Date: Thu, 23 Jun 2016 10:17:06 +1000 From: Matthew Fernandez <matthew.fernandez@...ta.com.au> To: Rich Felker <dalias@...c.org> CC: <musl@...ts.openwall.com> Subject: Re: Undetected failures in getdomainname On 23/06/16 02:31, Rich Felker wrote: > On Wed, Jun 22, 2016 at 06:15:25PM +1000, Matthew Fernandez wrote: >> Hi all, >> >> In the tip at time of writing >> (6cec7bc57f599f43f4041cec2093e3c9231dbaab) there are a couple of >> syscalls that are implemented by calling uname, notably gethostname >> and getdomainname. In gethostname, the return value of uname is >> checked and the code returns early if uname fails. However, in >> getdomainname the return value of uname is ignored. I think it >> should be following the same pattern as gethostname. Is this >> correct? > > In practice I don't think the difference matters unless someone has > hooked uname to fail (e.g. seccomp or perhaps LSMs), since the syscall > itself can't fail. It wouldn't hurt to make them consistent though. Good point. I hadn't factored in that the only uname failure case is when the buffer is invalid, which can never occur when called from getdomainname. >> Also, gethostname rolls its own strcpy, while getdomainname just >> calls strcpy. However, maybe there is a good reason for this. > > As written the behaviors are different. gethostname truncates while > getdomainname returns an error on excessive length. The former is > mandated by POSIX; the latter is documented (but not clearly specified > as a requirement vs just being an optional failure) in the Linux man > page, since getdomainname is not a standard function. Ah, nice. Learned something new today :) Thanks, Rich. ________________________________ The information in this e-mail may be confidential and subject to legal professional privilege and/or copyright. National ICT Australia Limited accepts no liability for any damage caused by this email or its attachments.
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