show-index: warn when falling back to SHA-1 outside a repository
When 'git show-index' is run outside of a repository and no hashing algorithm is specified via --object-format, it silently falls back to SHA-1, relying on the historical default. This works for existing SHA-1 based index files, but the behavior can be ambiguous and confusing when the input index file uses a different hash algorithm, such as SHA-256. Add a warning when this fallback happens to make the assumption explicit and to guide users toward using --object-format when needed. Signed-off-by: Shreyansh Paliwal <shreyanshpaliwalcmsmn@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Shreyansh Paliwal committed
Jan 30, 2026 at 21:01 UTC
ea39808a22714b8f61b9472de7ef467ced15efea
1 file changed
+6
-3
builtin/show-index.c
+6
-3
@@ -43,11 +43,14 @@ int cmd_show_index(int argc,
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/*
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* Fallback to SHA1 if we are running outside of a repository.
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*
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- * TODO: Figure out and implement a way to detect the hash algorithm in use by the
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- * the index file passed in and use that instead.
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+ * TODO: If a future implementation of index file version encodes the hash
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+ * algorithm in its header, enable show-index to infer it from the
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+ * header rather than relying on repository context or a default fallback.
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*/
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- if (!the_hash_algo)
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+ if (!the_hash_algo) {
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+ warning(_("assuming SHA-1; use --object-format to override"));
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repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
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+ }
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hashsz = the_hash_algo->rawsz;
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