var: add config file locations

Much like with attributes files, sometimes programs would like to know
the location of configuration files at the global or system levels.
However, it isn't always clear where these may live, especially for the
system file, which may have been hard-coded at compile time or computed
dynamically based on the runtime prefix.

Since other parties cannot intuitively know how Git was compiled and
where it looks for these files, help them by providing variables that
can be queried.  Because we have multiple paths for global config
values, print them in order from highest to lowest priority, and be sure
to split on newlines so that "git var -l" produces two entries for the
global value.

However, be careful not to split all values on newlines, since our
editor values could well contain such characters, and we don't want to
split them in such a case.

Note in the documentation that some values may contain multiple paths
and that callers should be prepared for that fact.  This helps people
write code that will continue to work in the event we allow multiple
items elsewhere in the future.

Signed-off-by: brian m. carlson <bk2204@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 56 insertions, 1 deletions

diff --git a/builtin/var.c b/builtin/var.c
index 79f7bdf55f..ef45710a20 100644
--- a/builtin/var.c
+++ b/builtin/var.c
@@ -72,9 +72,45 @@ static char *git_attr_val_global(int ident_flag UNUSED)
 	return NULL;
 }
 
+static char *git_config_val_system(int ident_flag UNUSED)
+{
+	if (git_config_system()) {
+		char *file = git_system_config();
+		normalize_path_copy(file, file);
+		return file;
+	}
+	return NULL;
+}
+
+static char *git_config_val_global(int ident_flag UNUSED)
+{
+	struct strbuf buf = STRBUF_INIT;
+	char *user, *xdg;
+	size_t unused;
+
+	git_global_config(&user, &xdg);
+	if (xdg && *xdg) {
+		normalize_path_copy(xdg, xdg);
+		strbuf_addf(&buf, "%s\n", xdg);
+	}
+	if (user && *user) {
+		normalize_path_copy(user, user);
+		strbuf_addf(&buf, "%s\n", user);
+	}
+	free(xdg);
+	free(user);
+	strbuf_trim_trailing_newline(&buf);
+	if (buf.len == 0) {
+		strbuf_release(&buf);
+		return NULL;
+	}
+	return strbuf_detach(&buf, &unused);
+}
+
 struct git_var {
 	const char *name;
 	char *(*read)(int);
+	int multivalued;
 };
 static struct git_var git_vars[] = {
 	{
@@ -114,6 +150,15 @@ static struct git_var git_vars[] = {
 		.read = git_attr_val_global,
 	},
 	{
+		.name = "GIT_CONFIG_SYSTEM",
+		.read = git_config_val_system,
+	},
+	{
+		.name = "GIT_CONFIG_GLOBAL",
+		.read = git_config_val_global,
+		.multivalued = 1,
+	},
+	{
 		.name = "",
 		.read = NULL,
 	},
@@ -126,7 +171,17 @@ static void list_vars(void)
 
 	for (ptr = git_vars; ptr->read; ptr++)
 		if ((val = ptr->read(0))) {
-			printf("%s=%s\n", ptr->name, val);
+			if (ptr->multivalued && *val) {
+				struct string_list list = STRING_LIST_INIT_DUP;
+				int i;
+
+				string_list_split(&list, val, '\n', -1);
+				for (i = 0; i < list.nr; i++)
+					printf("%s=%s\n", ptr->name, list.items[i].string);
+				string_list_clear(&list, 0);
+			} else {
+				printf("%s=%s\n", ptr->name, val);
+			}
 			free(val);
 		}
 }