-*- indented-text -*-

BUGS ---------------------------------------------------------------

rsync-url barfs on upload

rsync foo rsync://localhost/transfer/

Fix the parser.

There seems to be a bug with hardlinks

mbp/2 build$ ls -l /tmp/a /tmp/b -i

/tmp/a:

total 32

2568307 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a1

2568307 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a2

2568307 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a3

2568310 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a4

2568310 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a5

2568310 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b1

2568310 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b2

2568310 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b3

/tmp/b:

total 32

2568309 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a1

2568309 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a2

2568309 -rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a3

2568311 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a4

2568311 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a5

2568311 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b1

2568311 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b2

2568311 -rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b3

mbp/2 build$ rm -r /tmp/b && ./rsync -avH /tmp/a/ /tmp/b

building file list ... done

created directory /tmp/b

./

a1

a4

a2 => a1

a3 => a2

wrote 350 bytes read 52 bytes 804.00 bytes/sec

total size is 232 speedup is 0.58

mbp/2 build$ rm -r /tmp/b

mbp/2 build$ ls -l /tmp/b

ls: /tmp/b: No such file or directory

mbp/2 build$ rm -r /tmp/b && ./rsync -avH /tmp/a/ /tmp/b

rm: cannot remove `/tmp/b': No such file or directory

mbp/2 build$ rm -f -r /tmp/b && ./rsync -avH /tmp/a/ /tmp/b

building file list ... done

created directory /tmp/b

./

a1

a4

a2 => a1

a3 => a2

wrote 350 bytes read 52 bytes 804.00 bytes/sec

total size is 232 speedup is 0.58

mbp/2 build$ ls -l /tmp/b

total 32

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a1

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a2

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a3

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a4

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a5

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b1

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b2

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b3

mbp/2 build$ ls -l /tmp/a

total 32

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a1

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a2

-rw-rw-r-- 3 mbp mbp 29 Mar 25 17:30 a3

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a4

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 a5

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b1

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b2

-rw-rw-r-- 5 mbp mbp 29 Mar 25 17:30 b3

Progress indicator can produce corrupt output when transferring directories:

main/binary-arm/

main/binary-arm/admin/

main/binary-arm/base/

main/binary-arm/comm/8.56kB/s 0:00:52

main/binary-arm/devel/

main/binary-arm/doc/

main/binary-arm/editors/

main/binary-arm/electronics/s 0:00:53

main/binary-arm/games/

main/binary-arm/graphics/

main/binary-arm/hamradio/

main/binary-arm/interpreters/

main/binary-arm/libs/6.61kB/s 0:00:54

main/binary-arm/mail/

main/binary-arm/math/

main/binary-arm/misc/

lchmod

I don't think we handle this properly on systems that don't have the

call. Are there any such?

Cross-test versions

Part of the regression suite should be making sure that we don't

break backwards compatibility: old clients vs new servers and so

on. Ideally we would test the cross product of versions.

It might be sufficient to test downloads from well-known public

rsync servers running different versions of rsync. This will give

some testing and also be the most common case for having different

versions and not being able to upgrade.

--no-blocking-io might be broken

in the same way as --no-whole-file; somebody needs to check.

Do not rely on having a group called "nobody"

http://www.linuxbase.org/spec/refspecs/LSB_1.1.0/gLSB/usernames.html

On Debian it's "nogroup"

DAEMON --------------------------------------------------------------

server-imposed bandwidth limits

rsyncd over ssh

There are already some patches to do this.

BitKeeper uses a server whose login shell is set to bkd. That's

probably a reasonable approach.

FEATURES ------------------------------------------------------------

--dry-run is too dry

Mark Santcroos points out that -n fails to list files which have

only metadata changes, though it probably should.

There may be a Debian bug about this as well.

use chroot

If the platform doesn't support it, then don't even try.

If running as non-root, then don't fail, just give a warning.

(There was a thread about this a while ago?)

http://lists.samba.org/pipermail/rsync/2001-August/thread.html

http://lists.samba.org/pipermail/rsync/2001-September/thread.html

supplementary groups

Perhaps allow supplementary groups to be specified in rsyncd.conf;

then make the first one the primary gid and all the rest be

supplementary gids.

File list structure in memory

Rather than one big array, perhaps have a tree in memory mirroring

the directory tree.

This might make sorting much faster! (I'm not sure it's a big CPU

problem, mind you.)

It might also reduce memory use in storing repeated directory names

-- again I'm not sure this is a problem.

Performance

Traverse just one directory at a time. Tridge says it's possible.

At the moment rsync reads the whole file list into memory at the

start, which makes us use a lot of memory and also not pipeline

network access as much as we could.

Handling duplicate names

We need to be careful of duplicate names getting into the file list.

See clean_flist(). This could happen if multiple arguments include

the same file. Bad.

I think duplicates are only a problem if they're both flowing

through the pipeline at the same time. For example we might have

updated the first occurrence after reading the checksums for the

second. So possibly we just need to make sure that we don't have

both in the pipeline at the same time.

Possibly if we did one directory at a time that would be sufficient.

Alternatively we could pre-process the arguments to make sure no

duplicates will ever be inserted. There could be some bad cases

when we're collapsing symlinks.

We could have a hash table.

The root of the problem is that we do not want more than one file

list entry referring to the same file. At first glance there are

several ways this could happen: symlinks, hardlinks, and repeated

names on the command line.

If names are repeated on the command line, they may be present in

different forms, perhaps by traversing directory paths in different

ways, traversing paths including symlinks. Also we need to allow

for expansion of globs by rsync.

At the moment, clean_flist() requires having the entire file list in

memory. Duplicate names are detected just by a string comparison.

We don't need to worry about hard links causing duplicates because

files are never updated in place. Similarly for symlinks.

I think even if we're using a different symlink mode we don't need

to worry.

Unless we're really clever this will introduce a protocol

incompatibility, so we need to be able to accept the old format as

well.

Memory accounting

At exit, show how much memory was used for the file list, etc.

Also we do a wierd exponential-growth allocation in flist.c. I'm

not sure this makes sense with modern mallocs. At any rate it will

make us allocate a huge amount of memory for large file lists.

Hard-link handling

At the moment hardlink handling is very expensive, so it's off by

default. It does not need to be so.

Since most of the solutions are rather intertwined with the file

list it is probably better to fix that first, although fixing

hardlinks is possibly simpler.

We can rule out hardlinked directories since they will probably

screw us up in all kinds of ways. They simply should not be used.

At the moment rsync only cares about hardlinks to regular files. I

guess you could also use them for sockets, devices and other beasts,

but I have not seen them.

When trying to reproduce hard links, we only need to worry about

files that have more than one name (nlinks>1 && !S_ISDIR).

The basic point of this is to discover alternate names that refer to

the same file. All operations, including creating the file and

writing modifications to it need only to be done for the first name.

For all later names, we just create the link and then leave it

alone.

If hard links are to be preserved:

Before the generator/receiver fork, the list of files is received

from the sender (recv_file_list), and a table for detecting hard

links is built.

The generator looks for hard links within the file list and does

not send checksums for them, though it does send other metadata.

The sender sends the device number and inode with file entries, so

that files are uniquely identified.

The receiver goes through and creates hard links (do_hard_links)

after all data has been written, but before directory permissions

are set.

At the moment device and inum are sent as 4-byte integers, which

will probably cause problems on large filesystems. On Linux the

kernel uses 64-bit ino_t's internally, and people will soon have

filesystems big enough to use them. We ought to follow NFS4 in

using 64-bit device and inode identification, perhaps with a

protocol version bump.

Once we've seen all the names for a particular file, we no longer

need to think about it and we can deallocate the memory.

We can also have the case where there are links to a file that are

not in the tree being transferred. There's nothing we can do about

that. Because we rename the destination into place after writing,

any hardlinks to the old file are always going to be orphaned. In

fact that is almost necessary because otherwise we'd get really

confused if we were generating checksums for one name of a file and

modifying another.

At the moment the code seems to make a whole second copy of the file

list, which seems unnecessary.

We should have a test case that exercises hard links. Since it

might be hard to compare ./tls output where the inodes change we

might need a little program to check whether several names refer to

the same file.

Handling IPv6 on old machines

The KAME IPv6 patch is nice in theory but has proved a bit of a

nightmare in practice. The basic idea of their patch is that rsync

is rewritten to use the new getaddrinfo()/getnameinfo() interface,

rather than gethostbyname()/gethostbyaddr() as in rsync 2.4.6.

Systems that don't have the new interface are handled by providing

our own implementation in lib/, which is selectively linked in.

The problem with this is that it is really hard to get right on

platforms that have a half-working implementation, so redefining

these functions clashes with system headers, and leaving them out

breaks. This affects at least OSF/1, RedHat 5, and Cobalt, which

are moderately improtant.

Perhaps the simplest solution would be to have two different files

implementing the same interface, and choose either the new or the

old API. This is probably necessary for systems that e.g. have

IPv6, but gethostbyaddr() can't handle it. The Linux manpage claims

this is currently the case.

In fact, our internal sockets interface (things like

open_socket_out(), etc) is much narrower than the getaddrinfo()

interface, and so probably simpler to get right. In addition, the

old code is known to work well on old machines.

We could drop the rather large lib/getaddrinfo files.

Other IPv6 stuff:

Implement suggestions from http://www.kame.net/newsletter/19980604/

and ftp://ftp.iij.ad.jp/pub/RFC/rfc2553.txt

If a host has multiple addresses, then listen try to connect to all

in order until we get through. (getaddrinfo may return multiple

addresses.) This is kind of implemented already.

Possibly also when starting as a server we may need to listen on

multiple passive addresses. This might be a bit harder, because we

may need to select on all of them. Hm.

Define a syntax for IPv6 literal addresses. Since they include

colons, they tend to break most naming systems, including ours.

Based on the HTTP IPv6 syntax, I think we should use

rsync://[::1]/foo/bar [::1]::bar

which should just take a small change to the parser code.

Errors

If we hang or get SIGINT, then explain where we were up to. Perhaps

have a static buffer that contains the current function name, or

some kind of description of what we were trying to do. This is a

little easier on people than needing to run strace/truss.

"The dungeon collapses! You are killed." Rather than "unexpected

eof" give a message that is more detailed if possible and also more

helpful.

If we get an error writing to a socket, then we should perhaps

continue trying to read to see if an error message comes across

explaining why the socket is closed. I'm not sure if this would

work, but it would certainly make our messages more helpful.

What happens if a directory is missing -x attributes. Do we lose

our load? (Debian #28416) Probably fixed now, but a test case would

be good.

File attributes

Device major/minor numbers should be at least 32 bits each. See

http://lists.samba.org/pipermail/rsync/2001-November/005357.html

Transfer ACLs. Need to think of a standard representation.

Probably better not to even try to convert between NT and POSIX.

Possibly can share some code with Samba.

Empty directories

With the current common --include '*/' --exclude '*' pattern, people

can end up with many empty directories. We might avoid this by

lazily creating such directories.

zlib

Perhaps don't use our own zlib.

Advantages:

- will automatically be up to date with bugfixes in zlib

- can leave it out for small rsync on e.g. recovery disks

- can use a shared library

- avoids people breaking rsync by trying to do this themselves and

messing up

Should we ship zlib for systems that don't have it, or require

people to install it separately?

Apparently this will make us incompatible with versions of rsync

that use the patched version of rsync. Probably the simplest way to

do this is to just disable gzip (with a warning) when talking to old

versions.

logging

Perhaps flush stdout after each filename, so that people trying to

monitor progress in a log file can do so more easily. See

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=48108

At the connections that just get a list of modules are not logged,

but they should be.

If a child of the rsync daemon dies with a signal, we should notice

that when we reap it and log a message.

Keep stderr and stdout properly separated (Debian #23626)

After we get the @RSYNCD greeting from the server, we know it's

version but we have not yet sent the command line, so we could just

remove the -z option if the server is too old.

For ssh invocation it's not so simple, because we actually use the

command line to start the remote process. However, we only actually

do compression in token.c, and we could therefore once we discover

the remote version emit an error if it's too old. I'm not sure if

that's a good tradeoff or not.

proxy authentication

Allow RSYNC_PROXY to be http://user:pass@proxy.foo:3128/, and do

HTTP Basic Proxy-Authentication.

Multiple schemes are possible, up to and including the insanity that

is NTLM, but Basic probably covers most cases.

SOCKS

Add --with-socks, and then perhaps a command-line option to put them

on or off. This might be more reliable than LD_PRELOAD hacks.

FAT support

rsync to a FAT partition on a Unix machine doesn't work very well at

the moment. I think we get errors about invalid filenames and

perhaps also trying to do atomic renames.

I guess the code to do this is currently #ifdef'd on Windows;

perhaps we ought to intelligently fall back to it on Unix too.

Better statistics:

<Rasmus> mbp: hey, how about an rsync option that just gives you the

summary without the list of files? And perhaps gives more

information like the number of new files, number of changed,

deleted, etc. ? <mbp> Rasmus: nice idea <mbp> there is --stats

<mbp> but at the moment it's very tridge-oriented <mbp> rather than

user-friendly <mbp> it would be nice to improve it <mbp> that would

also work well with --dryrun

TDB:

Rather than storing the file list in memory, store it in a TDB.

This *might* make memory usage lower while building the file list.

Hashtable lookup will mean files are not transmitted in order,

though... hm.

This would neatly eliminate one of the major post-fork shared data

structures.

chmod:

On 12 Mar 2002, Dave Dykstra <dwd@bell-labs.com> wrote: > If we

would add an option to do that functionality, I would vote for one >

that was more general which could mask off any set of permission bits

and > possibly add any set of bits. Perhaps a chmod-like syntax if it

could be > implemented simply.

I think that would be good too. For example, people uploading files

to a web server might like to say

rsync -avzP --chmod a+rX ./ sourcefrog.net:/home/www/sourcefrog/

Ideally the patch would implement as many of the gnu chmod semantics

as possible. I think the mode parser should be a separate function

that passes back something like (mask,set) description to the rest

of the program. For bonus points there would be a test case for the

parser.

Possibly also --chown

(Debian #23628)

--diff

Allow people to specify the diff command. (Might want to use wdiff,

gnudiff, etc.)

Just diff the temporary file with the destination file, and delete

the tmp file rather than moving it into place.

Interaction with --partial.

Security interactions with daemon mode?

(Suggestion from david.e.sewell)

Incorrect timestamps (Debian #100295)

A bit hard to believe, but apparently it happens.

Check "refuse options works"

We need a test case for this...

Was this broken when we changed to popt?

PERFORMANCE ----------------------------------------------------------

MD4 file_sum

If we're doing a local transfer, or using -W, then perhaps don't

send the file checksum. If we're doing a local transfer, then

calculating MD4 checksums uses 90% of CPU and is unlikely to be

useful.

Indeed for transfers over zlib or ssh we can also rely on the

transport to have quite strong protection against corruption.

Perhaps we should have an option to disable this, analogous to

--whole-file, although it would default to disabled. The file

checksum takes up a definite space in the protocol -- we can either

set it to 0, or perhaps just leave it out.

MD4

Perhaps borrow an assembler MD4 from someone?

Make sure we call MD4 with properly-sized blocks whenever possible

to avoid copying into the residue region?

String area code

Test whether this is actually faster than just using malloc(). If

it's not (anymore), throw it out.

PLATFORMS ------------------------------------------------------------

Win32

Don't detach, because this messes up --srvany.

http://sources.redhat.com/ml/cygwin/2001-08/msg00234.html

DEVELOPMENT ----------------------------------------------------------

Splint

Build rsync with SPLINT to try to find security holes. Add

annotations as necessary. Keep track of the number of warnings

found initially, and see how many of them are real bugs, or real

security bugs. Knowing the percentage of likely hits would be

really interesting for other projects.

Torture test

Something that just keeps running rsync continuously over a data set

likely to generate problems.

Cross-testing

Run current rsync versions against significant past releases.

Memory debugger

jra recommends Valgrind:

http://devel-home.kde.org/~sewardj/

Release script

Update spec files

Build tar file; upload

Send announcement to mailing list and c.o.l.a.

Make freshmeat announcement

Update web site

TESTING --------------------------------------------------------------

Cross-test versions

Part of the regression suite should be making sure that we don't

break backwards compatibility: old clients vs new servers and so on.

Ideally we would test both up and down from the current release to

all old versions.

We might need to omit broken old versions, or versions in which

particular functionality is broken

It might be sufficient to test downloads from well-known public

rsync servers running different versions of rsync. This will give

some testing and also be the most common case for having different

versions and not being able to upgrade.

Test on kernel source

Download all versions of kernel; unpack, sync between them. Also

sync between uncompressed tarballs. Compare directories after

transfer.

Use local mode; ssh; daemon; --whole-file and --no-whole-file.

Use awk to pull out the 'speedup' number for each transfer. Make

sure it is >= x.

Test large files

Sparse and non-sparse

Mutator program

Insert bytes, delete bytes, swap blocks, ...

configure option to enable dangerous tests

If tests are skipped, say why.

Test daemon feature to disallow particular options.

Pipe program that makes slow/jerky connections.

Versions of read() and write() that corrupt the stream, or abruptly

fail

Separate makefile target to run rough tests -- or perhaps just run

them every time?

Test "refuse options" works

What about for --recursive?

If you specify an unrecognized option here, you should get an error.

DOCUMENTATION --------------------------------------------------------

Update README

Keep list of open issues and todos on the web site

Update web site from CVS

Perhaps redo manual as SGML

The man page is getting rather large, and there is more information

that ought to be added.

TexInfo source is probably a dying format.

Linuxdoc looks like the most likely contender. I know DocBook is

favoured by some people, but it's so bloody verbose, even with emacs

support.

BUILD FARM -----------------------------------------------------------

Add machines

Cygwin (on different versions of Win32?)

HP-UX variants (via HP?)

SCO

LOGGING --------------------------------------------------------------

Perhaps flush stdout after each filename, so that people trying to

monitor progress in a log file can do so more easily. See

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=48108

At the connections that just get a list of modules are not logged,

but they should be.

If a child of the rsync daemon dies with a signal, we should notice

that when we reap it and log a message.

Keep stderr and stdout properly separated (Debian #23626)

Use a separate function for reporting errors; prefix it with

"rsync:" or "rsync(remote)", or perhaps even "rsync(local

generator): ".

verbose output

Indicate whether files are new, updated, or deleted

At end of transfer, show how many files were or were not transferred

correctly.

-vv

Explain *why* every file is transferred or not (e.g. "local mtime

123123 newer than 1283198")

debugging of daemon

Add an rsyncd.conf parameter to turn on debugging on the server.

NICE -----------------------------------------------------------------

--no-detach and --no-fork options

Very useful for debugging. Also good when running under a

daemon-monitoring process that tries to restart the service when the

parent exits.

hang/timeout friendliness

internationalization

Change to using gettext(). Probably need to ship this for platforms

that don't have it.

Solicit translations.

Does anyone care? Before we bother modifying the code, we ought to

get the manual translated first, because that's possibly more useful

and at any rate demonstrates desire.

rsyncsh

Write a small emulation of interactive ftp as a Pythonn program

that calls rsync. Commands such as "cd", "ls", "ls *.c" etc map

fairly directly into rsync commands: it just needs to remember the

current host, directory and so on. We can probably even do

completion of remote filenames.

RELATED PROJECTS -----------------------------------------------------

http://rsync.samba.org/rsync-and-debian/

rsyncable gzip patch

Exhaustive, tortuous testing

Cleanups?

rsyncsplit as alternative to real integration with gzip?

reverse rsync over HTTP Range

Goswin Brederlow suggested this on Debian; I think tridge and I

talked about it previous in relation to rproxy.