rgw: clarify the error message when trying to create an existed user

[zhuangzeqiang]

Modify the error message when trying to create an existed user to indicate which of uid, email or key actually causes the conflict.

Signed-off-by: Zeqiang Zhuang zhuang.zeqiang@h3c.com

[zhuangzeqiang]

when creating a user with existing email or key,the error message is "user:xxx exists"

eg.execute " radosgw-admin user create --uid=tid --display-name=tname --email=temail", user tid is successfully created.
execute "radosgw-admin user create --uid=testid --display-name=testname --email=temail",failed with the error message "could not create user: unable to create user, user: tid exists"

We cannot tell which actually causes the conflict (uid, email or key), so I believe it is necessary to print more detailed error messages.

[loic-bot]

SUCCESS: http://jenkins.ceph.dachary.org/job/ceph/7782/

• SUCCESS http://jenkins.ceph.dachary.org/job/ceph/LABELS=centos-7&&x86_64/7782/
• SUCCESS http://jenkins.ceph.dachary.org/job/ceph/LABELS=ubuntu-14.04&&x86_64/7782/

[shinobu-x]

👍

[loic-bot]

SUCCESS: http://jenkins.ceph.dachary.org/job/ceph/7816/

• SUCCESS http://jenkins.ceph.dachary.org/job/ceph/LABELS=centos-7&&x86_64/7816/

[yehudasa]

@zhuangzeqiang looking good, I'll need to get it through testing before merging it

[zhuangzeqiang]

@yehudasa，thx，and I have another question to ask you.
In the following code，can we take uid instead of email ? i think uid is the most important index for user.what do you think ?

/*
if (!op_state.exclusive &&
(user_email.empty() || old_info.user_email == user_email) &&
old_info.display_name == display_name) {
return execute_modify(op_state, err_msg);
}
*/

[yehudasa]

@zhuangzeqiang I'm not sure about the context of this code, don't we already know that the uid is the same at that point?

[zhuangzeqiang]

@yehudasa can it to be merged