Re: [libvirt] [PATCH]virsh: track alias option and improve error message when option duplicate its alias

-----Original Message----- From: Peter Krempa [mailto:pkrempa@redhat.com] Sent: Wednesday, October 30, 2013 10:04 PM To: Eric Blake; Chen Hanxiao; libvir-list(a)redhat.com Subject: Re: [libvirt] [PATCH]virsh: track alias option and improve error message when option duplicate its alias On 10/30/13 14:59, Eric Blake wrote: > On 10/30/2013 07:41 AM, Peter Krempa wrote: > >>> if ((*opts_seen & (1 << i)) && opt->type != VSH_OT_ARGV) { >>> - vshError(ctl, _("option --%s already seen"), name); >>> - goto cleanup; >>> + if ((*opts_seen & (1 << (i - 1)))) { >>> + vshError(ctl, _("option '--%s' duplicates its alias '--%s'"), >>> + cmd->opts[i].name, cmd->opts[i-1].name); >> >> This is not right. This code depends on the aliased option being right >> before the target option in the array describing the options. If you >> move the options in the array around you may get strange error messages. > > We already have a check baked into vshCmddefOptParse that guarantees > that all alias options appear in the list earlier than what the alias > expands to, so the rest of the code base is free to rely on that. > >> >> The idea is good, but you need to make sure that the code doesn't depend >> on ordering of the options in the array. > > I haven't looked closely at the patch, but we CAN depend on the order of > options within the array. Either way, offset of "-1" to the current option can't be guaranteed in case we have for example multiple aliases for the same main command or just put some in between, when the aliases will be before the command but not _RIGHT_ before. (I actually tried it.)

Peter