Originální popis anglicky:
fattach - attach a STREAMS-based file descriptor to a file in the file system
name space (
STREAMS)
Návod, kniha: POSIX Programmer's Manual
#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 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 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 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.
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);
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 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.
None.
fdetach() ,
isastream() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<stropts.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- 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
.
