On Fri, 3 Mar 2000, Paul Hoffman wrote:

>How many characters are allowed in user names and group names? And where 
>could I have found this information in the man pages? :-)

I don't believe there is an actual limit on the length of user and group
names in /etc/passwd and /etc/group (or the corresponding NIS maps).
And all the implementations of get{pw|gr}xxx return pointers of
a buffer, so there's no problem there.

There is a restriction with [wu]tmp, which has a fixed field for the username
(UT_NAMESIZE, defined as 8 in utmp.h).  And sod knows how many programs
use fixed buffers of UT_NAMESIZE+1, and how many of those don't bother to
use strncpy!  So if you put longer usernames in /etc/passwd, at best they're
going to get truncated in some places and not others, and at worst you're
going to get buffer overruns all over the place.


Roger

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Roger Brooks (Systems Programmer),          |  Email: R.S.Brooks@liv.ac.uk
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