CODEWITHSUNDEEP
tcl
sanjay
sanjay

Reputation: 717

TCL socket reports broken pipe upon writing from server

When attempting to return a multi-line output via TCL server, the server reports a broken pipe even though the client is able to receive all the data.

Server:

proc Echo_Server {port} {
    set s [socket -server EchoAccept $port]
    vwait forever
}

proc EchoAccept {sock addr port} {
    puts "Accept $sock from $addr port $port"
    fconfigure $sock -buffering line
    fileevent $sock readable [list Echo $sock]
}

proc Echo {sock} {
    if { [eof $sock] || [catch {gets $sock line}] } {
        puts "Close $sock"
        close $sock
    } else {
        set returnData "
        Hi

        How are you?

        This is test data

        Close
        "
        puts $sock $returnData
        puts $sock "EOF"
        flush $sock
    }
}

Echo_Server 2500
vwait forever

Client code to send/receive data:

proc Echo_Client {host port} {
    set s [socket $host $port]
    fconfigure $s -buffering full -buffersize 1000000
    #fconfigure $s -buffering line -blocking 0
    return $s
}

set s [Echo_Client localhost 2500] ; puts $s "dummy command" ; flush $s 

set pp 1 ; while { $pp == 1 } { set line [gets $s] ; puts $line ; if { [regexp "EOF" $line] } { set pp 0 } } ; flush $s ; close $s

The client receives the data sent from the server but the server reports the following:

% source /edascratch/nobackup/sanjaynn/scripts/simple_server.tcl
Accept sock6 from 127.0.0.1 port 59814
error writing "sock6": broken pipe
    while executing
"puts $sock $returnData"
    (procedure "Echo" line 15)
    invoked from within
"Echo sock6"

Is there something obvious that I am missing?

Upvotes: 0

Views: 635

Answers (1)

Sergei Golovan
Sergei Golovan

Reputation: 611

The [eof $sock] condition isn't set before the read in [gets $sock line], and the [gets] call doesn't return an error here, it returns -1 to indicate that there's no data available. Just reverse the conditions order and the server will start working properly:

...
if { [catch {gets $sock line}] || [eof $sock] } {
...

Upvotes: 2

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