for execute/search permission) or the existence test,
+.Dv F_OK .
+All components of the pathname
+.Fa path
+are checked for access permissions (including
+.Dv F_OK ) .
+.Pp
+The real user ID is used in place of the effective user ID
+and the real group access list

 (including the real group ID) are
 (including the real group ID) are

-used in verifying permission, so this call
-is useful to set-UID programs.
-.PP
-Notice that only access bits are checked.
-A directory may be indicated as writable by
-.IR access ,
-but an attempt to open it for writing will fail
-(although files may be created there);
-a file may look executable, but
-.I execve
-will fail unless it is in proper format.
-.SH "RETURN VALUE
+used in place of the effective ID for verifying permission.
+.Pp
+Even if a process has appropriate privileges and indicates success for
+.Dv X_OK ,
+the file may not actually have execute permission bits set.
+Likewise for
+.Dv R_OK
+and
+.Dv W_OK .
+.Sh RETURN VALUES

 If
 If

-.I path
+.Fa path

 cannot be found or if any of the desired access modes would
 cannot be found or if any of the desired access modes would

-not be granted, then a \-1 value is returned; otherwise
+not be granted, then a -1 value is returned; otherwise

 a 0 value is returned.
 a 0 value is returned.

-.SH "ERRORS
-Access to the file is denied if one or more of the following are true:
-.TP 15
-[ENOTDIR]
+.Sh ERRORS
+Access to the file is denied if:
+.Bl -tag -width Er
+.It Bq Er ENOTDIR

 A component of the path prefix is not a directory.
 A component of the path prefix is not a directory.

-.TP 15
-[EINVAL]
+.It Bq Er EINVAL

 The pathname contains a character with the high-order bit set.
 The pathname contains a character with the high-order bit set.

-.TP 15
-[ENAMETOOLONG]
+.It Bq Er ENAMETOOLONG

 A component of a pathname exceeded 255 characters,
 or an entire path name exceeded 1023 characters.
 A component of a pathname exceeded 255 characters,
 or an entire path name exceeded 1023 characters.

-.TP 15
-[ENOENT]
+.It Bq Er ENOENT

 The named file does not exist.
 The named file does not exist.

-.TP 15
-[EACCES]
+.It Bq Er EACCES

 Search permission is denied for a component of the path prefix.
 Search permission is denied for a component of the path prefix.

-.TP 15
-[ELOOP]
+.It Bq Er ELOOP

 Too many symbolic links were encountered in translating the pathname.
 Too many symbolic links were encountered in translating the pathname.

-.TP 15
-[EROFS]
+.It Bq Er EROFS

 Write access is requested for a file on a read-only file system.
 Write access is requested for a file on a read-only file system.

-.TP 15
-[ETXTBSY]
+.It Bq Er ETXTBSY

 Write access is requested for a pure procedure (shared text)
 Write access is requested for a pure procedure (shared text)

-file that is being executed.
-.TP 15
-[EACCES]
+file presently being executed.
+.It Bq Er EACCES

 Permission bits of the file mode do not permit the requested
 access, or search permission is denied on a component of the
 path prefix.  The owner of a file has permission checked with
 Permission bits of the file mode do not permit the requested
 access, or search permission is denied on a component of the
 path prefix.  The owner of a file has permission checked with


@@ -91,12 +113,20 @@ members of the file's group other than the owner have permission
 checked with respect to the ``group'' mode bits, and all
 others have permissions checked with respect to the ``other''
 mode bits.
 checked with respect to the ``group'' mode bits, and all
 others have permissions checked with respect to the ``other''
 mode bits.

-.TP 15
-[EFAULT]
-.I Path
+.It Bq Er EFAULT
+.Fa Path

 points outside the process's allocated address space.
 points outside the process's allocated address space.

-.TP 15
-[EIO]
+.It Bq Er EIO

 An I/O error occurred while reading from or writing to the file system.
 An I/O error occurred while reading from or writing to the file system.

-.SH "SEE ALSO
-chmod(2), stat(2)
+.El
+.Sh SEE ALSO
+.Xr chmod 2 ,
+.Xr stat 2
+.Sh STANDARDS
+.Fn Access
+conforms to IEEE Std 1003.1-1988
+.Pq Dq Tn POSIX .
+.Sh CAVEAT
+.Fn Access
+is a potential security hole and
+should never be used.