[PATCH 4/6] config: return configset value for current_config_ functions

[Jeff King <peff@peff.net>]

When 473166b (config: add 'origin_type' to config_source
struct, 2016-02-19) added accessor functions for the origin
type and name, it taught them only to look at the "cf"
struct that is filled in while we are parsing the config.
This is sufficient to make it work with git-config, which
uses git_config_with_options() under the hood. That function
freshly parses the config files and triggers the callback
when it parses each key.

Most git programs, however, use git_config(). This interface
will populate a cache during the actual parse, and then
serve values from the cache. Calling current_config_filename()
in a callback here will find a NULL cf and produce an error.
There are no such callers right now, but let's prepare for
adding some by making this work.

We already record source information in a struct attached to
each value. We just need to make it globally available and
then consult it from the accessor functions.

Signed-off-by: Jeff King <peff@peff.net>
---
 cache.h                |  1 +
 config.c               | 51 +++++++++++++++++++++++++++++++++++++++++---------
 t/helper/test-config.c | 20 ++++++++++++++++++++
 t/t1308-config-set.sh  | 23 +++++++++++++++++++++++
 4 files changed, 86 insertions(+), 9 deletions(-)

diff --git a/cache.h b/cache.h
index 6b80a17..29c579b 100644
--- a/cache.h
+++ b/cache.h
@@ -1693,6 +1693,7 @@ extern int ignore_untracked_cache_config;
 struct key_value_info {
 	const char *filename;
 	int linenr;
+	const char *origin_type;
 };
 
 extern NORETURN void git_die_config(const char *key, const char *err, ...) __attribute__((format(printf, 2, 3)));
diff --git a/config.c b/config.c
index 4beba52..75afdd7 100644
--- a/config.c
+++ b/config.c
@@ -38,7 +38,24 @@ struct config_source {
 	long (*do_ftell)(struct config_source *c);
 };
 
+/*
+ * These variables record the "current" config source, which
+ * can be accessed by parsing callbacks.
+ *
+ * The "cf" variable will be non-NULL only when we are actually parsing a real
+ * config source (file, blob, cmdline, etc).
+ *
+ * The "current_config_kvi" variable will be non-NULL only when we are feeding
+ * cached config from a configset into a callback.
+ *
+ * They should generally never be non-NULL at the same time. If they are both
+ * NULL, then we aren't parsing anything (and depending on the function looking
+ * at the variables, it's either a bug for it to be called in the first place,
+ * or it's a function which can be reused for non-config purposes, and should
+ * fall back to some sane behavior).
+ */
 static struct config_source *cf;
+static struct key_value_info *current_config_kvi;
 
 static int zlib_compression_seen;
 
@@ -1288,16 +1305,20 @@ static void configset_iter(struct config_set *cs, config_fn_t fn, void *data)
 	struct string_list *values;
 	struct config_set_element *entry;
 	struct configset_list *list = &cs->list;
-	struct key_value_info *kv_info;
 
 	for (i = 0; i < list->nr; i++) {
 		entry = list->items[i].e;
 		value_index = list->items[i].value_index;
 		values = &entry->value_list;
-		if (fn(entry->key, values->items[value_index].string, data) < 0) {
-			kv_info = values->items[value_index].util;
-			git_die_config_linenr(entry->key, kv_info->filename, kv_info->linenr);
-		}
+
+		current_config_kvi = values->items[value_index].util;
+
+		if (fn(entry->key, values->items[value_index].string, data) < 0)
+			git_die_config_linenr(entry->key,
+					      current_config_kvi->filename,
+					      current_config_kvi->linenr);
+
+		current_config_kvi = NULL;
 	}
 }
 
@@ -1359,10 +1380,12 @@ static int configset_add_value(struct config_set *cs, const char *key, const cha
 	if (cf->name) {
 		kv_info->filename = strintern(cf->name);
 		kv_info->linenr = cf->linenr;
+		kv_info->origin_type = strintern(cf->origin_type);
 	} else {
 		/* for values read from `git_config_from_parameters()` */
 		kv_info->filename = NULL;
 		kv_info->linenr = -1;
+		kv_info->origin_type = NULL;
 	}
 	si->util = kv_info;
 
@@ -2442,14 +2465,24 @@ int parse_config_key(const char *var,
 
 const char *current_config_origin_type(void)
 {
-	if (!cf)
+	const char *type;
+	if (current_config_kvi)
+		type = current_config_kvi->origin_type;
+	else if(cf)
+		type = cf->origin_type;
+	else
 		die("BUG: current_config_origin_type called outside config callback");
-	return cf->origin_type ? cf->origin_type : "command line";
+	return type ? type : "command line";
 }
 
 const char *current_config_name(void)
 {
-	if (!cf)
+	const char *name;
+	if (current_config_kvi)
+		name = current_config_kvi->filename;
+	else if (cf)
+		name = cf->name;
+	else
 		die("BUG: current_config_name called outside config callback");
-	return cf->name ? cf->name : "";
+	return name ? name : "";
 }
diff --git a/t/helper/test-config.c b/t/helper/test-config.c
index 6a77552..3605ef8 100644
--- a/t/helper/test-config.c
+++ b/t/helper/test-config.c
@@ -25,6 +25,9 @@
  * 				ascending order of priority from a config_set
  * 				constructed from files entered as arguments.
  *
+ * iterate -> iterate over all values using git_config(), and print some
+ *            data for each
+ *
  * Examples:
  *
  * To print the value with highest priority for key "foo.bAr Baz.rock":
@@ -32,6 +35,20 @@
  *
  */
 
+static int iterate_cb(const char *var, const char *value, void *data)
+{
+	static int nr;
+
+	if (nr++)
+		putchar('\n');
+
+	printf("key=%s\n", var);
+	printf("value=%s\n", value ? value : "(null)");
+	printf("origin=%s\n", current_config_origin_type());
+	printf("name=%s\n", current_config_name());
+
+	return 0;
+}
 
 int main(int argc, char **argv)
 {
@@ -134,6 +151,9 @@ int main(int argc, char **argv)
 			printf("Value not found for \"%s\"\n", argv[2]);
 			goto exit1;
 		}
+	} else if (!strcmp(argv[1], "iterate")) {
+		git_config(iterate_cb, NULL);
+		goto exit0;
 	}
 
 	die("%s: Please check the syntax and the function name", argv[0]);
diff --git a/t/t1308-config-set.sh b/t/t1308-config-set.sh
index 005d66d..b241338 100755
--- a/t/t1308-config-set.sh
+++ b/t/t1308-config-set.sh
@@ -229,4 +229,27 @@ test_expect_success 'error on modifying repo config without repo' '
 	)
 '
 
+test_expect_success 'iteration shows correct origins' '
+	echo "[foo]bar = from-repo" >.git/config &&
+	echo "[alias]test-config = !test-config" >.gitconfig &&
+	cat >expect <<-EOF &&
+	key=alias.test-config
+	value=!test-config
+	origin=file
+	name=$(pwd)/.gitconfig
+
+	key=foo.bar
+	value=from-repo
+	origin=file
+	name=.git/config
+
+	key=foo.bar
+	value=from-cmdline
+	origin=command line
+	name=
+	EOF
+	git -c foo.bar=from-cmdline test-config iterate >actual &&
+	test_cmp expect actual
+'
+
 test_done
-- 
2.8.2.888.gecb1fe3