[PATCH 2/2] read-cache: fix reading of split index

[Thomas Gummerer <t.gummerer@gmail.com>]

The split index extension uses ewah bitmaps to mark index entries as
deleted, instead of removing them from the index directly.  This can
result in an on-disk index, in which entries of stage #0 and higher
stages appear, which are removed later when the index bases are merged.

15999d0 read_index_from(): catch out of order entries when reading an
index file introduces a check which checks if the entries are in order
after each index entry is read in do_read_index.  This check may however
fail when a split index is read.

Fix this by moving checking the index after we know there is no split
index or after the split index bases are successfully merged instead.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 read-cache.c | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/read-cache.c b/read-cache.c
index 8d71860..1bf78a4 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1486,18 +1486,25 @@ static struct cache_entry *create_from_disk(struct ondisk_cache_entry *ondisk,
 	return ce;
 }
 
-static void check_ce_order(struct cache_entry *ce, struct cache_entry *next_ce)
-{
-	int name_compare = strcmp(ce->name, next_ce->name);
-	if (0 < name_compare)
-		die("unordered stage entries in index");
-	if (!name_compare) {
-		if (!ce_stage(ce))
-			die("multiple stage entries for merged file '%s'",
-				ce->name);
-		if (ce_stage(ce) > ce_stage(next_ce))
-			die("unordered stage entries for '%s'",
-				ce->name);
+static void check_ce_order(struct index_state *istate)
+{
+	unsigned int i;
+
+	for (i = 1; i < istate->cache_nr; i++) {
+		struct cache_entry *ce = istate->cache[i - 1];
+		struct cache_entry *next_ce = istate->cache[i];
+		int name_compare = strcmp(ce->name, next_ce->name);
+
+		if (0 < name_compare)
+			die("unordered stage entries in index");
+		if (!name_compare) {
+			if (!ce_stage(ce))
+				die("multiple stage entries for merged file '%s'",
+				    ce->name);
+			if (ce_stage(ce) > ce_stage(next_ce))
+				die("unordered stage entries for '%s'",
+				    ce->name);
+		}
 	}
 }
 
@@ -1562,9 +1569,6 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 		ce = create_from_disk(disk_ce, &consumed, previous_name);
 		set_index_entry(istate, i, ce);
 
-		if (i > 0)
-			check_ce_order(istate->cache[i - 1], ce);
-
 		src_offset += consumed;
 	}
 	strbuf_release(&previous_name_buf);
@@ -1608,11 +1612,10 @@ int read_index_from(struct index_state *istate, const char *path)
 
 	ret = do_read_index(istate, path, 0);
 	split_index = istate->split_index;
-	if (!split_index)
-		return ret;
-
-	if (is_null_sha1(split_index->base_sha1))
+	if (!split_index || is_null_sha1(split_index->base_sha1)) {
+		check_ce_order(istate);
 		return ret;
+	}
 
 	if (split_index->base)
 		discard_index(split_index->base);
@@ -1628,6 +1631,7 @@ int read_index_from(struct index_state *istate, const char *path)
 				     sha1_to_hex(split_index->base_sha1)),
 		    sha1_to_hex(split_index->base->sha1));
 	merge_base_index(istate);
+	check_ce_order(istate);
 	return ret;
 }
 
-- 
2.1.0.264.g0463184.dirty