core: move config_parse_limit() to the generic conf-parser.[ch]

That way we can use it in nspawn.

Also, while we are at it, let's rename the call config_parse_rlimit(),
i.e. insert the "r", to clarify what kind of limit this is about.

src/shared/conf-parser.c

@@ -33,6 +33,7 @@
 #include "syslog-util.h"
 #include "time-util.h"
 #include "utf8.h"
+#include "rlimit-util.h"
 
 int config_item_table_lookup(
                 const void *table,
@@ -1214,3 +1215,42 @@ int config_parse_mtu(
 
         return 0;
 }
+
+int config_parse_rlimit(
+                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) {
+
+        struct rlimit **rl = data, d = {};
+        int r;
+
+        assert(rvalue);
+        assert(rl);
+
+        r = rlimit_parse(ltype, rvalue, &d);
+        if (r == -EILSEQ) {
+                log_syntax(unit, LOG_WARNING, filename, line, r, "Soft resource limit chosen higher than hard limit, ignoring: %s", rvalue);
+                return 0;
+        }
+        if (r < 0) {
+                log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse resource value, ignoring: %s", rvalue);
+                return 0;
+        }
+
+        if (rl[ltype])
+                *rl[ltype] = d;
+        else {
+                rl[ltype] = newdup(struct rlimit, &d, 1);
+                if (!rl[ltype])
+                        return log_oom();
+        }
+
+        return 0;
+}

src/shared/conf-parser.h

@@ -147,6 +147,7 @@ int config_parse_ifname(GENERIC_PARSER_ARGS);
 int config_parse_ip_port(GENERIC_PARSER_ARGS);
 int config_parse_join_controllers(GENERIC_PARSER_ARGS);
 int config_parse_mtu(GENERIC_PARSER_ARGS);
+int config_parse_rlimit(GENERIC_PARSER_ARGS);
 
 typedef enum Disabled {
         DISABLED_CONFIGURATION,