fattach - Attach a STREAMS-based file descriptor to a file
in the file system name space
#include <stropts.h>
int fattach(
int fd,
const char *path );
Standard C Library (libc)
Interfaces documented on this reference page conform to
industry standards as follows:
fattach(): XSH4.0, XSH4.2, XSH5.0
Refer to standards(5) for more information about industry
standards and associated tags.
Specifies a valid open file descriptor that is associated
with a STREAMS file. Specifies the pathname of an existing
regular file or directory.
The fattach() function associates a STREAMS-based file
descriptor to the file pointed to by the path parameter.
A successful call to the fattach() function causes all
pathnames that name the file named by the path parameter
to name the STREAMS file associated with the fd parameter
until the STREAMS file is detached from the file. The
STREAMS file is detached from the file by using the fdetach()
function. 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 are initialized
as follows: The group ID, user ID, times, and permissions
are set to those of the file pointed to by the path parameter.
The number of links is set to 1. The size and the
device identifier are set to those of the STREAMS file
that is associated with the fd parameter.
If any of the attributes of the named STREAMS file are
subsequently changed, for example by the chmod() function,
the change affects neither the attributes of the underlying
file nor the attributes of the STREAMS file to which
the fd parameter refers.
Any file descriptors referring to the underlying file that
were opened prior to an fattach() call continue to refer
to the underlying file.
The fattach() function uses the File-on-File Mounting
(FFM) file system. Instead of mounting a file system on a
mount point, the fattach() function ffm mounts a file
descriptor on a mount point, which can be either a
directory or a regular file. See ffm(4).
[Tru64 UNIX] The fattach() function requires that the
FFM_FS kernel option be configured. See System Administration
for information on configuring kernel options.
Upon successful completion, the fattach() function returns
a value of 0 (zero). Otherwise, it returns a value of -1,
and errno is set to indicate the error.
If any of the following conditions occurs, the fattach()
function sets errno to the value that corresponds to the
condition.
Although the user is the owner of path, the user has no
write permissions for it, or the object designated by fd
is locked. The fd parameter is an invalid file descriptor.
The existing object specified by the path parameter
is already mounted or has a STREAMS file descriptor
attached to it. [Tru64 UNIX] The path parameter points
to a location outside of the allocated address space of
the process. The fd parameter refers to a socket and not
a STREAMS file.
[Tru64 UNIX] The superblock for the file system
had an incorrect magic number or an out of range
block size.
[Tru64 UNIX] The pathname is incorrect. When path
was translated, too many symbolic links were found.
[Tru64 UNIX] There are too many file descriptors
attached (system-wide). An element of the path
parameter does not exist or is an empty string.
[Tru64 UNIX] The system resources have been
exhausted. The directory portion of the path
parameter does not exist. [Tru64 UNIX] The size
of a pathname component is longer than NAME_MAX
when _POSIX_NO_TRUNC is in effect.
The pathname length is longer than PATH_MAX or the
length of the intermediate result of a pathname
resolution of a symbolic link is longer than
PATH_MAX. The current effective user ID is not the
owner of the existing file specified by the path
parameter. Another cause of the error is if the
current effective user ID does not specify a user
with the correct privileges. A link to a file on
another file system has been attempted.
The following example shows a program that attaches a
STREAMS file to a regular file and results in a df display
that indicates the File-on-File Mounting (FFM) is the
mounted file system.
#include <fcntl.h> #include <sys/stat.h> #include
<sys/types.h> #include <stropts.h> #include <stdio.h>
#include <errno.h> #include <unistd.h>
main (int argc, char **argv) {
int fd;
int error;
if ((fd = open("/tmp/astream", O_RDONLY, 0)) ==
-1) {
perror ("open");
exit(error);
}
printf("opened\n");
if ((error = isastream(fd)) != 1) {
printf("not a stream\n"); if
(error == -1)
perror("isastream");
exit(-1);
}
printf("is a stream\n");
if ((error = fattach(fd, "/tmp/afile")) == -1) {
perror ("fattach");
exit(error);
}
printf("fattached\n");
exit(0); }
% df /tmp/afile Filesystem 512-blocks Used Available
Capacity Mounted on file-on-file mount 0
0 0 100% /tmp/afile
Functions: fdetach(3), isastream(3), chmod(2), stat(2),
mount(2)
Commands: fdetach(8)
Interfaces: streamio(7)
Files: ffm(4)
Standards: standards(5)
Network Programmer's Guide
fattach(3)
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