Subject: [PATCH v2 3/8] environment: move `zlib_compression_level` into repo_config_values

From: Olamide Caleb Bello <[email-masked]>
Date: Tue, 24 Mar 2026 13:37:45 +0100

The `zlib_compression_level` configuration is currently stored in the
global variable `zlib_compression_level`, which makes it shared across
repository instances within a single process.

Store it instead in `repo_config_values` so the value is associated
with the repository from which it was read. This preserves existing
behavior while avoiding cross-repository state leakage and continues
the effort to reduce reliance on global configuration state.

Update all references to use repo_config_values().

Mentored-by: Christian Couder <[email-masked]>
Mentored-by: Usman Akinyemi <[email-masked]>
Signed-off-by: Olamide Caleb Bello <[email-masked]>
---
 builtin/index-pack.c | 3 ++-
 diff.c               | 3 ++-
 environment.c        | 6 +++---
 environment.h        | 2 +-
 http-push.c          | 3 ++-
 object-file.c        | 3 ++-
 6 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index b67fb0256c..dd82eed76f 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1416,8 +1416,9 @@ static int write_compressed(struct hashfile *f, void *in, unsigned int size)
 	git_zstream stream;
 	int status;
 	unsigned char outbuf[4096];
+	struct repo_config_values *cfg = repo_config_values(the_repository);
 
-	git_deflate_init(&stream, zlib_compression_level);
+	git_deflate_init(&stream, cfg->zlib_compression_level);
 	stream.next_in = in;
 	stream.avail_in = size;
 
diff --git a/diff.c b/diff.c
index 501648a5c4..4bc0297873 100644
--- a/diff.c
+++ b/diff.c
@@ -3365,8 +3365,9 @@ static unsigned char *deflate_it(char *data,
 	int bound;
 	unsigned char *deflated;
 	git_zstream stream;
+	struct repo_config_values *cfg = repo_config_values(the_repository);
 
-	git_deflate_init(&stream, zlib_compression_level);
+	git_deflate_init(&stream, cfg->zlib_compression_level);
 	bound = git_deflate_bound(&stream, size);
 	deflated = xmalloc(bound);
 	stream.next_out = deflated;
diff --git a/environment.c b/environment.c
index 8542ac3141..5b0e88b65c 100644
--- a/environment.c
+++ b/environment.c
@@ -52,7 +52,6 @@ char *git_commit_encoding;
 char *git_log_output_encoding;
 char *apply_default_whitespace;
 char *apply_default_ignorewhitespace;
-int zlib_compression_level = Z_BEST_SPEED;
 int pack_compression_level = Z_DEFAULT_COMPRESSION;
 int fsync_object_files = -1;
 int use_fsync = -1;
@@ -377,7 +376,7 @@ int git_default_core_config(const char *var, const char *value,
 			level = Z_DEFAULT_COMPRESSION;
 		else if (level < 0 || level > Z_BEST_COMPRESSION)
 			die(_("bad zlib compression level %d"), level);
-		zlib_compression_level = level;
+		cfg->zlib_compression_level = level;
 		zlib_compression_seen = 1;
 		return 0;
 	}
@@ -389,7 +388,7 @@ int git_default_core_config(const char *var, const char *value,
 		else if (level < 0 || level > Z_BEST_COMPRESSION)
 			die(_("bad zlib compression level %d"), level);
 		if (!zlib_compression_seen)
-			zlib_compression_level = level;
+			cfg->zlib_compression_level = level;
 		if (!pack_compression_seen)
 			pack_compression_level = level;
 		return 0;
@@ -721,4 +720,5 @@ void repo_config_values_init(struct repo_config_values *cfg)
 	cfg->branch_track = BRANCH_TRACK_REMOTE;
 	cfg->trust_ctime = 1;
 	cfg->check_stat = 1;
+	cfg->zlib_compression_level = Z_BEST_SPEED;
 }
diff --git a/environment.h b/environment.h
index 1d3e2e4f23..93201620af 100644
--- a/environment.h
+++ b/environment.h
@@ -93,6 +93,7 @@ struct repo_config_values {
 	int apply_sparse_checkout;
 	int trust_ctime;
 	int check_stat;
+	int zlib_compression_level;
 
 	/* section "branch" config values */
 	enum branch_track branch_track;
@@ -170,7 +171,6 @@ extern int assume_unchanged;
 extern int warn_on_object_refname_ambiguity;
 extern char *apply_default_whitespace;
 extern char *apply_default_ignorewhitespace;
-extern int zlib_compression_level;
 extern int pack_compression_level;
 extern unsigned long pack_size_limit_cfg;
 
diff --git a/http-push.c b/http-push.c
index 9ae6062198..c6bf9ff387 100644
--- a/http-push.c
+++ b/http-push.c
@@ -369,13 +369,14 @@ static void start_put(struct transfer_request *request)
 	int hdrlen;
 	ssize_t size;
 	git_zstream stream;
+	struct repo_config_values *cfg = repo_config_values(the_repository);
 
 	unpacked = odb_read_object(the_repository->objects, &request->obj->oid,
 				   &type, &len);
 	hdrlen = format_object_header(hdr, sizeof(hdr), type, len);
 
 	/* Set it up */
-	git_deflate_init(&stream, zlib_compression_level);
+	git_deflate_init(&stream, cfg->zlib_compression_level);
 	size = git_deflate_bound(&stream, len + hdrlen);
 	strbuf_grow(&request->buffer.buf, size);
 	request->buffer.posn = 0;
diff --git a/object-file.c b/object-file.c
index 3094140055..8b719a915c 100644
--- a/object-file.c
+++ b/object-file.c
@@ -891,6 +891,7 @@ static int start_loose_object_common(struct odb_source *source,
 	const struct git_hash_algo *algo = source->odb->repo->hash_algo;
 	const struct git_hash_algo *compat = source->odb->repo->compat_hash_algo;
 	int fd;
+	struct repo_config_values *cfg = repo_config_values(the_repository);
 
 	fd = create_tmpfile(source->odb->repo, tmp_file, filename);
 	if (fd < 0) {
@@ -906,7 +907,7 @@ static int start_loose_object_common(struct odb_source *source,
 	}
 
 	/*  Setup zlib stream for compression */
-	git_deflate_init(stream, zlib_compression_level);
+	git_deflate_init(stream, cfg->zlib_compression_level);
 	stream->next_out = buf;
 	stream->avail_out = buflen;
 	algo->init_fn(c);
-- 
2.53.0.155.g9f36b15afa