libplugin: make set callback for options take plugin ptr, check correct type.

I added a plugin arg and was surprised that compile didn't break.
This is because typesafe_cb et al are conditional casts: if the type
isn't as expected it has no effect, but we're passing plugin_option() through
varargs, so everything is accepted!

Add a noop inline to check type, and fix up the two cases where we
used `const char *` instead of `char *`.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/funder.c

@@ -1202,7 +1202,7 @@ param_funder_opt(struct command *cmd, const char *name,
 	opt_str = tal_strndup(cmd, buffer + tok->start,
 			      tok->end - tok->start);
 
-	err = funding_option(opt_str, *opt);
+	err = funding_option(cmd->plugin, opt_str, *opt);
 	if (err)
 		return command_fail_badparam(cmd, name, buffer, tok, err);
 
@@ -1222,7 +1222,7 @@ param_policy_mod(struct command *cmd, const char *name,
 	arg_str = tal_strndup(cmd, buffer + tok->start,
 			      tok->end - tok->start);
 
-	err = u64_option(arg_str, *mod);
+	err = u64_option(cmd->plugin, arg_str, *mod);
 	if (err) {
 		tal_free(err);
 		if (!parse_amount_sat(&sats, arg_str, strlen(arg_str)))
@@ -1518,7 +1518,7 @@ const struct plugin_notification notifs[] = {
 	},
 };
 
-static char *option_channel_base(const char *arg, struct funder_policy *policy)
+static char *option_channel_base(struct plugin *plugin, const char *arg, struct funder_policy *policy)
 {
 	struct amount_msat amt;
 
@@ -1536,15 +1536,16 @@ static char *option_channel_base(const char *arg, struct funder_policy *policy)
 }
 
 static char *
-option_channel_fee_proportional_thousandths_max(const char *arg,
+option_channel_fee_proportional_thousandths_max(struct plugin *plugin,
+						const char *arg,
 						struct funder_policy *policy)
 {
 	if (!policy->rates)
 		policy->rates = default_lease_rates(policy);
-	return u16_option(arg, &policy->rates->channel_fee_max_proportional_thousandths);
+	return u16_option(plugin, arg, &policy->rates->channel_fee_max_proportional_thousandths);
 }
 
-static char *amount_option(const char *arg, struct amount_sat *amt)
+static char *amount_option(struct plugin *plugin, const char *arg, struct amount_sat *amt)
 {
 	if (!parse_amount_sat(amt, arg, strlen(arg)))
 		return tal_fmt(tmpctx, "Unable to parse amount '%s'", arg);
@@ -1552,7 +1553,7 @@ static char *amount_option(const char *arg, struct amount_sat *amt)
 	return NULL;
 }
 
-static char *option_lease_fee_base(const char *arg,
+static char *option_lease_fee_base(struct plugin *plugin, const char *arg,
 				   struct funder_policy *policy)
 {
 	struct amount_sat amt;
@@ -1560,7 +1561,7 @@ static char *option_lease_fee_base(const char *arg,
 	if (!policy->rates)
 		policy->rates = default_lease_rates(policy);
 
-	err = amount_option(arg, &amt);
+	err = amount_option(plugin, arg, &amt);
 	if (err)
 		return err;
 
@@ -1571,28 +1572,29 @@ static char *option_lease_fee_base(const char *arg,
 	return NULL;
 }
 
-static char *option_lease_fee_basis(const char *arg,
+static char *option_lease_fee_basis(struct plugin *plugin, const char *arg,
 				    struct funder_policy *policy)
 {
 	if (!policy->rates)
 		policy->rates = default_lease_rates(policy);
-	return u16_option(arg, &policy->rates->lease_fee_basis);
+	return u16_option(plugin, arg, &policy->rates->lease_fee_basis);
 }
 
-static char *option_lease_weight_max(const char *arg,
+static char *option_lease_weight_max(struct plugin *plugin, const char *arg,
 				     struct funder_policy *policy)
 {
 	if (!policy->rates)
 		policy->rates = default_lease_rates(policy);
-	return u16_option(arg, &policy->rates->funding_weight);
+	return u16_option(plugin, arg, &policy->rates->funding_weight);
 }
 
-static char *amount_sat_or_u64_option(const char *arg, u64 *amt)
+static char *amount_sat_or_u64_option(struct plugin *plugin,
+				      const char *arg, u64 *amt)
 {
 	struct amount_sat sats;
 	char *err;
 
-	err = u64_option(arg, amt);
+	err = u64_option(plugin, arg, amt);
 	if (err) {
 		tal_free(err);
 		if (!parse_amount_sat(&sats, arg, strlen(arg)))

plugins/funder_policy.c

@@ -21,7 +21,7 @@ const char *funder_opt_name(enum funder_opt opt)
 	abort();
 }
 
-char *funding_option(const char *arg, enum funder_opt *opt)
+char *funding_option(struct plugin *plugin, const char *arg, enum funder_opt *opt)
 {
 	if (streq(arg, "match"))
 		*opt = MATCH;

plugins/funder_policy.h

@@ -3,6 +3,7 @@
 #include "config.h"
 #include <common/amount.h>
 
+struct plugin;
 struct lease_rates;
 struct node_id;
 
@@ -93,7 +94,7 @@ const char *funder_policy_desc(const tal_t *ctx,
 			       const struct funder_policy *policy);
 
 /* Convert a cmdline option to a funding_opt */
-char *funding_option(const char *arg, enum funder_opt *opt);
+char *funding_option(struct plugin *plugin, const char *arg, enum funder_opt *opt);
 
 /* Check policy settings, return error if fails */
 char *funder_check_policy(const struct funder_policy *policy);

plugins/libplugin.c

@@ -1202,7 +1202,7 @@ static struct command_result *handle_init(struct command *cmd,
 			char *problem;
 			if (!streq(p->opts[optnum].name, opt))
 				continue;
-			problem = p->opts[optnum].handle(json_strdup(opt, buf, t+1),
+			problem = p->opts[optnum].handle(p, json_strdup(opt, buf, t+1),
 							 p->opts[optnum].arg);
 			if (problem)
 				plugin_err(p, "option '%s': %s",
@@ -1225,7 +1225,7 @@ static struct command_result *handle_init(struct command *cmd,
 	return command_success(cmd, json_out_obj(cmd, NULL, NULL));
 }
 
-char *u64_option(const char *arg, u64 *i)
+char *u64_option(struct plugin *plugin, const char *arg, u64 *i)
 {
 	char *endp;
 
@@ -1239,7 +1239,7 @@ char *u64_option(const char *arg, u64 *i)
 	return NULL;
 }
 
-char *u32_option(const char *arg, u32 *i)
+char *u32_option(struct plugin *plugin, const char *arg, u32 *i)
 {
 	char *endp;
 	u64 n;
@@ -1258,7 +1258,7 @@ char *u32_option(const char *arg, u32 *i)
 	return NULL;
 }
 
-char *u16_option(const char *arg, u16 *i)
+char *u16_option(struct plugin *plugin, const char *arg, u16 *i)
 {
 	char *endp;
 	u64 n;
@@ -1277,7 +1277,7 @@ char *u16_option(const char *arg, u16 *i)
 	return NULL;
 }
 
-char *bool_option(const char *arg, bool *i)
+char *bool_option(struct plugin *plugin, const char *arg, bool *i)
 {
 	if (!streq(arg, "true") && !streq(arg, "false"))
 		return tal_fmt(tmpctx, "'%s' is not a bool, must be \"true\" or \"false\"", arg);
@@ -1286,7 +1286,7 @@ char *bool_option(const char *arg, bool *i)
 	return NULL;
 }
 
-char *flag_option(const char *arg, bool *i)
+char *flag_option(struct plugin *plugin, const char *arg, bool *i)
 {
 	/* We only get called if the flag was provided, so *i should be false
 	 * by default */
@@ -1298,7 +1298,7 @@ char *flag_option(const char *arg, bool *i)
 	return NULL;
 }
 
-char *charp_option(const char *arg, char **p)
+char *charp_option(struct plugin *plugin, const char *arg, char **p)
 {
 	*p = tal_strdup(NULL, arg);
 	return NULL;
@@ -1839,7 +1839,7 @@ static struct plugin *new_plugin(const tal_t *ctx,
 		o.name = optname;
 		o.type = va_arg(ap, const char *);
 		o.description = va_arg(ap, const char *);
-		o.handle = va_arg(ap, char *(*)(const char *str, void *arg));
+		o.handle = va_arg(ap, char *(*)(struct plugin *, const char *str, void *arg));
 		o.arg = va_arg(ap, void *);
 		o.deprecated = va_arg(ap, int); /* bool gets promoted! */
 		tal_arr_expand(&p->opts, o);

plugins/libplugin.h

@@ -77,7 +77,7 @@ struct plugin_option {
 	const char *name;
 	const char *type;
 	const char *description;
-	char *(*handle)(const char *str, void *arg);
+	char *(*handle)(struct plugin *plugin, const char *str, void *arg);
 	void *arg;
 	/* If true, this options *disabled* if allow-deprecated-apis = false */
 	bool deprecated;
@@ -393,12 +393,22 @@ void plugin_notify_progress(struct command *cmd,
 			    u32 num_stages, u32 stage,
 			    u32 num_progress, u32 progress);
 
+/* Simply exists to check that `set` to plugin_option* is correct type */
+static inline void *plugin_option_cb_check(char *(*set)(struct plugin *plugin,
+							const char *arg, void *))
+{
+	return set;
+}
+
 /* Macro to define arguments */
 #define plugin_option_(name, type, description, set, arg, deprecated)	\
 	(name),								\
 	(type),								\
 	(description),							\
-	typesafe_cb_preargs(char *, void *, (set), (arg), const char *),	\
+	plugin_option_cb_check(typesafe_cb_preargs(char *, void *,	\
+						   (set), (arg),	\
+						   struct plugin *,	\
+						   const char *)),	\
 	(arg),								\
 	(deprecated)
 
@@ -409,12 +419,12 @@ void plugin_notify_progress(struct command *cmd,
 	plugin_option_((name), (type), (description), (set), (arg), true)
 
 /* Standard helpers */
-char *u64_option(const char *arg, u64 *i);
-char *u32_option(const char *arg, u32 *i);
-char *u16_option(const char *arg, u16 *i);
-char *bool_option(const char *arg, bool *i);
-char *charp_option(const char *arg, char **p);
-char *flag_option(const char *arg, bool *i);
+char *u64_option(struct plugin *plugin, const char *arg, u64 *i);
+char *u32_option(struct plugin *plugin, const char *arg, u32 *i);
+char *u16_option(struct plugin *plugin, const char *arg, u16 *i);
+char *bool_option(struct plugin *plugin, const char *arg, bool *i);
+char *charp_option(struct plugin *plugin, const char *arg, char **p);
+char *flag_option(struct plugin *plugin, const char *arg, bool *i);
 
 /* The main plugin runner: append with 0 or more plugin_option(), then NULL. */
 void NORETURN LAST_ARG_NULL plugin_main(char *argv[],

plugins/sql.c

@@ -114,7 +114,7 @@ struct table_desc {
 static STRMAP(struct table_desc *) tablemap;
 static size_t max_dbmem = 500000000;
 static struct sqlite3 *db;
-static const char *dbfilename;
+static char *dbfilename;
 static int gosstore_fd = -1;
 static size_t gosstore_nodes_off = 0, gosstore_channels_off = 0;
 static u64 next_rowid = 1;

tests/plugins/test_libplugin.c

@@ -6,7 +6,7 @@
 #include <common/memleak.h>
 #include <plugins/libplugin.h>
 
-static const char *somearg;
+static char *somearg;
 static bool self_disable = false;
 static bool dont_shutdown = false;