From 64719b115d61582fa501690ee6caff4c478b4b1a Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Sat, 24 Jun 2017 12:02:39 -0700
Subject: Revert "split-index: add and use unshare_split_index()"

This reverts commit f9d7abec2ad2f9eb3d8873169cc28c34273df082;
see public-inbox.org/git/CAP8UFD0bOfzY-_hBDKddOcJdPUpP2KEVaX_SrCgvAMYAHtseiQ@mail.gmail.com

diff --git a/read-cache.c b/read-cache.c
index 8da84ae..0d0081a 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1877,9 +1877,15 @@ int discard_index(struct index_state *istate)
 {
 	int i;
 
-	unshare_split_index(istate, 1);
-	for (i = 0; i < istate->cache_nr; i++)
+	for (i = 0; i < istate->cache_nr; i++) {
+		if (istate->cache[i]->index &&
+		    istate->split_index &&
+		    istate->split_index->base &&
+		    istate->cache[i]->index <= istate->split_index->base->cache_nr &&
+		    istate->cache[i] == istate->split_index->base->cache[istate->cache[i]->index - 1])
+			continue;
 		free(istate->cache[i]);
+	}
 	resolve_undo_clear_index(istate);
 	istate->cache_nr = 0;
 	istate->cache_changed = 0;
diff --git a/split-index.c b/split-index.c
index 49bd197..f519e60 100644
--- a/split-index.c
+++ b/split-index.c
@@ -73,17 +73,10 @@ void move_cache_to_base_index(struct index_state *istate)
 	int i;
 
 	/*
-	 * If "si" is shared with another index_state (e.g. by
-	 * unpack-trees code), we will need to duplicate split_index
-	 * struct. It's not happening now though, luckily.
+	 * do not delete old si->base, its index entries may be shared
+	 * with istate->cache[]. Accept a bit of leaking here because
+	 * this code is only used by short-lived update-index.
 	 */
-	assert(si->refcount <= 1);
-
-	unshare_split_index(istate, 0);
-	if (si->base) {
-		discard_index(si->base);
-		free(si->base);
-	}
 	si->base = xcalloc(1, sizeof(*si->base));
 	si->base->version = istate->version;
 	/* zero timestamp disables racy test in ce_write_index() */
@@ -282,41 +275,11 @@ void finish_writing_split_index(struct index_state *istate)
 	istate->cache_nr = si->saved_cache_nr;
 }
 
-void unshare_split_index(struct index_state *istate, int discard)
-{
-	struct split_index *si = istate->split_index;
-	int i;
-
-	if (!si || !si->base)
-		return;
-
-	for (i = 0; i < istate->cache_nr; i++) {
-		struct cache_entry *ce = istate->cache[i];
-		struct cache_entry *new = NULL;
-
-		if (!ce->index ||
-		    ce->index > si->base->cache_nr ||
-		    ce != si->base->cache[ce->index - 1])
-			continue;
-
-		if (!discard) {
-			int len = ce_namelen(ce);
-			new = xcalloc(1, cache_entry_size(len));
-			copy_cache_entry(new, ce);
-			memcpy(new->name, ce->name, len);
-			new->index = 0;
-		}
-		istate->cache[i] = new;
-	}
-}
-
-
 void discard_split_index(struct index_state *istate)
 {
 	struct split_index *si = istate->split_index;
 	if (!si)
 		return;
-	unshare_split_index(istate, 0);
 	istate->split_index = NULL;
 	si->refcount--;
 	if (si->refcount)
@@ -365,8 +328,14 @@ void add_split_index(struct index_state *istate)
 
 void remove_split_index(struct index_state *istate)
 {
-	if (!istate->split_index)
-		return;
-	discard_split_index(istate);
-	istate->cache_changed |= SOMETHING_CHANGED;
+	if (istate->split_index) {
+		/*
+		 * can't discard_split_index(&the_index); because that
+		 * will destroy split_index->base->cache[], which may
+		 * be shared with the_index.cache[]. So yeah we're
+		 * leaking a bit here.
+		 */
+		istate->split_index = NULL;
+		istate->cache_changed |= SOMETHING_CHANGED;
+	}
 }
diff --git a/split-index.h b/split-index.h
index 65c0f09..df91c1b 100644
--- a/split-index.h
+++ b/split-index.h
@@ -33,6 +33,5 @@ void finish_writing_split_index(struct index_state *istate);
 void discard_split_index(struct index_state *istate);
 void add_split_index(struct index_state *istate);
 void remove_split_index(struct index_state *istate);
-void unshare_split_index(struct index_state *istate, int discard);
 
 #endif
-- 
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