Date: Wed, 22 Jun 2016 12:31:51 -0400 From: Rich Felker <dalias@...c.org> To: Matthew Fernandez <matthew.fernandez@...ta.com.au> Cc: musl@...ts.openwall.com Subject: Re: Undetected failures in getdomainname 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. > 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. Rich
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