Subject: [PATCH v3 03/16] hash: use uint32_t for object_id algorithm

From: "brian m. carlson" <[email-masked]>
Date: Sat, 7 Feb 2026 20:04:33 +0000

We currently use an int for this value, but we'll define this structure
from Rust in a future commit and we want to ensure that our data types
are exactly identical.  To make that possible, use a uint32_t for the
hash algorithm.

Signed-off-by: brian m. carlson <[email-masked]>
---
 hash.c       |  6 +++---
 hash.h       | 10 +++++-----
 oidtree.c    |  2 +-
 repository.c |  6 +++---
 repository.h |  4 ++--
 serve.c      |  2 +-
 6 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/hash.c b/hash.c
index 4a04ecb50e..81b4f87027 100644
--- a/hash.c
+++ b/hash.c
@@ -241,7 +241,7 @@ const char *empty_tree_oid_hex(const struct git_hash_algo *algop)
 	return oid_to_hex_r(buf, algop->empty_tree);
 }
 
-int hash_algo_by_name(const char *name)
+uint32_t hash_algo_by_name(const char *name)
 {
 	if (!name)
 		return GIT_HASH_UNKNOWN;
@@ -251,7 +251,7 @@ int hash_algo_by_name(const char *name)
 	return GIT_HASH_UNKNOWN;
 }
 
-int hash_algo_by_id(uint32_t format_id)
+uint32_t hash_algo_by_id(uint32_t format_id)
 {
 	for (size_t i = 1; i < GIT_HASH_NALGOS; i++)
 		if (format_id == hash_algos[i].format_id)
@@ -259,7 +259,7 @@ int hash_algo_by_id(uint32_t format_id)
 	return GIT_HASH_UNKNOWN;
 }
 
-int hash_algo_by_length(size_t len)
+uint32_t hash_algo_by_length(size_t len)
 {
 	for (size_t i = 1; i < GIT_HASH_NALGOS; i++)
 		if (len == hash_algos[i].rawsz)
diff --git a/hash.h b/hash.h
index fae966b23c..99c9c2a0a8 100644
--- a/hash.h
+++ b/hash.h
@@ -211,7 +211,7 @@ static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *s
 
 struct object_id {
 	unsigned char hash[GIT_MAX_RAWSZ];
-	int algo;	/* XXX requires 4-byte alignment */
+	uint32_t algo;	/* XXX requires 4-byte alignment */
 };
 
 #define GET_OID_QUIETLY                  01
@@ -344,13 +344,13 @@ static inline void git_hash_final_oid(struct object_id *oid, struct git_hash_ctx
  * Return a GIT_HASH_* constant based on the name.  Returns GIT_HASH_UNKNOWN if
  * the name doesn't match a known algorithm.
  */
-int hash_algo_by_name(const char *name);
+uint32_t hash_algo_by_name(const char *name);
 /* Identical, except based on the format ID. */
-int hash_algo_by_id(uint32_t format_id);
+uint32_t hash_algo_by_id(uint32_t format_id);
 /* Identical, except based on the length. */
-int hash_algo_by_length(size_t len);
+uint32_t hash_algo_by_length(size_t len);
 /* Identical, except for a pointer to struct git_hash_algo. */
-static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
+static inline uint32_t hash_algo_by_ptr(const struct git_hash_algo *p)
 {
 	size_t i;
 	for (i = 0; i < GIT_HASH_NALGOS; i++) {
diff --git a/oidtree.c b/oidtree.c
index 151568f74f..324de94934 100644
--- a/oidtree.c
+++ b/oidtree.c
@@ -10,7 +10,7 @@ struct oidtree_iter_data {
 	oidtree_iter fn;
 	void *arg;
 	size_t *last_nibble_at;
-	int algo;
+	uint32_t algo;
 	uint8_t last_byte;
 };
 
diff --git a/repository.c b/repository.c
index 9ebbb7afd8..08422d2188 100644
--- a/repository.c
+++ b/repository.c
@@ -39,7 +39,7 @@ struct repository *the_repository = &the_repo;
 static void set_default_hash_algo(struct repository *repo)
 {
 	const char *hash_name;
-	int algo;
+	uint32_t algo;
 
 	hash_name = getenv("GIT_TEST_DEFAULT_HASH_ALGO");
 	if (!hash_name)
@@ -179,12 +179,12 @@ void repo_set_gitdir(struct repository *repo,
 			repo->gitdir, "index");
 }
 
-void repo_set_hash_algo(struct repository *repo, int hash_algo)
+void repo_set_hash_algo(struct repository *repo, uint32_t hash_algo)
 {
 	repo->hash_algo = &hash_algos[hash_algo];
 }
 
-void repo_set_compat_hash_algo(struct repository *repo MAYBE_UNUSED, int algo)
+void repo_set_compat_hash_algo(struct repository *repo MAYBE_UNUSED, uint32_t algo)
 {
 #ifdef WITH_RUST
 	if (hash_algo_by_ptr(repo->hash_algo) == algo)
diff --git a/repository.h b/repository.h
index 7141237f97..46a3beabec 100644
--- a/repository.h
+++ b/repository.h
@@ -202,8 +202,8 @@ struct set_gitdir_args {
 void repo_set_gitdir(struct repository *repo, const char *root,
 		     const struct set_gitdir_args *extra_args);
 void repo_set_worktree(struct repository *repo, const char *path);
-void repo_set_hash_algo(struct repository *repo, int algo);
-void repo_set_compat_hash_algo(struct repository *repo, int compat_algo);
+void repo_set_hash_algo(struct repository *repo, uint32_t algo);
+void repo_set_compat_hash_algo(struct repository *repo, uint32_t compat_algo);
 void repo_set_ref_storage_format(struct repository *repo,
 				 enum ref_storage_format format);
 void initialize_repository(struct repository *repo);
diff --git a/serve.c b/serve.c
index 53ecab3b42..49a6e39b1d 100644
--- a/serve.c
+++ b/serve.c
@@ -14,7 +14,7 @@
 
 static int advertise_sid = -1;
 static int advertise_object_info = -1;
-static int client_hash_algo = GIT_HASH_SHA1_LEGACY;
+static uint32_t client_hash_algo = GIT_HASH_SHA1_LEGACY;
 
 static int always_advertise(struct repository *r UNUSED,
 			    struct strbuf *value UNUSED)