conf-parser: introduce config section parser wrapper

It will be used later.

src/network/networkd-routing-policy-rule.c

@@ -1639,13 +1639,19 @@ static DEFINE_CONFIG_PARSE_ENUM_WITH_DEFAULT(
                 AddressFamily,
                 ADDRESS_FAMILY_NO);
 
-typedef struct RoutingPolicyRuleConfParser {
-        ConfigParserCallback parser;
-        int ltype;
-        size_t offset;
-} RoutingPolicyRuleConfParser;
+int config_parse_routing_policy_rule(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
 
-static RoutingPolicyRuleConfParser routing_policy_rule_conf_parser_table[_ROUTING_POLICY_RULE_CONF_PARSER_MAX] = {
+        static const ConfigSectionParser table[_ROUTING_POLICY_RULE_CONF_PARSER_MAX] = {
                 [ROUTING_POLICY_RULE_IIF]                = { .parser = config_parse_ifname,                         .ltype = 0,               .offset = offsetof(RoutingPolicyRule, iif),                },
                 [ROUTING_POLICY_RULE_OIF]                = { .parser = config_parse_ifname,                         .ltype = 0,               .offset = offsetof(RoutingPolicyRule, oif),                },
                 [ROUTING_POLICY_RULE_FAMILY]             = { .parser = config_parse_routing_policy_rule_family,     .ltype = 0,               .offset = offsetof(RoutingPolicyRule, address_family),     },
@@ -1666,36 +1672,18 @@ static RoutingPolicyRuleConfParser routing_policy_rule_conf_parser_table[_ROUTIN
                 [ROUTING_POLICY_RULE_UID_RANGE]          = { .parser = config_parse_routing_policy_rule_uid_range,  .ltype = 0,               .offset = offsetof(RoutingPolicyRule, uid_range),          },
         };
 
-int config_parse_routing_policy_rule(
-                const char *unit,
-                const char *filename,
-                unsigned line,
-                const char *section,
-                unsigned section_line,
-                const char *lvalue,
-                int ltype,
-                const char *rvalue,
-                void *data,
-                void *userdata) {
-
         _cleanup_(routing_policy_rule_unref_or_set_invalidp) RoutingPolicyRule *rule = NULL;
         Network *network = ASSERT_PTR(userdata);
         int r;
 
         assert(filename);
-        assert(ltype >= 0);
-        assert(ltype < _ROUTING_POLICY_RULE_CONF_PARSER_MAX);
 
         r = routing_policy_rule_new_static(network, filename, section_line, &rule);
         if (r < 0)
                 return log_oom();
 
-        RoutingPolicyRuleConfParser *e = routing_policy_rule_conf_parser_table + ltype;
-        assert(e->parser);
-        assert(e->offset < sizeof(RoutingPolicyRule));
-
-        r = e->parser(unit, filename, line, section, section_line, lvalue, e->ltype, rvalue,
-                      (uint8_t*) rule + e->offset, rule);
+        r = config_section_parse(table, ELEMENTSOF(table),
+                                 unit, filename, line, section, section_line, lvalue, ltype, rvalue, rule);
         if (r <= 0) /* 0 means non-critical error, but the section will be ignored. */
                 return r;
 

src/shared/conf-parser.c

@@ -793,6 +793,37 @@ bool stats_by_path_equal(Hashmap *a, Hashmap *b) {
         return true;
 }
 
+int config_section_parse(
+                const ConfigSectionParser *parsers,
+                size_t n_parsers,
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *userdata) {
+
+        assert(parsers);
+        assert(n_parsers > 0);
+        assert(ltype >= 0);
+        assert((size_t) ltype < n_parsers);
+        assert(userdata);
+
+        const ConfigSectionParser *e = parsers + ltype;
+        assert(e->parser);
+
+        /* This is used when a object is dynamically allocated per [SECTION] in a config parser, e.g.
+         * [Address] for systemd.network. Takes the allocated object as 'userdata', then it is passed to
+         * config parsers in the table. The 'data' field points to an element of the passed object, where
+         * its offset is given by the table. */
+
+        return e->parser(unit, filename, line, section, section_line, lvalue, e->ltype, rvalue,
+                         (uint8_t*) userdata + e->offset, userdata);
+}
+
 void config_section_hash_func(const ConfigSection *c, struct siphash *state) {
         siphash24_compress_string(c->filename, state);
         siphash24_compress_typesafe(c->line, state);

src/shared/conf-parser.h

@@ -147,6 +147,25 @@ int config_get_stats_by_path(
 int hashmap_put_stats_by_path(Hashmap **stats_by_path, const char *path, const struct stat *st);
 bool stats_by_path_equal(Hashmap *a, Hashmap *b);
 
+typedef struct ConfigSectionParser {
+        ConfigParserCallback parser;
+        int ltype;
+        size_t offset;
+} ConfigSectionParser;
+
+int config_section_parse(
+                const ConfigSectionParser *parsers,
+                size_t n_parsers,
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *userdata);
+
 typedef struct ConfigSection {
         unsigned line;
         bool invalid;