(This series is based on tb/pack-bitmap-traversal-with-boundary due to wanting to modify prepare_repo_settings() in a similar way.) The replace-refs can be ignored via the core.useReplaceRefs=false config setting. This setting is possible to miss in some Git commands if they do not load default config at the appropriate time. See [1] for a recent example of this. [1] https://lore.kernel.org/git/pull.1530.git.1683745654800.gitgitgadget@xxxxxxxxx/ This series aims to avoid this kind of error from happening in the future. The idea is to encapsulate the setting in such a way that we can guarantee that config has been checked before using the in-memory value. Further, we must be careful that some Git commands want to disable replace refs unconditionally, as if GIT_NO_REPLACE_REFS was enabled in the environment. The approach taken here is to split the global into two different sources. First, read_replace_refs is kept (but moved to replace-objects.c scope) and reflects whether or not the feature is permitted by the environment and the current command. Second, a new value is added to repo-settings and this is checked after using prepare_repo_settings() to guarantee the config has been read. This presents a potential behavior change, in that now core.useReplaceRefs is specific to each in-memory repository instead of applying the superproject value to all submodules. I could not find a Git command that has multiple in-memory repositories and follows OIDs to object contents, so I'm not sure how to demonstrate it in a test. Here is the breakdown of the series: * Patch 1 creates disable_replace_refs() to encapsulate the global disabling of the feature. * Patch 2 creates replace_refs_enabled() to check if the feature is enabled (with respect to a given repository). This is a thin wrapper of the global at this point, but does allow us to remove it from environment.h. * Patch 3 creates the value in repo-settings as well as ensures that the repo settings have been prepared before accessing the value within replace_refs_enabled(). A test is added to demonstrate how the config value is now scoped on a per-repository basis. Updates in v2 ============= Thanks for the careful review on v1! * disable_replace_refs() now replaces "read_replace_refs = 0" in the exact same line to avoid possible behavior change. * Stale comments, include headers, and commit messages are updated to include the latest status. * Patch 3 contains a test of the repo-scoped value using 'git grep'. Thanks, -Stolee Derrick Stolee (3): repository: create disable_replace_refs() replace-objects: create wrapper around setting repository: create read_replace_refs setting builtin/cat-file.c | 2 +- builtin/commit-graph.c | 2 +- builtin/fsck.c | 2 +- builtin/index-pack.c | 2 +- builtin/pack-objects.c | 2 +- builtin/prune.c | 2 +- builtin/replace.c | 2 +- builtin/unpack-objects.c | 2 +- builtin/upload-pack.c | 2 +- commit-graph.c | 4 +-- config.c | 5 ---- environment.c | 3 +-- git.c | 2 +- log-tree.c | 2 +- replace-object.c | 23 ++++++++++++++++- replace-object.h | 31 ++++++++++++++++------- repo-settings.c | 1 + repository.h | 9 +++++++ t/t7814-grep-recurse-submodules.sh | 40 ++++++++++++++++++++++++++++++ 19 files changed, 107 insertions(+), 31 deletions(-) base-commit: b0afdce5dab61f224fd66c13768facc36a7f8705 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1537%2Fderrickstolee%2Freplace-refs-safety-v2 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1537/derrickstolee/replace-refs-safety-v2 Pull-Request: https://github.com/gitgitgadget/git/pull/1537 Range-diff vs v1: 1: 56544abc15d ! 1: 0616fdbf303 repository: create disable_replace_refs() @@ Commit message transition by abstracting the purpose of these global assignments with a method call. - We will never scope this to an in-memory repository as we want to make - sure that we never use replace refs throughout the life of the process - if this method is called. + We will need to keep this read_replace_refs global forever, as we want + to make sure that we never use replace refs throughout the life of the + process if this method is called. Future changes may present a + repository-scoped version of the variable to represent that repository's + core.useReplaceRefs config value, but a zero-valued read_replace_refs + will always override such a setting. Signed-off-by: Derrick Stolee <derrickstolee@xxxxxxxxxx> @@ builtin/cat-file.c: static int batch_objects(struct batch_options *opt) cb.expand = &data; ## builtin/commit-graph.c ## -@@ builtin/commit-graph.c: static int graph_verify(int argc, const char **argv, const char *prefix) - return ret; - } - --extern int read_replace_refs; - static struct commit_graph_opts write_opts; - - static int write_option_parse_split(const struct option *opt, const char *arg, @@ builtin/commit-graph.c: int cmd_commit_graph(int argc, const char **argv, const char *prefix) - struct option *options = parse_options_concat(builtin_commit_graph_options, common_opts); git_config(git_default_config, NULL); -- + - read_replace_refs = 0; ++ disable_replace_refs(); save_commit_buffer = 0; argc = parse_options(argc, argv, prefix, options, - builtin_commit_graph_usage, 0); - FREE_AND_NULL(options); - -+ disable_replace_refs(); -+ - return fn(argc, argv, prefix); - } ## builtin/fsck.c ## @@ builtin/fsck.c: int cmd_fsck(int argc, const char **argv, const char *prefix) @@ builtin/fsck.c: int cmd_fsck(int argc, const char **argv, const char *prefix) errors_found = 0; - read_replace_refs = 0; ++ disable_replace_refs(); save_commit_buffer = 0; argc = parse_options(argc, argv, prefix, fsck_opts, fsck_usage, 0); -@@ builtin/fsck.c: int cmd_fsck(int argc, const char **argv, const char *prefix) - - git_config(git_fsck_config, &fsck_obj_options); - prepare_repo_settings(the_repository); -+ disable_replace_refs(); - - if (connectivity_only) { - for_each_loose_object(mark_loose_for_connectivity, NULL, 0); ## builtin/index-pack.c ## @@ builtin/index-pack.c: int cmd_index_pack(int argc, const char **argv, const char *prefix) @@ builtin/pack-objects.c: int cmd_pack_objects(int argc, const char **argv, const BUG("too many dfs states, increase OE_DFS_STATE_BITS"); - read_replace_refs = 0; -- - sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1); + disable_replace_refs(); + + sparse = git_env_bool("GIT_TEST_PACK_SPARSE", -1); if (the_repository->gitdir) { - prepare_repo_settings(the_repository); - if (sparse < 0) ## builtin/prune.c ## @@ builtin/prune.c: int cmd_prune(int argc, const char **argv, const char *prefix) @@ builtin/prune.c: int cmd_prune(int argc, const char **argv, const char *prefix) expire = TIME_MAX; save_commit_buffer = 0; - read_replace_refs = 0; ++ disable_replace_refs(); repo_init_revisions(the_repository, &revs, prefix); argc = parse_options(argc, argv, prefix, options, prune_usage, 0); -@@ builtin/prune.c: int cmd_prune(int argc, const char **argv, const char *prefix) - if (repository_format_precious_objects) - die(_("cannot prune in a precious-objects repo")); - -+ disable_replace_refs(); -+ - while (argc--) { - struct object_id oid; - const char *name = *argv++; ## builtin/replace.c ## @@ builtin/replace.c: int cmd_replace(int argc, const char **argv, const char *prefix) @@ builtin/replace.c: int cmd_replace(int argc, const char **argv, const char *pref }; - read_replace_refs = 0; ++ disable_replace_refs(); git_config(git_default_config, NULL); argc = parse_options(argc, argv, prefix, options, git_replace_usage, 0); - -+ disable_replace_refs(); -+ - if (!cmdmode) - cmdmode = argc ? MODE_REPLACE : MODE_LIST; - ## builtin/unpack-objects.c ## @@ builtin/unpack-objects.c: int cmd_unpack_objects(int argc, const char **argv, const char *prefix UNUSED) @@ builtin/unpack-objects.c: int cmd_unpack_objects(int argc, const char **argv, co struct object_id oid; - read_replace_refs = 0; -- - git_config(git_default_config, NULL); + disable_replace_refs(); - quiet = !isatty(2); + git_config(git_default_config, NULL); ## builtin/upload-pack.c ## @@ builtin/upload-pack.c: int cmd_upload_pack(int argc, const char **argv, const ch packet_trace_identity("upload-pack"); - read_replace_refs = 0; ++ disable_replace_refs(); argc = parse_options(argc, argv, prefix, options, upload_pack_usage, 0); -@@ builtin/upload-pack.c: int cmd_upload_pack(int argc, const char **argv, const char *prefix) - if (!enter_repo(dir, strict)) - die("'%s' does not appear to be a git repository", dir); - -+ disable_replace_refs(); -+ - switch (determine_protocol_version_server()) { - case protocol_v2: - if (advertise_refs) ## environment.c ## @@ environment.c: void setup_git_env(const char *git_dir) @@ replace-object.h: static inline const struct object_id *lookup_replace_object(st +void disable_replace_refs(void); + #endif /* REPLACE_OBJECT_H */ - - ## repo-settings.c ## -@@ - #include "repository.h" - #include "midx.h" - #include "compat/fsmonitor/fsm-listen.h" -+#include "environment.h" - - static void repo_cfg_bool(struct repository *r, const char *key, int *dest, - int def) 2: 5fc2f923d9e = 2: 0831e7f8b5e replace-objects: create wrapper around setting 3: 481a81a515e ! 3: 4c7dbeb8c6d repository: create read_replace_refs setting @@ Commit message then it would now respect the core.useReplaceRefs config value in each repository. - Unfortunately, the existing processes that recurse into submodules do - not appear to follow object IDs to their contents, so this behavior - change is not visible in the current implementation. It is something - valuable for future behavior changes. + 'git grep --recurse-submodules' is such a command that recurses into + submodules in-process. We can demonstrate the granularity of this config + value via a test in t7814. Signed-off-by: Derrick Stolee <derrickstolee@xxxxxxxxxx> @@ repository.h: struct repo_settings { int pack_use_bitmap_boundary_traversal; + /* -+ * Do replace refs need to be checked this run? This variable is -+ * initialized to true unless --no-replace-object is used or -+ * $GIT_NO_REPLACE_OBJECTS is set, but is set to false by some -+ * commands that do not want replace references to be active. ++ * Has this repository have core.useReplaceRefs=true (on by ++ * default)? This provides a repository-scoped version of this ++ * config, though it could be disabled process-wide via some Git ++ * builtins or the --no-replace-objects option. See ++ * replace_refs_enabled() for more details. + */ + int read_replace_refs; + struct fsmonitor_settings *fsmonitor; /* lazily loaded */ int index_version; + + ## t/t7814-grep-recurse-submodules.sh ## +@@ t/t7814-grep-recurse-submodules.sh: test_expect_success 'grep partially-cloned submodule' ' + ) + ' + ++test_expect_success 'check scope of core.useReplaceRefs' ' ++ git init base && ++ git init base/sub && ++ ++ echo A >base/a && ++ echo B >base/b && ++ echo C >base/sub/c && ++ echo D >base/sub/d && ++ ++ git -C base/sub add c d && ++ git -C base/sub commit -m "Add files" && ++ ++ git -C base submodule add ./sub && ++ git -C base add a b sub && ++ git -C base commit -m "Add files and submodule" && ++ ++ A=$(git -C base rev-parse HEAD:a) && ++ B=$(git -C base rev-parse HEAD:b) && ++ C=$(git -C base/sub rev-parse HEAD:c) && ++ D=$(git -C base/sub rev-parse HEAD:d) && ++ ++ git -C base replace $A $B && ++ git -C base/sub replace $C $D && ++ ++ test_must_fail git -C base grep --cached --recurse-submodules A && ++ test_must_fail git -C base grep --cached --recurse-submodules C && ++ ++ git -C base config core.useReplaceRefs false && ++ git -C base grep --recurse-submodules A && ++ test_must_fail git -C base grep --cached --recurse-submodules C && ++ ++ git -C base/sub config core.useReplaceRefs false && ++ git -C base grep --cached --recurse-submodules A && ++ git -C base grep --cached --recurse-submodules C && ++ ++ git -C base config --unset core.useReplaceRefs && ++ test_must_fail git -C base grep --cached --recurse-submodules A && ++ git -C base grep --cached --recurse-submodules C ++' ++ + test_done -- gitgitgadget
