json: add json_to_bool() helper.

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

common/json.c

@@ -2,6 +2,7 @@
 #include "json.h"
 #include <assert.h>
 #include <ccan/build_assert/build_assert.h>
+#include <ccan/mem/mem.h>
 #include <ccan/str/hex/hex.h>
 #include <ccan/tal/str/str.h>
 #include <common/utils.h>
@@ -111,6 +112,21 @@ bool json_to_int(const char *buffer, const jsmntok_t *tok, int *num)
 	return true;
 }
 
+bool json_to_bool(const char *buffer, const jsmntok_t *tok, bool *b)
+{
+	if (tok->type != JSMN_PRIMITIVE)
+		return false;
+	if (memeqstr(buffer + tok->start, tok->end - tok->start, "true")) {
+		*b = true;
+		return true;
+	}
+	if (memeqstr(buffer + tok->start, tok->end - tok->start, "false")) {
+		*b = false;
+		return true;
+	}
+	return false;
+}
+
 bool json_to_bitcoin_amount(const char *buffer, const jsmntok_t *tok,
 			    uint64_t *satoshi)
 {

common/json.h

@@ -40,6 +40,9 @@ bool json_to_double(const char *buffer, const jsmntok_t *tok, double *num);
 /* Extract signed integer from this (may be a string, or a number literal) */
 bool json_to_int(const char *buffer, const jsmntok_t *tok, int *num);
 
+/* Extract boolean from this */
+bool json_to_bool(const char *buffer, const jsmntok_t *tok, bool *b);
+
 /* Extract satoshis from this (may be a string, or a decimal number literal) */
 bool json_to_bitcoin_amount(const char *buffer, const jsmntok_t *tok,
 			    uint64_t *satoshi);

common/json_tok.c

@@ -1,4 +1,3 @@
-#include <ccan/mem/mem.h>
 #include <ccan/str/hex/hex.h>
 #include <ccan/tal/str/str.h>
 #include <common/json_command.h>
@@ -25,16 +24,8 @@ bool json_tok_bool(struct command *cmd, const char *name,
 		   bool **b)
 {
 	*b = tal(cmd, bool);
-	if (tok->type == JSMN_PRIMITIVE) {
+	if (json_to_bool(buffer, tok, *b))
-		if (memeqstr(buffer + tok->start, tok->end - tok->start, "true")) {
+		return true;
-			**b = true;
-			return true;
-		}
-		if (memeqstr(buffer + tok->start, tok->end - tok->start, "false")) {
-			**b = false;
-			return true;
-		}
-	}
 	command_fail(cmd, JSONRPC2_INVALID_PARAMS,
 		     "'%s' should be 'true' or 'false', not '%.*s'",
 		     name, tok->end - tok->start, buffer + tok->start);