bundle-uri: parse bundle list in config format

When a bundle provider wants to operate independently from a Git remote,
they want to provide a single, consistent URI that users can use in
their 'git clone --bundle-uri' commands. At this point, the Git client
expects that URI to be a single bundle that can be unbundled and used to
bootstrap the rest of the clone from the Git server. This single bundle
cannot be re-used to assist with future incremental fetches.

To allow for the incremental fetch case, teach Git to understand a
bundle list that could be advertised at an independent bundle URI. Such
a bundle list is likely to be inspected by human readers, even if only
by the bundle provider creating the list. For this reason, we can take
our expected "key=value" pairs and instead format them using Git config
format.

Create bundle_uri_parse_config_format() to parse a file in config format
and convert that into a 'struct bundle_list' filled with its
understanding of the contents.

Be careful to use error_action CONFIG_ERROR_ERROR when calling
git_config_from_file_with_options() because the default action for
git_config_from_file() is to die() on a parsing error.  The current
warning isn't particularly helpful if it arises to a user, but it will
be made more verbose at a higher layer later.

Update 'test-tool bundle-uri' to take this config file format as input.
It uses a filename instead of stdin because there is no existing way to
parse a FILE pointer in the config machinery. Using
git_config_from_mem() is overly complicated and more likely to introduce
bugs than this simpler version.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 37 insertions, 12 deletions

diff --git a/t/helper/test-bundle-uri.c b/t/helper/test-bundle-uri.c
index 0329c56544..25afd39342 100644
--- a/t/helper/test-bundle-uri.c
+++ b/t/helper/test-bundle-uri.c
@@ -4,12 +4,21 @@
 #include "strbuf.h"
 #include "string-list.h"
 
-static int cmd__bundle_uri_parse(int argc, const char **argv)
+enum input_mode {
+	KEY_VALUE_PAIRS,
+	CONFIG_FILE,
+};
+
+static int cmd__bundle_uri_parse(int argc, const char **argv, enum input_mode mode)
 {
 	const char *key_value_usage[] = {
 		"test-tool bundle-uri parse-key-values <input>",
 		NULL
 	};
+	const char *config_usage[] = {
+		"test-tool bundle-uri parse-config <input>",
+		NULL
+	};
 	const char **usage = key_value_usage;
 	struct option options[] = {
 		OPT_END(),
@@ -19,21 +28,35 @@ static int cmd__bundle_uri_parse(int argc, const char **argv)
 	int err = 0;
 	FILE *fp;
 
-	argc = parse_options(argc, argv, NULL, options, usage, 0);
-	if (argc != 1)
-		goto usage;
+	if (mode == CONFIG_FILE)
+		usage = config_usage;
+
+	argc = parse_options(argc, argv, NULL, options, usage,
+			     PARSE_OPT_STOP_AT_NON_OPTION);
 
 	init_bundle_list(&list);
-	fp = fopen(argv[0], "r");
-	if (!fp)
-		die("failed to open '%s'", argv[0]);
 
-	while (strbuf_getline(&sb, fp) != EOF) {
-		if (bundle_uri_parse_line(&list, sb.buf))
-			err = error("bad line: '%s'", sb.buf);
+	switch (mode) {
+	case KEY_VALUE_PAIRS:
+		if (argc != 1)
+			goto usage;
+		fp = fopen(argv[0], "r");
+		if (!fp)
+			die("failed to open '%s'", argv[0]);
+		while (strbuf_getline(&sb, fp) != EOF) {
+			if (bundle_uri_parse_line(&list, sb.buf))
+				err = error("bad line: '%s'", sb.buf);
+		}
+		fclose(fp);
+		break;
+
+	case CONFIG_FILE:
+		if (argc != 1)
+			goto usage;
+		err = bundle_uri_parse_config_format("<uri>", argv[0], &list);
+		break;
 	}
 	strbuf_release(&sb);
-	fclose(fp);
 
 	print_bundle_list(stdout, &list);
 
@@ -62,7 +85,9 @@ int cmd__bundle_uri(int argc, const char **argv)
 		goto usage;
 
 	if (!strcmp(argv[1], "parse-key-values"))
-		return cmd__bundle_uri_parse(argc - 1, argv + 1);
+		return cmd__bundle_uri_parse(argc - 1, argv + 1, KEY_VALUE_PAIRS);
+	if (!strcmp(argv[1], "parse-config"))
+		return cmd__bundle_uri_parse(argc - 1, argv + 1, CONFIG_FILE);
 	error("there is no test-tool bundle-uri tool '%s'", argv[1]);
 
 usage: