commit-graph: verify generation number

diff --git a/commit-graph.c b/commit-graph.c
index a79b06f37a674ff800393bbebf9aac682a1015b9..de656ebbaff88d692fc26b3f8a57d3d8798070ba 100644 (file)
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -846,10 +846,14 @@ static void graph_report(const char *fmt, ...)
        va_end(ap);
 }
 
+#define GENERATION_ZERO_EXISTS 1
+#define GENERATION_NUMBER_EXISTS 2
+
 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 {
        uint32_t i, cur_fanout_pos = 0;
        struct object_id prev_oid, cur_oid;
+       int generation_zero = 0;
 
        if (!g) {
                graph_report("no commit-graph file loaded");
@@ -911,6 +915,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
        for (i = 0; i < g->num_commits; i++) {
                struct commit *graph_commit, *odb_commit;
                struct commit_list *graph_parents, *odb_parents;
+               uint32_t max_generation = 0;
 
                hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 
@@ -945,6 +950,9 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
                                             oid_to_hex(&graph_parents->item->object.oid),
                                             oid_to_hex(&odb_parents->item->object.oid));
 
+                       if (graph_parents->item->generation > max_generation)
+                               max_generation = graph_parents->item->generation;
+
                        graph_parents = graph_parents->next;
                        odb_parents = odb_parents->next;
                }
@@ -952,6 +960,32 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
                if (odb_parents != NULL)
                        graph_report("commit-graph parent list for commit %s terminates early",
                                     oid_to_hex(&cur_oid));
+
+               if (!graph_commit->generation) {
+                       if (generation_zero == GENERATION_NUMBER_EXISTS)
+                               graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
+                                            oid_to_hex(&cur_oid));
+                       generation_zero = GENERATION_ZERO_EXISTS;
+               } else if (generation_zero == GENERATION_ZERO_EXISTS)
+                       graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
+                                    oid_to_hex(&cur_oid));
+
+               if (generation_zero == GENERATION_ZERO_EXISTS)
+                       continue;
+
+               /*
+                * If one of our parents has generation GENERATION_NUMBER_MAX, then
+                * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
+                * extra logic in the following condition.
+                */
+               if (max_generation == GENERATION_NUMBER_MAX)
+                       max_generation--;
+
+               if (graph_commit->generation != max_generation + 1)
+                       graph_report("commit-graph generation for commit %s is %u != %u",
+                                    oid_to_hex(&cur_oid),
+                                    graph_commit->generation,
+                                    max_generation + 1);
        }
 
        return verify_commit_graph_error;