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fattach(3)
NAME
fattach - Attach a STREAMS-based file descriptor to a file in the file
system name space
SYNOPSIS
#include <stropts.h>
int fattach(
int fd,
const char *path );
LIBRARY
Standard C Library (libc)
STANDARDS
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.
PARAMETERS
fd Specifies a valid open file descriptor that is associated with a
STREAMS file.
path
Specifies the pathname of an existing regular file or directory.
DESCRIPTION
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).
RESTRICTIONS
[Tru64 UNIX] The fattach() function requires that the FFM_FS kernel option
be configured. See System Administration for information on configuring
kernel options.
RETURN VALUES
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.
ERRORS
If any of the following conditions occurs, the fattach() function sets
errno to the value that corresponds to the condition.
[EACCES]
Although the user is the owner of path, the user has no write
permissions for it, or the object designated by fd is locked.
[EBADF]
The fd parameter is an invalid file descriptor.
[EBUSY]
The existing object specified by the path parameter is already mounted
or has a STREAMS file descriptor attached to it.
[EFAULT]
[Tru64 UNIX] The path parameter points to a location outside of the
allocated address space of the process.
[EINVAL]
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.
[ELOOP]
When path was translated, too many symbolic links were found.
[EMFILE]
[Tru64 UNIX] There are too many file descriptors attached (system-
wide).
[ENOENT]
An element of the path parameter does not exist or is an empty string.
[ENOMEM]
[Tru64 UNIX] The system resources have been exhausted.
[ENOTDIR]
The directory portion of the path parameter does not exist.
[ENAMETOOLONG]
[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.
[EPERM]
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.
[EXDEV]
A link to a file on another file system has been attempted.
EXAMPLES
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
SEE ALSO
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
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