Hello,
I have posted a question on Stack Overflow [1]. I would like to post it
here as well since nobody has answered it yet.
Let's immediately start with a scrap of the `pre-receive` hook that I've
already written:
#!/bin/sh
##
format_bold='\e[1m'
format_red='\e[31m'
format_normal='\e[0m'
##
log_error="${format_bold}${format_red}error${format_normal}"
##
stdout() {
printf "${1}" "${@:2}"
}
##
stderr() {
stdout "${@}" 1>&2
}
##
output() {
stdout "${1}\n" "${@:2}"
}
##
error() {
stderr "${log_error}: ${1}\n" "${@:2}"
}
##
die() {
error "${@}"
exit 1
}
##
list() {
git rev-list "${@}"
}
##
clang_format() {
git --no-pager clang-format --style='file' "${@}"
}
##
while read sha1_old sha1_new ref; do
case "${ref}" in
refs/heads/*)
branch="$(expr "${ref}" : 'refs/heads/\(.*\)')"
if [ "$(expr "${sha1_new}" : '0*$')" -ne 0 ]; then # delete
unset sha1_new
# ...
else # update
if [ "$(expr "${sha1_old}" : '0*$')" -ne 0 ]; then # create
unset sha1_old
sha1_range="${sha1_new}"
else
sha1_range="${sha1_old}..${sha1_new}"
# ...
fi
fi
# ...
GIT_WORK_TREE="$(mktemp --tmpdir -d 'gitXX')"
export GIT_WORK_TREE
GIT_DIR="${GIT_WORK_TREE}/.git"
export GIT_DIR
mkdir -p "${GIT_DIR}"
cp -a * "${GIT_DIR}/"
ln -s "${PWD}/../.clang-format" "${GIT_WORK_TREE}/"
error=
for sha1 in $(list "${sha1_range}"); do
git checkout --force "${sha1}" > '/dev/null' 2>&1
if [ "$(list --count "${sha1}")" -eq 1 ]; then
# What should I put here?
else
git reset --soft 'HEAD~1' > '/dev/null' 2>&1
fi
diff="$(clang_format --diff)"
if [ "${diff%% *}" = 'diff' ]; then
error=1
error '%s: %s\n%s' \
'Code style issues detected' \
"${sha1}" \
"${diff}" \
1>&2
fi
done
if [ -n "${error}" ]; then
die '%s' 'Code style issues detected'
fi
fi
;;
refs/tags/*)
tag="$(expr "${ref}" : 'refs/tags/\(.*\)')"
# ...
;;
*)
# ...
;;
esac
done
exit 0
**NOTE:**
Places with irrelevant code are stubbed with `# ...`.
**NOTE:**
If you are not familiar with `git-clang-format`, take a look [here][2].
That hook works as expected, and so far, I didn't notice any bugs, but
if you spot any problem or have an improvement suggestion, I'd
appreciate any report. Probably, I should give a comment on what's the
intention behind this hook. Well, it does check every pushed revision
for compliance with code style conventions using `git-clang-format`, and
if any of them does not comply, it will output the relevant diff (the
one telling developers what should be fixed) for each of them.
Basically, I have two in-depth questions regarding this hook.
First, notice that I perform copy of the remote's (server) bare
repository to some temporary directory and check out the code for
analysis there. Let me explain the intention of this. Note that I do
several `git checkout`s and `git reset`s (due to `for` loop) in order to
analyze all of the pushed revisions individually with
`git-clang-format`. What I am trying to avoid here, is the (possible)
concurrency issue on push access to the remote's (server) bare
repository. That is, I'm under impression that if multiple developers
will try to push at the same time to a remote with this `pre-receive`
hook installed, that might cause problems if each of these push
"sessions" does not do `git checkout`s and `git reset`s with its private
copy of the repository. So, to put it simple, does `git-daemon` have
built-in lock management for concurrent push "sessions"? Will it
execute the corresponding `pre-receive` hook instances strictly
sequentially or there is a possibility of interleaving (which can
potentially cause undefined behavior)? Something tells me that there
should be a built-in solution for this problem with concrete guarantees,
otherwise how would remotes work in general (even without complex hooks)
being subjected to concurrent pushes? If there is such a built-in
solution, then the copy is redundant and simply reusing the bare
repository would actually speed up the processing. By the way, any
reference to official documentation regarding this question is very welcome.
Second, `git-clang-format` processes on
