71 lines
1.9 KiB
Bash
Executable File
71 lines
1.9 KiB
Bash
Executable File
#!/bin/sh
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#
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# Filter the history of a git repository to only include the named
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# files.
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set -e
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if [ $# -lt 1 ]; then
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echo "Usage $0 <files to keep>"
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exit 1
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fi
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set -x
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files_to_keep="$@"
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# Build the grep pattern for ignoring files that we want to keep
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keep_pattern="\($(echo $files_to_keep | sed -e 's/ /\\|/g')\)"
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# Prune all other files in every commit
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pruner="git ls-files | grep -v \"$keep_pattern\" | git update-index --force-remove --stdin; git ls-files > /dev/stderr"
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# Find all first commits with listed files and find a subset of them that
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# predates all others
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roots=""
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for file in $files_to_keep; do
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file_root=$(git rev-list --reverse HEAD -- $file | head -n1)
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fail=0
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for root in $roots; do
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if git merge-base --is-ancestor $root $file_root; then
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fail=1
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break
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elif ! git merge-base --is-ancestor $file_root $root; then
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new_roots="$new_roots $root"
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fi
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done
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if [ $fail -ne 1 ]; then
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roots="$new_roots $file_root"
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fi
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done
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# Purge all parents for those commits
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set_roots="
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if [ 1 -eq 0 $(for root in $roots; do echo " -o \"\$GIT_COMMIT\" = '$root' "; done) ]; then
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echo '';
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else
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cat;
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fi"
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# Enhance git_commit_non_empty_tree to skip merges with:
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# a) either two equal parents (commit that was about to land got purged as well
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# as all commits on mainline);
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# b) or with second parent being an ancestor to the first one (just as with a)
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# but when there are some commits on mainline).
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# In both cases drop second parent and let git_commit_non_empty_tree to decide
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# if commit worth doing (most likely not).
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skip_empty=$(cat << \EOF
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if [ $# = 5 ] && git merge-base --is-ancestor $5 $3; then
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git_commit_non_empty_tree $1 -p $3
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else
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git_commit_non_empty_tree "$@"
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fi
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EOF
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)
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# Filter out commits for unrelated files
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echo "Pruning commits for unrelated files..."
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git filter-branch --index-filter "$pruner" --parent-filter "$set_roots" --commit-filter "$skip_empty" HEAD
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