Messages in this thread |  | | From | Daniel Kabs <> | Subject | Re: Problem with unix sockets: SOCK_DGRAM ignores MSG_TRUNC | Date | Wed, 7 Feb 2007 10:31:57 +0100 |
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On Monday 05 February 2007 01:52, David Miller wrote: > What UDP is doing is different, it's returning the full packet length > when the packet is larger then the given buffer size, but it does this > irregardless of whether you set MSG_TRUNC in the recvmsg() passed-in > flags. UDP itself sets the MSG_TRUNC flag when it detects this > situation.
I hope that I am researching the appropriate kernel source tree, but if I am not mistaken, this behaviour was introduced with change 1.66 according to bitkeeper: http://linux.bkbits.net:8080/linux-2.6/net/ipv4/udp.c?PAGE=history
I think the bitkeeper comment on that change (1.66) is misleading: "[UDP]: Return true length if user specifies MSG_TRUNC."
As you said, this is wrong. The true length is returned, regardless whether the user specified MSG_TRUNC.
Exploring this topic I learned a lot about browsing and reading kernel source code, e.g. that commit statements have to be taken with a grain of salt :-)
Cheers Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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