fdetach.3

7号信令功能代码,为开源代码

'\" rtp
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.so lis.macros
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.\"
.\"
.TH FDETACH 3 "2004/01/12 23:32:49" "LiS-2_16_18-8" "Linux STREAMS"
.SH NAME
.B fdetach
\- detach any \fISTREAMS\fR file from a path name in the file system
.SH SYNOPSIS
.PP
.B "#include <stropts.h> "
.HP
.BI "int fdetach( const char *" path " ); "
.SH DESCRIPTION
.PP
.BR fdetach "() "
detaches an open
.I STREAMS
file from a path name in the file system.
.BR fdetach "() "
will also
.BR close "(2) "
the
.I STREAMS
file if it represents the last
.BR open "(2) "
of that file.
.SH "RETURN VALUE"
.PP
Upon successful completion,
.BR fdetach "() "
returns 0.  Upon failure,
.B fattach
return -1, and
.BR errno "(3) "
is set to indicate the error causing the failure (see below).
.SH ERRORS
.PP
.BR fdetach "() "
may fail with at least the following error indications:
.TP 12
.B "[EINVAL]"
No
.I STREAMS
file is currently attached to the
.I path
given as an argument.
.SH "APPLICATION USAGE"
.PP
Applications wishing to use the version of the
.BR fdetach "() "
function described herein must link with the
.B LiS
.[
LiS
.]
library which
provides it.  The
Linux/GNU C library otherwise provides a stub supporting calls to
.BR fdetach "() "
which only generates an error indicating that it is not implemented.
.SH WARNINGS
.PP
The effect of calling
.BR fdetach "() "
on an attached
.I STREAMS
file occurs automatically when a
.I hangup
indication is received, unless passed file descriptors (in the form of
.B M_PASSFP
messages) are pending receipt via the
.B I_RECVFD
.I ioctl.
This will occur normally in two situations: when the file is a
pipe end and the other end is closed for the last time and released;
and when a driver sends an
.B M_HANGUP
message upward to the stream head.
In this state, the
.I STREAMS
file becomes unusable for normal message traffic, and
the automatic detachment ensures that it will be closed and its
resources released.
It should be noted, however, that this behavior is not common to
other
.ISTREAMS
implementations and should be considered a non-standard extension.
.SH "FUTURE DIRECTIONS"
.PP
.BR fdetach "() "
is currently implemented as an IOCTL operation on an anonymous
.I STREAMS
file.
Should
.B LiS
.[
LiS
.]
ever become part of the Linux kernel, it may become a
system call; a system call implementation is in fact already
included within
.B LiS\c
.
.[
LiS
.]
.SH "SEE ALSO"
.PP
.BR fattach "(3), "
.BR fattach "(8), "
.BR fdetach "(8), "
.BR STREAMS "(4) "
.SH HISTORY
.PP
UNIX\(rg\ System V Release 4 (SVR4)
.[
svr4
.]
.SH AUTHOR
.PP
John Boyd, protologos LLC.
.[
$LIST$
.]
.TI