1FATTACH(3P) POSIX Programmer's Manual FATTACH(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 fattach - attach a STREAMS-based file descriptor to a file in the file
13 system name space (STREAMS)
14
16 #include <stropts.h>
17 int fattach(int fildes, const char *path);
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22 The fattach() function shall attach a STREAMS-based file descriptor to
23 a file, effectively associating a pathname with fildes. The application
24 shall ensure that the fildes argument is a valid open file descriptor
25 associated with a STREAMS file. The path argument points to a pathname
26 of an existing file. The application shall have the appropriate privi‐
27 leges or be the owner of the file named by path and have write permis‐
28 sion. A successful call to fattach() shall cause all pathnames that
29 name the file named by path to name the STREAMS file associated with
30 fildes, until the STREAMS file is detached from the file. A STREAMS
31 file can be attached to more than one file and can have several path‐
32 names associated with it.
33 The attributes of the named STREAMS file shall be initialized as fol‐
35 lows: the permissions, user ID, group ID, and times are set to those of
36 the file named by path, the number of links is set to 1, and the size
37 and device identifier are set to those of the STREAMS file associated
38 with fildes. If any attributes of the named STREAMS file are subse‐
39 quently changed (for example, by chmod()), neither the attributes of
40 the underlying file nor the attributes of the STREAMS file to which
41 fildes refers shall be affected.
42 File descriptors referring to the underlying file, opened prior to an
44 fattach() call, shall continue to refer to the underlying file.
45
47 Upon successful completion, fattach() shall return 0. Otherwise, -1
48 shall be returned and errno set to indicate the error.
49
51 The fattach() function shall fail if:
52 EACCES Search permission is denied for a component of the path prefix,
54 or the process is the owner of path but does not have write per‐
55 missions on the file named by path.
56 EBADF The fildes argument is not a valid open file descriptor.
58 EBUSY The file named by path is currently a mount point or has a
60 STREAMS file attached to it.
61 ELOOP A loop exists in symbolic links encountered during resolution of
63 the path argument.
64 ENAMETOOLONG
66 The size of path exceeds {PATH_MAX} or a component of path is
67 longer than {NAME_MAX}.
68 ENOENT A component of path does not name an existing file or path is an
70 empty string.
71 ENOTDIR
73 A component of the path prefix is not a directory.
74 EPERM The effective user ID of the process is not the owner of the
76 file named by path and the process does not have appropriate
77 privilege.
78 The fattach() function may fail if:
81 EINVAL The fildes argument does not refer to a STREAMS file.
83 ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
85 resolution of the path argument.
86 ENAMETOOLONG
88 Pathname resolution of a symbolic link produced an intermediate
89 result whose length exceeds {PATH_MAX}.
90 EXDEV A link to a file on another file system was attempted.
92 The following sections are informative.
95
97 Attaching a File Descriptor to a File
98 In the following example, fd refers to an open STREAMS file. The call
99 to fattach() associates this STREAM with the file /tmp/named-STREAM,
100 such that any future calls to open /tmp/named-STREAM, prior to breaking
101 the attachment via a call to fdetach(), will instead create a new file
102 handle referring to the STREAMS file associated with fd.
103 #include <stropts.h>
106 ...
107 int fd;
108 char *filename = "/tmp/named-STREAM";
109 int ret;
110 ret = fattach(fd, filename);
113
115 The fattach() function behaves similarly to the traditional mount()
116 function in the way a file is temporarily replaced by the root direc‐
117 tory of the mounted file system. In the case of fattach(), the replaced
118 file need not be a directory and the replacing file is a STREAMS file.
119
121 The file attributes of a file which has been the subject of an fat‐
122 tach() call are specifically set because of an artefact of the original
123 implementation. The internal mechanism was the same as for the mount()
124 function. Since mount() is typically only applied to directories, the
125 effects when applied to a regular file are a little surprising, espe‐
126 cially as regards the link count which rigidly remains one, even if
127 there were several links originally and despite the fact that all orig‐
128 inal links refer to the STREAM as long as the fattach() remains in
129 effect.
130
132 None.
133
135 fdetach(), isastream(), the Base Definitions volume of
136 IEEE Std 1003.1-2001, <stropts.h>
137
139 Portions of this text are reprinted and reproduced in electronic form
140 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
141 -- Portable Operating System Interface (POSIX), The Open Group Base
142 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
143 Electrical and Electronics Engineers, Inc and The Open Group. In the
144 event of any discrepancy between this version and the original IEEE and
145 The Open Group Standard, the original IEEE and The Open Group Standard
146 is the referee document. The original Standard can be obtained online
147 at http://www.opengroup.org/unix/online.html .
148IEEE/The Open Group 2003 FATTACH(3P)