@matheusbsbs / matheus-bagliano / commits / d9fd674c8b

bundle: verify using check_connected()

When Git verifies a bundle to see if it is safe for unbundling, it first looks to see if the prerequisite commits are in the object store. This is an easy way to "fail fast" but it is not a sufficient check for updating refs that guarantee closure under reachability. There could still be issues if those commits are not reachable from the repository's references. The repository only has guarantees that its object store is closed under reachability for the objects that are reachable from references. Thus, the code in verify_bundle() has previously had the additional check that all prerequisite commits are reachable from repository references. This is done via a revision walk from all references, stopping only if all prerequisite commits are discovered or all commits are walked. This uses a custom walk to verify_bundle(). This check is more strict than what Git applies to fetched pack-files. In the fetch case, Git guarantees that the new references are closed under reachability by walking from the new references until walking commits that are reachable from repository refs. This is done through the well-used check_connected() method. To better align with the restrictions required by 'git fetch', reimplement this check in verify_bundle() to use check_connected(). This also simplifies the code significantly. The previous change added a test that verified the behavior of 'git bundle verify' and 'git bundle unbundle' in this case, and the error messages looked like this: error: Could not read <missing-commit> fatal: Failed to traverse parents of commit <extant-commit> However, by changing the revision walk slightly within check_connected() and using its quiet mode, we can omit those messages. Instead, we get only this message, tailored to describing the current state of the repository: error: some prerequisite commits exist in the object store, but are not connected to the repository's history (Line break added here for the commit message formatting, only.) While this message does not include any object IDs, there is no guarantee that those object IDs would help the user diagnose what is going on, as they could be separated from the prerequisite commits by some distance. At minimum, this situation describes the situation in a more informative way than the previous error messages. Signed-off-by: Derrick Stolee <derrickstolee@github.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed Jan 31, 2023 at 13:29 UTC d9fd674c8b26c376b37e02d974b92033acb99732

2 files changed +33 -50

bundle.c

+29 -46

@@ -12,6 +12,7 @@

12 #include "refs.h"

13 #include "strvec.h"

14 #include "list-objects-filter-options.h"

15 +#include "connected.h"

17 static const char v2_bundle_signature[] = "# v2 git bundle\n";

18 static const char v3_bundle_signature[] = "# v3 git bundle\n";

@@ -187,6 +188,21 @@ static int list_refs(struct string_list *r, int argc, const char **argv)

188 /* Remember to update object flag allocation in object.h */

189 #define PREREQ_MARK (1u<<16)

190

191 +struct string_list_iterator {

192 + struct string_list *list;

193 + size_t cur;

194 +};

195 +

196 +static const struct object_id *iterate_ref_map(void *cb_data)

197 +{

198 + struct string_list_iterator *iter = cb_data;

199 +

200 + if (iter->cur >= iter->list->nr)

201 + return NULL;

202 +

203 + return iter->list->items[iter->cur++].util;

204 +}

205 +

206 int verify_bundle(struct repository *r,

207 struct bundle_header *header,

208 enum verify_bundle_flags flags)

@@ -196,26 +212,25 @@ int verify_bundle(struct repository *r,

212 * to be verbose about the errors

213 */

214 struct string_list *p = &header->prerequisites;

199 - struct rev_info revs = REV_INFO_INIT;

200 - const char *argv[] = {NULL, "--all", NULL};

201 - struct commit *commit;

202 - int i, ret = 0, req_nr;

215 + int i, ret = 0;

216 const char *message = _("Repository lacks these prerequisite commits:");

217 + struct string_list_iterator iter = {

218 + .list = p,

219 + };

220 + struct check_connected_options opts = {

221 + .quiet = 1,

222 + };

223

224 if (!r || !r->objects || !r->objects->odb)

225 return error(_("need a repository to verify a bundle"));

226

208 - repo_init_revisions(r, &revs, NULL);

227 for (i = 0; i < p->nr; i++) {

228 struct string_list_item *e = p->items + i;

229 const char *name = e->string;

230 struct object_id *oid = e->util;

231 struct object *o = parse_object(r, oid);

214 - if (o) {

215 - o->flags |= PREREQ_MARK;

216 - add_pending_object(&revs, o, name);

232 + if (o)

233 continue;

218 - }

234 ret++;

235 if (flags & VERIFY_BUNDLE_QUIET)

236 continue;

@@ -223,37 +238,14 @@ int verify_bundle(struct repository *r,

238 error("%s", message);

239 error("%s %s", oid_to_hex(oid), name);

240 }

226 - if (revs.pending.nr != p->nr)

241 + if (ret)

242 goto cleanup;

228 - req_nr = revs.pending.nr;

229 - setup_revisions(2, argv, &revs, NULL);

230 -

231 - list_objects_filter_copy(&revs.filter, &header->filter);

232 -

233 - if (prepare_revision_walk(&revs))

234 - die(_("revision walk setup failed"));

243

236 - i = req_nr;

237 - while (i && (commit = get_revision(&revs)))

238 - if (commit->object.flags & PREREQ_MARK)

239 - i--;

240 -

241 - for (i = 0; i < p->nr; i++) {

242 - struct string_list_item *e = p->items + i;

243 - const char *name = e->string;

244 - const struct object_id *oid = e->util;

245 - struct object *o = parse_object(r, oid);

246 - assert(o); /* otherwise we'd have returned early */

247 - if (o->flags & SHOWN)

248 - continue;

249 - ret++;

250 - if (flags & VERIFY_BUNDLE_QUIET)

251 - continue;

252 - if (ret == 1)

253 - error("%s", message);

254 - error("%s %s", oid_to_hex(oid), name);

255 - }

244 + if ((ret = check_connected(iterate_ref_map, &iter, &opts)))

245 + error(_("some prerequisite commits exist in the object store, "

246 + "but are not connected to the repository's history"));

247

248 + /* TODO: preserve this verbose language. */

249 if (flags & VERIFY_BUNDLE_VERBOSE) {

250 struct string_list *r;

251

@@ -282,15 +274,6 @@ int verify_bundle(struct repository *r,

274 list_objects_filter_spec(&header->filter));

275 }

276 cleanup:

285 - /* Clean up objects used, as they will be reused. */

286 - for (i = 0; i < p->nr; i++) {

287 - struct string_list_item *e = p->items + i;

288 - struct object_id *oid = e->util;

289 - commit = lookup_commit_reference_gently(r, oid, 1);

290 - if (commit)

291 - clear_commit_marks(commit, ALL_REV_FLAGS | PREREQ_MARK);

292 - }

293 - release_revisions(&revs);

277 return ret;

278 }

279

t/t6020-bundle-misc.sh

+4 -4

@@ -588,14 +588,14 @@ test_expect_success 'verify catches unreachable, broken prerequisites' '

588 # Verify should fail

589 test_must_fail git bundle verify \

590 ../clone-from/tip.bundle 2>err &&

591 - grep "Could not read $BAD_OID" err &&

592 - grep "Failed to traverse parents of commit $TIP_OID" err &&

591 + grep "some prerequisite commits .* are not connected" err &&

592 + test_line_count = 1 err &&

593

594 # Unbundling should fail

595 test_must_fail git bundle unbundle \

596 ../clone-from/tip.bundle 2>err &&

597 - grep "Could not read $BAD_OID" err &&

598 - grep "Failed to traverse parents of commit $TIP_OID" err

597 + grep "some prerequisite commits .* are not connected" err &&

598 + test_line_count = 1 err

599 )

600 '

601