Re: bdiff

From	blmblm@myrealbox.com <blmblm.myrealbox@gmail.com>
Newsgroups	comp.lang.c
Subject	Re: bdiff
Date	2011-06-20 19:14 +0000
Organization	None
Message-ID	<969kgpFjduU2@mid.individual.net> (permalink)
References	<94mfhcFngqU1@mid.individual.net> <87boy6241i.fsf@blp.benpfaff.org> <95crfqF60lU1@mid.individual.net> <isrgpj$4qq$1@speranza.aioe.org>

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In article <isrgpj$4qq$1@speranza.aioe.org>,
Alan Curry <pacman@kosh.dhis.org> wrote:
> In article <95crfqF60lU1@mid.individual.net>, Uno  <Uno@example.invalid> wrote:

[ snip ]

> FTP was invented when dinosaurs roamed the Internet. The dinosaurs growled,
> roared, and screeched ASCII, which was presented to the users on hardcopy
> terminals - typewriters, basically.

That may be true of the dinosaurs that wanted to use this newfangled
file transfer protocol, but some of them (I'm thinking of the ones
made by IBM) mostly used another format, EBCDIC, for representing
character data.  Just sayin' (after a rather long delay, for which
I apologize).

> [If you're not old enough to have ever seen a typewriter, google up an image
> of one now, or preferably a video of one in use.]

Good heavens -- are they really people who have never encountered a
typewriter at all?  cue chorus of "I feel old", maybe ....

[ snip ]

> The dinosaurs were a rowdy bunch, and they fought over how to properly store
> text on non-typewriter-like media (like tapes and disks), but they were all
> able to understand the typewriter-like ASCII-with-CRLF format. It was the
> universal text representation. And it was incorporated into FTP as the
> standard format for transmission of text files.

I just made a quick attempt to confirm my recollections about
whether the IBM 360/370 architecture included support for ASCII,
and -- it's kind of interesting that the Wikipedia articles say
that the 360 architecture included some features intended to
support ASCII (which had not been finalized), but that these were
not used, or not used widely, and the 370 architecture dropped at
least some of them.  I wonder whether there was some consternation
when it became desirable to support FTP, it being ASCII-based.

(I'll leave the rest of this in because it's kind of charming.)

> A bit later, UNIX was created. It was like a small mammal, hiding
> underground, barely noticed and definitely not respected by the dinosaurs.
> And the UNIX guys observed that text files on disk were becoming more
> numerous than text printouts. And they said that soon typewriters as a user
> interface would be obsolete, replaced by CRTs. and that eventually people
> would send text to each other without even using paper.
> 
> In such a future it would make no sense to keep using that old pair of
> typewriter commands to separate lines of text. It would be much better to
> take "end this line, begin next line" as a single logical operation and allow
> it to be represented by a single control code. They called this new control
> code "NEWLINE". It was a revolutionary idea.
> 
> And the dinosaurs ignored it, and kept making up Internet protocols with
> mandatory typewriter-style line endings.
> 
> When later generations of UNIX got big enough to climb out of their
> underground tunnels and talk to the Internet, they had a problem: all of
> their private text files and utilities were designed around the NEWLINE idea,
> but all of the Internet protocols, including FTP, required CRLF. FTP clients
> and servers on UNIX have to perform translation. When sending a file, they
> transform it from NEWLINE format to CRLF format. When receiving it, they do
> the opposite.
> 
> When sending a text file, UNIX FTP changes the file into the dinosaur
> typewriter format by inserting a CR (13) before every NEWLINE (10). When
> receiving a text, it changes each CRLF pair into NEWLINE. Note that it
> doesn't have to actually look for CRLF pairs. It can just delete all the CRs,
> since LF and NEWLINE have the same numerical value (10) and a CR that is not
> part of a CRLF pair is not allowed.
> 
> When those transformations are applied to things that aren't actually text
> files, the result can be a disaster, because bytes with value 13 can
> disappear, or can be added before bytes with value 10. The transformation
> isn't reversible when the input contains unpaired CR or LF bytes.
> 
> So your file got corrupted because you used ASCII mode FTP and you got caught
> speaking ungrammatical dinosaur typewriter Esperanto.
> 
> Use binary mode. (Technically, in the language of FTP, "TYPE IMAGE", but most
> clients call it "binary mode")
> 
> And yeah, you could have just googled "FTP binary" but I felt like writing a
> story about dinosaurs anyway so here you go.

-- 
B. L. Massingill
ObDisclaimer:  I don't speak for my employers; they return the favor.

Thread

variable-length strings Uno <Uno@example.invalid> - 2011-06-01 03:36 -0600
  Re: variable-length strings ccc31807 <cartercc@gmail.com> - 2011-06-01 07:13 -0700
    Re: variable-length strings Uno <Uno@example.invalid> - 2011-06-02 10:54 -0600
  Re: variable-length strings "George Mpouras" <nospam.gravitalsun@hotmail.com.nospam> - 2011-06-01 17:01 +0300
  Re: variable-length strings "Peter J. Holzer" <hjp-usenet2@hjp.at> - 2011-06-02 15:33 +0200
  Re: variable-length strings "Peter J. Holzer" <hjp-usenet2@hjp.at> - 2011-06-02 15:44 +0200
    Re: bdiff Uno <Uno@example.invalid> - 2011-06-08 21:59 -0600
      Re: bdiff Ian Collins <ian-news@hotmail.com> - 2011-06-09 16:08 +1200
        Re: bdiff Uno <Uno@example.invalid> - 2011-06-08 22:20 -0600
          Re: bdiff Uno <Uno@example.invalid> - 2011-06-09 02:57 -0600
            Re: bdiff Janis Papanagnou <janis_papanagnou@hotmail.com> - 2011-06-09 11:10 +0200
              Re: bdiff Uno <Uno@example.invalid> - 2011-06-09 13:19 -0600
                Re: bdiff James Waldby <not@valid.invalid> - 2011-06-09 19:32 +0000
                Re: bdiff Angel <angel+news@spamcop.net> - 2011-06-09 19:32 +0000
                Re: bdiff Uno <Uno@example.invalid> - 2011-06-09 15:28 -0600
                Re: bdiff blp@cs.stanford.edu (Ben Pfaff) - 2011-06-09 12:33 -0700
                Re: bdiff Uno <Uno@example.invalid> - 2011-06-09 15:15 -0600
                Re: bdiff pacman@kosh.dhis.org (Alan Curry) - 2011-06-09 22:17 +0000
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-20 19:14 +0000
                Re: bdiff Robert Wessel <robertwessel2@yahoo.com> - 2011-06-20 18:43 -0500
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-21 20:39 +0000
                Re: bdiff Joe Wright <joewwright@comcast.net> - 2011-06-21 18:38 -0400
                Re: bdiff Robert Wessel <robertwessel2@yahoo.com> - 2011-06-21 18:11 -0500
                Re: bdiff Michael Press <rubrum@pacbell.net> - 2011-06-22 15:51 -0700
                Re: bdiff Stephen Sprunk <stephen@sprunk.org> - 2011-06-21 07:49 -0500
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-21 20:40 +0000
                Re: bdiff superpollo <superpollo@tznvy.pbz> - 2011-06-22 09:59 +0200
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-22 19:57 +0000
                Re: bdiff superpollo <superpollo@tznvy.pbz> - 2011-06-23 21:16 +0200
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-24 19:36 +0000
                Re: bdiff superpollo <superpollo@tznvy.pbz> - 2011-06-24 22:48 +0200
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-24 21:17 +0000
                Re: bdiff Robert Wessel <robertwessel2@yahoo.com> - 2011-06-24 17:20 -0500
                Re: bdiff blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-22 19:55 +0000
                Re: bdiff Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-21 21:40 -0400
                Re: bdiff Azazel <azazel@remove.azazel.net> - 2011-06-22 09:06 -0500
                Re: bdiff Ben Bacarisse <ben.usenet@bsb.me.uk> - 2011-06-22 16:47 +0100
                Re: bdiff Stephen Sprunk <stephen@sprunk.org> - 2011-06-22 11:23 -0500
                Re: bdiff Ike Naar <ike@sverige.freeshell.org> - 2011-06-09 21:37 +0000
            Re: bdiff bonomi@host122.r-bonomi.com (Robert Bonomi) - 2011-06-19 06:10 -0500
      Re: bdiff Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-09 07:13 -0400
        Re: bdiff Uno <Uno@example.invalid> - 2011-06-09 13:30 -0600
          Re: bdiff Keith Thompson <kst-u@mib.org> - 2011-06-09 13:29 -0700
            Re: bdiff Uno <merrilljensen@q.com> - 2011-06-09 21:11 -0700
              Re: bdiff "Morris Keesan" <mkeesan@post.harvard.edu> - 2011-06-09 23:58 -0400
                Re: bdiff Uno <Uno@example.invalid> - 2011-06-12 00:47 -0600
                Re: bdiff Angel <angel+news@spamcop.net> - 2011-06-12 07:53 +0000
                Re: bdiff Shao Miller <sha0.miller@gmail.com> - 2011-06-12 12:02 -0500
                Re: bdiff Keith Thompson <kst-u@mib.org> - 2011-06-12 01:24 -0700
                Re: bdiff Shao Miller <sha0.miller@gmail.com> - 2011-06-12 12:18 -0500

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