Hello Edward, thanks a lot ... this resembles very much to what I am experiencing ... :-)
A nice weekend, Nick 2012/4/29 Edward Z. Yang <ezy...@mit.edu> > Hello Nick, > > The GHC runtime system uses alarm signals for a variety of purposes, > and part of this means that your code needs to properly handle > EINTR. Please see: > http://hackage.haskell.org/trac/ghc/wiki/Commentary/Rts/Signals > for more information. > > Cheers, > Edward > > Excerpts from Nick Rudnick's message of Sat Apr 28 07:21:30 -0400 2012: > > Dear all, > > > > after noticing problems with libssh2, and trying to fix this myself, I > ran > > into a strange experience which I wish to get an explanation for. > > > > After compiling an OpenSSH server and a raw C libssh2 (for comparison) > with > > debug messaging, I with support of the libssh2 community was able to > trace > > the problem back to a call to poll(3) in > session.c::_libssh2_wait_socket(), > > > > rc = poll(sockets, 1, has_timeout?ms_to_next: -1); > > > > where sockets consists of a single socket, session->socket_fd. > > > > This is roughly a polling with timeout for the connection – and, with the > > Haskell FFI, an > > > > error 4 / EINTR / Interrupted system call > > > > is thrown, and I was explained that this probably is caused by another > > signal of the same code unit. Not finding anything, I at the end extended > > libssh2 by a function, > > > > LIBSSH2_API void libssh2_test(void){ > > struct sockaddr_in sin; > > LIBSSH2_SESSION *session; > > const char *fingerprint; > > LIBSSH2_CHANNEL *channel; > > const unsigned long hostaddr= htonl(0x7F000001); > > const char *username= "i"; > > const char *keyfile1="/home/i/.ssh/id_rsa.pub"; > > const char *keyfile2="/home/i/.ssh/id_rsa"; > > const char *password= "D0r1nha23"; > > int got= 0; > > int sock= socket(AF_INET, SOCK_STREAM, 0); > > sin.sin_family= AF_INET; > > sin.sin_port= htons(22); > > sin.sin_addr.s_addr= hostaddr; > > if(connect( sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in) > > ) != 0 ) { > > fprintf(stderr, "failed to connect!\n"); > > return; > > } > > session= libssh2_session_init(); > > libssh2_trace(session,~0); > > if(libssh2_session_handshake(session, sock)) { > > _libssh2_debug(session, LIBSSH2_TRACE_TRANS > > , "Failure establishing SSH session" ); > > return; > > } > > fingerprint= libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1); > > libssh2_userauth_list(session, username, strlen(username)); // ?? > > if(libssh2_userauth_publickey_fromfile( session > > , username > > , keyfile1 > > , keyfile2 > > , password )) { > > _libssh2_debug(session, LIBSSH2_TRACE_TRANS > > , "\tAuthentication by public key failed!" ); > > return; > > } else { > > _libssh2_debug( session, LIBSSH2_TRACE_TRANS > > , "\tAuthentication by public key succeeded." ); > > if(!(channel= libssh2_channel_open_session(session))) { > > _libssh2_debug( session, LIBSSH2_TRACE_TRANS > > , "Unable to open a session" ); > > return; > > } else { > > libssh2_channel_setenv(channel, "FOO", "bar"); > > if(libssh2_channel_request_pty(channel, "vanilla")) { > > _libssh2_debug( session, LIBSSH2_TRACE_TRANS > > , "Failed requesting pty" ); > > } else { > > if(libssh2_channel_shell(channel)) { > > _libssh2_debug( session, LIBSSH2_TRACE_TRANS > > , "Unable to request shell on allocated pty" ); > > } else { > > if(channel){ > > libssh2_channel_free(channel); > > channel= NULL; > > } > > } > > } > > } > > } > > libssh2_session_disconnect( session > > , "Normal Shutdown, Thank you for playing" ); > > libssh2_session_free(session); > > close(sock); > > libssh2_exit(); > > return; > > } > > > > and called it by > > > > foreign import ccall unsafe "libssh2_test" > > libssh2Test:: IO () > > > > as well as > > > > {# context lib="ssh2" prefix="libssh2" #} > > {# fun test as test { } -> `()' #} > > > > With both approaches, I still got the same EINTR error, while coalling > > libssh2_test() from C works completely flawless. > > > > Is it possible that an interfering signal comes from the FFI? If yes, is > > there a workaround? > > > > Grateful for any kind of enlightenment... :-) > > > > Thanks a lot in advance, Nick >
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