.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved .TH "FATTACH" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual" .\" fattach .SH NAME fattach \- attach a STREAMS-based file descriptor to a file in the file system name space (\fBSTREAMS\fP) .SH SYNOPSIS .LP \fB#include .br .sp int fattach(int\fP \fIfildes\fP\fB, const char *\fP\fIpath\fP\fB); \fP \fB .br \fP .SH DESCRIPTION .LP The \fIfattach\fP() function shall attach a STREAMS-based file descriptor to a file, effectively associating a pathname with \fIfildes\fP. The application shall ensure that the \fIfildes\fP argument is a valid open file descriptor associated with a STREAMS file. The \fIpath\fP 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 \fIpath\fP and have write permission. A successful call to \fIfattach\fP() shall cause all pathnames that name the file named by \fIpath\fP to name the STREAMS file associated with \fIfildes\fP, 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. .LP 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 \fIpath\fP, the number of links is set to 1, and the size and device identifier are set to those of the STREAMS file associated with \fIfildes\fP. If any attributes of the named STREAMS file are subsequently changed (for example, by \fIchmod\fP()), neither the attributes of the underlying file nor the attributes of the STREAMS file to which \fIfildes\fP refers shall be affected. .LP File descriptors referring to the underlying file, opened prior to an \fIfattach\fP() call, shall continue to refer to the underlying file. .SH RETURN VALUE .LP Upon successful completion, \fIfattach\fP() shall return 0. Otherwise, -1 shall be returned and \fIerrno\fP set to indicate the error. .SH ERRORS .LP The \fIfattach\fP() function shall fail if: .TP 7 .B EACCES Search permission is denied for a component of the path prefix, or the process is the owner of \fIpath\fP but does not have write permissions on the file named by \fIpath\fP. .TP 7 .B EBADF The \fIfildes\fP argument is not a valid open file descriptor. .TP 7 .B EBUSY The file named by \fIpath\fP is currently a mount point or has a STREAMS file attached to it. .TP 7 .B ELOOP A loop exists in symbolic links encountered during resolution of the \fIpath\fP argument. .TP 7 .B ENAMETOOLONG The size of \fIpath\fP exceeds {PATH_MAX} or a component of \fIpath\fP is longer than {NAME_MAX}. .TP 7 .B ENOENT A component of \fIpath\fP does not name an existing file or \fIpath\fP is an empty string. .TP 7 .B ENOTDIR A component of the path prefix is not a directory. .TP 7 .B EPERM The effective user ID of the process is not the owner of the file named by \fIpath\fP and the process does not have appropriate privilege. .sp .LP The \fIfattach\fP() function may fail if: .TP 7 .B EINVAL The \fIfildes\fP argument does not refer to a STREAMS file. .TP 7 .B ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the \fIpath\fP argument. .TP 7 .B ENAMETOOLONG Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}. .TP 7 .B EXDEV A link to a file on another file system was attempted. .sp .LP \fIThe following sections are informative.\fP .SH EXAMPLES .SS Attaching a File Descriptor to a File .LP In the following example, \fIfd\fP refers to an open STREAMS file. The call to \fIfattach\fP() associates this STREAM with the file \fB/tmp/named-STREAM\fP, such that any future calls to open \fB/tmp/named-STREAM\fP, prior to breaking the attachment via a call to \fIfdetach\fP(), will instead create a new file handle referring to the STREAMS file associated with \fIfd\fP. .sp .RS .nf \fB#include \&... int fd; char *filename = "/tmp/named-STREAM"; int ret; .sp ret = fattach(fd, filename); \fP .fi .RE .SH APPLICATION USAGE .LP The \fIfattach\fP() function behaves similarly to the traditional \fImount\fP() function in the way a file is temporarily replaced by the root directory of the mounted file system. In the case of \fIfattach\fP(), the replaced file need not be a directory and the replacing file is a STREAMS file. .SH RATIONALE .LP The file attributes of a file which has been the subject of an \fIfattach\fP() call are specifically set because of an artefact of the original implementation. The internal mechanism was the same as for the \fImount\fP() function. Since \fImount\fP() 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 \fIfattach\fP() remains in effect. .SH FUTURE DIRECTIONS .LP None. .SH SEE ALSO .LP \fIfdetach\fP() , \fIisastream\fP() , the Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI\fP .SH COPYRIGHT 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 .