183 lines
6.5 KiB
Plaintext
183 lines
6.5 KiB
Plaintext
|
'\"
|
||
|
'\" Copyright (c) 1993 The Regents of the University of California.
|
||
|
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
|
||
|
'\"
|
||
|
'\" See the file "license.terms" for information on usage and redistribution
|
||
|
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
|
||
|
'\"
|
||
|
.TH fcopy n 8.0 Tcl "Tcl Built-In Commands"
|
||
|
.so man.macros
|
||
|
.BS
|
||
|
'\" Note: do not modify the .SH NAME line immediately below!
|
||
|
.SH NAME
|
||
|
fcopy \- Copy data from one channel to another
|
||
|
.SH SYNOPSIS
|
||
|
\fBfcopy \fIinchan\fR \fIoutchan\fR ?\fB\-size \fIsize\fR? ?\fB\-command \fIcallback\fR?
|
||
|
.BE
|
||
|
|
||
|
.SH DESCRIPTION
|
||
|
.PP
|
||
|
The \fBfcopy\fR command copies data from one I/O channel, \fIinchan\fR to another I/O channel, \fIoutchan\fR.
|
||
|
The \fBfcopy\fR command leverages the buffering in the Tcl I/O system to
|
||
|
avoid extra copies and to avoid buffering too much data in
|
||
|
main memory when copying large files to slow destinations like
|
||
|
network sockets.
|
||
|
.PP
|
||
|
The \fBfcopy\fR
|
||
|
command transfers data from \fIinchan\fR until end of file
|
||
|
or \fIsize\fR bytes or characters have been
|
||
|
transferred; \fIsize\fR is in bytes if the two channels are using the
|
||
|
same encoding, and is in characters otherwise.
|
||
|
If no \fB\-size\fR argument is given,
|
||
|
then the copy goes until end of file.
|
||
|
All the data read from \fIinchan\fR is copied to \fIoutchan\fR.
|
||
|
Without the \fB\-command\fR option, \fBfcopy\fR blocks until the copy is complete
|
||
|
and returns the number of bytes or characters (using the same rules as
|
||
|
for the \fB\-size\fR option) written to \fIoutchan\fR.
|
||
|
.PP
|
||
|
The \fB\-command\fR argument makes \fBfcopy\fR work in the background.
|
||
|
In this case it returns immediately and the \fIcallback\fR is invoked
|
||
|
later when the copy completes.
|
||
|
The \fIcallback\fR is called with
|
||
|
one or two additional
|
||
|
arguments that indicates how many bytes were written to \fIoutchan\fR.
|
||
|
If an error occurred during the background copy, the second argument is the
|
||
|
error string associated with the error.
|
||
|
With a background copy,
|
||
|
it is not necessary to put \fIinchan\fR or \fIoutchan\fR into
|
||
|
non-blocking mode; the \fBfcopy\fR command takes care of that automatically.
|
||
|
However, it is necessary to enter the event loop by using
|
||
|
the \fBvwait\fR command or by using Tk.
|
||
|
.PP
|
||
|
You are not allowed to do other input operations with \fIinchan\fR, or
|
||
|
output operations with \fIoutchan\fR, during a background
|
||
|
\fBfcopy\fR. The converse is entirely legitimate, as exhibited by the
|
||
|
bidirectional fcopy example below.
|
||
|
.PP
|
||
|
If either \fIinchan\fR or \fIoutchan\fR get closed
|
||
|
while the copy is in progress, the current copy is stopped
|
||
|
and the command callback is \fInot\fR made.
|
||
|
If \fIinchan\fR is closed,
|
||
|
then all data already queued for \fIoutchan\fR is written out.
|
||
|
.PP
|
||
|
Note that \fIinchan\fR can become readable during a background copy.
|
||
|
You should turn off any \fBfileevent\fR handlers during a background
|
||
|
copy so those handlers do not interfere with the copy.
|
||
|
Any wrong-sided I/O attempted (by a \fBfileevent\fR handler or otherwise) will get a
|
||
|
.QW "channel busy"
|
||
|
error.
|
||
|
.PP
|
||
|
\fBFcopy\fR translates end-of-line sequences in \fIinchan\fR and \fIoutchan\fR
|
||
|
according to the \fB\-translation\fR option
|
||
|
for these channels.
|
||
|
See the manual entry for \fBfconfigure\fR for details on the
|
||
|
\fB\-translation\fR option.
|
||
|
The translations mean that the number of bytes read from \fIinchan\fR
|
||
|
can be different than the number of bytes written to \fIoutchan\fR.
|
||
|
Only the number of bytes written to \fIoutchan\fR is reported,
|
||
|
either as the return value of a synchronous \fBfcopy\fR or
|
||
|
as the argument to the callback for an asynchronous \fBfcopy\fR.
|
||
|
.PP
|
||
|
\fBFcopy\fR obeys the encodings and character translations configured
|
||
|
for the channels. This
|
||
|
means that the incoming characters are converted internally first
|
||
|
UTF-8 and then into the encoding of the channel \fBfcopy\fR writes
|
||
|
to. See the manual entry for \fBfconfigure\fR for details on the
|
||
|
\fB\-encoding\fR and \fB\-translation\fR options. No conversion is
|
||
|
done if both channels are
|
||
|
set to encoding
|
||
|
.QW binary
|
||
|
and have matching translations. If only the output channel is set to encoding
|
||
|
.QW binary
|
||
|
the system will write the internal UTF-8 representation of the incoming
|
||
|
characters. If only the input channel is set to encoding
|
||
|
.QW binary
|
||
|
the system will assume that the incoming
|
||
|
bytes are valid UTF-8 characters and convert them according to the
|
||
|
output encoding. The behaviour of the system for bytes which are not
|
||
|
valid UTF-8 characters is undefined in this case.
|
||
|
.SH EXAMPLES
|
||
|
.PP
|
||
|
The first example transfers the contents of one channel exactly to
|
||
|
another. Note that when copying one file to another, it is better to
|
||
|
use \fBfile copy\fR which also copies file metadata (e.g. the file
|
||
|
access permissions) where possible.
|
||
|
.PP
|
||
|
.CS
|
||
|
fconfigure $in -translation binary
|
||
|
fconfigure $out -translation binary
|
||
|
\fBfcopy\fR $in $out
|
||
|
.CE
|
||
|
.PP
|
||
|
This second example shows how the callback gets
|
||
|
passed the number of bytes transferred.
|
||
|
It also uses vwait to put the application into the event loop.
|
||
|
Of course, this simplified example could be done without the command
|
||
|
callback.
|
||
|
.PP
|
||
|
.CS
|
||
|
proc Cleanup {in out bytes {error {}}} {
|
||
|
global total
|
||
|
set total $bytes
|
||
|
close $in
|
||
|
close $out
|
||
|
if {[string length $error] != 0} {
|
||
|
# error occurred during the copy
|
||
|
}
|
||
|
}
|
||
|
set in [open $file1]
|
||
|
set out [socket $server $port]
|
||
|
\fBfcopy\fR $in $out -command [list Cleanup $in $out]
|
||
|
vwait total
|
||
|
.CE
|
||
|
.PP
|
||
|
The third example copies in chunks and tests for end of file
|
||
|
in the command callback.
|
||
|
.PP
|
||
|
.CS
|
||
|
proc CopyMore {in out chunk bytes {error {}}} {
|
||
|
global total done
|
||
|
incr total $bytes
|
||
|
if {([string length $error] != 0) || [eof $in]} {
|
||
|
set done $total
|
||
|
close $in
|
||
|
close $out
|
||
|
} else {
|
||
|
\fBfcopy\fR $in $out -size $chunk \e
|
||
|
-command [list CopyMore $in $out $chunk]
|
||
|
}
|
||
|
}
|
||
|
set in [open $file1]
|
||
|
set out [socket $server $port]
|
||
|
set chunk 1024
|
||
|
set total 0
|
||
|
\fBfcopy\fR $in $out -size $chunk \e
|
||
|
-command [list CopyMore $in $out $chunk]
|
||
|
vwait done
|
||
|
.CE
|
||
|
.PP
|
||
|
The fourth example starts an asynchronous, bidirectional fcopy between
|
||
|
two sockets. Those could also be pipes from two [open "|hal 9000" r+]
|
||
|
(though their conversation would remain secret to the script, since
|
||
|
all four fileevent slots are busy).
|
||
|
.PP
|
||
|
.CS
|
||
|
set flows 2
|
||
|
proc Done {dir args} {
|
||
|
global flows done
|
||
|
puts "$dir is over."
|
||
|
incr flows -1
|
||
|
if {$flows<=0} {set done 1}
|
||
|
}
|
||
|
\fBfcopy\fR $sok1 $sok2 -command [list Done UP]
|
||
|
\fBfcopy\fR $sok2 $sok1 -command [list Done DOWN]
|
||
|
vwait done
|
||
|
.CE
|
||
|
.SH "SEE ALSO"
|
||
|
eof(n), fblocked(n), fconfigure(n), file(n)
|
||
|
.SH KEYWORDS
|
||
|
blocking, channel, end of line, end of file, nonblocking, read, translation
|
||
|
'\" Local Variables:
|
||
|
'\" mode: nroff
|
||
|
'\" End:
|