[PATCH v2 00/17] Fixes and improvements for ref consistency checks

Hi,

this patch series contains a bunch of fixes and improvements for ref consistency checks. It is structured as follows:

  - Patches 1 to 4 contain a couple of cleanups for the consistency
    checks done by the "files" backend.

  - Patches 5 to 7 introduce checks for root refs for the "files"
    backend.

  - Patches 9 to 14 introduce infrastructure for shared checks with the
    "files" and "reftable" backend.

  - Patches 15 to 17 move some ref consistency checks that were still
    driven by git-fsck(1) into `git refs verify`.

Changes in v2:
  - Remove unused `errors_found` field.
  - Fix a commit message typo.
  - Fix a copy-paste error in a function comment.
  - Link to v1: https://lore.kernel.org/r/20260109-pks-refs-verify-fixes-v1-0-3587dba18294@pks.im

Thanks!

Patrick

---
Patrick Steinhardt (17):
      refs/files: simplify iterating through root refs
      refs/files: move fsck functions into global scope
      refs/files: remove `refs_check_dir` parameter
      refs/files: remove useless indirection
      refs/files: extract function to check single ref
      refs/files: improve error handling when verifying symrefs
      refs/files: perform consistency checks for root refs
      fsck: drop unused fields from `struct fsck_ref_report`
      refs/files: extract generic symref target checks
      refs/files: introduce function to perform normal ref checks
      refs/reftable: adapt includes to become consistent
      refs/reftable: extract function to retrieve backend for worktree
      refs/reftable: fix consistency checks with worktrees
      refs/reftable: introduce generic checks for refs
      builtin/fsck: move generic object ID checks into `refs_fsck()`
      builtin/fsck: move generic HEAD check into `refs_fsck()`
      builtin/fsck: drop `fsck_head_link()`

 Documentation/fsck-msgids.adoc |   6 ++
 builtin/fsck.c                 |  46 +--------
 fsck.c                         |   5 -
 fsck.h                         |   4 +-
 refs.c                         |  43 ++++++++
 refs.h                         |  18 ++++
 refs/files-backend.c           | 228 ++++++++++++++++++++++++-----------------
 refs/reftable-backend.c        | 167 ++++++++++++++++++++++--------
 t/t0602-reffiles-fsck.sh       |  30 ++++++
 t/t0614-reftable-fsck.sh       |  44 ++++++++
 t/t1450-fsck.sh                |  10 +-
 11 files changed, 414 insertions(+), 187 deletions(-)

Range-diff versus v1:

 1:  201451626d =  1:  21531efb05 refs/files: simplify iterating through root refs
 2:  88252f2b99 =  2:  861bd57d6e refs/files: move fsck functions into global scope
 3:  56d8ce2c85 =  3:  e06b8bdd23 refs/files: remove `refs_check_dir` parameter
 4:  ddf450134c =  4:  92992a522e refs/files: remove useless indirection
 5:  2d3ebf80fd =  5:  904fecf80e refs/files: extract function to check single ref
 6:  316dafeff8 =  6:  b5f5e86f1f refs/files: improve error handling when verifying symrefs
 7:  94a9b3d58b !  7:  d1abff98f8 refs/files: perform consistency checks for root refs
    @@ refs/files-backend.c: static int files_fsck_refs_dir(struct ref_store *ref_store
     +	struct worktree *wt;
     +	struct strbuf refname;
     +	struct strbuf path;
    -+	bool errors_found;
     +};
     +
     +static int files_fsck_root_ref(const char *refname, void *cb_data)
    @@ refs/files-backend.c: static int files_fsck_refs_dir(struct ref_store *ref_store
      	if (files_fsck_refs_dir(ref_store, o, wt) < 0)
      		ret = -1;
     +
    -+	if (for_each_root_ref(refs, files_fsck_root_ref, &data) < 0 ||
    -+	    data.errors_found)
    ++	if (for_each_root_ref(refs, files_fsck_root_ref, &data) < 0)
     +		ret = -1;
     +
      	if (refs->packed_ref_store->be->fsck(refs->packed_ref_store, o, wt) < 0)
 8:  a773fd65e9 =  8:  0b0e0e0033 fsck: drop unused fields from `struct fsck_ref_report`
 9:  12cf39ce8c !  9:  4bf249e530 refs/files: extract generic symref target checks
    @@ Commit message
     
         Reimplementing these checks for every single backend doesn't really make
         sense. Extract it into a generic `refs_fsck_symref()` function that can
    -    be used my other backends, as well. The "reftable" backend will be wired
    +    be used by other backends, as well. The "reftable" backend will be wired
         up in a subsequent commit.
     
         While at it, improve the consistency checks so that we don't complain
10:  9ae96c0acb ! 10:  5bd34fb53c refs/files: introduce function to perform normal ref checks
    @@ refs.h: int check_refname_format(const char *refname, int flags);
      struct fsck_ref_report;
      
     +/*
    -+ * Perform generic checks for a specific symref target. This function is
    ++ * Perform generic checks for a specific direct ref. This function is
     + * expected to be called by the ref backends for every symbolic ref.
     + */
     +int refs_fsck_ref(struct ref_store *refs, struct fsck_options *o,
11:  c2b0a1f517 = 11:  ca62b50abc refs/reftable: adapt includes to become consistent
12:  608b689d9e = 12:  66b5d6c981 refs/reftable: extract function to retrieve backend for worktree
13:  d39733206f = 13:  d31b7fb348 refs/reftable: fix consistency checks with worktrees
14:  37b8d22941 = 14:  eb960e66f2 refs/reftable: introduce generic checks for refs
15:  72b81062d2 = 15:  d0e2e3fe33 builtin/fsck: move generic object ID checks into `refs_fsck()`
16:  07a2403bc7 = 16:  029d02dd8a builtin/fsck: move generic HEAD check into `refs_fsck()`
17:  e944a0e430 = 17:  99eb06f153 builtin/fsck: drop `fsck_head_link()`

--- base-commit: d529f3a197364881746f558e5652f0236131eb86 change-id: 20260109-pks-refs-verify-fixes-1e47872317cf