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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FATTACH(3P) POSIX Programmer's Manual FATTACH(3P)
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.
fattach — attach a STREAMS-based file descriptor to a file in the
file system name space (STREAMS)
#include <stropts.h>
int fattach(int fildes, const char *path);
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.
Upon successful completion, fattach() shall return 0. Otherwise,
-1 shall be returned and errno set to indicate the error.
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.
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);
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.
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.
The fattach() function may be removed in a future version.
fdetach(3p), isastream(3p)
The Base Definitions volume of POSIX.1‐2017, stropts.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
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 2017 FATTACH(3P)
Pages that refer to this page: stropts.h(0p), close(3p), fdetach(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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