(fwd from uke@jeremy.org) thanks and patch

[Dave Dykstra]

Wouldn't encrypting the file with gpg change the timestamp as well as the
size, so rsync would still copy the file?

- Dave Dykstra

On Tue, Mar 19, 2002 at 08:21:36AM -0800, jeremy bornstein wrote:
> Martin,
> 
> The encryption program I'm using, gpg, includes a small bit of header
> information with the encrypted file, thus changing the size.  Gpg is a
> public key encryption program which at least includes the numeric key
> ID of the recipient's key.  Since folks can have many keys, this is
> useful information to have with each bit of data.  It might be
> possible to strip this information off, but then the whole process
> would be version-sensitive and thus error-prone, which is not what I'd
> like in a backup program!
> 
> (There's much more info at <URL:http://www.gnupg.org/> if you like.)
> 
> I suspect I'm not the only one who would be interested in using this
> feature for this purpose, but of course I can't say for certain.
> 
> Best,
> 
> -jeremy
> 
> On Tue, Mar 19, 2002 at 06:11:44AM +1100, Martin Pool wrote:
> > Jeremy, 
> > 
> > I'm glad you like rsync.
> > 
> > Why does your encryption program not produce a file of the same size
> > every time it is run on the same input?  I can see what the patch
> > does, but I'm having a bit of trouble understanding whether it would
> > be generally useful.
> > 
> > -- 
> > Martin 
> 
> > Date: Sun, 17 Mar 2002 06:31:40 -0800
> > From: jeremy bornstein <uke at jeremy.org>
> > To: Martin Pool <mbp at sourcefrog.net>
> > Subject: thanks and patch
> > 
> > Greetings, and thanks for all of your work on the wonderful rsync!
> > 
> > I recently had the need to transfer files only with different mod
> > dates (and to *not* transfer them based on file size differences).
> > This is because I'm backing up files remotely on an untrusted machine,
> > so I'm encrypting them with gpg before transfer.  I discovered that
> > rsync didn't already have a --date-only flag, so I added one and am
> > enclosing the diffs in case you (as I hope) decide to include this
> > option in future releases.
> > 
> > Again, thanks!
> > 
> > Best Regards,
> > Jeremy Bornstein
> 
> > diff rsync-2.5.4/README rsync-2.5.4-patched/README
> > 70a71
> > >      --date-only             only use modification date when determining if a file should be transferred
> > Common subdirectories: rsync-2.5.4/doc and rsync-2.5.4-patched/doc
> > diff rsync-2.5.4/generator.c rsync-2.5.4-patched/generator.c
> > 39a40
> > > extern int date_only;
> > 50a52,56
> > > 	if (date_only) {
> > > 		return (cmp_modtime(st->st_mtime,file->modtime) == 0);
> > > 	}
> > > 
> > > 
> > Common subdirectories: rsync-2.5.4/lib and rsync-2.5.4-patched/lib
> > diff rsync-2.5.4/options.c rsync-2.5.4-patched/options.c
> > 64a65
> > > int date_only=0;
> > 223a225
> > >   rprintf(F,"     --date-only             only use modification date when determining if a file should be transferred\n");
> > 265c267
> > <       OPT_LOG_FORMAT, OPT_PASSWORD_FILE, OPT_SIZE_ONLY, OPT_ADDRESS,
> > ---
> > >       OPT_LOG_FORMAT, OPT_PASSWORD_FILE, OPT_SIZE_ONLY, OPT_DATE_ONLY, OPT_ADDRESS,
> > 278a281
> > >   {"date-only",        0,  POPT_ARG_NONE,   &date_only},
> > 704a708,710
> > > 
> > > 	if (date_only)
> > > 		args[ac++] = "--date-only";
> > Common subdirectories: rsync-2.5.4/packaging and rsync-2.5.4-patched/packaging
> > Common subdirectories: rsync-2.5.4/popt and rsync-2.5.4-patched/popt
> > diff rsync-2.5.4/rsync.1 rsync-2.5.4-patched/rsync.1
> > 289a290
> > >      --date-only             only use modification date when determining if a file should be transferred
> > 363a365,371
> > > .IP 
> > > .IP "\fB--date-only\fP" 
> > > Normally rsync will skip any files that are
> > > already the same length and have the same time-stamp\&. With the
> > > --date-only option files will be skipped if they have the same timestamp,
> > > regardless of size\&. This may be useful when the remote files have passed
> > > through a size-changing filter, e.g. for encryption\&.
> > diff rsync-2.5.4/rsync.yo rsync-2.5.4-patched/rsync.yo
> > 260a261
> > >      --date-only             only use modification date when determining if a file should be transferred
> > 326a328,333
> > > 
> > > dit(bf(--date-only)) Normally rsync will skip any files that are
> > > already the same length and have the same time-stamp. With the
> > > --date-only option files will be skipped if they have the same
> > > timestamp, regardless of size. This may be useful when the remote
> > > files have passed through a size-changing filter, e.g. for encryption.
> > Common subdirectories: rsync-2.5.4/testhelp and rsync-2.5.4-patched/testhelp
> > Common subdirectories: rsync-2.5.4/testsuite and rsync-2.5.4-patched/testsuite
> > Common subdirectories: rsync-2.5.4/zlib and rsync-2.5.4-patched/zlib
> 
> 
> 
> -- 
>                    jeremy bornstein <jeremy at thinger.org>
>                                     -*-
>       to be free of all authority, of your own and that of another, is
>        to die to everything of yesterday, so that your mind is always
>          fresh, always young, innocent, full of vigour and passion.
>                 [j. krishnamurti, _freedom from the known_]
>                                     -*-
>                              http://jeremy.org/
> 
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