commit-graph.c: write non-split graphs as read-only

In the previous commit, Git learned 'hold_lock_file_for_update_mode' to
allow the caller to specify the permission bits (prior to further
adjustment by the umask and shared repository permissions) used when
acquiring a temporary file.

Use this in the commit-graph machinery for writing a non-split graph to
acquire an opened temporary file with permissions read-only permissions
to match the split behavior. (In the split case, Git uses
git_mkstemp_mode' for each of the commit-graph layers with permission
bits '0444').

One can notice this discrepancy when moving a non-split graph to be part
of a new chain. This causes a commit-graph chain where all layers have
read-only permission bits, except for the base layer, which is writable
for the current user.

Resolve this discrepancy by using the new
'hold_lock_file_for_update_mode' and passing the desired permission
bits.

Doing so causes some test fallout in t5318 and t6600. In t5318, this
occurs in tests that corrupt a commit-graph file by writing into it. For
these, 'chmod u+w'-ing the file beforehand resolves the issue. The
additional spot in 'corrupt_graph_verify' is necessary because of the
extra 'git commit-graph write' beforehand (which *does* rewrite the
commit-graph file). In t6600, this is caused by copying a read-only
commit-graph file into place and then trying to replace it. For these,
make these files writable.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit-graph.c b/commit-graph.c
index f013a84e294b13b552b62257bbf2fa7e1c353a82..5b5047a7dd89285ae977c8cf25591c35f4c0b705 100644 (file)
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1388,7 +1388,8 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
 
                f = hashfd(fd, ctx->graph_name);
        } else {
-               hold_lock_file_for_update(&lk, ctx->graph_name, LOCK_DIE_ON_ERROR);
+               hold_lock_file_for_update_mode(&lk, ctx->graph_name,
+                                              LOCK_DIE_ON_ERROR, 0444);
                fd = lk.tempfile->fd;
                f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
        }

diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 9bf920ae1716dd3703d206be05605cfdfde21984..901eb3ecfb4699c22b7bb467b6cf733c27d6357f 100755 (executable)
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -12,6 +12,10 @@ test_expect_success 'setup full repo' '
        test_oid_init
 '
 
+test_expect_success POSIXPERM 'tweak umask for modebit tests' '
+       umask 022
+'
+
 test_expect_success 'verify graph with no graph file' '
        cd "$TRASH_DIRECTORY/full" &&
        git commit-graph verify
@@ -96,6 +100,13 @@ test_expect_success 'write graph' '
        graph_read_expect "3"
 '
 
+test_expect_success POSIXPERM 'write graph has correct permissions' '
+       test_path_is_file $objdir/info/commit-graph &&
+       echo "-r--r--r--" >expect &&
+       test_modebits $objdir/info/commit-graph >actual &&
+       test_cmp expect actual
+'
+
 graph_git_behavior 'graph exists' full commits/3 commits/1
 
 test_expect_success 'Add more commits' '
@@ -421,7 +432,8 @@ GRAPH_BYTE_FOOTER=$(($GRAPH_OCTOPUS_DATA_OFFSET + 4 * $NUM_OCTOPUS_EDGES))
 corrupt_graph_setup() {
        cd "$TRASH_DIRECTORY/full" &&
        test_when_finished mv commit-graph-backup $objdir/info/commit-graph &&
-       cp $objdir/info/commit-graph commit-graph-backup
+       cp $objdir/info/commit-graph commit-graph-backup &&
+       chmod u+w $objdir/info/commit-graph
 }
 
 corrupt_graph_verify() {
@@ -435,6 +447,7 @@ corrupt_graph_verify() {
        fi &&
        git status --short &&
        GIT_TEST_COMMIT_GRAPH_DIE_ON_LOAD=true git commit-graph write &&
+       chmod u+w $objdir/info/commit-graph &&
        git commit-graph verify
 }
 

diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index b24d85003606bf2076902d944fb395bf55761d5a..475564bee70ab705f7e28de82c687da6ea6a82c1 100755 (executable)
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -51,8 +51,10 @@ test_expect_success 'setup' '
        done &&
        git commit-graph write --reachable &&
        mv .git/objects/info/commit-graph commit-graph-full &&
+       chmod u+w commit-graph-full &&
        git show-ref -s commit-5-5 | git commit-graph write --stdin-commits &&
        mv .git/objects/info/commit-graph commit-graph-half &&
+       chmod u+w commit-graph-half &&
        git config core.commitGraph true
 '