PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

FATTACH(3P)               POSIX Programmer's Manual              FATTACH(3P)

PROLOG         top

       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         top

       fattach — attach a STREAMS-based file descriptor to a file in the
       file system name space (STREAMS)

SYNOPSIS         top

       #include <stropts.h>

       int fattach(int fildes, const char *path);

DESCRIPTION         top

       The fattach() function shall attach a STREAMS-based file descriptor
       to a file, effectively associating a pathname with fildes.  The
       application 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
       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         top

       Upon successful completion, fattach() shall return 0. Otherwise, −1
       shall be returned and errno set to indicate the error.

ERRORS         top

       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 permissions 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
              resolution 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         top

   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         top

       The fattach() function behaves similarly to the traditional mount()
       function in the way a file is temporarily replaced by the root
       directory 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         top

       The file attributes of a file which has been the subject of an
       fattach() 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, 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         top

       The fattach() function may be removed in a future version.

SEE ALSO         top

       fdetach(3p), isastream(3p)

       The Base Definitions volume of POSIX.1‐2008, stropts.h(0p)

COPYRIGHT         top

       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 Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                 2013                         FATTACH(3P)

Pages that refer to this page: stropts.h(0p)close(3p)fdetach(3p)