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 correspond-
       ing 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 the 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 asso-
       ciated 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 follows: 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 subsequently 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  permis-
	      sions 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 size of path exceeds {PATH_MAX} or a component of path 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 is not a directory.

       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 privilege.

       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
	      Pathname resolution of a symbolic link produced an intermediate result whose length 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 *filename = "/tmp/named-STREAM";
		  int ret;

		  ret = fattach(fd, filename);

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 fattach() call are specifically set because of an artefact 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, especially as regards the link count which rigidly remains one, even if
       there were several links originally and despite the fact that all original links refer to the STREAM as long as the  fattach()  remains	in
       effect.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fdetach(), isastream(), the Base Definitions volume of IEEE Std 1003.1-2001, <stropts.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       FATTACH(3P)