From: Taylor Blau <me@xxxxxxxxxxxx>
Prior to ab14d0676c (commit-graph: pass a 'struct repository *' in more
places, 2020-09-09), parsing a commit-graph was a pure function
depending only on the contents of the commit-graph itself. Commit
ab14d0676c introduced a dependency on a `struct repository` pointer, and
later commits such as b66d84756f (commit-graph: respect
'commitGraph.readChangedPaths', 2020-09-09) added dependencies on config
settings, which were accessed through the `settings` field of the
repository pointer. This field was initialized via a call to
`prepare_repo_settings()`.
In 44c7e62 (2021-12-06, repo-settings:prepare_repo_settings only in git
repos), prepare_repo_settings was changed to issue a BUG() if it is
called by a process whose CWD is not a Git repository.
This series of changes broke fuzz-commit-graph, which attempts to parse
arbitrary fuzzing-engine-provided bytes as a commit graph file.
commit-graph.c:parse_commit_graph() calls prepare_repo_settings(), but
since we run the fuzz tests without a valid repository, we are hitting
the BUG() from 44c7e62 for every test case.
Fix this by moving the majority of the implementaiton of
`parse_commit_graph()` into a new function,
`parse_commit_graph_settings()` that accepts a repo_settings pointer.
This allows fuzz-commit-graph to continue to test the commit-graph
parser implementation without relying on prepare_repo_settings().
Additionally, properly initialize the
repo_settings.commit_graph_generation_version field in
prepare_repo_settings(). Load the value from the config if present, and
default to version 2 otherwise.
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
Signed-off-by: Josh Steadmon <steadmon@xxxxxxxxxx>
---
Range-diff against v2:
1: 2c2bfc7b43 ! 1: 9b56496b08 commit-graph: refactor to avoid prepare_repo_settings
@@ fuzz-commit-graph.c: int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size
initialize_the_repository();
- g = parse_commit_graph(the_repository, (void *)data, size);
+ /*
-+ * Manually initialize commit-graph settings, to avoid the need to run
-+ * in an actual repository.
++ * Initialize the_repository with commit-graph settings that would
++ * normally be read from the repository's gitdir. We want to avoid
++ * touching the disk to keep the individual fuzz-test cases as fast as
++ * possible.
+ */
+ the_repository->settings.commit_graph_generation_version = 2;
+ the_repository->settings.commit_graph_read_changed_paths = 1;
commit-graph.c | 22 ++++++++++------------
commit-graph.h | 2 ++
fuzz-commit-graph.c | 10 +++++++++-
repo-settings.c | 12 +++++++++++-
repository.h | 1 +
5 files changed, 33 insertions(+), 14 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 265c010122..c54a734619 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -96,13 +96,6 @@ define_commit_slab(commit_graph_data_slab, struct commit_graph_data);
static struct commit_graph_data_slab commit_graph_data_slab =
COMMIT_SLAB_INIT(1, commit_graph_data_slab);
-static int get_configured_generation_version(struct repository *r)
-{
- int version = 2;
- repo_config_get_int(r, "commitgraph.generationversion", &version);
- return version;
-}
-
uint32_t commit_graph_position(const struct commit *c)
{
struct commit_graph_data *data =
@@ -335,6 +328,13 @@ static int graph_read_bloom_data(const unsigned char *chunk_start,
struct commit_graph *parse_commit_graph(struct repository *r,
void *graph_map, size_t graph_size)
+{
+ prepare_repo_settings(r);
+ return parse_commit_graph_settings(&r->settings, graph_map, graph_size);
+}
+
+struct commit_graph *parse_commit_graph_settings(struct repo_settings *s,
+ void *graph_map, size_t graph_size)
{
const unsigned char *data;
struct commit_graph *graph;
@@ -371,8 +371,6 @@ struct commit_graph *parse_commit_graph(struct repository *r,
return NULL;
}
- prepare_repo_settings(r);
-
graph = alloc_commit_graph();
graph->hash_len = the_hash_algo->rawsz;
@@ -402,14 +400,14 @@ struct commit_graph *parse_commit_graph(struct repository *r,
pair_chunk(cf, GRAPH_CHUNKID_EXTRAEDGES, &graph->chunk_extra_edges);
pair_chunk(cf, GRAPH_CHUNKID_BASE, &graph->chunk_base_graphs);
- if (get_configured_generation_version(r) >= 2) {
+ if (s->commit_graph_generation_version >= 2) {
pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA,
&graph->chunk_generation_data);
pair_chunk(cf, GRAPH_CHUNKID_GENERATION_DATA_OVERFLOW,
&graph->chunk_generation_data_overflow);
}
- if (r->settings.commit_graph_read_changed_paths) {
+ if (s->commit_graph_read_changed_paths) {
pair_chunk(cf, GRAPH_CHUNKID_BLOOMINDEXES,
&graph->chunk_bloom_indexes);
read_chunk(cf, GRAPH_CHUNKID_BLOOMDATA,
@@ -2288,7 +2286,7 @@ int write_commit_graph(struct object_directory *odb,
ctx->split = flags & COMMIT_GRAPH_WRITE_SPLIT ? 1 : 0;
ctx->opts = opts;
ctx->total_bloom_filter_data_size = 0;
- ctx->write_generation_data = (get_configured_generation_version(r) == 2);
+ ctx->write_generation_data = (r->settings.commit_graph_generation_version == 2);
ctx->num_generation_data_overflows = 0;
bloom_settings.bits_per_entry = git_env_ulong("GIT_TEST_BLOOM_SETTINGS_BITS_PER_ENTRY",
diff --git a/commit-graph.h b/commit-graph.h
index 04a94e1830..0f0d28b129 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -95,6 +95,8 @@ struct commit_graph *read_commit_graph_one(struct repository *r,
struct object_directory *odb);
struct commit_graph *parse_commit_graph(struct repository *r,
void *graph_map, size_t graph_size);
+struct commit_graph *parse_commit_graph_settings(struct repo_settings *s,
+ void *graph_map, size_t graph_size);
/*
* Return 1 if and only if the repository has a commit-graph
diff --git a/fuzz-commit-graph.c b/fuzz-commit-graph.c
index e7cf6d5b0f..810b1a8001 100644
--- a/fuzz-commit-graph.c
+++ b/fuzz-commit-graph.c
@@ -11,7 +11,15 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
struct commit_graph *g;
initialize_the_repository();
- g = parse_commit_graph(the_repository, (void *)data, size);
+ /*
+ * Initialize the_repository with commit-graph settings that would
+ * normally be read from the repository's gitdir. We want to avoid
+ * touching the disk to keep the individual fuzz-test cases as fast as
+ * possible.
+ */
+ the_repository->settings.commit_graph_generation_version = 2;
+ the_repository->settings.commit_graph_read_changed_paths = 1;
+ g = parse_commit_graph_settings(&the_repository->settings, (void *)data, size);
repo_clear(the_repository);
free_commit_graph(g);
diff --git a/repo-settings.c b/repo-settings.c
index b4fbd16cdc..26241c1c2c 100644
--- a/repo-settings.c
+++ b/repo-settings.c
@@ -10,6 +10,13 @@ static void repo_cfg_bool(struct repository *r, const char *key, int *dest,
*dest = def;
}
+static void repo_cfg_int(struct repository *r, const char *key, int *dest,
+ int def)
+{
+ if (repo_config_get_int(r, key, dest))
+ *dest = def;
+}
+
void prepare_repo_settings(struct repository *r)
{
int experimental;
@@ -41,11 +48,14 @@ void prepare_repo_settings(struct repository *r)
r->settings.core_untracked_cache = UNTRACKED_CACHE_WRITE;
}
- /* Boolean config or default, does not cascade (simple) */
+ /* Commit graph config or default, does not cascade (simple) */
repo_cfg_bool(r, "core.commitgraph", &r->settings.core_commit_graph, 1);
+ repo_cfg_int(r, "commitgraph.generationversion", &r->settings.commit_graph_generation_version, 2);
repo_cfg_bool(r, "commitgraph.readchangedpaths", &r->settings.commit_graph_read_changed_paths, 1);
repo_cfg_bool(r, "gc.writecommitgraph", &r->settings.gc_write_commit_graph, 1);
repo_cfg_bool(r, "fetch.writecommitgraph", &r->settings.fetch_write_commit_graph, 0);
+
+ /* Boolean config or default, does not cascade (simple) */
repo_cfg_bool(r, "pack.usesparse", &r->settings.pack_use_sparse, 1);
repo_cfg_bool(r, "core.multipackindex", &r->settings.core_multi_pack_index, 1);
repo_cfg_bool(r, "index.sparse", &r->settings.sparse_index, 0);
diff --git a/repository.h b/repository.h
index ca837cb9e9..4f8275f97c 100644
--- a/repository.h
+++ b/repository.h
@@ -29,6 +29,7 @@ struct repo_settings {
int initialized;
int core_commit_graph;
+ int commit_graph_generation_version;
int commit_graph_read_changed_paths;
int gc_write_commit_graph;
int fetch_write_commit_graph;
base-commit: 715d08a9e51251ad8290b181b6ac3b9e1f9719d7
--
2.36.1.476.g0c4daa206d-goog
