FATTACH(3P) POSIX Programmer's Manual FATTACH(3P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAME
fattach -- attach a STREAMS-based file descriptor to a file in the file
system name space (STREAMS)
SYNOPSIS
#include <stropts.h>
int fattach(int fildes, const char *path);
DESCRIPTION
The fattach() function shall attach a STREAMS-based file descriptor to
a file, effectively associating a pathname with fildes. The applica-
tion shall ensure that the fildes argument is a valid open file
descriptor associated with a STREAMS file. The path argument points to
a pathname of an existing file. The application shall have appropriate
privileges or be the owner of the file named by path and have write
permission. A successful call to fattach() shall cause all pathnames
that name the file named by path to name the STREAMS file associated
with fildes, until the STREAMS file is detached from the file. A
STREAMS file can be attached to more than one file and can have several
pathnames associated with it.
The attributes of the named STREAMS file shall be initialized as fol-
lows: the permissions, user ID, group ID, and times are set to those of
the file named by path, the number of links is set to 1, and the size
and device identifier are set to those of the STREAMS file associated
with fildes. If any attributes of the named STREAMS file are subse-
quently changed (for example, by chmod()), neither the attributes of
the underlying file nor the attributes of the STREAMS file to which
fildes refers shall be affected.
File descriptors referring to the underlying file, opened prior to an
fattach() call, shall continue to refer to the underlying file.
RETURN VALUE
Upon successful completion, fattach() shall return 0. Otherwise, -1
shall be returned and errno set to indicate the error.
ERRORS
The fattach() function shall fail if:
EACCES Search permission is denied for a component of the path prefix,
or the process is the owner of path but does not have write per-
missions on the file named by path.
EBADF The fildes argument is not a valid open file descriptor.
EBUSY The file named by path is currently a mount point or has a
STREAMS file attached to it.
ELOOP A loop exists in symbolic links encountered during resolution of
the path argument.
ENAMETOOLONG
The length of a component of a pathname is longer than
{NAME_MAX}.
ENOENT A component of path does not name an existing file or path is an
empty string.
ENOTDIR
A component of the path prefix names an existing file that is
neither a directory nor a symbolic link to a directory, or the
path argument contains at least one non-<slash> character and
ends with one or more trailing <slash> characters.
EPERM The effective user ID of the process is not the owner of the
file named by path and the process does not have appropriate
privileges.
The fattach() function may fail if:
EINVAL The fildes argument does not refer to a STREAMS file.
ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
resolution of the path argument.
ENAMETOOLONG
The length of a pathname exceeds {PATH_MAX}, or pathname resolu-
tion of a symbolic link produced an intermediate result with a
length that exceeds {PATH_MAX}.
EXDEV A link to a file on another file system was attempted.
The following sections are informative.
EXAMPLES
Attaching a File Descriptor to a File
In the following example, fd refers to an open STREAMS file. The call
to fattach() associates this STREAM with the file /tmp/named-STREAM,
such that any future calls to open /tmp/named-STREAM, prior to breaking
the attachment via a call to fdetach(), will instead create a new file
handle referring to the STREAMS file associated with fd.
#include <stropts.h>
...
int fd;
char *pathname = "/tmp/named-STREAM";
int ret;
ret = fattach(fd, pathname);
APPLICATION USAGE
The fattach() function behaves similarly to the traditional mount()
function in the way a file is temporarily replaced by the root direc-
tory of the mounted file system. In the case of fattach(), the replaced
file need not be a directory and the replacing file is a STREAMS file.
RATIONALE
The file attributes of a file which has been the subject of an fat-
tach() call are specifically set because of an artifact of the original
implementation. The internal mechanism was the same as for the mount()
function. Since mount() is typically only applied to directories, the
effects when applied to a regular file are a little surprising, espe-
cially as regards the link count which rigidly remains one, even if
there were several links originally and despite the fact that all orig-
inal links refer to the STREAM as long as the fattach() remains in
effect.
FUTURE DIRECTIONS
The fattach() function may be removed in a future version.
SEE ALSO
fdetach(), isastream()
The Base Definitions volume of POSIX.1-2008, <stropts.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker-
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 FATTACH(3P)
Linux-Distributionen
Huschi als Linux-Admin