Date: Wed, 19 Mar 2003 11:30:02 +0200 From: Peter Pentchev <roam@ringlet.net> To: net@FreeBSD.org Cc: Tristan Goode <tgoode@iprimus.com.au> Subject: write(2) SIGPIPE on a closed socket? Message-ID: <20030319093002.GT468@straylight.oblivion.bg>
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[-- Attachment #1 --] Hi, In http://marc.theaimsgroup.com/?l=djbdns&m=104796742521473&w=2 and http://marc.theaimsgroup.com/?l=djbdns&m=104802936220297&w=2 Tristan Goode describes a weird problem on FreeBSD 4.5: a program (DJB's dnscache) getting a SIGPIPE when attempting to write to an incoming connection's socket. Presumably, the client closed the connection in the meantime, possibly due to a timeout; the funny part is that the ktrace's show the following sequence of events: line 320845: accept() returns fd 170 line 320875-325758: successive read()'s return data line 325784: a successful write() returns the full amount of data written line 325794-328586: more read()'s line 328612: another successful write() (repeat a few more times, exactly the same pattern) line 334354: the last successful write() line 334364-335002: more read()'s, all successful line 335028: another attempted write() line 335029: PSIG SIGPIPE The question: if the client closed the socket, shouldn't a write(2) return -1 with errno == EPIPE before sending a SIGPIPE? Does anyone know anything about problems with writing to closed sockets in FreeBSD 4.5 or such? A bzipped version of the tracefile is available at http://people.FreeBSD.org/~roam/dnscache-ktrace.txt.bz2 G'luck, Peter -- Peter Pentchev roam@ringlet.net roam@sbnd.net roam@FreeBSD.org PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553 because I didn't think of a good beginning of it. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+eDia7Ri2jRYZRVMRAgtHAKChd4gfAIaqX2vHBzcqohk85v75EwCfeiAX DvIjje7srzUoSkmNZCEcPqc= =wcwf -----END PGP SIGNATURE-----help
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