tests/test-hgweb-raw.t

internals: document CBOR utilization

I spoke with some people at Mozilla about CBOR and they advised me
that we should be careful about the subset of CBOR we use in order
to mitigate security, performance, and compatibility concerns.

This commit establishes a document that attempts to formalize our
use of CBOR.

Its main limitations are on what types are allowed. It explicitly
enumerates which types are supported. Notable missing features
include:

* Indefinite-length arrays and maps
* Text strings (bytes all the way)
* Floats
* Date/time types
* Big integers
* Use of indefinite-length byte strings for map keys, values in
  containers.

If we have a need for any of these, we can have a discussion about
them when the time comes.

Differential Revision: https://phab.mercurial-scm.org/D4412

#require serve

Test raw style of hgweb

  $ hg init test
  $ cd test
  $ mkdir sub
  $ cat >'sub/some text%.txt' <<ENDSOME
  > This is just some random text
  > that will go inside the file and take a few lines.
  > It is very boring to read, but computers don't
  > care about things like that.
  > ENDSOME
  $ hg add 'sub/some text%.txt'
  $ hg commit -d "1 0" -m "Just some text"

  $ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid

  $ cat hg.pid >> $DAEMON_PIDS
  $ (get-with-headers.py localhost:$HGPORT 'raw-file/bf0ff59095c9/sub/some%20text%25.txt' content-type content-length content-disposition) >getoutput.txt

  $ killdaemons.py hg.pid

  $ cat getoutput.txt
  200 Script output follows
  content-type: application/binary
  content-length: 157
  content-disposition: inline; filename="some text%.txt"
  
  This is just some random text
  that will go inside the file and take a few lines.
  It is very boring to read, but computers don't
  care about things like that.
  $ cat access.log error.log
  $LOCALIP - - [$LOGDATE$] "GET /raw-file/bf0ff59095c9/sub/some%20text%25.txt HTTP/1.1" 200 - (glob)

  $ rm access.log error.log
  $ hg serve -p $HGPORT -A access.log -E error.log -d --pid-file=hg.pid \
  > --config web.guessmime=True

  $ cat hg.pid >> $DAEMON_PIDS
  $ (get-with-headers.py localhost:$HGPORT 'raw-file/bf0ff59095c9/sub/some%20text%25.txt' content-type content-length content-disposition) >getoutput.txt
  $ killdaemons.py hg.pid

  $ cat getoutput.txt
  200 Script output follows
  content-type: text/plain; charset="ascii"
  content-length: 157
  content-disposition: inline; filename="some text%.txt"
  
  This is just some random text
  that will go inside the file and take a few lines.
  It is very boring to read, but computers don't
  care about things like that.
  $ cat access.log error.log
  $LOCALIP - - [$LOGDATE$] "GET /raw-file/bf0ff59095c9/sub/some%20text%25.txt HTTP/1.1" 200 - (glob)

  $ cd ..