[PATCH] templates: make example pre-commit hook verify submodule commits exist

[Sam Vilain-2]

With submodules it can be quite easy to end up with a situation where the
version in the supermodule doesn't exist in the submodule.  Add to the
example pre-commit hook a script which checks before every commit whether
the submodule commit is likely to exist at the URL defined in the
.gitmodules file.

Signed-off-by: Sam Vilain <[hidden email]>
---
 This should be useful for those using submodules.  Perhaps it should also
 have an equivalent in the 'git submodule' command.

 templates/hooks--pre-commit.sample |   56 +++++++++++++++++++++++++++++++++++-
 1 files changed, 55 insertions(+), 1 deletions(-)

diff --git a/templates/hooks--pre-commit.sample b/templates/hooks--pre-commit.sample
index 0e49279..26e7cf2 100755
--- a/templates/hooks--pre-commit.sample
+++ b/templates/hooks--pre-commit.sample
@@ -7,7 +7,61 @@
 #
 # To enable this hook, rename this file to "pre-commit".
 
-if git-rev-parse --verify HEAD 2>/dev/null
+# first, check that all submodule commits are available by a remote
+# which has the same URL as the one they are listed in.
+if [ -n "$GIT_WORK_TREE" ]
+then
+ cd "$GIT_WORK_TREE"
+fi
+
+git ls-tree $(git write-tree) | grep commit |
+while read mode type sha1 submodule
+do
+ module=$(GIT_CONFIG=.gitmodules git config --list |
+ grep '\.path='"$submodule"\$ |
+ sed 's/submodule\.\([^\.]*\)\..*/\1/')
+ if [ -z "$module" ]
+ then
+ echo "path $submodule is a submodule, but is not" \
+ "listed in .gitmodules" >&2
+ exit 1
+ fi
+ submodule_url=$(GIT_CONFIG=.gitmodules git config \
+ submodule.$submodule.url)
+
+ remotes=$(GIT_DIR=$submodule/.git git config --list |
+ grep '^remote\..*\.url='"$submodule_url" |
+ sed 's/remote\.\([^\.]*\)\..*/\1/')
+
+ found=
+ for remote in $remotes
+ do
+ found=$(GIT_DIR=$submodule/.git git name-rev \
+ --refs=refs/remotes/$remote/* $sha1 2>/dev/null |
+ grep -vw undefined)
+ [ -n "$found" ] && break
+ done
+
+ if [ -z "$found" ]
+ then
+ echo "submodule commit does not appear under tracked remote refs" >&2
+ echo "  submodule = $submodule"
+ echo ".gitmodules = $module"
+ echo "        url = $submodule_url"
+ echo "     commit = $sha1"
+ echo "  tried remotes:" $remotes
+ exit 2
+ fi
+done
+
+# this is the return code of the | while sub-shell above
+rc=$?
+if [ $rc -ne 0 ]
+then
+ exit $rc
+fi
+
+if git-rev-parse --verify HEAD >/dev/null 2>&1
 then
  against=HEAD
 else
--
1.6.0

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[Junio C Hamano]

Sam Vilain <[hidden email]> writes:

> With submodules it can be quite easy to end up with a situation where the
> version in the supermodule doesn't exist in the submodule.  Add to the
> example pre-commit hook a script which checks before every commit whether
> the submodule commit is likely to exist at the URL defined in the
> .gitmodules file.
>
> Signed-off-by: Sam Vilain <[hidden email]>
> ---
>  This should be useful for those using submodules.  Perhaps it should also
>  have an equivalent in the 'git submodule' command.

If I am a developer who is not interested in any of the submodules in the
project at all (i.e. I do not have any submodule checked out), my commits
will never touch any of the submodules.  In such a case, I shouldn't be
forced to fetch/clone the submodule nor have a checkout.

Which means...

> +# first, check that all submodule commits are available by a remote
> +# which has the same URL as the one they are listed in.
> +if [ -n "$GIT_WORK_TREE" ]
> +then
> + cd "$GIT_WORK_TREE"
> +fi
> +
> +git ls-tree $(git write-tree) | grep commit |
> +while read mode type sha1 submodule
> +do

... the input fed to this while look utterly wrong.  At least, you should
be checking *new* commit that is introduced to the tree with this commit.

I didn't read the body of the while loop; no matter what it does, if its
input is wrong, its end result cannot be correct.
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