[PATCH 04/12] commit-graph: verify fanout and lookup table

[Derrick Stolee]

While running 'git commit-graph verify', verify that the object IDs
are listed in lexicographic order and that the fanout table correctly
navigates into that list of object IDs.

Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
 commit-graph.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/commit-graph.c b/commit-graph.c
index ce11af1d20..b4c146c423 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -839,6 +839,9 @@ static int verify_commit_graph_error;
 
 int verify_commit_graph(struct commit_graph *g)
 {
+       uint32_t i, cur_fanout_pos = 0;
+       struct object_id prev_oid, cur_oid;
+
        if (!g) {
                graph_report(_("no commit-graph file loaded"));
                return 1;
@@ -853,5 +856,35 @@ int verify_commit_graph(struct commit_graph *g)
        if (!g->chunk_commit_data)
                graph_report(_("commit-graph is missing the Commit Data 
chunk"));
 
+       for (i = 0; i < g->num_commits; i++) {
+               hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
+
+               if (i > 0 && oidcmp(&prev_oid, &cur_oid) >= 0)
+                       graph_report(_("commit-graph has incorrect oid order: 
%s then %s"),
+
+               oid_to_hex(&prev_oid),
+               oid_to_hex(&cur_oid));
+               oidcpy(&prev_oid, &cur_oid);
+
+               while (cur_oid.hash[0] > cur_fanout_pos) {
+                       uint32_t fanout_value = get_be32(g->chunk_oid_fanout + 
cur_fanout_pos);
+                       if (i != fanout_value)
+                               graph_report(_("commit-graph has incorrect 
fanout value: fanout[%d] = %u != %u"),
+                                            cur_fanout_pos, fanout_value, i);
+
+                       cur_fanout_pos++;
+               }
+       }
+
+       while (cur_fanout_pos < 256) {
+               uint32_t fanout_value = get_be32(g->chunk_oid_fanout + 
cur_fanout_pos);
+
+               if (g->num_commits != fanout_value)
+                       graph_report(_("commit-graph has incorrect fanout 
value: fanout[%d] = %u != %u"),
+                                    cur_fanout_pos, fanout_value, i);
+
+               cur_fanout_pos++;
+       }
+
        return verify_commit_graph_error;
 }
-- 
2.16.2.329.gfb62395de6