From 43d356180556180b4ef6ac232a14498a5bb2b446 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=C3=86var=20Arnfj=C3=B6r=C3=B0=20Bjarmason?= Date: Mon, 25 Mar 2019 13:08:33 +0100 Subject: [PATCH] commit-graph write: don't die if the existing graph is corrupt MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When the commit-graph is written we end up calling parse_commit(). This will in turn invoke code that'll consult the existing commit-graph about the commit, if the graph is corrupted we die. We thus get into a state where a failing "commit-graph verify" can't be followed-up with a "commit-graph write" if core.commitGraph=true is set, the graph either needs to be manually removed to proceed, or core.commitGraph needs to be set to "false". Change the "commit-graph write" codepath to use a new parse_commit_no_graph() helper instead of parse_commit() to avoid this. The latter will call repo_parse_commit_internal() with use_commit_graph=1 as seen in 177722b344 ("commit: integrate commit graph with commit parsing", 2018-04-10). Not using the old graph at all slows down the writing of the new graph by some small amount, but is a sensible way to prevent an error in the existing commit-graph from spreading. Just fixing the current issue would be likely to result in code that's inadvertently broken in the future. New code might use the commit-graph at a distance. To detect such cases introduce a "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD" setting used when we do our corruption tests, and test that a "write/verify" combo works after every one of our current test cases where we now detect commit-graph corruption. Some of the code changes here might be strictly unnecessary, e.g. I was unable to find cases where the parse_commit() called from write_graph_chunk_data() didn't exit early due to "item->object.parsed" being true in repo_parse_commit_internal() (before the use_commit_graph=1 has any effect). But let's also convert those cases for good measure, we do not have exhaustive tests for all possible types of commit-graph corruption. This might need to be re-visited if we learn to write the commit-graph incrementally, but probably not. Hopefully we'll just start by finding out what commits we have in total, then read the old graph(s) to see what they cover, and finally write a new graph file with everything that's missing. In that case the new graph writing code just needs to continue to use e.g. a parse_commit() that doesn't consult the existing commit-graphs. Signed-off-by: Ævar Arnfjörð Bjarmason Signed-off-by: Junio C Hamano --- commit-graph.c | 10 +++++++--- commit-graph.h | 1 + commit.h | 6 ++++++ t/t5318-commit-graph.sh | 11 +++++++++-- 4 files changed, 23 insertions(+), 5 deletions(-) diff --git a/commit-graph.c b/commit-graph.c index a26d266663..34ecaaf857 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -311,6 +311,10 @@ static int prepare_commit_graph(struct repository *r) struct object_directory *odb; int config_value; + if (git_env_bool(GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD, 0)) + die("dying as requested by the '%s' variable on commit-graph load!", + GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD); + if (r->objects->commit_graph_attempted) return !!r->objects->commit_graph; r->objects->commit_graph_attempted = 1; @@ -575,7 +579,7 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len, uint32_t packedDate[2]; display_progress(progress, ++*progress_cnt); - parse_commit(*list); + parse_commit_no_graph(*list); hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len); parent = (*list)->parents; @@ -772,7 +776,7 @@ static void close_reachable(struct packed_oid_list *oids, int report_progress) display_progress(progress, i + 1); commit = lookup_commit(the_repository, &oids->list[i]); - if (commit && !parse_commit(commit)) + if (commit && !parse_commit_no_graph(commit)) add_missing_parents(oids, commit); } stop_progress(&progress); @@ -1021,7 +1025,7 @@ void write_commit_graph(const char *obj_dir, continue; commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]); - parse_commit(commits.list[commits.nr]); + parse_commit_no_graph(commits.list[commits.nr]); for (parent = commits.list[commits.nr]->parents; parent; parent = parent->next) diff --git a/commit-graph.h b/commit-graph.h index ada7aea9ed..7dfb8c896f 100644 --- a/commit-graph.h +++ b/commit-graph.h @@ -7,6 +7,7 @@ #include "cache.h" #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH" +#define GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD "GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD" struct commit; diff --git a/commit.h b/commit.h index 42728c2906..5d33477e78 100644 --- a/commit.h +++ b/commit.h @@ -89,6 +89,12 @@ static inline int repo_parse_commit(struct repository *r, struct commit *item) { return repo_parse_commit_gently(r, item, 0); } + +static inline int parse_commit_no_graph(struct commit *commit) +{ + return repo_parse_commit_internal(the_repository, commit, 0, 0); +} + #ifndef NO_THE_REPOSITORY_COMPATIBILITY_MACROS #define parse_commit_internal(item, quiet, use) repo_parse_commit_internal(the_repository, item, quiet, use) #define parse_commit_gently(item, quiet) repo_parse_commit_gently(the_repository, item, quiet) diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index 4601732b99..e80c1cac02 100755 --- a/t/t5318-commit-graph.sh +++ b/t/t5318-commit-graph.sh @@ -377,7 +377,13 @@ corrupt_graph_verify() { test_must_fail git commit-graph verify 2>test_err && grep -v "^+" test_err >err && test_i18ngrep "$grepstr" err && - git status --short + if test "$2" != "no-copy" + then + cp $objdir/info/commit-graph commit-graph-pre-write-test + fi && + git status --short && + GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD=true git commit-graph write && + git commit-graph verify } # usage: corrupt_graph_and_verify [] @@ -403,7 +409,7 @@ corrupt_graph_and_verify() { test_expect_success POSIXPERM,SANITY 'detect permission problem' ' corrupt_graph_setup && chmod 000 $objdir/info/commit-graph && - corrupt_graph_verify "Could not open" + corrupt_graph_verify "Could not open" "no-copy" ' test_expect_success 'detect too small' ' @@ -522,6 +528,7 @@ test_expect_success 'git fsck (checks commit-graph)' ' git fsck && corrupt_graph_and_verify $GRAPH_BYTE_FOOTER "\00" \ "incorrect checksum" && + cp commit-graph-pre-write-test $objdir/info/commit-graph && test_must_fail git fsck '