tests/test-clone-cgi.t

lock: block signal interrupt while making a lock file

On Windows where symlink isn't supported, util.makelock() could leave an empty
file if interrupted immediately after os.open(). This empty lock never dies
as it has no process id recorded.

    ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
    # an interrupt may occur here
    os.write(ld, info)
    os.close(ld)

This was a long-standing bug of TortoiseHg which runs a command-server and
kills it by CTRL_C_EVENT, reported by random Windows users.

https://bitbucket.org/tortoisehg/thg/issues/4873/#comment-43591129

At first, I tried to fix makelock() to clean up a stale lock file, which
turned out to be hard because any instructions may be interrupted by a
signal.

    ld = None
    try:
        # CALL_FUNCTION  # os.open(...)
        # an interrupt may occur here
        # STORE_FAST     # ld = ...
        ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
        os.write(ld, info)
        ...
        return True
    except:
        if ld:
            ...
            os.unlink(pathname)
        return False

So I decided to block signals by temporarily replacing the signal handlers
so makelcok() and held = 1 will never be interrupted.

Many thanks to Fernando Najera for investigating the issue.

#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)