git-sub-commit-changelog

#! /bin/bash

# Commit the changelog for a pending submodule
#
# Commits the updated submodule with the changelog as the commit description.
#
# Options:
# --verbose  Show the changelog.

f() {
    verbose=false
    if [[ $1 == --verbose ]]; then
        verbose=true
        shift
    fi

    module=$1
    if [ ! -d $module ] ; then
        echo
        echo "Error: Submodule $module does not exist."
        return -1
    fi

    git add $module
    if [ $? -ne 0 ] ; then
        echo
        echo "Error: No changes in submodule $module."
        return -1
    fi

    prev_head=$(git diff --staged $module | sed -n -e's/-Subproject commit \(.*\)/\1/p')
    if [[ -z $prev_head ]]; then
        git reset -- $module
        echo
        echo "Error: No changes in submodule $module."
        return -1
    fi

    changelog=$(git -C $module log --pretty=%s --first-parent $prev_head..HEAD)
    if [[ $? > 0 ]]; then
        # Git error
        git reset -- $module
        echo
        echo "Error: Git didn't understand revision range. Often occurs when committed"
        echo "submodule contains unpushed commits. Likely the working copy submodule is out"
        echo "of date."
        echo "       Try git sub-update."
        return -1

    elif [[ $(echo "$changelog" | wc -c) -eq 1 ]]; then
        # One character means just a newline. No data.
        git reset -- $module
        echo
        echo "Error: No changes in changelog. Often occurs when working copy submodule is"
        echo "older than committed submodule."
        echo "       Try git sub-update."
        echo
        echo "Changes in committed submodule that are missing from working copy:"
        git -C $module log --pretty="  * %s" --first-parent HEAD..$prev_head
        echo
        return -1
    fi

    echo "$changelog" | cat \
        <(printf 'Update %s\n\nChangelog:\n' $module) \
        - | git commit --file=-

    if [[ "$verbose" == true ]]; then
        echo
        echo "Submitted with changelog:"
        echo
        echo "$changelog"
    fi
}

f $*