[PATCH 11/14] unpack_trees(): add support for sparse checkout

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

This patch teaches unpack_trees() to checkout/remove entries
on working directories appropriately when sparse checkout area is
changed. There are three kind of changes:

 - new_narrow_path: reset workdir to a completely new checkout area
 - add_narrow_path: keep current areas and add more entries
 - remove_narrow_path: remove some entries from current areas

CE_WD_REMOVE is introduced to remove entries from working directories,
but still keep them in index

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 cache.h        |    3 ++
 unpack-trees.c |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 unpack-trees.h |    4 +++
 3 files changed, 80 insertions(+), 1 deletions(-)

diff --git a/cache.h b/cache.h
index 6e875d5..f4025b5 100644
--- a/cache.h
+++ b/cache.h
@@ -167,6 +167,9 @@ struct cache_entry {
 #define CE_HASHED    (0x100000)
 #define CE_UNHASHED  (0x200000)
 
+/* Only remove in work directory, not index */
+#define CE_WD_REMOVE (0x400000)
+
 /*
  * Extended on-disk flags
  */
diff --git a/unpack-trees.c b/unpack-trees.c
index ce4c826..10f377c 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -96,7 +96,7 @@ static int check_updates(struct unpack_trees_options *o)
 	if (o->update && o->verbose_update) {
 		for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
 			struct cache_entry *ce = index->cache[cnt];
-			if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
+			if (ce->ce_flags & (CE_UPDATE | CE_REMOVE | CE_WD_REMOVE))
 				total++;
 		}
 
@@ -108,6 +108,13 @@ static int check_updates(struct unpack_trees_options *o)
 	for (i = 0; i < index->cache_nr; i++) {
 		struct cache_entry *ce = index->cache[i];
 
+		if (ce->ce_flags & CE_WD_REMOVE) {
+			display_progress(progress, ++cnt);
+			if (o->update)
+				unlink_entry(ce);
+			continue;
+		}
+
 		if (ce->ce_flags & CE_REMOVE) {
 			display_progress(progress, ++cnt);
 			if (o->update)
@@ -133,6 +140,66 @@ static int check_updates(struct unpack_trees_options *o)
 	return errs != 0;
 }
 
+static int verify_uptodate(struct cache_entry *ce, struct unpack_trees_options *o);
+static int apply_narrow_spec(struct unpack_trees_options *o)
+{
+	struct index_state *index = &o->result;
+	int i;
+
+	if (!(o->new_narrow_path | o->add_narrow_path | o->remove_narrow_path))
+		return 0;
+
+	for (i = 0; i < index->cache_nr; i++) {
+		struct cache_entry *ce = index->cache[i];
+		int was_checkout = ce_checkout(ce);
+		int match = match_narrow_spec(o->narrow_spec, ce->name);
+
+		if (ce_stage(ce))
+			continue;
+
+		if (o->new_narrow_path) {
+			if (match)
+				ce_mark_checkout(ce);
+			else
+				ce_mark_no_checkout(ce);
+		}
+
+		if (o->add_narrow_path && match)
+			ce_mark_checkout(ce);
+
+		if (o->remove_narrow_path && match)
+			ce_mark_no_checkout(ce);
+
+		/* Update worktree, add/remove entries if needed */
+
+		/*
+		 * We only care about files getting into the checkout area
+		 * If merge strategies want to remove some, go ahead
+		 */
+		if (ce->ce_flags & CE_REMOVE)
+			continue;
+
+		if (was_checkout && ce_no_checkout(ce)) {
+			/*
+			 * If CE_UPDATE is set, verify_uptodate() must be called already
+			 * also stat info may have lost after merged_entry() so calling
+			 * verify_uptodate() again may fail
+			 */
+			if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate(ce, o))
+				return -1;
+			ce->ce_flags |= CE_WD_REMOVE;
+		}
+		if (!was_checkout && ce_checkout(ce))
+			ce->ce_flags |= CE_UPDATE;
+
+		/* merge strategies may set CE_UPDATE outside checkout area */
+		if (ce_no_checkout(ce))
+			ce->ce_flags &= ~CE_UPDATE;
+
+	}
+	return 0;
+}
+
 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 {
 	int ret = o->fn(src, o);
@@ -409,6 +476,9 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	if (o->trivial_merges_only && o->nontrivial_merge)
 		return unpack_failed(o, "Merge requires file-level merging");
 
+	if (apply_narrow_spec(o))
+		return unpack_failed(o, NULL);
+
 	o->src_index = NULL;
 	ret = check_updates(o) ? (-2) : 0;
 	if (o->dst_index)
@@ -677,6 +747,8 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 				return -1;
 			invalidate_ce_path(old, o);
 		}
+		if (ce_no_checkout(old))
+			update |= CE_NO_CHECKOUT;
 	}
 	else {
 		if (verify_absent(merge, "overwritten", o))
diff --git a/unpack-trees.h b/unpack-trees.h
index 6b1971f..0d899b6 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -43,6 +43,9 @@ struct unpack_trees_options {
 		     aggressive:1,
 		     skip_unmerged:1,
 		     initial_checkout:1,
+		     new_narrow_path:1,
+		     add_narrow_path:2,
+		     remove_narrow_path:2,
 		     gently:1;
 	const char *prefix;
 	int pos;
@@ -54,6 +57,7 @@ struct unpack_trees_options {
 	int merge_size;
 
 	struct cache_entry *df_conflict_entry;
+	struct narrow_spec *narrow_spec;
 	void *unpack_data;
 
 	struct index_state *dst_index;
-- 
1.6.0.96.g2fad1.dirty