config: add ctx arg to config_fn_t

Add a new "const struct config_context *ctx" arg to config_fn_t to hold
additional information about the config iteration operation.
config_context has a "struct key_value_info kvi" member that holds
metadata about the config source being read (e.g. what kind of config
source it is, the filename, etc). In this series, we're only interested
in .kvi, so we could have just used "struct key_value_info" as an arg,
but config_context makes it possible to add/adjust members in the future
without changing the config_fn_t signature. We could also consider other
ways of organizing the args (e.g. moving the config name and value into
config_context or key_value_info), but in my experiments, the
incremental benefit doesn't justify the added complexity (e.g. a
config_fn_t will sometimes invoke another config_fn_t but with a
different config value).

In subsequent commits, the .kvi member will replace the global "struct
config_reader" in config.c, making config iteration a global-free
operation. It requires much more work for the machinery to provide
meaningful values of .kvi, so for now, merely change the signature and
call sites, pass NULL as a placeholder value, and don't rely on the arg
in any meaningful way.

Most of the changes are performed by
contrib/coccinelle/config_fn_ctx.pending.cocci, which, for every
config_fn_t:

- Modifies the signature to accept "const struct config_context *ctx"
- Passes "ctx" to any inner config_fn_t, if needed
- Adds UNUSED attributes to "ctx", if needed

Most config_fn_t instances are easily identified by seeing if they are
called by the various config functions. Most of the remaining ones are
manually named in the .cocci patch. Manual cleanups are still needed,
but the majority of it is trivial; it's either adjusting config_fn_t
that the .cocci patch didn't catch, or adding forward declarations of
"struct config_context ctx" to make the signatures make sense.

The non-trivial changes are in cases where we are invoking a config_fn_t
outside of config machinery, and we now need to decide what value of
"ctx" to pass. These cases are:

- trace2/tr2_cfg.c:tr2_cfg_set_fl()

  This is indirectly called by git_config_set() so that the trace2
  machinery can notice the new config values and update its settings
  using the tr2 config parsing function, i.e. tr2_cfg_cb().

- builtin/checkout.c:checkout_main()

  This calls git_xmerge_config() as a shorthand for parsing a CLI arg.
  This might be worth refactoring away in the future, since
  git_xmerge_config() can call git_default_config(), which can do much
  more than just parsing.

Handle them by creating a KVI_INIT macro that initializes "struct
key_value_info" to a reasonable default, and use that to construct the
"ctx" arg.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 14 deletions

diff --git a/config.c b/config.c
index 2eeb662142..850e432e30 100644
--- a/config.c
+++ b/config.c
@@ -209,7 +209,8 @@ struct config_include_data {
 };
 #define CONFIG_INCLUDE_INIT { 0 }
 
-static int git_config_include(const char *var, const char *value, void *data);
+static int git_config_include(const char *var, const char *value,
+			      const struct config_context *ctx, void *data);
 
 #define MAX_INCLUDE_DEPTH 10
 static const char include_depth_advice[] = N_(
@@ -388,7 +389,8 @@ static int include_by_branch(const char *cond, size_t cond_len)
 	return ret;
 }
 
-static int add_remote_url(const char *var, const char *value, void *data)
+static int add_remote_url(const char *var, const char *value,
+			  const struct config_context *ctx UNUSED, void *data)
 {
 	struct string_list *remote_urls = data;
 	const char *remote_name;
@@ -423,6 +425,7 @@ static void populate_remote_urls(struct config_include_data *inc)
 }
 
 static int forbid_remote_url(const char *var, const char *value UNUSED,
+			     const struct config_context *ctx UNUSED,
 			     void *data UNUSED)
 {
 	const char *remote_name;
@@ -486,7 +489,9 @@ static int include_condition_is_true(struct config_source *cs,
 	return 0;
 }
 
-static int git_config_include(const char *var, const char *value, void *data)
+static int git_config_include(const char *var, const char *value,
+			      const struct config_context *ctx,
+			      void *data)
 {
 	struct config_include_data *inc = data;
 	struct config_source *cs = inc->config_reader->source;
@@ -498,7 +503,7 @@ static int git_config_include(const char *var, const char *value, void *data)
 	 * Pass along all values, including "include" directives; this makes it
 	 * possible to query information on the includes themselves.
 	 */
-	ret = inc->fn(var, value, inc->data);
+	ret = inc->fn(var, value, NULL, inc->data);
 	if (ret < 0)
 		return ret;
 
@@ -680,7 +685,7 @@ static int config_parse_pair(const char *key, const char *value,
 	if (git_config_parse_key(key, &canonical_name, NULL))
 		return -1;
 
-	ret = (fn(canonical_name, value, data) < 0) ? -1 : 0;
+	ret = (fn(canonical_name, value, NULL, data) < 0) ? -1 : 0;
 	free(canonical_name);
 	return ret;
 }
@@ -968,7 +973,7 @@ static int get_value(struct config_source *cs, config_fn_t fn, void *data,
 	 * accurate line number in error messages.
 	 */
 	cs->linenr--;
-	ret = fn(name->buf, value, data);
+	ret = fn(name->buf, value, NULL, data);
 	if (ret >= 0)
 		cs->linenr++;
 	return ret;
@@ -1562,7 +1567,8 @@ int git_config_color(char *dest, const char *var, const char *value)
 	return 0;
 }
 
-static int git_default_core_config(const char *var, const char *value, void *cb)
+static int git_default_core_config(const char *var, const char *value,
+				   const struct config_context *ctx, void *cb)
 {
 	/* This needs a better name */
 	if (!strcmp(var, "core.filemode")) {
@@ -1842,7 +1848,7 @@ static int git_default_core_config(const char *var, const char *value, void *cb)
 	}
 
 	/* Add other config variables here and to Documentation/config.txt. */
-	return platform_core_config(var, value, cb);
+	return platform_core_config(var, value, ctx, cb);
 }
 
 static int git_default_sparse_config(const char *var, const char *value)
@@ -1944,15 +1950,16 @@ static int git_default_mailmap_config(const char *var, const char *value)
 	return 0;
 }
 
-int git_default_config(const char *var, const char *value, void *cb)
+int git_default_config(const char *var, const char *value,
+		       const struct config_context *ctx, void *cb)
 {
 	if (starts_with(var, "core."))
-		return git_default_core_config(var, value, cb);
+		return git_default_core_config(var, value, ctx, cb);
 
 	if (starts_with(var, "user.") ||
 	    starts_with(var, "author.") ||
 	    starts_with(var, "committer."))
-		return git_ident_config(var, value, cb);
+		return git_ident_config(var, value, ctx, cb);
 
 	if (starts_with(var, "i18n."))
 		return git_default_i18n_config(var, value);
@@ -2318,7 +2325,7 @@ static void configset_iter(struct config_reader *reader, struct config_set *set,
 
 		config_reader_set_kvi(reader, values->items[value_index].util);
 
-		if (fn(entry->key, values->items[value_index].string, data) < 0)
+		if (fn(entry->key, values->items[value_index].string, NULL, data) < 0)
 			git_die_config_linenr(entry->key,
 					      reader->config_kvi->filename,
 					      reader->config_kvi->linenr);
@@ -2496,7 +2503,9 @@ struct configset_add_data {
 };
 #define CONFIGSET_ADD_INIT { 0 }
 
-static int config_set_callback(const char *key, const char *value, void *cb)
+static int config_set_callback(const char *key, const char *value,
+			       const struct config_context *ctx UNUSED,
+			       void *cb)
 {
 	struct configset_add_data *data = cb;
 	configset_add_value(data->config_reader, data->config_set, key, value);
@@ -3106,7 +3115,8 @@ static int store_aux_event(enum config_event_t type,
 	return 0;
 }
 
-static int store_aux(const char *key, const char *value, void *cb)
+static int store_aux(const char *key, const char *value,
+		     const struct config_context *ctx UNUSED, void *cb)
 {
 	struct config_store_data *store = cb;