[Bug 3277] New: [Feature req] "I couldn't do something you asked" warning

[bugzilla-daemon at dp3.samba.org]

https://bugzilla.samba.org/show_bug.cgi?id=3277

           Summary: [Feature req] "I couldn't do something you asked"
                    warning
           Product: rsync
           Version: 2.6.7
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: foner-rsync-bugzilla at media.mit.edu
         QAContact: rsync-qa at samba.org


I've recently been burned a couple of times by trying to copy filesystems with
--numeric-id and forgetting to do it as root.  The transfer succeeds just fine,
but of course the owner/group etc info can't be set, and this was
-particularly- easy to overlook because the same users (mostly) existed at both
ends, but with different UIDs, so it's easy to miss that something went wrong
because mostly you see what looks like "correct" output from ls & friends, but
is actually wrong because some of the UIDs weren't set, etc.  (This was
actually what I was mostly doing with your recent file-attr-restore script...)

Even though I was running with -v, I don't recall seeing any errors emitted
when this happened.  I'm wondering whether it would be a good idea to create an
option to make this much more obvious, so the cautious among us can set it by
default in aliases & scripts & whatnot and hence be warned when we're about to
make an annoying-to-fix mistake; it would also make it less critical to
carefully scan for these hard-to-notice failures---after all, rsync is supposed
to -save- us from that sort of thing...

Just enabling it with excessive verbosity is probably not the right thing,
since it'd get lost in the noise, and most people probably don't run at high
verbosities if they're not -already- debugging something.  I'm of mixed
opinions about whether the behavior should be a default, since it could be
irritating to see thousands of "couldn't set uid/gid" messages if you're okay
with not running as root.  If the option is enabled, a warning should
definitely be emitted at the end of the run (where it's not buried) that
something went wrong (and probably the exit status should change).  And perhaps
there should be another option that emits a warning for each file?  Or
something like --warn-me=none,end,all or something like that.

There are probably other things besides uid/gid that might benefit from this
(tiemstamps? ACLs?), but I fear either a huge number of warnings if they're all
enabled, or the hair of a warning bitmask ("tell me about UID/GID, but not
about problems setting permissions") or something.

If this looks like the sort of thing that might be better hashed out on the
list, I can forward this there instead; let me know.

Thanks!


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