1FATTACH(P) POSIX Programmer's Manual FATTACH(P)
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6 fattach - attach a STREAMS-based file descriptor to a file in the file
7 system name space (STREAMS)
8
10 #include <stropts.h>
11 int fattach(int fildes, const char *path);
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16 The fattach() function shall attach a STREAMS-based file descriptor to
17 a file, effectively associating a pathname with fildes. The application
18 shall ensure that the fildes argument is a valid open file descriptor
19 associated with a STREAMS file. The path argument points to a pathname
20 of an existing file. The application shall have the appropriate privi‐
21 leges or be the owner of the file named by path and have write permis‐
22 sion. A successful call to fattach() shall cause all pathnames that
23 name the file named by path to name the STREAMS file associated with
24 fildes, until the STREAMS file is detached from the file. A STREAMS
25 file can be attached to more than one file and can have several path‐
26 names associated with it.
27 The attributes of the named STREAMS file shall be initialized as fol‐
29 lows: the permissions, user ID, group ID, and times are set to those of
30 the file named by path, the number of links is set to 1, and the size
31 and device identifier are set to those of the STREAMS file associated
32 with fildes. If any attributes of the named STREAMS file are subse‐
33 quently changed (for example, by chmod()), neither the attributes of
34 the underlying file nor the attributes of the STREAMS file to which
35 fildes refers shall be affected.
36 File descriptors referring to the underlying file, opened prior to an
38 fattach() call, shall continue to refer to the underlying file.
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41 Upon successful completion, fattach() shall return 0. Otherwise, -1
42 shall be returned and errno set to indicate the error.
43
45 The fattach() function shall fail if:
46 EACCES Search permission is denied for a component of the path prefix,
48 or the process is the owner of path but does not have write per‐
49 missions on the file named by path.
50 EBADF The fildes argument is not a valid open file descriptor.
52 EBUSY The file named by path is currently a mount point or has a
54 STREAMS file attached to it.
55 ELOOP A loop exists in symbolic links encountered during resolution of
57 the path argument.
58 ENAMETOOLONG
60 The size of path exceeds {PATH_MAX} or a component of path is
61 longer than {NAME_MAX}.
62 ENOENT A component of path does not name an existing file or path is an
64 empty string.
65 ENOTDIR
67 A component of the path prefix is not a directory.
68 EPERM The effective user ID of the process is not the owner of the
70 file named by path and the process does not have appropriate
71 privilege.
72 The fattach() function may fail if:
75 EINVAL The fildes argument does not refer to a STREAMS file.
77 ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
79 resolution of the path argument.
80 ENAMETOOLONG
82 Pathname resolution of a symbolic link produced an intermediate
83 result whose length exceeds {PATH_MAX}.
84 EXDEV A link to a file on another file system was attempted.
86 The following sections are informative.
89
91 Attaching a File Descriptor to a File
92 In the following example, fd refers to an open STREAMS file. The call
93 to fattach() associates this STREAM with the file /tmp/named-STREAM,
94 such that any future calls to open /tmp/named-STREAM, prior to breaking
95 the attachment via a call to fdetach(), will instead create a new file
96 handle referring to the STREAMS file associated with fd.
97 #include <stropts.h>
100 ...
101 int fd;
102 char *filename = "/tmp/named-STREAM";
103 int ret;
104 ret = fattach(fd, filename);
107
109 The fattach() function behaves similarly to the traditional mount()
110 function in the way a file is temporarily replaced by the root direc‐
111 tory of the mounted file system. In the case of fattach(), the replaced
112 file need not be a directory and the replacing file is a STREAMS file.
113
115 The file attributes of a file which has been the subject of an fat‐
116 tach() call are specifically set because of an artefact of the original
117 implementation. The internal mechanism was the same as for the mount()
118 function. Since mount() is typically only applied to directories, the
119 effects when applied to a regular file are a little surprising, espe‐
120 cially as regards the link count which rigidly remains one, even if
121 there were several links originally and despite the fact that all orig‐
122 inal links refer to the STREAM as long as the fattach() remains in
123 effect.
124
126 None.
127
129 fdetach() , isastream() , the Base Definitions volume of
130 IEEE Std 1003.1-2001, <stropts.h>
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133 Portions of this text are reprinted and reproduced in electronic form
134 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
135 -- Portable Operating System Interface (POSIX), The Open Group Base
136 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
137 Electrical and Electronics Engineers, Inc and The Open Group. In the
138 event of any discrepancy between this version and the original IEEE and
139 The Open Group Standard, the original IEEE and The Open Group Standard
140 is the referee document. The original Standard can be obtained online
141 at http://www.opengroup.org/unix/online.html .
142IEEE/The Open Group 2003 FATTACH(P)