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:
The fattach() function may fail if:
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.
fdetach() , isastream() , the Base Definitions volume of IEEE Std 1003.1-2001, <stropts.h>