filter-branch: nearest-ancestor rewriting outside subdir filter
Since a0e4639 (filter-branch: fix ref rewriting with --subdirectory-filter, 2008-08-12) git-filter-branch has done nearest-ancestor rewriting when using a --subdirectory-filter. However, that rewriting strategy is also a useful building block in other tasks. For example, if you want to split out a subset of files from your history, you would typically call git filter-branch -- <refs> -- <files> But this fails for all refs that do not point directly to a commit that affects <files>, because their referenced commit will not be rewritten and the ref remains untouched. The code was already there for the --subdirectory-filter case, so just introduce an option that enables it independently. Signed-off-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Johannes Sixt <j6t@kdbg.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Thomas Rast committed
Nov 10, 2009 at 22:04 UTC
f2f3a6b802e3dae09a1c414cd8516ff2a546a527
3 files changed
+43
-6
Documentation/git-filter-branch.txt
+12
-1
@@ -159,7 +159,18 @@ to other tags will be rewritten to point to the underlying commit.
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--subdirectory-filter <directory>::
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Only look at the history which touches the given subdirectory.
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The result will contain that directory (and only that) as its
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- project root.
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+ project root. Implies --remap-to-ancestor.
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+
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+--remap-to-ancestor::
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+ Rewrite refs to the nearest rewritten ancestor instead of
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+ ignoring them.
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++
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+Normally, positive refs on the command line are only changed if the
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+commit they point to was rewritten. However, you can limit the extent
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+of this rewriting by using linkgit:rev-list[1] arguments, e.g., path
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+limiters. Refs pointing to such excluded commits would then normally
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+be ignored. With this option, they are instead rewritten to point at
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+the nearest ancestor that was not excluded.
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--prune-empty::
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Some kind of filters will generate empty commits, that left the tree
git-filter-branch.sh
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-5
@@ -125,6 +125,7 @@ filter_subdir=
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orig_namespace=refs/original/
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force=
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prune_empty=
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+remap_to_ancestor=
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while :
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do
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case "$1" in
@@ -137,6 +138,11 @@ do
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force=t
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continue
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;;
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+ --remap-to-ancestor)
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+ shift
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+ remap_to_ancestor=t
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+ continue
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+ ;;
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--prune-empty)
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shift
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prune_empty=t
@@ -182,6 +188,7 @@ do
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;;
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--subdirectory-filter)
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filter_subdir="$OPTARG"
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+ remap_to_ancestor=t
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;;
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--original)
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orig_namespace=$(expr "$OPTARG/" : '\(.*[^/]\)/*$')/
@@ -354,12 +361,13 @@ while read commit parents; do
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die "could not write rewritten commit"
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done <../revs
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-# In case of a subdirectory filter, it is possible that a specified head
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-# is not in the set of rewritten commits, because it was pruned by the
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-# revision walker. Fix it by mapping these heads to the unique nearest
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-# ancestor that survived the pruning.
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+# If we are filtering for paths, as in the case of a subdirectory
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+# filter, it is possible that a specified head is not in the set of
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+# rewritten commits, because it was pruned by the revision walker.
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+# Ancestor remapping fixes this by mapping these heads to the unique
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+# nearest ancestor that survived the pruning.
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-if test "$filter_subdir"
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+if test "$remap_to_ancestor" = t
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then
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while read ref
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do
t/t7003-filter-branch.sh
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@@ -288,4 +288,22 @@ test_expect_success 'Prune empty commits' '
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test_cmp expect actual
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'
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+test_expect_success '--remap-to-ancestor with filename filters' '
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+ git checkout master &&
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+ git reset --hard A &&
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+ test_commit add-foo foo 1 &&
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+ git branch moved-foo &&
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+ test_commit add-bar bar a &&
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+ git branch invariant &&
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+ orig_invariant=$(git rev-parse invariant) &&
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+ git branch moved-bar &&
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+ test_commit change-foo foo 2 &&
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+ git filter-branch -f --remap-to-ancestor \
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+ moved-foo moved-bar A..master \
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+ -- -- foo &&
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+ test $(git rev-parse moved-foo) = $(git rev-parse moved-bar) &&
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+ test $(git rev-parse moved-foo) = $(git rev-parse master^) &&
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+ test $orig_invariant = $(git rev-parse invariant)
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+'
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+
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test_done