promisor-remote: refactor to get rid of 'struct strvec'

In a following commit, we will use the new 'promisor-remote' protocol
capability introduced by d460267 (Add 'promisor-remote' capability
to protocol v2, 2025-02-18) to pass and process more information
about promisor remotes than just their name and url.

For that purpose, we will need to store information about other
fields, especially information that might or might not be available
for different promisor remotes. Unfortunately using 'struct strvec',
as we currently do, to store information about the promisor remotes
with one 'struct strvec' for each field like "name" or "url" does not
scale easily in that case.

Let's refactor this and introduce a new 'struct promisor_info' linked
list which for now only contains a 'next' pointer, a 'name' member for
the promisor remote name and an 'url' member for its URL.

Explicit members are used within 'struct promisor_info' for type
safety and clarity regarding the specific information being handled,
rather than a generic key-value store. We want to specify and document
each field and its content, so adding new members to the struct as
more fields are supported is fine.

Signed-off-by: Christian Couder <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: chriscool

promisor-remote.c

@@ -314,10 +314,37 @@ static int allow_unsanitized(char ch)
 	return ch > 32 && ch < 127;
 }
 
-static void promisor_info_vecs(struct repository *repo,
-			       struct strvec *names,
-			       struct strvec *urls)
+/*
+ * Linked list for promisor remotes involved in the "promisor-remote"
+ * protocol capability.
+ *
+ * Except for "next" and "name", each <member> in this struct and its
+ * <value> should correspond to a "remote.<name>.<member>" config
+ * variable set to <value> where "<name>" is a promisor remote name.
+ */
+struct promisor_info {
+	struct promisor_info *next;
+	const char *name;
+	const char *url;
+};
+
+static void promisor_info_list_free(struct promisor_info *p)
+{
+	struct promisor_info *next;
+
+	for (; p; p = next) {
+		next = p->next;
+		free((char *)p->name);
+		free((char *)p->url);
+		free(p);
+	}
+}
+
+/* Prepare a 'struct promisor_info' linked list with config information. */
+static struct promisor_info *promisor_config_info_list(struct repository *repo)
 {
+	struct promisor_info *infos = NULL;
+	struct promisor_info **last_info = &infos;
 	struct promisor_remote *r;
 
 	promisor_remote_init(repo);
@@ -328,57 +355,65 @@ static void promisor_info_vecs(struct repository *repo,
 
 		/* Only add remotes with a non empty URL */
 		if (!git_config_get_string_tmp(url_key, &url) && *url) {
-			strvec_push(names, r->name);
-			strvec_push(urls, url);
+			struct promisor_info *new_info = xcalloc(1, sizeof(*new_info));
+
+			new_info->name = xstrdup(r->name);
+			new_info->url = xstrdup(url);
+
+			*last_info = new_info;
+			last_info = &new_info->next;
 		}
 
 		free(url_key);
 	}
+
+	return infos;
 }
 
 char *promisor_remote_info(struct repository *repo)
 {
 	struct strbuf sb = STRBUF_INIT;
 	int advertise_promisors = 0;
-	struct strvec names = STRVEC_INIT;
-	struct strvec urls = STRVEC_INIT;
+	struct promisor_info *config_info;
+	struct promisor_info *p;
 
 	git_config_get_bool("promisor.advertise", &advertise_promisors);
 
 	if (!advertise_promisors)
 		return NULL;
 
-	promisor_info_vecs(repo, &names, &urls);
+	config_info = promisor_config_info_list(repo);
 
-	if (!names.nr)
+	if (!config_info)
 		return NULL;
 
-	for (size_t i = 0; i < names.nr; i++) {
-		if (i)
+	for (p = config_info; p; p = p->next) {
+		if (p != config_info)
 			strbuf_addch(&sb, ';');
+
 		strbuf_addstr(&sb, "name=");
-		strbuf_addstr_urlencode(&sb, names.v[i], allow_unsanitized);
+		strbuf_addstr_urlencode(&sb, p->name, allow_unsanitized);
 		strbuf_addstr(&sb, ",url=");
-		strbuf_addstr_urlencode(&sb, urls.v[i], allow_unsanitized);
+		strbuf_addstr_urlencode(&sb, p->url, allow_unsanitized);
 	}
 
-	strvec_clear(&names);
-	strvec_clear(&urls);
+	promisor_info_list_free(config_info);
 
 	return strbuf_detach(&sb, NULL);
 }
 
 /*
- * Find first index of 'nicks' where there is 'nick'. 'nick' is
- * compared case sensitively to the strings in 'nicks'. If not found
- * 'nicks->nr' is returned.
+ * Find first element of 'p' where the 'name' member is 'nick'. 'nick'
+ * is compared case sensitively to the strings in 'p'. If not found
+ * NULL is returned.
  */
-static size_t remote_nick_find(struct strvec *nicks, const char *nick)
+static struct promisor_info *remote_nick_find(struct promisor_info *p, const char *nick)
 {
-	for (size_t i = 0; i < nicks->nr; i++)
-		if (!strcmp(nicks->v[i], nick))
-			return i;
-	return nicks->nr;
+	for (; p; p = p->next) {
+		if (!strcmp(p->name, nick))
+			return p;
+	}
+	return NULL;
 }
 
 enum accept_promisor {
@@ -390,16 +425,16 @@ enum accept_promisor {
 
 static int should_accept_remote(enum accept_promisor accept,
 				const char *remote_name, const char *remote_url,
-				struct strvec *names, struct strvec *urls)
+				struct promisor_info *config_info)
 {
-	size_t i;
+	struct promisor_info *p;
 
 	if (accept == ACCEPT_ALL)
 		return 1;
 
-	i = remote_nick_find(names, remote_name);
+	p = remote_nick_find(config_info, remote_name);
 
-	if (i >= names->nr)
+	if (!p)
 		/* We don't know about that remote */
 		return 0;
 
@@ -414,11 +449,15 @@ static int should_accept_remote(enum accept_promisor accept,
 		return 0;
 	}
 
-	if (!strcmp(urls->v[i], remote_url))
+	if (!p->url)
+		BUG("Bad config_info (invalid URL) for remote '%s'.\n",
+		    remote_name);
+
+	if (!strcmp(p->url, remote_url))
 		return 1;
 
 	warning(_("known remote named '%s' but with URL '%s' instead of '%s'"),
-		remote_name, urls->v[i], remote_url);
+		remote_name, p->url, remote_url);
 
 	return 0;
 }
@@ -430,8 +469,7 @@ static void filter_promisor_remote(struct repository *repo,
 	struct strbuf **remotes;
 	const char *accept_str;
 	enum accept_promisor accept = ACCEPT_NONE;
-	struct strvec names = STRVEC_INIT;
-	struct strvec urls = STRVEC_INIT;
+	struct promisor_info *config_info = NULL;
 
 	if (!git_config_get_string_tmp("promisor.acceptfromserver", &accept_str)) {
 		if (!*accept_str || !strcasecmp("None", accept_str))
@@ -451,7 +489,7 @@ static void filter_promisor_remote(struct repository *repo,
 		return;
 
 	if (accept != ACCEPT_ALL)
-		promisor_info_vecs(repo, &names, &urls);
+		config_info = promisor_config_info_list(repo);
 
 	/* Parse remote info received */
 
@@ -482,16 +520,15 @@ static void filter_promisor_remote(struct repository *repo,
 		if (remote_url)
 			decoded_url = url_percent_decode(remote_url);
 
-		if (decoded_name && should_accept_remote(accept, decoded_name, decoded_url, &names, &urls))
+		if (decoded_name && should_accept_remote(accept, decoded_name, decoded_url, config_info))
 			strvec_push(accepted, decoded_name);
 
 		strbuf_list_free(elems);
 		free(decoded_name);
 		free(decoded_url);
 	}
 
-	strvec_clear(&names);
-	strvec_clear(&urls);
+	promisor_info_list_free(config_info);
 	strbuf_list_free(remotes);
 }