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[PATCH v5 07/10] refs: classify HEAD as a root ref

From
Patrick Steinhardt <ps@pks.im>
Date
May 15, 2024, 06:50 UTC
Message-ID
<b719fb7110249e88b80e0cd9943a2d864b18d0e0.1715755591.git.ps@pks.im>
In-Reply-To
<cover.1715755591.git.ps@pks.im>

Root refs are those refs that live in the root of the ref hierarchy. Our old and venerable "HEAD" reference falls into this category, but we don't yet classify it as such in `is_root_ref()`.

Adapt the function to also treat "HEAD" as a root ref. This change is safe to do for all current callers:

  - `ref_kind_from_refname()` already handles "HEAD" explicitly before
    calling `is_root_ref()`.
  - The "files" and "reftable" backends explicitly call both
    `is_root_ref()` and `is_headref()` together.

This also aligns behaviour or `is_root_ref()` and `is_headref()` such that we stop checking for ref existence. This changes semantics for our backends:

  - In the reftable backend we already know that the ref must exist
    because `is_headref()` is called as part of the ref iterator. The
    existence check is thus redundant, and the change is safe to do.
  - In the files backend we use it when populating root refs, where we
    would skip adding the "HEAD" file if it was not possible to resolve
    it. The new behaviour is to instead mark "HEAD" as broken, which
    will cause us to emit warnings in various places.

As there are no callers of `is_headref()` left afer the refactoring, we can absorb it completely into `is_root_ref()`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 refs.c                  | 9 +--------
 refs.h                  | 5 ++---
 refs/files-backend.c    | 3 +--
 refs/reftable-backend.c | 3 +--
 4 files changed, 5 insertions(+), 15 deletions(-)
diff --git a/refs.c b/refs.c
index 4fec29e660..9fb1061d52 100644
--- a/refs.c
+++ b/refs.c
@@ -859,6 +859,7 @@ static int is_root_ref_syntax(const char *refname)
 int is_root_ref(const char *refname)
 {
 	static const char *const irregular_root_refs[] = {
+		"HEAD",
 		"AUTO_MERGE",
 		"BISECT_EXPECTED_REV",
 		"NOTES_MERGE_PARTIAL",
@@ -880,14 +881,6 @@ int is_root_ref(const char *refname)
 	return 0;
 }
 
-int is_headref(struct ref_store *refs, const char *refname)
-{
-	if (!strcmp(refname, "HEAD"))
-		return refs_ref_exists(refs, refname);
-
-	return 0;
-}
-
 static int is_current_worktree_ref(const char *ref) {
 	return is_root_ref_syntax(ref) || is_per_worktree_ref(ref);
 }
diff --git a/refs.h b/refs.h
index 8a574a22c7..8489b45265 100644
--- a/refs.h
+++ b/refs.h
@@ -1060,7 +1060,8 @@ void update_ref_namespace(enum ref_namespace namespace, char *ref);
  *
  *   - Their name must be all-uppercase or underscores ("_").
  *
- *   - Their name must end with "_HEAD".
+ *   - Their name must end with "_HEAD". As a special rule, "HEAD" is a root
+ *     ref, as well.
  *
  *   - Their name may not contain a slash.
  *
@@ -1079,6 +1080,4 @@ void update_ref_namespace(enum ref_namespace namespace, char *ref);
  */
 int is_root_ref(const char *refname);
 
-int is_headref(struct ref_store *refs, const char *refname);
-
 #endif /* REFS_H */
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 06240ce327..6f9a631592 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -351,8 +351,7 @@ static void add_pseudoref_and_head_entries(struct ref_store *ref_store,
 		strbuf_addstr(&refname, de->d_name);
 
 		dtype = get_dtype(de, &path, 1);
-		if (dtype == DT_REG && (is_root_ref(de->d_name) ||
-					is_headref(ref_store, de->d_name)))
+		if (dtype == DT_REG && is_root_ref(de->d_name))
 			loose_fill_ref_dir_regular_file(refs, refname.buf, dir);
 
 		strbuf_setlen(&refname, dirnamelen);
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index bc927ef17b..821acd461a 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -354,8 +354,7 @@ static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		 */
 		if (!starts_with(iter->ref.refname, "refs/") &&
 		    !(iter->flags & DO_FOR_EACH_INCLUDE_ROOT_REFS &&
-		     (is_root_ref(iter->ref.refname) ||
-		      is_headref(&iter->refs->base, iter->ref.refname)))) {
+		      is_root_ref(iter->ref.refname))) {
 			continue;
 		}
 
-- 
2.45.GIT
Previous: Patrick SteinhardtNext: Justin Tobler
Message 89 of 93 in “Clarify pseudo-ref terminology”
  1. 0/3 Clarify pseudo-ref terminologyPatrick Steinhardt, Apr 29, 2024
  2. 1/3 refs: move `is_special_ref()`Patrick Steinhardt, Apr 29, 2024
  3. 2/3 refs: do not label special refs as pseudo refsPatrick Steinhardt, Apr 29, 2024
  4. Phillip WoodApr 29, 2024
  5. Patrick SteinhardtApr 30, 2024
  6. Phillip WoodApr 30, 2024
  7. Patrick SteinhardtApr 30, 2024
  8. Jeff KingApr 30, 2024
  9. Karthik NayakApr 30, 2024
  10. Patrick SteinhardtApr 30, 2024
  11. Patrick SteinhardtApr 30, 2024
  12. Junio C HamanoApr 29, 2024
  13. Justin ToblerApr 29, 2024
  14. Patrick SteinhardtApr 30, 2024
  15. Jean-Noël AVILAMay 9, 2024
  16. Patrick SteinhardtMay 10, 2024
  17. 3/3 refs: fix segfault in `is_pseudoref()` when ref cannot be resolvedPatrick Steinhardt, Apr 29, 2024
  18. Phillip WoodApr 29, 2024
  19. Karthik NayakApr 29, 2024
  20. Phillip WoodApr 29, 2024
  21. Karthik NayakApr 29, 2024
  22. Patrick SteinhardtApr 30, 2024
  23. 00/10 Clarify pseudo-ref terminologyPatrick Steinhardt, Apr 30, 2024
  24. 01/10 Documentation/glossary: redefine pseudorefs as special refsPatrick Steinhardt, Apr 30, 2024
  25. Karthik NayakApr 30, 2024
  26. Justin ToblerApr 30, 2024
  27. Junio C HamanoApr 30, 2024
  28. Patrick SteinhardtMay 2, 2024
  29. 02/10 Documentation/glossary: clarify limitations of pseudorefsPatrick Steinhardt, Apr 30, 2024
  30. Kristoffer HaugsbakkApr 30, 2024
  31. 03/10 Documentation/glossary: define root refs as refsPatrick Steinhardt, Apr 30, 2024
  32. Karthik NayakApr 30, 2024
  33. 04/10 refs: rename `is_pseudoref()` to `is_root_ref()`Patrick Steinhardt, Apr 30, 2024
  34. Junio C HamanoApr 30, 2024
  35. 05/10 refs: refname `is_special_ref()` to `is_pseudo_ref()`Patrick Steinhardt, Apr 30, 2024
  36. Karthik NayakApr 30, 2024
  37. 06/10 refs: classify HEAD as a root refPatrick Steinhardt, Apr 30, 2024
  38. 07/10 refs: root refs can be symbolic refsPatrick Steinhardt, Apr 30, 2024
  39. Justin ToblerApr 30, 2024
  40. Patrick SteinhardtMay 2, 2024
  41. Justin ToblerMay 3, 2024
  42. Patrick SteinhardtMay 7, 2024
  43. 08/10 refs: pseudorefs are no refsPatrick Steinhardt, Apr 30, 2024
  44. 09/10 ref-filter: properly distinuish pseudo and root refsPatrick Steinhardt, Apr 30, 2024
  45. Karthik NayakApr 30, 2024
  46. Patrick SteinhardtMay 2, 2024
  47. Karthik NayakMay 2, 2024
  48. 10/10 refs: refuse to write pseudorefsPatrick Steinhardt, Apr 30, 2024
  49. 00/10 Clarify pseudo-ref terminologyPatrick Steinhardt, May 2, 2024
  50. 01/10 Documentation/glossary: redefine pseudorefs as special refsPatrick Steinhardt, May 2, 2024
  51. 02/10 Documentation/glossary: clarify limitations of pseudorefsPatrick Steinhardt, May 2, 2024
  52. 03/10 Documentation/glossary: define root refs as refsPatrick Steinhardt, May 2, 2024
  53. 04/10 refs: rename `is_pseudoref()` to `is_root_ref()`Patrick Steinhardt, May 2, 2024
  54. 05/10 refs: refname `is_special_ref()` to `is_pseudo_ref()`Patrick Steinhardt, May 2, 2024
  55. 06/10 refs: classify HEAD as a root refPatrick Steinhardt, May 2, 2024
  56. 07/10 refs: root refs can be symbolic refsPatrick Steinhardt, May 2, 2024
  57. Jeff KingMay 3, 2024
  58. Patrick SteinhardtMay 15, 2024
  59. Patrick SteinhardtMay 15, 2024
  60. Jeff KingMay 15, 2024
  61. Patrick SteinhardtMay 15, 2024
  62. Jeff KingMay 15, 2024
  63. Patrick SteinhardtMay 15, 2024
  64. Jeff KingMay 15, 2024
  65. 08/10 refs: pseudorefs are no refsPatrick Steinhardt, May 2, 2024
  66. 09/10 ref-filter: properly distinuish pseudo and root refsPatrick Steinhardt, May 2, 2024
  67. 10/10 refs: refuse to write pseudorefsPatrick Steinhardt, May 2, 2024
  68. 00/10 Clarify pseudo-ref terminologyPatrick Steinhardt, May 10, 2024
  69. 01/10 Documentation/glossary: redefine pseudorefs as special refsPatrick Steinhardt, May 10, 2024
  70. 02/10 Documentation/glossary: clarify limitations of pseudorefsPatrick Steinhardt, May 10, 2024
  71. 03/10 Documentation/glossary: define root refs as refsPatrick Steinhardt, May 10, 2024
  72. 04/10 refs: rename `is_pseudoref()` to `is_root_ref()`Patrick Steinhardt, May 10, 2024
  73. 05/10 refs: refname `is_special_ref()` to `is_pseudo_ref()`Patrick Steinhardt, May 10, 2024
  74. 06/10 refs: root refs can be symbolic refsPatrick Steinhardt, May 10, 2024
  75. 07/10 refs: classify HEAD as a root refPatrick Steinhardt, May 10, 2024
  76. 08/10 refs: pseudorefs are no refsPatrick Steinhardt, May 10, 2024
  77. 09/10 ref-filter: properly distinuish pseudo and root refsPatrick Steinhardt, May 10, 2024
  78. 10/10 refs: refuse to write pseudorefsPatrick Steinhardt, May 10, 2024
  79. Junio C HamanoMay 10, 2024
  80. 00/10 Clarify pseudo-ref terminologyPatrick Steinhardt, May 15, 2024
  81. 01/10 Documentation/glossary: redefine pseudorefs as special refsPatrick Steinhardt, May 15, 2024
  82. 02/10 Documentation/glossary: clarify limitations of pseudorefsPatrick Steinhardt, May 15, 2024
  83. 03/10 Documentation/glossary: define root refs as refsPatrick Steinhardt, May 15, 2024
  84. 04/10 refs: rename `is_pseudoref()` to `is_root_ref()`Patrick Steinhardt, May 15, 2024
  85. 05/10 refs: rename `is_special_ref()` to `is_pseudo_ref()`Patrick Steinhardt, May 15, 2024
  86. 06/10 refs: do not check ref existence in `is_root_ref()`Patrick Steinhardt, May 15, 2024
  87. Justin ToblerMay 15, 2024
  88. Patrick SteinhardtMay 16, 2024
  89. 07/10 refs: classify HEAD as a root refPatrick Steinhardt, May 15, 2024
  90. Justin ToblerMay 15, 2024
  91. 08/10 refs: pseudorefs are no refsPatrick Steinhardt, May 15, 2024
  92. 09/10 ref-filter: properly distinuish pseudo and root refsPatrick Steinhardt, May 15, 2024
  93. 10/10 refs: refuse to write pseudorefsPatrick Steinhardt, May 15, 2024

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