Hi Stefan,

On Mon, 10 Oct 2016, Stefan Beller wrote:

> Before 63e95beb0 (2016-04-15, submodule: port resolve_relative_url from
> shell to C), it did not matter if the superprojects URL had a trailing
> slash or not. It was just chopped off as one of the first steps
> (The "remoteurl=${remoteurl%/}" near the beginning of
> resolve_relative_url(), which was removed in said commit).
> 
> When porting this to the C version, an off-by-one error was introduced
> and we did not check the actual last character to be a slash, but the
> NULL delimiter.

It is a NUL delimiter, not a NULL delimiter.

> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index 444ec06..a7841a5 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -95,6 +95,8 @@ static int chop_last_dir(char **remoteurl, int is_relative)
>   * NEEDSWORK: This works incorrectly on the domain and protocol part.
>   * remote_url      url              outcome          expectation
>   * http://a.com/b  ../c             http://a.com/c   as is
> + * http://a.com/b/ ../c             http://a.com/c   same as previous line, 
> but
> + *                                                   ignore trailing slash 
> in url
>   * http://a.com/b  ../../c          http://c         error out
>   * http://a.com/b  ../../../c       http:/c          error out
>   * http://a.com/b  ../../../../c    http:c           error out
> @@ -113,8 +115,8 @@ static char *relative_url(const char *remote_url,
>       struct strbuf sb = STRBUF_INIT;
>       size_t len = strlen(remoteurl);
>  
> -     if (is_dir_sep(remoteurl[len]))
> -             remoteurl[len] = '\0';
> +     if (is_dir_sep(remoteurl[len-1]))
> +             remoteurl[len-1] = '\0';
>  
>       if (!url_is_local_not_ssh(remoteurl) || is_absolute_path(remoteurl))
>               is_relative = 0;
> diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
> index bf2deee..82b98f8 100755
> --- a/t/t0060-path-utils.sh
> +++ b/t/t0060-path-utils.sh
> @@ -319,6 +319,7 @@ test_submodule_relative_url "../" "foo/bar" 
> "../submodule" "../foo/submodule"
>  test_submodule_relative_url "../" "foo" "../submodule" "../submodule"
>  
>  test_submodule_relative_url "(null)" "../foo/bar" "../sub/a/b/c" 
> "../foo/sub/a/b/c"
> +test_submodule_relative_url "(null)" "../foo/bar/" "../sub/a/b/c" 
> "../foo/sub/a/b/c"
>  test_submodule_relative_url "(null)" "../foo/bar" "../submodule" 
> "../foo/submodule"
>  test_submodule_relative_url "(null)" "../foo/submodule" "../submodule" 
> "../foo/submodule"
>  test_submodule_relative_url "(null)" "../foo" "../submodule" "../submodule"

I see that this already made it to `next`. I saw that because it breaks
the build of Git for Windows (this was not noticed earlier because other
compile failures prevented the tests from running), as now the test cases
173 and 177 of t0060 fail (*not* the newly introduced 163).

Here is the output with -v -x:

-- snip --
[...]
expecting success:
                actual=$(git submodule--helper resolve-relative-url-test 
'(null)' '/usr/src/git/wip/t/trash directory.t0060-path-utils/.' '../.') &&
                test "$actual" = 'C:/git-sdk-64/usr/src/git/wip/t/trash 
directory.t0060-path-utils/.'

+++ git submodule--helper resolve-relative-url-test '(null)' 
'/usr/src/git/wip/t/trash directory.t0060-path-utils/.' ../.
++ actual=C:/git-sdk-64/usr/src/git/wip/t/.
++ test C:/git-sdk-64/usr/src/git/wip/t/. = 
'C:/git-sdk-64/usr/src/git/wip/t/trash directory.t0060-path-utils/.'
error: last command exited with $?=1
not ok 172 - test_submodule_relative_url: (null) /usr/src/git/wip/t/trash 
directory.t0060-path-utils/. ../. => C:/git-sdk-64/usr/src/git/wip/t/trash 
directory.t0060-path-utils/.
#
#                       actual=$(git submodule--helper
#                       resolve-relative-url-test '(null)'
#                       '/usr/src/git/wip/t/trash
#                       directory.t0060-path-utils/.' '../.') &&
#                       test "$actual" =
#                       'C:/git-sdk-64/usr/src/git/wip/t/trash
#                       directory.t0060-path-utils/.'
#
[...]
expecting success:
                actual=$(git submodule--helper resolve-relative-url-test 
'(null)' '/usr/src/git/wip/t/trash directory.t0060-path-utils/.' 
'../submodule') &&
                test "$actual" = 'C:/git-sdk-64/usr/src/git/wip/t/trash 
directory.t0060-path-utils/submodule'

+++ git submodule--helper resolve-relative-url-test '(null)' 
'/usr/src/git/wip/t/trash directory.t0060-path-utils/.' ../submodule
++ actual=C:/git-sdk-64/usr/src/git/wip/t/submodule
++ test C:/git-sdk-64/usr/src/git/wip/t/submodule = 
'C:/git-sdk-64/usr/src/git/wip/t/trash directory.t0060-path-utils/submodule'
error: last command exited with $?=1
not ok 176 - test_submodule_relative_url: (null) /usr/src/git/wip/t/trash 
directory.t0060-path-utils/. ../submodule => 
C:/git-sdk-64/usr/src/git/wip/t/trash directory.t0060-path-utils/submodule
#
#                       actual=$(git submodule--helper
#                       resolve-relative-url-test '(null)'
#                       '/usr/src/git/wip/t/trash
#                       directory.t0060-path-utils/.' '../submodule') &&
#                       test "$actual" =
#                       'C:/git-sdk-64/usr/src/git/wip/t/trash
#                       directory.t0060-path-utils/submodule'
#
[...]
-- snap --

For comparison, this is how it succeeds in an Ubuntu VM:

-- snap --
expecting success:
                actual=$(git submodule--helper resolve-relative-url-test 
'(null)' '/home/virtualbox/git/wip/t/trash directory.t0060-path-utils/.' 
'../.') &&
                test "$actual" = '/home/virtualbox/git/wip/t/trash 
directory.t0060-path-utils/.'

+++ git submodule--helper resolve-relative-url-test '(null)' 
'/home/virtualbox/git/wip/t/trash directory.t0060-path-utils/.' ../.
++ actual='/home/virtualbox/git/wip/t/trash directory.t0060-path-utils/.'
++ test '/home/virtualbox/git/wip/t/trash directory.t0060-path-utils/.' = 
'/home/virtualbox/git/wip/t/trash directory.t0060-path-utils/.'
+ test_eval_ret_=0
+ want_trace
+ test t = t
+ test t = t
+ set +x
ok 173 - test_submodule_relative_url: (null) /home/virtualbox/git/wip/t/trash 
directory.t0060-path-utils/. ../. => /home/virtualbox/git/wip/t/trash 
directory.t0060-path-utils/.
-- snap --

The reason that this fails on Windows is that the POSIX->Windows path
mangling of the MSYS2 shell strips the trailing . from "/some/directory/."
when converting it to "C:/git-sdk-64/some/directory", and for a good
reason: most Windows programs do not handle the trailing "." very well.

One very, very ugly workaround for this newly-introduced breakage would be
this:

-- snip --
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index 82b98f8..abd82e9 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -328,11 +328,11 @@ test_submodule_relative_url "(null)" "./foo" 
"../submodule" "submodule"
 test_submodule_relative_url "(null)" "//somewhere else/repo" "../subrepo" 
"//somewhere else/subrepo"
 test_submodule_relative_url "(null)" "$PWD/subsuper_update_r" 
"../subsubsuper_update_r" "$(pwd)/subsubsuper_update_r"
 test_submodule_relative_url "(null)" "$PWD/super_update_r2" 
"../subsuper_update_r" "$(pwd)/subsuper_update_r"
-test_submodule_relative_url "(null)" "$PWD/." "../." "$(pwd)/."
+test_submodule_relative_url "(null)" "$(pwd)/." "../." "$(pwd)/."
 test_submodule_relative_url "(null)" "$PWD" "./." "$(pwd)/."
 test_submodule_relative_url "(null)" "$PWD/addtest" "../repo" "$(pwd)/repo"
 test_submodule_relative_url "(null)" "$PWD" "./ " "$(pwd)/ "
-test_submodule_relative_url "(null)" "$PWD/." "../submodule" "$(pwd)/submodule"
+test_submodule_relative_url "(null)" "$(pwd)/." "../submodule" 
"$(pwd)/submodule"
 test_submodule_relative_url "(null)" "$PWD/submodule" "../submodule" 
"$(pwd)/submodule"
 test_submodule_relative_url "(null)" "$PWD/home2/../remote" "../bundle1" 
"$(pwd)/home2/../bundle1"
 test_submodule_relative_url "(null)" "$PWD/submodule_update_repo" "./." 
"$(pwd)/submodule_update_repo/."
-- snap --

The reasons this is ugly: we specifically test for *Unixy* paths when we
use $PWD, as opposed to *Windowsy* paths when using $(pwd). We do this to
ensure a certain level of confidence that running things such as

        git clone --recurse-submodules /z/project/.

work. And now that does not work anymore.

So where to go from here?

Ciao,
Dscho

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