Interrupted System Call Socket Error
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Interrupted System Call In Unix
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Interrupted System Call Recv
down vote favorite 1 I discovered an issue with thread implementation, that is strange to me. Maybe some of you can explain it to me, would be great. I am working on something like a proxy, a program (running on different machines) that receives packets over eth0 and sends it through ath0 (wireless) to another machine which is doing the exactly same thing. Actually I am not at all sure interrupted system call c what is causing my problem, that's because I am new to everything, linux and c programming. I start two threads, one is listening (socket) on eth0 for incoming packets and sends it out through ath0 (also socket) and the other thread is listening on ath0 and sends through eth0. If I use threads, I get an error like that: sh-2.05b# ./socketex Failed to send network header packet. : Interrupted system call If I use fork(), the program works as expected. Can someone explain that behaviour to me? Just to show the sender implementation here comes its code snippet: while(keep_going) { memset(&buffer[0], '\0', sizeof(buffer)); recvlen = recvfrom(sockfd_in, buffer, BUFLEN, 0, (struct sockaddr *) &incoming, &ilen); if(recvlen < 0) { perror("something went wrong / incoming\n"); exit(-1); } strcpy(msg, buffer); buflen = strlen(msg); sentlen = ath_sendto(sfd, &btpinfo, &addrnwh, &nwh, buflen, msg, &selpv2, &depv); if(sentlen == E_ERR) { perror("Failed to send network header packet.\n"); exit(-1); } } UPDATE: my main file, starting either threads or processes (fork) int main(void) { port_config pConfig; memset(&pConfig, 0, sizeof(pConfig)); pConfig.inPort = 2002; pConfig.outPort = 2003; pid_t retval = fork(); if(retval == 0) { // child process pc2wsuThread((void *) &pConfig); } else if (retval < 0) { perror("fork not successful\n"); } else { //
point about the behavior of the Unix (socket API) connect() system call when it is interrupted by a signal. It points out how obscure the Single Unix Specification is, and notes that many existing
Select Interrupted System Call
Unix implementations seem to have f*cked this up somehow. The question is this:
Interrupted System Call (code=4)
if a blocking connect() (on a blocking stream socket, that is) is interrupted by a signal, returning EINTR, in what connect interrupted system call state is the socket left, and is it permissible to restart the system call? What happens if a second connect() with the same arguments is attempted immediately after one failed with EINTR? http://stackoverflow.com/questions/6030310/c-interrupted-system-call-fork-vs-thread The reference for connect() (hereafter, “the Spec”) is part of the Open Group's Single Unix Specification, version3 (note: you may need to register to read this; see also here). Here is the relevant part of it: If the initiating socket is connection-mode, then connect() shall attempt to establish a connection to the address specified by the address argument. If the connection cannot be established immediately http://www.madore.org/~david/computers/connect-intr.html and O_NONBLOCK is not set for the file descriptor for the socket, connect() shall block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() shall fail and the connection attempt shall be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set connect() to [EINTR], but the connection request shall not be aborted, and the connection shall be established asynchronously. If the connection cannot be established immediately and O_NONBLOCK is set for the file descriptor for the socket, connect() shall fail and set errno to [EINPROGRESS], but the connection request shall not be aborted, and the connection shall be established asynchronously. Subsequent calls to connect() for the same socket, before the connection is established, shall fail and set errno to [EALREADY]. When the connection has been established asynchronously, select() and poll() shall indicate that the file descriptor for the socket is ready for writing. Later on, when listing possible error codes for connect(), the Spec mentions: The connect() function shall fail if: […] [EALREADY] A connection request
Sign in Pricing Blog Support Search GitHub This repository Watch 28 Star 443 Fork 68 pebbe/zmq4 Code Issues 11 Pull https://github.com/pebbe/zmq4/issues/17 requests 0 Projects 0 Wiki Pulse Graphs New issue Getting "interrupted system call" (EINTR) on socket.RecvMessage() #17 Closed veegee opened this Issue Jul 25, 2014 · 12 comments Projects None yet Labels None yet Milestone No milestone Assignees No one assigned 4 participants veegee commented Jul 25, 2014 This bug report is posted interrupted system as recommended by the good people who have replied to my question here: https://groups.google.com/forum/#!topic/Golang-nuts/TeZwtP6z98w socket.RecvMessage() is getting interrupted with EINTR for some reason and according to the golang-nuts replies, this should be hidden from the user and automatically retried. Owner pebbe commented Jul 25, 2014 The error comes from the underlying C library, and is reported interrupted system call for you to handle. This is no bug. pebbe closed this Jul 25, 2014 tchap commented Jul 25, 2014 Yeah, that is how ZeroMQ works, but the thing is that in Go you want to use os.Signal, I don't remember a scenario where I would actually want to get EINTR from ZeroMQ. To me it looks like an interesting idea to actually ignore it and let people interested in it use os.Signal... pebbe reopened this Jul 25, 2014 Owner pebbe commented Jul 25, 2014 This issue has come up before. I don't see how I can decide how errors from ZeroMQ should be handled. Retrying on some error? When? How soon, and how often? In what circumstances? I don't know. What about different platforms? ZeroMQ has its own signal handling, that you can't catch in Go. See interrupt.go in the examples directory. Any suggestion welcome. I won't change this thing until I fully understand how and why it should be changed, and it should not i