Thanks a lot, Rich!  I revised my proposal based upon your suggestions.  Some comments are in-line...
--noriko

On 08/26/2009 09:13 AM, Rich Megginson wrote:
[...]
About this code:
    if (new_attrs)
    {
-        *attrs = new_attrs;
+        charray_merge_nodup(attrs, new_attrs, 0);
+        slapi_ch_free((void **)&new_attrs);
    }

the 0 flag to charray_merge_nodup() means "do not copy" - so the strings in new_attrs will be moved to attrs, if they are not duplicates.  If they are duplicates, they will not be moved - how will they be freed?  There's no way for the caller of charray_merge_nodup to know which strings were moved and which were not (except by comparing pointers in attrs with new_attrs).
I wanted to avoid malloc/free as much as possible, but it looks I cannot... :(  Changing it as follows:
    if (new_attrs)
    {
        charray_merge_nodup(attrs, new_attrs, 1);
        slapi_ch_array_free(new_attrs);
    }


+            int i;
+            const char *val = slapi_value_get_string(sval);
+            for (i = slapi_attr_first_value(attr, &sval);

I don't think you should be calling slapi_value_get_string() here since sval is not initialized yet.
Thanks for finding it out!  My copy & paste error... :(  Changing it as follows:
            int i;
            const char *val = NULL;
            for (i = slapi_attr_first_value(attr, &sval);

I think slapi_set_plugin_default_config() should always to a modify/add, and just ignore "type or value exists" errors.  Or support single valued attributes only.  Or allow the user to specify to add or replace in the case of a multi-valued attribute.
I was thinking the value is preferably single, but I wanted to support multiple values if set (e.g., by manually adding dse.ldif as you mentioned).  That made the code uglier.  I changed slapi_set_plugin_default_config simply adds the given "attr: value" pair to the plugin default config entry instead of replacing the existing pair(s) with it.
What if the user modifies the list directly over LDAP or by editing dse.ldif?  An internal call to set the value will wipe out their settings. 

Also, there is a reference to frational attr in the slapi_set_plugin_default_config() code.
Thanks!  I removed it... :p

I think slapi_set_plugin_default_config() will leak the pblock used for the initial search if rc != LDAP_SUCCESS or entries is NULL or empty.
I think it's taken care here....  Valgrind shows no leak in slapi_set_plugin_default_config in both cases entries exist or don't exist.
2911     } else { /* cn=plugin default config does not exist. Let's add it. */
2912         LDAPMod *mods[3];
2913         LDAPMod mod[2];
2914         const char *objectclass[3];
2915         char *attrlist[2];
2916   
2917         slapi_free_search_results_internal(&pb);
2918         pblock_done(&pb);



slapi_get_plugin_default_config() - since you are assuming that the values of the requested attribute are all null terminated strings (since you are using slapi_value_get_string()), you could just use slapi_entry_attr_get_charray() to get all of the values as a char **.
Thanks!  This is what I needed...

Why does slapi_set_plugin_default_config() take a char * argument i.e. setting an attribute with a single string value, but slapi_get_plugin_default_config() returns multiple values from a single attribute?

I'm not sure what the code in usn_start() is doing.  Is nsds5ReplicatedAttributeList multi-valued?  If so, each char * in char **old_frac_attrs will be a full attribute list description "(objectclass=*) $ EXCLUDE ...".  Then I'm not sure what the code that adds the entryusn attribute to the default excluded list is doing - will it add entryusn to only the first value of nsds5ReplicatedAttributeList?  And wipe out the other values?  I think that's what will happen, since there is a break in the for loop if token == NULL - it will skip old_frac_attrs[1] etc.  Also the call to charray_add - the token argument is not a malloced string, so that will cause problems when slapi_ch_array_free() is called.

I cleaned up the code.  It just adds the attribute value as follows.
    /* add nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE entryusn
     * to cn=plugin default config,cn=config */
    rc = slapi_set_plugin_default_config("nsds5ReplicatedAttributeList",
                                         "(objectclass=*) $ EXCLUDE entryusn");

Sorry about the previous code I wiped out.  I wanted to do this...
Let's assume we found exisiting nsds5ReplicatedAttributeList lines:
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE type0
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE type1 type 2
I wanted to convert them in to one line:
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE type0 type1 type 2 entryusn

Instead, I changed to just add nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE entryusn to the entry.  So, it'll end up like this:
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE type0
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE type1 type 2
  nsds5ReplicatedAttributeList: (objectclass=*) $ EXCLUDE entryusn