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commit-graph.c: remove path normalization, comparison 

As of the previous patch, all calls to 'commit-graph.c' functions which
perform path normalization (for e.g., 'get_commit_graph_filename()') are
of the form 'ctx->odb->path', which is always in normalized form.

Now that there are no callers passing non-normalized paths to these
functions, ensure that future callers are bound by the same restrictions
by making these functions take a 'struct object_directory *' instead of
a 'const char *'. To match, replace all calls with arguments of the form
'ctx->odb->path' with 'ctx->odb' To recover the path, functions that
perform path manipulation simply use 'odb->path'.

Further, avoid string comparisons with arguments of the form
'odb->path', and instead prefer raw pointer comparisons, which
accomplish the same effect, but are far less brittle.

This has a pleasant side-effect of making these functions much more
robust to paths that cannot be normalized by 'normalize_path_copy()',
i.e., because they are outside of the current working directory.

For example, prior to this patch, Valgrind reports that the following
uninitialized memory read [1]:

  $ ( cd t && GIT_DIR=../.git valgrind git rev-parse HEAD^ )

because 'normalize_path_copy()' can't normalize '../.git' (since it's
relative to but above of the current working directory) [2].

By using a 'struct object_directory *' directly,
'get_commit_graph_filename()' does not need to normalize, because all
paths are relative to the current working directory since they are
always read from the '->path' of an object directory.

[1]: https://lore.kernel.org/git/20191027042116.GA5801@sigill.intra.peff.net.
[2]: The bug here is that 'get_commit_graph_filename()' returns the
     result of 'normalize_path_copy()' without checking the return
     value.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Taylor Blau 2020-02-03 13:18:02 -08:00 committed by Junio C Hamano
parent 13c2499249
commit ad2dd5bb63
4 changed files with 24 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
builtin/commit-graph.c
View File

@ -88,7 +88,7 @@ static int graph_verify(int argc, const char **argv)
flags |= COMMIT_GRAPH_WRITE_PROGRESS;
odb = find_odb(the_repository, opts.obj_dir);
graph_name = get_commit_graph_filename(odb->path);
graph_name = get_commit_graph_filename(odb);
open_ok = open_commit_graph(graph_name, &fd, &st);
if (!open_ok && errno != ENOENT)
die_errno(_("Could not open commit-graph '%s'"), graph_name);

47
commit-graph.c
View File

@ -44,30 +44,21 @@
/* Remember to update object flag allocation in object.h */
#define REACHABLE (1u<<15)
char *get_commit_graph_filename(const char *obj_dir)
char *get_commit_graph_filename(struct object_directory *odb)
{
char *filename = xstrfmt("%s/info/commit-graph", obj_dir);
char *normalized = xmalloc(strlen(filename) + 1);
normalize_path_copy(normalized, filename);
free(filename);
return normalized;
return xstrfmt("%s/info/commit-graph", odb->path);
}
static char *get_split_graph_filename(const char *obj_dir,
static char *get_split_graph_filename(struct object_directory *odb,
const char *oid_hex)
{
char *filename = xstrfmt("%s/info/commit-graphs/graph-%s.graph",
obj_dir,
oid_hex);
char *normalized = xmalloc(strlen(filename) + 1);
normalize_path_copy(normalized, filename);
free(filename);
return normalized;
return xstrfmt("%s/info/commit-graphs/graph-%s.graph", odb->path,
oid_hex);
}
static char *get_chain_filename(const char *obj_dir)
static char *get_chain_filename(struct object_directory *odb)
{
return xstrfmt("%s/info/commit-graphs/commit-graph-chain", obj_dir);
return xstrfmt("%s/info/commit-graphs/commit-graph-chain", odb->path);
}
static uint8_t oid_version(void)
@ -330,7 +321,7 @@ static struct commit_graph *load_commit_graph_one(const char *graph_file)
static struct commit_graph *load_commit_graph_v1(struct repository *r,
struct object_directory *odb)
{
char *graph_name = get_commit_graph_filename(odb->path);
char *graph_name = get_commit_graph_filename(odb);
struct commit_graph *g = load_commit_graph_one(graph_name);
free(graph_name);
@ -381,7 +372,7 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
struct stat st;
struct object_id *oids;
int i = 0, valid = 1, count;
char *chain_name = get_chain_filename(odb->path);
char *chain_name = get_chain_filename(odb);
FILE *fp;
int stat_res;
@ -414,7 +405,7 @@ static struct commit_graph *load_commit_graph_chain(struct repository *r,
valid = 0;
for (odb = r->objects->odb; odb; odb = odb->next) {
char *graph_name = get_split_graph_filename(odb->path, line.buf);
char *graph_name = get_split_graph_filename(odb, line.buf);
struct commit_graph *g = load_commit_graph_one(graph_name);
free(graph_name);
@ -1375,7 +1366,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
ctx->odb->path);
ctx->graph_name = strbuf_detach(&tmp_file, NULL);
} else {
ctx->graph_name = get_commit_graph_filename(ctx->odb->path);
ctx->graph_name = get_commit_graph_filename(ctx->odb);
}
if (safe_create_leading_directories(ctx->graph_name)) {
@ -1386,7 +1377,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
}
if (ctx->split) {
char *lock_name = get_chain_filename(ctx->odb->path);
char *lock_name = get_chain_filename(ctx->odb);
hold_lock_file_for_update(&lk, lock_name, LOCK_DIE_ON_ERROR);
@ -1474,7 +1465,7 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
if (ctx->split && ctx->base_graph_name && ctx->num_commit_graphs_after > 1) {
char *new_base_hash = xstrdup(oid_to_hex(&ctx->new_base_graph->oid));
char *new_base_name = get_split_graph_filename(ctx->new_base_graph->odb->path, new_base_hash);
char *new_base_name = get_split_graph_filename(ctx->new_base_graph->odb, new_base_hash);
free(ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 2]);
free(ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 2]);
@ -1510,12 +1501,12 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
}
}
} else {
char *graph_name = get_commit_graph_filename(ctx->odb->path);
char *graph_name = get_commit_graph_filename(ctx->odb);
unlink(graph_name);
}
ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1] = xstrdup(oid_to_hex(&file_hash));
final_graph_name = get_split_graph_filename(ctx->odb->path,
final_graph_name = get_split_graph_filename(ctx->odb,
ctx->commit_graph_hash_after[ctx->num_commit_graphs_after - 1]);
ctx->commit_graph_filenames_after[ctx->num_commit_graphs_after - 1] = final_graph_name;
@ -1557,7 +1548,7 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
while (g && (g->num_commits <= size_mult * num_commits ||
(max_commits && num_commits > max_commits))) {
if (strcmp(g->odb->path, ctx->odb->path))
if (g->odb != ctx->odb)
break;
num_commits += g->num_commits;
@ -1569,10 +1560,10 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
ctx->new_base_graph = g;
if (ctx->num_commit_graphs_after == 2) {
char *old_graph_name = get_commit_graph_filename(g->odb->path);
char *old_graph_name = get_commit_graph_filename(g->odb);
if (!strcmp(g->filename, old_graph_name) &&
strcmp(g->odb->path, ctx->odb->path)) {
g->odb != ctx->odb) {
ctx->num_commit_graphs_after = 1;
ctx->new_base_graph = NULL;
}
@ -1723,7 +1714,7 @@ static void expire_commit_graphs(struct write_commit_graph_context *ctx)
if (ctx->split_opts && ctx->split_opts->expire_time)
expire_time -= ctx->split_opts->expire_time;
if (!ctx->split) {
char *chain_file_name = get_chain_filename(ctx->odb->path);
char *chain_file_name = get_chain_filename(ctx->odb);
unlink(chain_file_name);
free(chain_file_name);
ctx->num_commit_graphs_after = 0;

2
commit-graph.h
View File

@ -12,7 +12,7 @@
struct commit;
char *get_commit_graph_filename(const char *obj_dir);
char *get_commit_graph_filename(struct object_directory *odb);
int open_commit_graph(const char *graph_file, int *fd, struct stat *st);
/*

6
t/helper/test-read-graph.c
View File

@ -11,12 +11,12 @@ int cmd__read_graph(int argc, const char **argv)
int open_ok;
int fd;
struct stat st;
const char *object_dir;
struct object_directory *odb;
setup_git_directory();
object_dir = get_object_directory();
odb = the_repository->objects->odb;
graph_name = get_commit_graph_filename(object_dir);
graph_name = get_commit_graph_filename(odb);
open_ok = open_commit_graph(graph_name, &fd, &st);
if (!open_ok)