Fix false "downloaded bytes" information from getftp.

[wget] / NEWS

GNU Wget NEWS -- history of user-visible changes.

Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007, 2008, 2009 Free Software Foundation, Inc.
See the end for copying conditions.

Please send GNU Wget bug reports to <bug-wget@gnu.org>.
\f
* Changes in Wget 1.12

** Mailing list MOVED to bug-wget@gnu.org

** SECURITY FIX: It had been possible to trick Wget into accepting
SSL certificates that don't match the host name, through the trick of
embedding NUL characters into the certs' common name. Fixed by Joao
Ferreira <joao@joaoff.com>.

** Added support for CSS. This includes:
     - Parsing links from CSS files, and from CSS content found in HTML
       style tags and attributes.
     - Supporting conversion of links found within CSS content, when
       --convert-links is specified.
     - Ensuring that CSS files end in the ".css" filename extension,
       when --convert-links is specified.

   CSS support in Wget is thanks to Ted Mielczarek
   <ted.mielczarek@gmail.com>.

** Added support for Internationalized Resource Identifiers (IRIs, RFC
3987). When support is enabled (requires libidn and libiconv), links
with non-ASCII bytes are translated from their source encoding to UTF-8
before percent-encoding.  IRI support was added by Saint Xavier
<wget@sxav.eu>, as his project for the Google Summer of Code.

** Wget now provides more sensible exit status codes when downloads
don't proceed as expected (see the manual).

** --default-page option (and associated wgetrc command) added to
support alternative default names for index.html.

** --ask-password option (and associated wgetrc command) added to
support password prompts at the console.
 
** The --input-file option now also handles retrieving links from
an external file.

** The output generated by the --version option now includes
information on how it was built, and the set of configure-time options
that were selected.

** --html-extension has been renamed to --adjust-extension, to reflect
the fact that it now also applies to CSS content. --html-extension is
still acceptable, but is now deprecated.

** An "ascii" specifier is now accepted by --restrict-file-names, which
forces the percent-encoding of all non-ASCII bytes

** Several previously existing, but undocumented .wgetrc options are
now documented: save_headers, spider, and user_agent,
auth_no_challenge, and keep_session_cookies. Also added documentation
for the "lowercase" and "uppercase" values for --restrict-file-names, which had been present since Wget 1.11.
\f
* Changes in Wget 1.11.4

** Fixed an issue (apparently a regression) where -O would refuse to
download when -nc was given, even though the file didn't exist.

** Fixed a situation where Wget could abort with --continue if the
remote server gives a content-length of zero when the file exists
locally with content.

** Fixed a crash on some systems, due to Wget casting a pointer-to-long
to a pointer-to-time_t.

** Translation updates for Catalan.
\f
* Changes in Wget 1.11.3

** Downgraded -N with -O to a warning, rather than an error.

** Translation updates
\f
* Changes in Wget 1.11.2

** Fixed a problem in authenticating over HTTPS through a proxy.
(Regression in 1.11 over 1.10.2.)

** The combination of -r or -p with -O, which was disallowed in 1.11,
has been downgraded to a warning in 1.11.2. (-O and -N, which was never
meaningful, is still an error.)

** Further improvements to progress bar displays in non-English locales
(too many spaces could be inserted, causing the display to scroll).

** Successive invocations of Wget on FTP URLS, with --no-remove-listing
and --continue, was causing Wget to append, rather than replace,
information in the .listing file, and thereby download the same files
multiple times. This has been fixed in 1.11.2.

** Wget 1.11 no longer allowed ".." to persist at the beginning of URLs,
for improved conformance with RFC 3986. However, this behavior presents
problems for some FTP setups, and so they are now preserved again, for
FTP URLs only.
\f
* Changes in Wget 1.11.1.

** Interrupted downloads no longer result in renaming the file
(regression in 1.11 over 1.10.2).

** Progress bar now displays correctly in non-English locales (and a
related assertion failure was fixed).

** Wget no longer issues a GET request over HTTP for files it should
know it's not going to download (regression in 1.11 over 1.10.2).

** Added option --auth-no-challenge, to support broken pre-1.11
authentication-before-server-challenge, which turns out to still be
useful for some limited cases.

** Documentation of accept/reject lists in the manual's "Types of
Files" section now explains various aspects of their behavior that may
be surprising, and notes that they may change in the future.

** Documentation of --no-parents now explains how a trailing slash, or
lack thereof, in the specified URL, will affect behavior.
\f
* Changes in Wget 1.11.

** Timestamping now uses the value from the most recent HTTP response,
rather than the first one it got.

** Authentication information is no longer sent as part of the Referer
header in recursive fetches.

** No authentication credentials are sent until a challenge is issued,
for improved security. Authentication handling is still not
RFC-compliant, as once a Basic challenge has been received, it will
assume it can send credentials to any URL at that same host, and not
just the ones at or below the original authenticated location.
Credentials for Digest authentication are still never saved or issued
automatically, and continue to require a challenge for each resource.

** Added --max-redirect option, allowing the user to specify what should
be the maximum number of HTTP redirects to follow.

** Wget now supports saving HTTP downloads using file names specified by
the `Content-Disposition' header.  This is a standard way of specifying
the file name used by many web dynamically generated pages. However, the
current implementation is inefficient, and known to have bugs. It is
EXPERIMENTAL only, and not enabled by default. Use --content-disposition
to enable it.

** The new option `--ignore-case' makes Wget ignore case when
matching files, directories, and wildcards.  This affects the -X, -I,
-A, and -R options, as well as globbing in FTP URLs.

** ETA projection is now displayed in "dot" progress output as well as
in the default progress bar.  (The dot progress is used by default when
logging Wget's output to file using the `-o' option.)

** The "lockable boolean" argument type is no longer supported.  It
was only used by the passive_ftp .wgetrc setting.  If you're running
broken scripts or Perl modules that unconditionally specify
`--passive-ftp' and your firewall disallows it, you can override them
by replacing wget with a script that execs wget "$@" --no-passive-ftp.

** The source code has been migrated to Mercurial. The repositories are
available at http://hg.addictivecode.org/. Prior to this, the source
code was hosted on Subversion (migrated from the original CVS); you can
still get access to older tags and branches for Wget in the Subversion
repository at http://addictivecode.org/svn/wget/.
\f
* Changes in Wget 1.10.

** Downloading files larger than 2GB, sometimes referred to as "large
files", now works on systems that support them.  This includes the
majority of modern Unixes, as well as MS Windows.

** IPv6 is now supported by Wget.  Unlike the experimental code in
1.9, this version supports dual-family systems.  The new flags
`--inet4' and `--inet6' (or `-4' and `-6' for short) force the use of
IPv4 and IPv6 respectively.  Note that IPv6 support has not yet been
tested on Windows.

** Microsoft's proprietary "NTLM" method of HTTP authentication is now
supported.  This authentication method is undocumented and only used
by IIS.  Note that *proxy* authentication is not supported in this
release; you can only authenticate to the target web site.

** Wget no longer truncates partially downloaded files when download
has to start over because the server doesn't support Range.  Instead,
with such servers Wget now simply ignores the data up to the byte
where the last attempt left off, and only then continues appending to
the file.  That way the downloaded file never shrinks, and download
retries from servers without support for partial downloads work even
when downloading to stdout.

** SSL/TLS changes:

*** SSL/TLS downloads now attempt to verify the server's certificate
against the recognized certificate authorities.  This requires CA
certificates to have been installed in a location visible to the
OpenSSL library.  If this is not the case, you can get the bundle
yourself from a source you trust (for example, the bundle extracted
from Mozilla available at http://curl.haxx.se/docs/caextract.html),
and point Wget to the PEM file using the `--ca-certificate'
command-line option or the corresponding `.wgetrc' command.

*** Secure downloads now verify that the host name in the URL matches
the "common name" in the certificate presented by the server.

*** Although the above checks provide more secure downloads, they
unavoidably break interoperability with some sites that worked with
previous versions, particularly those using self-signed, expired, or
otherwise invalid certificates.  If you encounter "certificate
verification" errors or complaints that "common name doesn't match
requested host name" and are convinced of the site's authenticity, you
can use `--no-check-certificate' to bypass both checks.

*** Talking to SSL/TLS servers over proxies now actually works.
Previous versions of Wget erroneously sent GET requests for https
URLs.  Wget 1.10 utilizes the CONNECT method designed for this
purpose.

*** The SSL/TLS-related options have been redesigned and, for the
first time, documented in the manual.  The old, undocumented, options
are no longer supported.

** Passive FTP is now the default FTP transfer mode.  Use
`--no-passive-ftp' or specify `passive_ftp = off' in your init file to
revert to the old behavior.

** The `--header' option can now be used to override generated
headers.  For example, `wget --header="Host: foo.bar"
http://127.0.0.1' tells Wget to connect to localhost, but to specify
"foo.bar" in the `Host' header.  In previous versions such use of
`--header' lead to duplicate headers in HTTP requests.

** The responses without headers, aka "HTTP 0.9" responses, are
detected and handled.  Although HTTP 0.9 has long been obsolete, it is
still occasionally used, sometimes by accident.

** The progress bar is now updated regularly even when the data does
not arrive from the network.

** Wget no longer preserves permissions of files retrieved by FTP by
default.  Anonymous FTP servers frequently use permissions like "664",
which might not be what the user wants.  The new option
`--preserve-permissions' and the corresponding `.wgetrc' variable can
be used to revert to the old behavior.

** The new option `--protocol-directories' instructs Wget to also use
the protocol name as a directory component of local file names.

** Options that previously unconditionally set or unset various flags
are now boolean options that can be invoked as either `--OPTION' or
`--no-OPTION'.  Options that required an argument "on" or "off" have
also been changed this way, but they still accept the old syntax for
backward compatibility.  For example, instead of `--glob=off' you can
write `--no-glob'.

Allowing `--no-OPTION' for every `--OPTION' and the other way around
is useful because it allows the user to override non-default behavior
specified via `.wgetrc'.

** The new option `--keep-session-cookies' causes `--save-cookies' to
save session cookies (normally only kept in memory) along with the
permanent ones.  This is useful because many sites track important
information, such as whether the user has authenticated, in session
cookies.  With this option multiple Wget runs are treated as a single
browser session.

** Wget now supports the --ftp-user and --ftp-password command
switches to set username and password for FTP, and the --user and
--password command switches to set username and password for both FTP
and HTTP.  The --http-passwd and --proxy-passwd command switches have
been renamed to --http-password and --proxy-password respectively, and
the related http_passwd and proxy_passwd .wgetrc commands to
http_password and proxy_password respectively.  The login and passwd
.wgetrc commands have been deprecated.

* `wget -b' now works correctly under Windows.
\f
* Wget 1.9.1 is a bugfix release with no user-visible changes.
\f
* Changes in Wget 1.9.

** It is now possible to specify that POST method be used for HTTP
requests.  For example, `wget --post-data="id=foo&data=bar" URL' will
send a POST request with the specified contents.

** IPv6 support is available, although it's still experimental.

** The `--timeout' option now also affects DNS lookup and establishing
the TCP connection.  Previously it only affected reading and writing
data.  Those three timeouts can be set separately using
`--dns-timeout', `--connection-timeout', and `--read-timeout',
respectively.

** Download speed shown by the progress bar is based on the data
recently read, rather than the average speed of the entire download.
The ETA projection is still based on the overall average.

** It is now possible to connect to FTP servers through FWTK
firewalls.  Set ftp_proxy to an FTP URL, and Wget will automatically
log on to the proxy as "username@host".

** The new option `--retry-connrefused' makes Wget retry downloads
even in the face of refused connections, which are otherwise
considered a fatal error.

** The new option `--no-dns-cache' may be used to prevent Wget from
caching DNS lookups.

** Wget no longer escapes characters in local file names based on
whether they're appropriate in URLs.  Escaping can still occur for
nonprintable characters or for '/', but no longer for frequent
characters such as space.  You can use the new option
--restrict-file-names to relax or strengthen these rules, which can be
useful if you dislike the default or if you're downloading to
non-native partitions.

** Handling of HTML comments has been dumbed down to conform to what
users expect and other browsers do: instead of being treated as SGML
declaration, a comment is terminated at the first occurrence of "-->".
Use `--strict-comments' to revert to the old behavior.

** Wget now correctly handles relative URIs that begin with "//", such
as "//img.foo.com/foo.jpg".

** Boolean options in `.wgetrc' and on the command line now accept
values "yes" and "no" along with the traditional "on" and "off".

** It is now possible to specify decimal values for timeouts, waiting
periods, and download rate.  For instance, `--wait=0.5' now works as
expected, as does `--dns-timeout=0.5' and even `--limit-rate=2.5k'.
\f
* Wget 1.8.2 is a bugfix release with no user-visible changes.
\f
* Wget 1.8.1 is a bugfix release with no user-visible changes.
\f
* Changes in Wget 1.8.

** A new progress indicator is now available and used by default.
You can choose the progress bar type with `--progress=TYPE'.  Two
types are available, "bar" (the new default), and "dot" (the old
dotted indicator).  You can permanently revert to the old progress
indicator by putting `progress = dot' in your `.wgetrc'.

** You can limit the download rate of the retrieval using the
`--limit-rate' option.  For example, `wget --limit-rate=15k URL' will
tell Wget not to download the body of the URL faster than 15 kilobytes
per second.

** Recursive retrieval and link conversion have been revamped:

*** Wget now traverses links breadth-first.  This makes the
calculation of depth much more reliable than before.  Also, recursive
downloads are faster and consume *significantly* less memory than
before.

*** Links are converted only when the entire retrieval is complete.
This is the only safe thing to do, as only then is it known what URLs
have been downloaded.

*** BASE tags are handled correctly when converting links.  Since Wget
already resolves <base href="..."> when resolving handling URLs, link
conversion now makes the BASE tags point to an empty string.

*** HTML anchors are now handled correctly.  Links to an anchor in the
same document (<a href="#anchorname">), which used to confuse Wget,
are now converted correctly.

*** When in page-requisites (-p) mode, no-parent (-np) is ignored when
retrieving for inline images, stylesheets, and other documents needed
to display the page.

*** Page-requisites (-p) mode now works with frames.  In other words,
`wget -p URL-THAT-USES-FRAMES' will now download the frame HTML files,
and all the files that they need to be displayed properly.

** `--base' now works conjunction with `--input-file', providing a
base for each URL and thereby allowing the URLs in the file to be
relative.

** If a host has more than one IP address, Wget uses the other
addresses when accessing the first one fails.

** Host directories now contain port information if the URL is at a
non-standard port.

** Wget now supports the robots.txt directives specified in
<http://www.robotstxt.org/wc/norobots-rfc.txt>.

** URL parser has been fixed, especially the infamous overzealous
quoting.  Wget no longer dequotes reserved characters, e.g. `%3F' is
no longer translated to `?', nor `%2B' to `+'.  Unsafe characters
which are not reserved are still escaped, of course.

** No more than 20 successive redirections are allowed.
\f
* Wget 1.7.1 is a bugfix release with no user-visible changes.
\f
* Changes in Wget 1.7.

** SSL (`https') pages now work if you compile Wget with SSL support;
use the `--with-ssl' configure flag.  You need to have OpenSSL
installed.

** Cookies are now supported.  Wget will accept cookies sent by the
server and return them in later requests.  Additionally, it can load
and save cookies to disk, in the same format that Netscape uses.

** "Keep-alive" (persistent) HTTP connections are now supported.
Using keep-alive allows Wget to share one TCP/IP connection for
many retrievals, making multiple-file downloads faster and less
stressing for the server and the network.

** Wget now recognizes FTP directory listings generated by NT and VMS
servers.

** It is now possible to recurse through FTP sites where logging in
puts you in some directory other than '/'.

** You may now use `~' to mean home directory in `.wgetrc'.  For
example, `load_cookies = ~/.netscape/cookies.txt' works as you would
expect.

** The HTML parser has been rewritten.  The new one works more
reliably, allows finer-grained control over which tags and attributes
are detected, and has better support for some features like correctly
skipping comments and declarations, decoding entities, etc.  It is
also more general.

** <meta name="robots"> tags are now respected.

** Wget's internal tables now use hash tables instead of linked lists
where appropriate.  This results in huge speedups when retrieving
large sites (thousands of documents).

** Wget now has a man page, automatically generated from the Texinfo
documentation.  (The last version that shipped with a man page was
1.4.5).  To get this, you need to have pod2man from the Perl
distribution installed on your system.
\f
* Changes in Wget 1.6

** Administrative changes.

*** Maintainership.  Due to Hrvoje being plagued with a "real job",
Dan Harkless is the most active maintainer (not that he doesn't have a
real job as well).  Hrvoje still participates occasionally, and both
are being helped by many other people.

*** Web page.  Thanks to Jan Prikryl, Wget has an "official" web page.
Take a look at:

    http://sunsite.dk/wget/

*** Anonymous CVS.  Thanks to ever-helpful Karsten Thygesen, Wget
sources are now available at an anonymous CVS server.  Take a look at
the web page for downloading instructions.

** New -K / --backup-converted / backup_converted = on option causes files
modified due to -k to be saved with a .orig prefix before being changed.  When
using -N as well, it is these .orig files that are compared against the server.

** New --follow-tags / follow_tags = ... option allows you to restrict
Wget to following only certain HTML tags when doing a recursive
retrieval.  -G / --ignore-tags / ignore_tags = ... is just the
opposite -- all tags but the ones you specify will be followed.

** New --waitretry / waitretry = SECONDS option allows waiting between retries
of failed downloads.  Wget will use "linear" backoff, waiting 1 second after the
first failure, 2 after the second, up to SECONDS.  waitretry is set to 10 by
default in the system wgetrc.

** New -p / --page-requisites / page_requisites = on option causes
Wget to download all ancillary files necessary to display a given HTML
page properly (e.g. inlined images).

** New -E / --html-extension / html_extension = on option causes Wget
to append ".html" to text/html filenames not ending in regexp
"\.[Hh][Tt][Mm][Ll]?".

** New type of .wgetrc command -- "lockable Boolean".  Can be set to on, off,
always, or never.  This allows the .wgetrc to override the commandline.  So far,
passive_ftp is the only .wgetrc command which takes a lockable Boolean.

** A number of new translation files have been added.

** New --bind-address / bind_address = <address> option for people on hosts 
bound to multiple IP addresses.

** wget now accepts (illegal per HTTP spec) relative URLs in HTTP redirects.
\f
* Wget 1.5.3 is a bugfix release with no user-visible changes.
\f
* Wget 1.5.2 is a bugfix release with no user-visible changes.
\f
* Wget 1.5.1 is a bugfix release with no user-visible changes.
\f
* Changes in Wget 1.5.0

** Wget speaks many languages!

On systems with gettext(), Wget will output messages in the language
set by the current locale, if available.  At this time we support
Czech, German, Croatian, Italian, Norwegian and Portuguese.

** Opie (Skey) is now supported with FTP.

** HTTP Digest Access Authentication (RFC2069) is now supported.

** The new `-b' option makes Wget go to background automatically.

** The `-I' and `-X' options now accept wildcard arguments.

** The `-w' option now accepts suffixes `s' for seconds, `m' for
minutes, `h' for hours, `d' for days and `w' for weeks.

** Upon getting SIGHUP, the whole previous log is now copied to
`wget-log'.

** Wget now understands proxy settings with explicit usernames and
passwords, e.g. `http://user:password@proxy.foo.com/'.

** You can use the new `--cut-dirs' option to make Wget create less
directories.

** The `;type=a' appendix to FTP URLs is now recognized.  For
instance, the following command will retrieve the welcoming message in
ASCII type transfer:

    wget "ftp://ftp.somewhere.com/welcome.msg;type=a"

** `--help' and `--version' options have been redone to to conform to
standards set by other GNU utilities.

** Wget should now be compilable under MS Windows environment.  MS
Visual C++ and Watcom C have been used successfully.

** If the file length is known, percentages are displayed during
download.

** The manual page, now hopelessly out of date, is no longer
distributed with Wget.
\f
* Wget 1.4.5 is a bugfix release with no user-visible changes.
\f
* Wget 1.4.4 is a bugfix release with no user-visible changes.
\f
* Changes in Wget 1.4.3

** Wget is now a GNU utility.

** Can do passive FTP.

** Reads .netrc.

** Info documentation expanded.

** Compiles on pre-ANSI compilers.

** Global wgetrc now goes to /usr/local/etc (i.e. $sysconfdir).

** Lots of bugfixes.
\f
* Changes in Wget 1.4.2

** New mirror site at ftp://sunsite.auc.dk/pub/infosystems/wget/,
thanks to Karsten Thygesen.

** Mailing list!  Mail to wget-request@sunsite.auc.dk to subscribe.

** New option --delete-after for proxy prefetching.

** New option --retr-symlinks to retrieve symbolic links like plain
files.

** rmold.pl -- script to remove files deleted on the remote server

** --convert-links should work now.

** Minor bugfixes.
\f
* Changes in Wget 1.4.1

** Minor bugfixes.

** Added -I (the opposite of -X).

** Dot tracing is now customizable; try wget --dot-style=binary
\f
* Changes in Wget 1.4.0

** Wget 1.4.0 [formerly known as Geturl] is an extensive rewrite of
Geturl.  Although many things look suspiciously similar, most of the
stuff was rewritten, like recursive retrieval, HTTP, FTP and mostly
everything else.  Wget should be now easier to debug, maintain and,
most importantly, use.

** Recursive HTTP should now work without glitches, even with Location
changes, server-generated directory listings and other naughty stuff.

** HTTP regetting is supported on servers that support Range
specification. WWW authorization is supported -- try
wget http://user:password@hostname/

** FTP support was rewritten and widely enhanced. Globbing should now
work flawlessly. Symbolic links are created locally. All the
information the Unix-style ls listing can give is now recognized.

** Recursive FTP is supported, e.g.
    wget -r ftp://gnjilux.cc.fer.hr/pub/unix/util/

** You can specify "rejected" directories, to which you do not want to
enter, e.g. with wget -X /pub

** Time-stamping is supported, with both HTTP and FTP. Try wget -N URL.

** A new texinfo reference manual is provided.  It can be read with
Emacs, standalone info, or converted to HTML, dvi or postscript.

** Fixed a long-standing bug, so that Wget now works over SLIP
connections.

** You can have a system-wide wgetrc (/usr/local/lib/wgetrc by
default). Settings in $HOME/.wgetrc override the global ones, of
course :-)

** You can set up quota in .wgetrc to prevent sucking too much
data. Try `quota = 5M' in .wgetrc (or quota = 100K if you want your
sysadmin to like you).

** Download rate is printed after retrieval.

** Wget now sends the `Referer' header when retrieving
recursively.

** With the new --no-parent option Wget can retrieve FTP recursively
through a proxy server.

** HTML parser, as well as the whole of Wget was rewritten to be much
faster and less memory-consuming (yes, both).

** Absolute links can be converted to relative links locally. Check
wget -k.

** Wget catches hangup, filtering the output to a log file and
resuming work. Try kill -HUP %?wget.

** User-defined headers can be sent.  Try

    wget http://fly.cc.her.hr/ --header='Accept-Charset: iso-8859-2'

** Acceptance/Rejection lists may contain wildcards.

** Wget can display HTTP headers and/or FTP server response with the
new `-S' option.  It can save the original HTTP headers with `-s'.

** socks library is now supported (thanks to Antonio Rosella
<Antonio.Rosella@agip.it>). Configure with --with-socks.

** There is a nicer display of REST-ed output.

** Many new options (like -x to force directory hierarchy, or -m to
turn on mirroring options).

** Wget is now distributed under GNU General Public License (GPL).

** Lots of small features I can't remember. :-)

** A host of bugfixes.
\f
* Changes in Geturl 1.3

** Added FTP globbing support (ftp://fly.cc.fer.hr/*)

** Added support for no_proxy

** Added support for ftp://user:password@host/

** Added support for %xx in URL syntax

** More natural command-line options

** Added -e switch to execute .geturlrc commands from the command-line

** Added support for robots.txt

** Fixed some minor bugs
\f
* Geturl 1.2 is a bugfix release with no user-visible changes.
\f
* Changes in Geturl 1.1

** REST supported in FTP

** Proxy servers supported

** GNU getopt used, which enables command-line arguments to be ordered
as you wish, e.g.  geturl http://fly.cc.fer.hr/ -vo log is the same as
geturl -vo log http://fly.cc.fer.hr/

** Netscape-compatible URL syntax for HTTP supported: host[:port]/dir/file

** NcFTP-compatible colon URL syntax for FTP supported: host:/dir/file

** <base href="xxx"> supported

** autoconf supported
\f
----------------------------------------------------------------------
Copyright information:

Copyright (C) 1997-2005 Free Software Foundation, Inc.

   Permission is granted to anyone to make or distribute verbatim
   copies of this document as received, in any medium, provided that
   the copyright notice and this permission notice are preserved, thus
   giving the recipient permission to redistribute in turn.

   Permission is granted to distribute modified versions of this
   document, or of portions of it, under the above conditions,
   provided also that they carry prominent notices stating who last
   changed them.