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

Hi,

Here's a brief reroll to incorporate suggestions from Junio and Peff in the sub-thread beginning at [1]. Not much at all has changed since v2, with the exception of:

* fixing the aforementioned issue by sprinkling in some 'umask 022's in throughout the new tests

* adding in a new final patch to apply the same treatment to the 'commit-graph-chain' file

[1]: https://lore.kernel.org/git/[email protected]/

Taylor Blau (5):
tempfile.c: introduce 'create_tempfile_mode' lockfile.c: introduce 'hold_lock_file_for_update_mode' commit-graph.c: write non-split graphs as read-only commit-graph.c: ensure graph layers respect core.sharedRepository commit-graph.c: make 'commit-graph-chain's read-only

 commit-graph.c                | 12 ++++++++++--
 lockfile.c                    | 18 ++++++++++--------
 lockfile.h                    | 32 ++++++++++++++++++++++++++++----
 t/t5318-commit-graph.sh       | 15 ++++++++++++++-
 t/t5324-split-commit-graph.sh | 24 ++++++++++++++++++++++++
 t/t6600-test-reach.sh         |  2 ++
 tempfile.c                    |  6 +++---
 tempfile.h                    | 10 +++++++++-
 8 files changed, 100 insertions(+), 19 deletions(-)

Range-diff against v2:

1:  03c975b0bd = 1:  03c975b0bd tempfile.c: introduce 'create_tempfile_mode'
2:  c1c84552bc = 2:  c1c84552bc lockfile.c: introduce 'hold_lock_file_for_update_mode'
3:  86cf29ce9c ! 3:  8d5503d2e6 commit-graph.c: write non-split graphs as read-only

@@ Commit message
commit-graph file into place and then trying to replace it. For these, make these files writable.

+ Helped-by: Junio C Hamano <[email protected]>

## commit-graph.c ##
@@ commit-graph.c: static int write_commit_graph_file(struct write_commit_graph_con
}

## t/t5318-commit-graph.sh ##
+@@ t/t5318-commit-graph.sh: 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
@@ t/t5318-commit-graph.sh: test_expect_success 'write graph' '
graph_read_expect "3"
'
4: f83437f130 ! 4: 4b74e23af2 commit-graph.c: ensure graph layers respect core.sharedRepository
@@ commit-graph.c: static int write_commit_graph_file(struct write_commit_graph_con
hold_lock_file_for_update_mode(&lk, ctx->graph_name,

## t/t5324-split-commit-graph.sh ##
+@@ t/t5324-split-commit-graph.sh: graph_read_expect() {
+ test_cmp expect output
+ }
+
++test_expect_success POSIXPERM 'tweak umask for modebit tests' '
++ umask 022
++'
++
+ test_expect_success 'create commits and write commit-graph' '
+ for i in $(test_seq 3)
+ do
@@ t/t5324-split-commit-graph.sh: test_expect_success 'split across alternate where alternate is not split' '
test_cmp commit-graph .git/objects/info/commit-graph
'
-: ---------- > 5: 864c916067 commit-graph.c: make 'commit-graph-chain's read-only
--
2.26.0.113.ge9739cdccc