libsnmp: Optimize read_config_save_objid()

Make this function slightly faster by eliminating a strlen() call.
Declare the 'oid' input parameter const. Remove a superfluous cast.

Author: bvanassche

include/net-snmp/library/read_config.h

@@ -106,7 +106,7 @@ extern          "C" {
                                                  oid ** objid,
                                                  size_t * len);
     NETSNMP_IMPORT
-    char           *read_config_save_objid(char *saveto, oid * objid,
+    char           *read_config_save_objid(char *saveto, const oid * objid,
                                            size_t len);
     NETSNMP_IMPORT
     char           *read_config_read_data(int type, char *readfrom,

snmplib/read_config.c

@@ -2126,7 +2126,7 @@ read_config_read_octet_string_const(const char *readfrom, u_char ** str,
  * read_config_save_objid(): saves an objid as a numerical string 
  */
 char           *
-read_config_save_objid(char *saveto, oid * objid, size_t len)
+read_config_save_objid(char *saveto, const oid *objid, size_t len)
 {
     int             i;
 
@@ -2139,10 +2139,9 @@ read_config_save_objid(char *saveto, oid * objid, size_t len)
     /*
      * in case len=0, this makes it easier to read it back in 
      */
-    for (i = 0; i < (int) len; i++) {
-        sprintf(saveto, ".%" NETSNMP_PRIo "d", objid[i]);
-        saveto += strlen(saveto);
-    }
+    for (i = 0; i < len; i++)
+        saveto += sprintf(saveto, ".%" NETSNMP_PRIo "d", objid[i]);
+
     return saveto;
 }