Merge branch 'ps/cache-tree-w-broken-index-entry'

Fail gracefully instead of crashing when attempting to write the
contents of a corrupt in-core index as a tree object.

* ps/cache-tree-w-broken-index-entry:
  unpack-trees: detect mismatching number of cache-tree/index entries
  cache-tree: detect mismatching number of index entries
  cache-tree: refactor verification to return error codes

1 files changed, 73 insertions, 29 deletions

diff --git a/cache-tree.c b/cache-tree.c
index b482167a69..c595e86120 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -1,6 +1,7 @@
 #define USE_THE_REPOSITORY_VARIABLE
 
 #include "git-compat-util.h"
+#include "gettext.h"
 #include "hex.h"
 #include "lockfile.h"
 #include "tree.h"
@@ -865,15 +866,15 @@ int cache_tree_matches_traversal(struct cache_tree *root,
 	return 0;
 }
 
-static void verify_one_sparse(struct index_state *istate,
-			      struct strbuf *path,
-			      int pos)
+static int verify_one_sparse(struct index_state *istate,
+			     struct strbuf *path,
+			     int pos)
 {
 	struct cache_entry *ce = istate->cache[pos];
-
 	if (!S_ISSPARSEDIR(ce->ce_mode))
-		BUG("directory '%s' is present in index, but not sparse",
-		    path->buf);
+		return error(_("directory '%s' is present in index, but not sparse"),
+			     path->buf);
+	return 0;
 }
 
 /*
@@ -882,6 +883,7 @@ static void verify_one_sparse(struct index_state *istate,
  *  1 - Restart verification - a call to ensure_full_index() freed the cache
  *      tree that is being verified and verification needs to be restarted from
  *      the new toplevel cache tree.
+ *  -1 - Verification failed.
  */
 static int verify_one(struct repository *r,
 		      struct index_state *istate,
@@ -891,18 +893,23 @@ static int verify_one(struct repository *r,
 	int i, pos, len = path->len;
 	struct strbuf tree_buf = STRBUF_INIT;
 	struct object_id new_oid;
+	int ret;
 
 	for (i = 0; i < it->subtree_nr; i++) {
 		strbuf_addf(path, "%s/", it->down[i]->name);
-		if (verify_one(r, istate, it->down[i]->cache_tree, path))
-			return 1;
+		ret = verify_one(r, istate, it->down[i]->cache_tree, path);
+		if (ret)
+			goto out;
+
 		strbuf_setlen(path, len);
 	}
 
 	if (it->entry_count < 0 ||
 	    /* no verification on tests (t7003) that replace trees */
-	    lookup_replace_object(r, &it->oid) != &it->oid)
-		return 0;
+	    lookup_replace_object(r, &it->oid) != &it->oid) {
+		ret = 0;
+		goto out;
+	}
 
 	if (path->len) {
 		/*
@@ -912,12 +919,14 @@ static int verify_one(struct repository *r,
 		 */
 		int is_sparse = istate->sparse_index;
 		pos = index_name_pos(istate, path->buf, path->len);
-		if (is_sparse && !istate->sparse_index)
-			return 1;
+		if (is_sparse && !istate->sparse_index) {
+			ret = 1;
+			goto out;
+		}
 
 		if (pos >= 0) {
-			verify_one_sparse(istate, path, pos);
-			return 0;
+			ret = verify_one_sparse(istate, path, pos);
+			goto out;
 		}
 
 		pos = -pos - 1;
@@ -925,6 +934,11 @@ static int verify_one(struct repository *r,
 		pos = 0;
 	}
 
+	if (it->entry_count + pos > istate->cache_nr) {
+		ret = error(_("corrupted cache-tree has entries not present in index"));
+		goto out;
+	}
+
 	i = 0;
 	while (i < it->entry_count) {
 		struct cache_entry *ce = istate->cache[pos + i];
@@ -935,16 +949,23 @@ static int verify_one(struct repository *r,
 		unsigned mode;
 		int entlen;
 
-		if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE))
-			BUG("%s with flags 0x%x should not be in cache-tree",
-			    ce->name, ce->ce_flags);
+		if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE)) {
+			ret = error(_("%s with flags 0x%x should not be in cache-tree"),
+				    ce->name, ce->ce_flags);
+			goto out;
+		}
+
 		name = ce->name + path->len;
 		slash = strchr(name, '/');
 		if (slash) {
 			entlen = slash - name;
+
 			sub = find_subtree(it, ce->name + path->len, entlen, 0);
-			if (!sub || sub->cache_tree->entry_count < 0)
-				BUG("bad subtree '%.*s'", entlen, name);
+			if (!sub || sub->cache_tree->entry_count < 0) {
+				ret = error(_("bad subtree '%.*s'"), entlen, name);
+				goto out;
+			}
+
 			oid = &sub->cache_tree->oid;
 			mode = S_IFDIR;
 			i += sub->cache_tree->entry_count;
@@ -957,27 +978,50 @@ static int verify_one(struct repository *r,
 		strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
 		strbuf_add(&tree_buf, oid->hash, r->hash_algo->rawsz);
 	}
+
 	hash_object_file(r->hash_algo, tree_buf.buf, tree_buf.len, OBJ_TREE,
 			 &new_oid);
-	if (!oideq(&new_oid, &it->oid))
-		BUG("cache-tree for path %.*s does not match. "
-		    "Expected %s got %s", len, path->buf,
-		    oid_to_hex(&new_oid), oid_to_hex(&it->oid));
+
+	if (!oideq(&new_oid, &it->oid)) {
+		ret = error(_("cache-tree for path %.*s does not match. "
+			      "Expected %s got %s"), len, path->buf,
+			    oid_to_hex(&new_oid), oid_to_hex(&it->oid));
+		goto out;
+	}
+
+	ret = 0;
+out:
 	strbuf_setlen(path, len);
 	strbuf_release(&tree_buf);
-	return 0;
+	return ret;
 }
 
-void cache_tree_verify(struct repository *r, struct index_state *istate)
+int cache_tree_verify(struct repository *r, struct index_state *istate)
 {
 	struct strbuf path = STRBUF_INIT;
+	int ret;
 
-	if (!istate->cache_tree)
-		return;
-	if (verify_one(r, istate, istate->cache_tree, &path)) {
+	if (!istate->cache_tree) {
+		ret = 0;
+		goto out;
+	}
+
+	ret = verify_one(r, istate, istate->cache_tree, &path);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
 		strbuf_reset(&path);
-		if (verify_one(r, istate, istate->cache_tree, &path))
+
+		ret = verify_one(r, istate, istate->cache_tree, &path);
+		if (ret < 0)
+			goto out;
+		if (ret > 0)
 			BUG("ensure_full_index() called twice while verifying cache tree");
 	}
+
+	ret = 0;
+
+out:
 	strbuf_release(&path);
+	return ret;
 }