commit-graph: error out on invalid commit oids in 'write --stdin-commits'

While 'git commit-graph write --stdin-commits' expects commit object
ids as input, it accepts and silently skips over any invalid commit
object ids, and still exits with success:

  # nonsense
  $ echo not-a-commit-oid | git commit-graph write --stdin-commits
  $ echo $?
  0
  # sometimes I forgot that refs are not good...
  $ echo HEAD | git commit-graph write --stdin-commits
  $ echo $?
  0
  # valid tree OID, but not a commit OID
  $ git rev-parse HEAD^{tree} | git commit-graph write --stdin-commits
  $ echo $?
  0
  $ ls -l .git/objects/info/commit-graph
  ls: cannot access '.git/objects/info/commit-graph': No such file or directory

Check that all input records are indeed valid commit object ids and
return with error otherwise, the same way '--stdin-packs' handles
invalid input; see e103f7276f (commit-graph: return with errors during
write, 2019-06-12).

Note that it should only return with error when encountering an
invalid commit object id coming from standard input.  However,
'--reachable' uses the same code path to process object ids pointed to
by all refs, and that includes tag object ids as well, which should
still be skipped over.  Therefore add a new flag to 'enum
commit_graph_write_flags' and a corresponding field to 'struct
write_commit_graph_context', so we can differentiate between those two
cases.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 4391007f4c..ab3eccf0fa 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -23,7 +23,7 @@ test_expect_success 'write graph with no packs' '
 	test_path_is_missing info/commit-graph
 '
 
-test_expect_success 'close with correct error on bad input' '
+test_expect_success 'exit with correct error on bad input to --stdin-packs' '
 	cd "$TRASH_DIRECTORY/full" &&
 	echo doesnotexist >in &&
 	test_expect_code 1 git commit-graph write --stdin-packs <in 2>stderr &&
@@ -40,6 +40,15 @@ test_expect_success 'create commits and repack' '
 	git repack
 '
 
+test_expect_success 'exit with correct error on bad input to --stdin-commits' '
+	cd "$TRASH_DIRECTORY/full" &&
+	echo HEAD | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
+	test_i18ngrep "invalid commit object id" stderr &&
+	# valid tree OID, but not a commit OID
+	git rev-parse HEAD^{tree} | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
+	test_i18ngrep "invalid commit object id" stderr
+'
+
 graph_git_two_modes() {
 	git -c core.commitGraph=true $1 >output
 	git -c core.commitGraph=false $1 >expect