On 04/12/2012 03:00 PM, Zulfiqar Malik wrote:
I am actually using libssh2_channel_write. I am basically just doing a cd <somedir> and then reading the output. The cd finishes and yet I am stuck in my loop since I never receive an EOF.
Can you paste some code? I'm not clear on what you mean here. Matt
I can use waitsocket. The Sleep is just test code. waitsocket doesn't imrpove the situation. On Thu, Apr 12, 2012 at 11:25 AM, Matthew Booth <[email protected] <mailto:[email protected]>> wrote: On 04/11/2012 05:55 PM, Zulfiqar Malik wrote: I am trying to write a very small shell client for some automation related things and am running into problems with libssh2_channel_read. Here are the two scenarios (application has to be single threaded.): 1. Blocking mode: libssh2_channel_read blocks if there's no data and never returns. Its impossible to use this function reliably. 2. Non-blocking mode: libssh2_channel_read doesn't block but keeps on returning -37 (LIBSSH2_ERROR_EAGAIN) and I end up with essentially the same problem i.e. stuck in an infinite loop. To top it off libssh2_channel_eof doesn't work and always returns 0. You don't say what's happening at the other end. Can we assuming it's something like: libssh2_channel_exec(channel, "cat foo"); and that you want to exit when the contents of foo have been returned? Is is possible, for example, that your channel is not returning eof because it isn't eof? I don't know what's wrong or what needs to be done but I cannot seem to find a way through this problem. I have tried libssh2 v 1.3.1 and the latest one 1.4.1 with the same result. Given below is my readOutput method which reads the output: for (;;count++) { /* loop until we block */ int rc; do { char buffer[1024]; rc = libssh2_channel_read(channel, buffer, sizeof(buffer)); if (rc > 0) { bytecount += rc; buffer[rc] = '\0'; Probably not related, but ^^^ corrupts the stack if libssh2_channel_read returns a full buffer. If you're going to explicitly null terminate the buffer, you need: rc = libssh2_channel_read(channel, buffer, sizeof(buffer) - 1); fprintf(stderr, "%s", buffer); count = 0; } else { if (rc != LIBSSH2_ERROR_EAGAIN) fprintf(stderr, "libssh2_channel_read returned %d\n", rc); } if (libssh2_channel_eof(channel)) { rc = 0; break; } } while(rc > 0); //::Sleep(3); /* this is due to blocking that would occur otherwise so we loop on this condition */ if(rc == LIBSSH2_ERROR_EAGAIN) { ::Sleep(5); //waitsocket(sock, sshSession); I'm assuming this references something like the waitsocket() example at http://www.libssh2.org/__examples/ssh2_exec.html <http://www.libssh2.org/examples/ssh2_exec.html>. Why the sleep instead? } else break; } Matt -- Matthew Booth, RHCA, RHCSS Red Hat Engineering, Virtualisation Team GPG ID: D33C3490 GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490 -- Regards, Zulfiqar Inayat Malik. _______________________________________________ libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
-- Matthew Booth, RHCA, RHCSS Red Hat Engineering, Virtualisation Team GPG ID: D33C3490 GPG FPR: 3733 612D 2D05 5458 8A8A 1600 3441 EA19 D33C 3490 _______________________________________________ libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
