Make 'unpack_trees()' have a separate source and destination index

We will always unpack into our own internal index, but we will take the
source from wherever specified, and we will optionally write the result
to a specified index (optionally, because not everybody even _wants_ any
result: the index diffing really wants to just walk the tree and index
in parallel).

This ends up removing a fair number more lines than it adds, for the
simple reason that we can now skip all the crud that tried to be
oh-so-careful about maintaining our position in the index as we were
traversing and modifying it.  Since we don't actually modify the source
index any more, we can just update the 'o->pos' pointer without worrying
about whether an index entry got removed or replaced or added to.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 72 insertions, 77 deletions

diff --git a/unpack-trees.c b/unpack-trees.c
index cb8f847968..0cdf19817d 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -8,10 +8,18 @@
 #include "progress.h"
 #include "refs.h"
 
-static inline void remove_entry(int remove, struct unpack_trees_options *o)
+static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
+	unsigned int set, unsigned int clear)
 {
-	if (remove >= 0)
-		remove_index_entry_at(o->index, remove);
+	unsigned int size = ce_size(ce);
+	struct cache_entry *new = xmalloc(size);
+
+	clear |= CE_HASHED | CE_UNHASHED;
+
+	memcpy(new, ce, size);
+	new->next = NULL;
+	new->ce_flags = (new->ce_flags & ~clear) | set;
+	add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
 }
 
 /* Unlink the last component and attempt to remove leading
@@ -51,11 +59,12 @@ static void check_updates(struct unpack_trees_options *o)
 	unsigned cnt = 0, total = 0;
 	struct progress *progress = NULL;
 	char last_symlink[PATH_MAX];
+	struct index_state *index = &o->result;
 	int i;
 
 	if (o->update && o->verbose_update) {
-		for (total = cnt = 0; cnt < o->index->cache_nr; cnt++) {
-			struct cache_entry *ce = o->index->cache[cnt];
+		for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
+			struct cache_entry *ce = index->cache[cnt];
 			if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
 				total++;
 		}
@@ -66,15 +75,15 @@ static void check_updates(struct unpack_trees_options *o)
 	}
 
 	*last_symlink = '\0';
-	for (i = 0; i < o->index->cache_nr; i++) {
-		struct cache_entry *ce = o->index->cache[i];
+	for (i = 0; i < index->cache_nr; i++) {
+		struct cache_entry *ce = index->cache[i];
 
 		if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
 			display_progress(progress, ++cnt);
 		if (ce->ce_flags & CE_REMOVE) {
 			if (o->update)
 				unlink_entry(ce->name, last_symlink);
-			remove_index_entry_at(o->index, i);
+			remove_index_entry_at(&o->result, i);
 			i--;
 			continue;
 		}
@@ -89,28 +98,27 @@ static void check_updates(struct unpack_trees_options *o)
 	stop_progress(&progress);
 }
 
-static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o, int remove)
+static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 {
-	int ret = o->fn(src, o, remove);
-	if (ret > 0) {
-		o->pos += ret;
+	int ret = o->fn(src, o);
+	if (ret > 0)
 		ret = 0;
-	}
 	return ret;
 }
 
 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 {
 	struct cache_entry *src[5] = { ce, };
+
+	o->pos++;
 	if (ce_stage(ce)) {
 		if (o->skip_unmerged) {
-			o->pos++;
-		} else {
-			remove_entry(o->pos, o);
+			add_entry(o, ce, 0, 0);
+			return 0;
 		}
 		return 0;
 	}
-	return call_unpack_fn(src, o, o->pos);
+	return call_unpack_fn(src, o);
 }
 
 int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
@@ -200,7 +208,7 @@ static struct cache_entry *create_ce_entry(const struct traverse_info *info, con
 }
 
 static int unpack_nondirectories(int n, unsigned long mask, unsigned long dirmask, struct cache_entry *src[5],
-	const struct name_entry *names, const struct traverse_info *info, int remove)
+	const struct name_entry *names, const struct traverse_info *info)
 {
 	int i;
 	struct unpack_trees_options *o = info->data;
@@ -240,12 +248,11 @@ static int unpack_nondirectories(int n, unsigned long mask, unsigned long dirmas
 	}
 
 	if (o->merge)
-		return call_unpack_fn(src, o, remove);
+		return call_unpack_fn(src, o);
 
 	n += o->merge;
-	remove_entry(remove, o);
 	for (i = 0; i < n; i++)
-		add_index_entry(o->index, src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
+		add_entry(o, src[i], 0, 0);
 	return 0;
 }
 
@@ -253,7 +260,6 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
 {
 	struct cache_entry *src[5] = { NULL, };
 	struct unpack_trees_options *o = info->data;
-	int remove = -1;
 	const struct name_entry *p = names;
 
 	/* Find first entry with a real name (we could use "mask" too) */
@@ -262,8 +268,8 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
 
 	/* Are we supposed to look at the index too? */
 	if (o->merge) {
-		while (o->pos < o->index->cache_nr) {
-			struct cache_entry *ce = o->index->cache[o->pos];
+		while (o->pos < o->src_index->cache_nr) {
+			struct cache_entry *ce = o->src_index->cache[o->pos];
 			int cmp = compare_entry(ce, info, p);
 			if (cmp < 0) {
 				if (unpack_index_entry(ce, o) < 0)
@@ -271,24 +277,25 @@ static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, str
 				continue;
 			}
 			if (!cmp) {
+				o->pos++;
 				if (ce_stage(ce)) {
 					/*
 					 * If we skip unmerged index entries, we'll skip this
 					 * entry *and* the tree entries associated with it!
 					 */
-					if (o->skip_unmerged)
+					if (o->skip_unmerged) {
+						add_entry(o, ce, 0, 0);
 						return mask;
-					remove_entry(o->pos, o);
+					}
 					continue;
 				}
 				src[0] = ce;
-				remove = o->pos;
 			}
 			break;
 		}
 	}
 
-	if (unpack_nondirectories(n, mask, dirmask, src, names, info, remove) < 0)
+	if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 		return -1;
 
 	/* Now handle any directories.. */
@@ -313,8 +320,6 @@ static int unpack_failed(struct unpack_trees_options *o, const char *message)
 			return error(message);
 		return -1;
 	}
-	discard_index(o->index);
-	read_index(o->index);
 	return -1;
 }
 
@@ -330,6 +335,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	state.quiet = 1;
 	state.refresh_cache = 1;
 
+	memset(&o->result, 0, sizeof(o->result));
 	o->merge_size = len;
 
 	if (!dfc)
@@ -350,8 +356,8 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 
 	/* Any left-over entries in the index? */
 	if (o->merge) {
-		while (o->pos < o->index->cache_nr) {
-			struct cache_entry *ce = o->index->cache[o->pos];
+		while (o->pos < o->src_index->cache_nr) {
+			struct cache_entry *ce = o->src_index->cache[o->pos];
 			if (unpack_index_entry(ce, o) < 0)
 				return unpack_failed(o, NULL);
 		}
@@ -360,7 +366,10 @@ 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");
 
+	o->src_index = NULL;
 	check_updates(o);
+	if (o->dst_index)
+		*o->dst_index = o->result;
 	return 0;
 }
 
@@ -396,7 +405,7 @@ static int verify_uptodate(struct cache_entry *ce,
 		return 0;
 
 	if (!lstat(ce->name, &st)) {
-		unsigned changed = ie_match_stat(o->index, ce, &st, CE_MATCH_IGNORE_VALID);
+		unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
 		if (!changed)
 			return 0;
 		/*
@@ -419,7 +428,7 @@ static int verify_uptodate(struct cache_entry *ce,
 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 {
 	if (ce)
-		cache_tree_invalidate_path(o->index->cache_tree, ce->name);
+		cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 }
 
 /*
@@ -464,12 +473,12 @@ static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 	 * in that directory.
 	 */
 	namelen = strlen(ce->name);
-	pos = index_name_pos(o->index, ce->name, namelen);
+	pos = index_name_pos(o->src_index, ce->name, namelen);
 	if (0 <= pos)
 		return cnt; /* we have it as nondirectory */
 	pos = -pos - 1;
-	for (i = pos; i < o->index->cache_nr; i++) {
-		struct cache_entry *ce = o->index->cache[i];
+	for (i = pos; i < o->src_index->cache_nr; i++) {
+		struct cache_entry *ce = o->src_index->cache[i];
 		int len = ce_namelen(ce);
 		if (len < namelen ||
 		    strncmp(ce->name, ce->name, namelen) ||
@@ -481,7 +490,7 @@ static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 		if (!ce_stage(ce)) {
 			if (verify_uptodate(ce, o))
 				return -1;
-			ce->ce_flags |= CE_REMOVE;
+			add_entry(o, ce, CE_REMOVE, 0);
 		}
 		cnt++;
 	}
@@ -567,9 +576,9 @@ static int verify_absent(struct cache_entry *ce, const char *action,
 		 * delete this path, which is in a subdirectory that
 		 * is being replaced with a blob.
 		 */
-		cnt = index_name_pos(o->index, ce->name, strlen(ce->name));
+		cnt = index_name_pos(&o->result, ce->name, strlen(ce->name));
 		if (0 <= cnt) {
-			struct cache_entry *ce = o->index->cache[cnt];
+			struct cache_entry *ce = o->result.cache[cnt];
 			if (ce->ce_flags & CE_REMOVE)
 				return 0;
 		}
@@ -584,7 +593,6 @@ static int verify_absent(struct cache_entry *ce, const char *action,
 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 		struct unpack_trees_options *o)
 {
-	merge->ce_flags |= CE_UPDATE;
 	if (old) {
 		/*
 		 * See if we can re-use the old CE directly?
@@ -607,29 +615,29 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 		invalidate_ce_path(merge, o);
 	}
 
-	merge->ce_flags &= ~CE_STAGEMASK;
-	add_index_entry(o->index, merge, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+	add_entry(o, merge, CE_UPDATE, CE_STAGEMASK);
 	return 1;
 }
 
 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 		struct unpack_trees_options *o)
 {
-	if (old) {
-		if (verify_uptodate(old, o))
-			return -1;
-	} else
+	/* Did it exist in the index? */
+	if (!old) {
 		if (verify_absent(ce, "removed", o))
 			return -1;
-	ce->ce_flags |= CE_REMOVE;
-	add_index_entry(o->index, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
+		return 0;
+	}
+	if (verify_uptodate(old, o))
+		return -1;
+	add_entry(o, ce, CE_REMOVE, 0);
 	invalidate_ce_path(ce, o);
 	return 1;
 }
 
 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 {
-	add_index_entry(o->index, ce, ADD_CACHE_OK_TO_ADD);
+	add_entry(o, ce, 0, 0);
 	return 1;
 }
 
@@ -649,9 +657,7 @@ static void show_stage_entry(FILE *o,
 }
 #endif
 
-int threeway_merge(struct cache_entry **stages,
-		struct unpack_trees_options *o,
-		int remove)
+int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 {
 	struct cache_entry *index;
 	struct cache_entry *head;
@@ -728,10 +734,8 @@ int threeway_merge(struct cache_entry **stages,
 	}
 
 	/* #1 */
-	if (!head && !remote && any_anc_missing) {
-		remove_entry(remove, o);
+	if (!head && !remote && any_anc_missing)
 		return 0;
-	}
 
 	/* Under the new "aggressive" rule, we resolve mostly trivial
 	 * cases that we historically had git-merge-one-file resolve.
@@ -763,10 +767,9 @@ int threeway_merge(struct cache_entry **stages,
 		if ((head_deleted && remote_deleted) ||
 		    (head_deleted && remote && remote_match) ||
 		    (remote_deleted && head && head_match)) {
-			remove_entry(remove, o);
 			if (index)
 				return deleted_entry(index, index, o);
-			else if (ce && !head_deleted) {
+			if (ce && !head_deleted) {
 				if (verify_absent(ce, "removed", o))
 					return -1;
 			}
@@ -789,7 +792,6 @@ int threeway_merge(struct cache_entry **stages,
 			return -1;
 	}
 
-	remove_entry(remove, o);
 	o->nontrivial_merge = 1;
 
 	/* #2, #3, #4, #6, #7, #9, #10, #11. */
@@ -824,9 +826,7 @@ int threeway_merge(struct cache_entry **stages,
  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
  *
  */
-int twoway_merge(struct cache_entry **src,
-		struct unpack_trees_options *o,
-		int remove)
+int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 {
 	struct cache_entry *current = src[0];
 	struct cache_entry *oldtree = src[1];
@@ -854,7 +854,6 @@ int twoway_merge(struct cache_entry **src,
 		}
 		else if (oldtree && !newtree && same(current, oldtree)) {
 			/* 10 or 11 */
-			remove_entry(remove, o);
 			return deleted_entry(oldtree, current, o);
 		}
 		else if (oldtree && newtree &&
@@ -864,7 +863,6 @@ int twoway_merge(struct cache_entry **src,
 		}
 		else {
 			/* all other failures */
-			remove_entry(remove, o);
 			if (oldtree)
 				return o->gently ? -1 : reject_merge(oldtree);
 			if (current)
@@ -876,7 +874,6 @@ int twoway_merge(struct cache_entry **src,
 	}
 	else if (newtree)
 		return merged_entry(newtree, current, o);
-	remove_entry(remove, o);
 	return deleted_entry(oldtree, current, o);
 }
 
@@ -887,8 +884,7 @@ int twoway_merge(struct cache_entry **src,
  * stage0 does not have anything there.
  */
 int bind_merge(struct cache_entry **src,
-		struct unpack_trees_options *o,
-		int remove)
+		struct unpack_trees_options *o)
 {
 	struct cache_entry *old = src[0];
 	struct cache_entry *a = src[1];
@@ -898,7 +894,7 @@ int bind_merge(struct cache_entry **src,
 			     o->merge_size);
 	if (a && old)
 		return o->gently ? -1 :
-			error("Entry '%s' overlaps.  Cannot bind.", a->name);
+			error("Entry '%s' overlaps with '%s'.  Cannot bind.", a->name, old->name);
 	if (!a)
 		return keep_entry(old, o);
 	else
@@ -911,9 +907,7 @@ int bind_merge(struct cache_entry **src,
  * The rule is:
  * - take the stat information from stage0, take the data from stage1
  */
-int oneway_merge(struct cache_entry **src,
-		struct unpack_trees_options *o,
-		int remove)
+int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 {
 	struct cache_entry *old = src[0];
 	struct cache_entry *a = src[1];
@@ -922,18 +916,19 @@ int oneway_merge(struct cache_entry **src,
 		return error("Cannot do a oneway merge of %d trees",
 			     o->merge_size);
 
-	if (!a) {
-		remove_entry(remove, o);
+	if (!a)
 		return deleted_entry(old, old, o);
-	}
+
 	if (old && same(old, a)) {
+		int update = 0;
 		if (o->reset) {
 			struct stat st;
 			if (lstat(old->name, &st) ||
-			    ie_match_stat(o->index, old, &st, CE_MATCH_IGNORE_VALID))
-				old->ce_flags |= CE_UPDATE;
+			    ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
+				update |= CE_UPDATE;
 		}
-		return keep_entry(old, o);
+		add_entry(o, old, update, 0);
+		return 0;
 	}
 	return merged_entry(a, old, o);
 }