Messages in this thread | | | Date | Mon, 24 Mar 2008 10:43:30 +0000 | From | Samuel Thibault <> | Subject | Re: [PATCH,TRIVIAL] AF_UNIX, accept() and addrlen |
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David Miller, le Sun 23 Mar 2008 21:56:41 -0700, a écrit : > From: Samuel Thibault <samuel.thibault@ens-lyon.org> > Date: Sat, 8 Mar 2008 02:23:21 +0000 > > > Accept and getpeername are supposed to return the amount of bytes > > written in the returned address. However, on unnamed sockets, only > > sizeof(short) is returned, while a 0 is put in the sun_path member. > > This patch adds 1 for that additional byte. > > > > Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> > > This change isn't correct. It's the fact that the > length returned is sizeof(short) that tells the caller > that the unix socket is unnamed.
Mmm, where that is documented?
I can't find any details about that in SUS, and man 7 unix says
`If sun_path starts with a null byte ('' '), then it refers to the abstract namespace main- tained by the Unix protocol module.'
It doesn't talk about the size being only sizeof(short) (which I guess you meant sizeof(sa_family_t) actually).
> We zero out the sun_path[0] member just to be polite and tidy. > > You would break applications if you changed this, so > marking this patch as "trivial" is extremely premature.
See documentation above. If applications don't follow documentation, then they deserve breaking :)
Note also that on some (BSD-ish) systems, sockaddr_un contains a sun_len field, containing the length of the data, and thus on them accept and getpeername return more that sizeof(sa_family_t) as length (it actually returns 16). So such applications are really broken.
Samuel -- 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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