odb/source: introduce source type for robustness
When a caller holds a `struct odb_source`, they have no way of telling what type the source is. This doesn't really cause any problems in the current status quo as we only have a single type anyway, "files". But going forward we expect to add more types, and if so it will become necessary to tell the sources apart. Introduce a new enum to cover this use case and assert that the given source actually matches the target source when performing the downcast. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Patrick Steinhardt committed
Mar 5, 2026 at 15:19 UTC
87842f68352040858f581b64509932fb91c64f0f
4 files changed
+22
-2
odb/source-files.c
+1
-1
@@ -36,7 +36,7 @@ struct odb_source_files *odb_source_files_new(struct object_database *odb,
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struct odb_source_files *files;
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CALLOC_ARRAY(files, 1);
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- odb_source_init(&files->base, odb, path, local);
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+ odb_source_init(&files->base, odb, ODB_SOURCE_FILES, path, local);
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files->loose = odb_source_loose_new(&files->base);
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files->packed = packfile_store_new(&files->base);
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odb/source-files.h
+4
-1
@@ -25,10 +25,13 @@ struct odb_source_files *odb_source_files_new(struct object_database *odb,
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void odb_source_files_free(struct odb_source_files *files);
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/*
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- * Cast the given object database source to the files backend.
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+ * Cast the given object database source to the files backend. This will cause
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+ * a BUG in case the source doesn't use this backend.
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*/
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static inline struct odb_source_files *odb_source_files_downcast(struct odb_source *source)
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{
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+ if (source->type != ODB_SOURCE_FILES)
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+ BUG("trying to downcast source of type '%d' to files", source->type);
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return container_of(source, struct odb_source_files, base);
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}
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odb/source.c
+2
@@ -13,10 +13,12 @@ struct odb_source *odb_source_new(struct object_database *odb,
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void odb_source_init(struct odb_source *source,
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struct object_database *odb,
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+ enum odb_source_type type,
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const char *path,
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bool local)
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{
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source->odb = odb;
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+ source->type = type;
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source->local = local;
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source->path = xstrdup(path);
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}
odb/source.h
+15
@@ -1,6 +1,17 @@
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#ifndef ODB_SOURCE_H
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#define ODB_SOURCE_H
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+enum odb_source_type {
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+ /*
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+ * The "unknown" type, which should never be in use. This type mostly
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+ * exists to catch cases where the type field remains zeroed out.
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+ */
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+ ODB_SOURCE_UNKNOWN,
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+
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+ /* The "files" backend that uses loose objects and packfiles. */
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+ ODB_SOURCE_FILES,
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+};
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+
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/*
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* The source is the part of the object database that stores the actual
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* objects. It thus encapsulates the logic to read and write the specific
@@ -19,6 +30,9 @@ struct odb_source {
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/* Object database that owns this object source. */
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struct object_database *odb;
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+ /* The type used by this source. */
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+ enum odb_source_type type;
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+
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/*
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* Figure out whether this is the local source of the owning
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* repository, which would typically be its ".git/objects" directory.
@@ -58,6 +72,7 @@ struct odb_source *odb_source_new(struct object_database *odb,
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*/
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void odb_source_init(struct odb_source *source,
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struct object_database *odb,
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+ enum odb_source_type type,
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const char *path,
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bool local);
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