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commit-graph: pass repo_settings instead of repository 

The parse_commit_graph() function takes a 'struct repository *' pointer,
but it only ever accesses config settings (either directly or through
the .settings field of the repo struct). Move all relevant config
settings into the repo_settings struct, and update parse_commit_graph()
and its existing callers so that it takes 'struct repo_settings *'
instead.

Callers of parse_commit_graph() will now need to call
prepare_repo_settings() themselves, or initialize a 'struct
repo_settings' directly.

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()`.

Additionally, this fixes an issue in fuzz-commit-graph: 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.

The combination of commits mentioned above broke fuzz-commit-graph,
which attempts to parse arbitrary fuzzing-engine-provided bytes as a
commit graph file. Prior to this change, parse_commit_graph() called
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.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau 2022-07-14 14:43:06 -07:00 committed by Junio C Hamano
parent 8168d5e9c2
commit a92d8523ce
5 changed files with 33 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
commit-graph.c
View File

@ -252,7 +252,8 @@ struct commit_graph *load_commit_graph_one_fd_st(struct repository *r,
}
graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
ret = parse_commit_graph(r, graph_map, graph_size);
prepare_repo_settings(r);
ret = parse_commit_graph(&r->settings, graph_map, graph_size);
if (ret)
ret->odb = odb;
@ -321,7 +322,7 @@ static int graph_read_bloom_data(const unsigned char *chunk_start,
return 0;
}
struct commit_graph *parse_commit_graph(struct repository *r,
struct commit_graph *parse_commit_graph(struct repo_settings *s,
void *graph_map, size_t graph_size)
{
const unsigned char *data;
@ -359,8 +360,6 @@ 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;
@ -390,7 +389,7 @@ 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,
@ -400,7 +399,7 @@ struct commit_graph *parse_commit_graph(struct repository *r,
graph->read_generation_data = 1;
}
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,

7
commit-graph.h
View File

@ -93,7 +93,12 @@ struct commit_graph *load_commit_graph_one_fd_st(struct repository *r,
struct object_directory *odb);
struct commit_graph *read_commit_graph_one(struct repository *r,
struct object_directory *odb);
struct commit_graph *parse_commit_graph(struct repository *r,
/*
* Callers should initialize the repo_settings with prepare_repo_settings()
* prior to calling parse_commit_graph().
*/
struct commit_graph *parse_commit_graph(struct repo_settings *s,
void *graph_map, size_t graph_size);
/*

12
fuzz-commit-graph.c
View File

@ -1,7 +1,7 @@
#include "commit-graph.h"
#include "repository.h"
struct commit_graph *parse_commit_graph(struct repository *r,
struct commit_graph *parse_commit_graph(struct repo_settings *s,
void *graph_map, size_t graph_size);
int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size);
@ -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(&the_repository->settings, (void *)data, size);
repo_clear(the_repository);
free_commit_graph(g);

12
repo-settings.c
View File

@ -11,6 +11,13 @@ 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;
@ -42,11 +49,14 @@ 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);

1
repository.h
View File

@ -30,6 +30,7 @@ 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;