!/bin/sh

# An example hook script to update a checked-out tree on a git push. # # This hook is invoked by git-receive-pack(1) when it reacts to git # push and updates reference(s) in its repository, and when the push # tries to update the branch that is currently checked out and the # receive.denyCurrentBranch configuration variable is set to # updateInstead. # # By default, such a push is refused if the working tree and the index # of the remote repository has any difference from the currently # checked out commit; when both the working tree and the index match # the current commit, they are updated to match the newly pushed tip # of the branch. This hook is to be used to override the default # behaviour; however the code below reimplements the default behaviour # as a starting point for convenient modification. # # The hook receives the commit with which the tip of the current # branch is going to be updated: commit=$1

# It can exit with a non-zero status to refuse the push (when it does # so, it must not modify the index or the working tree). die () {

echo >&2 "$*"
exit 1

}

# Or it can make any necessary changes to the working tree and to the # index to bring them to the desired state when the tip of the current # branch is updated to the new commit, and exit with a zero status. # # For example, the hook can simply run git read-tree -u -m HEAD “$1” # in order to emulate git fetch that is run in the reverse direction # with git push, as the two-tree form of git read-tree -u -m is # essentially the same as git switch or git checkout that switches # branches while keeping the local changes in the working tree that do # not interfere with the difference between the branches.

# The below is a more-or-less exact translation to shell of the C code # for the default behaviour for git’s push-to-checkout hook defined in # the push_to_deploy() function in builtin/receive-pack.c. # # Note that the hook will be executed from the repository directory, # not from the working tree, so if you want to perform operations on # the working tree, you will have to adapt your code accordingly, e.g. # by adding “cd ..” or using relative paths.

if ! git update-index -q –ignore-submodules –refresh then

die "Up-to-date check failed"

fi

if ! git diff-files –quiet –ignore-submodules – then

die "Working directory has unstaged changes"

fi

# This is a rough translation of: # # head_has_history() ? “HEAD” : EMPTY_TREE_SHA1_HEX if git cat-file -e HEAD 2>/dev/null then

head=HEAD

else

head=$(git hash-object -t tree --stdin </dev/null)

fi

if ! git diff-index –quiet –cached –ignore-submodules $head – then

die "Working directory has staged changes"

fi

if ! git read-tree -u -m “$commit” then

die "Could not update working tree to new HEAD"

fi