Re: [PATCH] libxl: Be more careful with error handling in libxl__dm_runas_helper()

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 12/01/2015 09:38 AM, Ian Campbell wrote:
> On Mon, 2015-11-30 at 13:24 -0500, Boris Ostrovsky wrote:
>>       root@orochi-c> cat /etc/redhat-release
>>       Fedora release 20 (Heisenbug)
>>       root@orochi-c> ./a.out foobar
>>       s = 2 errno = 2 result = (nil)
>>       getpwnam_r: No such file or directory
>>       root@orochi-c>
>>
>> which does look like a bug in F20 since the code above is taken from man
>> pages' EXAMPLE and doesn't look like it works as intended (which was to
>> produce "Not found" string)
> https://bugzilla.redhat.com/show_bug.cgi?id=988068 seems related (although
> is blaming "sssd" rather than glibc it seems).

This too:

https://sourceware.org/bugzilla/show_bug.cgi?id=17922

They claim that glibc v2.20 fails (i.e. returns non-zero/ENOENT) but in 
my case on fedora 21 with 2.20-8 I get 0. My "failing" fedora 20 uses 2.18.

I don't know whether it's really a bug in glibc since Linux man pages do 
allow ENOENT (and some other codes) to indicate absence of entry. (But 
then if this is not a bug in glibc then there is a bug in man pages' 
example code).

In any case, I think we need to account for this in libxl.

-boris