view tests/test-clone-cgi.t @ 31210:e1d035905b2e

similar: compare between actual file contents for exact identity

Before this patch, similarity detection logic (for addremove and
automv) depends entirely on SHA-1 digesting. But this causes incorrect
rename detection, if:

  - removing file A and adding file B occur at same committing, and
  - SHA-1 hash values of file A and B are same

This may prevent security experts from managing sample files for
SHAttered issue in Mercurial repository, for example.

  https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html
  https://shattered.it/

Hash collision itself isn't so serious for core repository
functionality of Mercurial, described by mpm as below, though.

  https://www.mercurial-scm.org/wiki/mpm/SHA1

This patch compares between actual file contents after hash comparison
for exact identity.

Even after this patch, SHA-1 is still used, because it is reasonable
enough to quickly detect existence of "(almost) same" file.

  - replacing SHA-1 causes decreasing performance, and
  - replacement of it has ambiguity, yet

Getting content of removed file (= rfctx.data()) at each exact
comparison should be cheap enough, even though getting content of
added one costs much.

  ======= ============== =====================
  file    fctx           data() reads from
  ======= ============== =====================
  removed filectx        in-memory revlog data
  added   workingfilectx storage
  ======= ============== =====================

#require no-msys # MSYS will translate web paths as if they were file paths

This is a test of the wire protocol over CGI-based hgweb.
initialize repository

  $ hg init test
  $ cd test
  $ echo a > a
  $ hg ci -Ama
  adding a
  $ cd ..
  $ cat >hgweb.cgi <<HGWEB
  > #
  > # An example CGI script to use hgweb, edit as necessary
  > import cgitb
  > cgitb.enable()
  > from mercurial import demandimport; demandimport.enable()
  > from mercurial.hgweb import hgweb
  > from mercurial.hgweb import wsgicgi
  > application = hgweb("test", "Empty test repository")
  > wsgicgi.launch(application)
  > HGWEB
  $ chmod 755 hgweb.cgi

try hgweb request

  $ . "$TESTDIR/cgienv"
  $ QUERY_STRING="cmd=changegroup&roots=0000000000000000000000000000000000000000"; export QUERY_STRING
  $ python hgweb.cgi >page1 2>&1
  $ python "$TESTDIR/md5sum.py" page1
  1f424bb22ec05c3c6bc866b6e67efe43  page1

make sure headers are sent even when there is no body

  $ QUERY_STRING="cmd=listkeys&namespace=nosuchnamespace" python hgweb.cgi
  Status: 200 Script output follows\r (esc)
  Content-Type: application/mercurial-0.1\r (esc)
  Content-Length: 0\r (esc)
  \r (esc)