On Sat, Jun 13, 2020 at 12:10:12AM +0530, Abhishek Kumar wrote:
> diff --git a/commit-graph.c b/commit-graph.c
> index 2ff042fbf4..91120ba3d3 100644
> --- a/commit-graph.c
> +++ b/commit-graph.c
> @@ -87,6 +87,55 @@ static int commit_pos_cmp(const void *va, const void *vb)
> commit_pos_at(&commit_pos, b);
> }
>
> +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);
> +
> +uint32_t commit_graph_position(const struct commit *c)
> +{
> + struct commit_graph_data *data =
> + commit_graph_data_slab_peek(&commit_graph_data_slab, c);
> +
> + return data ? data->graph_pos : COMMIT_NOT_FROM_GRAPH;
> +}
> +
> +uint32_t commit_graph_generation(const struct commit *c)
> +{
> + struct commit_graph_data *data =
> + commit_graph_data_slab_peek(&commit_graph_data_slab, c);
> +
> + if (!data)
> + return GENERATION_NUMBER_INFINITY;
> + else if (data->graph_pos == COMMIT_NOT_FROM_GRAPH)
> + return GENERATION_NUMBER_INFINITY;
> +
> + return data->generation;
> +}
> +
> +static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
commit-graph.c: At top level:
commit-graph.c:115:34: error: ‘commit_graph_data_at’ defined but not used [-Werror=unused-function]
static struct commit_graph_data *commit_graph_data_at(const struct commit *c)
^
Please make sure that each and every commit of your series can be
built with DEVELOPER=1 and passes the test suite.
> +{
> + uint32_t i = commit_graph_data_slab.slab_count, j;
> + uint32_t slab_size = commit_graph_data_slab.slab_size;
> + struct commit_graph_data *data =
> + commit_graph_data_slab_at(&commit_graph_data_slab, c);
> +
> + /*
> + * commit-slab initializes elements with zero, overwrite this with
> + * COMMIT_NOT_FROM_GRAPH for graph_pos.
> + *
> + * We avoid initializing generation with checking if graph position
> + * is not COMMIT_NOT_FROM_GRAPH.
> + */
> + for (; i < commit_graph_data_slab.slab_count; i++) {
> + for (j = 0; j < slab_size; j++) {
> + commit_graph_data_slab[i][j].graph_pos =
commit-graph.c: In function ‘commit_graph_data_at’:
commit-graph.c:131:26: error: subscripted value is neither array nor pointer nor vector
commit_graph_data_slab[i][j].graph_pos =
^
Once the next patch is applied Git can be built again, but then:
$ ~/src/git/git -C webkit.git commit-graph write
Finding commits for commit graph among packed objects: 100% (3984415/3984415), done.
Expanding reachable commits in commit graph: 219420, done.
Segmentation fault
Looking at it with a debugger:
Program received signal SIGSEGV, Segmentation fault.
0x00000000005079b2 in commit_graph_data_at (c=0x1ad9aa0) at commit-graph.c:131
131 commit_graph_data_slab.slab[i][j].graph_pos =
(gdb) bt
#0 0x00000000005079b2 in commit_graph_data_at (c=0x1ad9aa0)
at commit-graph.c:131
#1 0x000000000050a6a7 in compute_generation_numbers (ctx=0x9d61a0)
at commit-graph.c:1304
#2 0x000000000050d37d in write_commit_graph (odb=0x9d3d80, pack_indexes=0x0,
commits=0x0, flags=COMMIT_GRAPH_WRITE_PROGRESS,
split_opts=0x98e730 <split_opts>) at commit-graph.c:2178
#3 0x000000000042bb7e in graph_write (argc=0, argv=0x7fffffffe2f0)
at builtin/commit-graph.c:242
#4 0x000000000042bc8d in cmd_commit_graph (argc=1, argv=0x7fffffffe2f0,
prefix=0x0) at builtin/commit-graph.c:278
#5 0x00000000004061d1 in run_builtin (p=0x97b950 <commands+528>, argc=2,
argv=0x7fffffffe2f0) at git.c:448
#6 0x0000000000406521 in handle_builtin (argc=2, argv=0x7fffffffe2f0)
at git.c:673
#7 0x00000000004067c9 in run_argv (argcp=0x7fffffffe18c, argv=0x7fffffffe180)
at git.c:740
#8 0x0000000000406c3a in cmd_main (argc=2, argv=0x7fffffffe2f0) at git.c:871
#9 0x00000000004cfbda in main (argc=5, argv=0x7fffffffe2d8)
at common-main.c:52
(gdb) p commit_graph_data_slab
$1 = {
slab_size = 65532,
stride = 1,
slab_count = 4,
slab = 0x4f68690
}
(gdb) p i
$2 = 0
(gdb) p commit_graph_data_slab.slab[i]
$3 = (struct commit_graph_data *) 0x0
(gdb) p c->index
$4 = 213506
(gdb) up
#1 0x000000000050a6a7 in compute_generation_numbers (ctx=0x9d61a0)
at commit-graph.c:1304
1304 uint32_t generation = commit_graph_data_at(ctx->commits.list[i])->generation;
(gdb) p i
$5 = 0
The way the loop variable 'i' is initialized and is used in the loop
header suggests that you assume that all slabs with an index
<slab_count are allocated. That's not the case, only those slabs are
allocated that contain data associated with a commit that has already
been looked at.
> + COMMIT_NOT_FROM_GRAPH;
> + }
> + }
> +
> + return data;
> +}
> +
> static int commit_gen_cmp(const void *va, const void *vb)
> {
> const struct commit *a = *(const struct commit **)va;
> diff --git a/commit-graph.h b/commit-graph.h
> index 3ba0da1e5f..cc76757007 100644
> --- a/commit-graph.h
> +++ b/commit-graph.h
> @@ -135,4 +135,14 @@ void free_commit_graph(struct commit_graph *);
> */
> void disable_commit_graph(struct repository *r);
>
> +struct commit_graph_data {
> + uint32_t graph_pos;
> + uint32_t generation;
> +};
> +
> +/*
This line adds a trailing space which is then removed in next patch.
Please don't add it in the first place.
> + * Commits should be parsed before accessing generation, graph positions.
> + */
> +uint32_t commit_graph_generation(const struct commit *);
> +uint32_t commit_graph_position(const struct commit *);
> #endif
> --
> 2.27.0
>
