In the predefined actions (merge, rebase, none, checkout), we use
the display path, which is relative to the current working directory.
Also use the display path when running a custom command.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The new test which is a replica of the previous test except
that it executes from a sub directory. Prior to this patch
the test failed by having too many '../' prefixed:

  --- expect	2016-03-29 19:02:33.087336115 +0000
  +++ actual	2016-03-29 19:02:33.359343311 +0000
  @@ -1,7 +1,7 @@
    b23f134787d96fae589a6b76da41f4db112fc8db ../nested1 (heads/master)
  -+25d56d1ddfb35c3e91ff7d8f12331c2e53147dcc ../nested1/nested2 (file2)
  - 5ec83512b76a0b8170b899f8e643913c3e9b72d9 ../nested1/nested2/nested3 (heads/master)
  - 509f622a4f36a3e472affcf28fa959174f3dd5b5 ../nested1/nested2/nested3/submodule (heads/master)
  ++25d56d1ddfb35c3e91ff7d8f12331c2e53147dcc ../../nested1/nested2 (file2)
  + 5ec83512b76a0b8170b899f8e643913c3e9b72d9 ../../../nested1/nested2/nested3 (heads/master)
  + 509f622a4f36a3e472affcf28fa959174f3dd5b5 ../../../../nested1/nested2/nested3/submodule (heads/master)
    0c90624ab7f1aaa301d3bb79f60dcfed1ec4897f ../sub1 (0c90624)
    0c90624ab7f1aaa301d3bb79f60dcfed1ec4897f ../sub2 (0c90624)
    509f622a4f36a3e472affcf28fa959174f3dd5b5 ../sub3 (heads/master)

The path code in question:
  displaypath=$(relative_path "$prefix$sm_path")
  prefix=$displaypath
  if recursive:
    eval cmd_status

That way we change `prefix` each iteration to contain another
'../', because of the the relative_path computation is done
on an already computed relative path.

We must call relative_path exactly once with `wt_prefix` non empty.
Further calls in recursive instances to to calculate the displaypath
already incorporate the correct prefix from before. Fix the issue by
clearing `wt_prefix` in recursive calls.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When calling `git submodule init` from a recursive instance of
`git submodule update --recursive`, the reported path is wrong as it
skips the nested submodules.

The new test demonstrates a failure in the code prior to this patch.
Instead of getting the expected
    Submodule 'submodule' (${pwd}/submodule) registered for path '../super/submodule'
the `super` directory is omitted and you get
    Submodule 'submodule' (${pwd}/submodule) registered for path '../submodule'
instead.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The `prefix` was put in front of the display path unconditionally.
This is wrong as any relative path computation would need to be at
the front, so include the prefix into the display path.

The new test replicates the previous test with the difference of executing
from a sub directory. By executing from a sub directory all we would
expect all displayed paths to be prefixed by '../'.

Prior to this patch the test would report
    Entering 'nested1/nested2/../nested3'
instead of the expected
    Entering '../nested1/nested2/nested3'

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

When reviewing a change that also updates a submodule in Gerrit, a
common review practice is to download and cherry-pick the patch
locally to test it. However when testing it locally, the 'git
submodule update' may fail fetching the correct submodule sha1 as
the corresponding commit in the submodule is not yet part of the
project history, but also just a proposed change.

If $sha1 was not part of the default fetch, we try to fetch the $sha1
directly. Some servers however do not support direct fetch by sha1,
which leads git-fetch to fail quickly. We can fail ourselves here as
the still missing sha1 would lead to a failure later in the checkout
stage anyway, so failing here is as good as we can get.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The infrastructure to rewrite "git submodule" in C is being built
incrementally.  Let's polish these early parts well enough and make
them graduate to 'next' and 'master', so that the more involved
follow-up can start cooking on a solid ground.

* sb/submodule-helper:
  submodule: rewrite `module_clone` shell function in C
  submodule: rewrite `module_name` shell function in C
  submodule: rewrite `module_list` shell function in C

Some protocols (like git-remote-ext) can execute arbitrary
code found in the URL. The URLs that submodules use may come
from arbitrary sources (e.g., .gitmodules files in a remote
repository). Let's restrict submodules to fetching from a
known-good subset of protocols.

Note that we apply this restriction to all submodule
commands, whether the URL comes from .gitmodules or not.
This is more restrictive than we need to be; for example, in
the tests we run:

  git submodule add ext::...

which should be trusted, as the URL comes directly from the
command line provided by the user. But doing it this way is
simpler, and makes it much less likely that we would miss a
case. And since such protocols should be an exception
(especially because nobody who clones from them will be able
to update the submodules!), it's not likely to inconvenience
anyone in practice.

Reported-by: Blake Burkhart <bburky@bburky.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Error string fix.

* ah/submodule-typofix-in-error:
  git-submodule: remove extraneous space from error message