Re: [libvirt] [PATCH] macvtap: Fix error return values to -1 instead of 1

On 10/27/2011 05:57 PM, Roopa Prabhu wrote: >> > Also, looks like no where else in libvirt code we return errno. We only > print errno but always return -1. And the -ETIMEDOUT case in macvtap is an > exception, cause the upper layer requires the cause of this particular > error. We have a few places that return -1 on most errors, 0 on normal success, and -2 on timeout; that is, the < 0 check can filter out all non-success, but callers that care about the particular failure can compare against -1. If all errors can map to errno, we do have some examples of API that return -errno; but those tend to be lower level API (lots in util/util.c, not so many elsewhere); it tends to be easier to return -1 and document if errno is set to a sane value on failure. > I don't mind changing everything to errno. But that seems to be not the > convention. And I cant find a clean way to not return -ETIMEDOUT. I can > however return status of the command in an argument and return -1 for the > ETIMEDOUT case. I will do that unless you have other suggestions. Thanks. Returning -1 and -errno in the same function doesn't work (since -1 would be ambiguous with EACCES, on some systems), but returning -1 vs. -2 to distinguish timeout from normal errors is fine.