WriteMethod function

Hi!

To write  a value,  we need  to assign a  function to  write_method. The
function will be  called several time with a  different action each time
(RESERVE1, RESERVE2, ACTION, COMMIT, UNDO, FREE). The function will also
have access to OID to be written and to the value from GET.

Looking at interfaces.c, I see:

#v+
long            admin_status = 0;
long            oldadmin_status = 0;
[...]
int
writeIfEntry(int action,
             u_char * var_val,
             u_char var_val_type,
             size_t var_val_len,
             u_char * statP, oid * name, size_t name_len)
{
[...]
    case ACTION:
        /*
         * Save the old value, in case of UNDO 
         */

        oldadmin_status = admin_status;
        admin_status = (int) *var_val;
        break;
#v-

This is a bit odd for me. Let's suppose that I use:

snmpset ifAdminStatus.5 = up ifAdminStatus.6 = up

Since I suppose that before  each phase (RESERVE1, RESERVE2, etc), we go
into var_ifEntry, then admin_status is set correctly each time. However,
oldadmin_status  seems inaccurate  to me.  ACTION will  be  executed for
column 5 first  then for column 6 and the  only value of oldadmin_status
we have saved would be the second one, right?

Moreover,  since   ACTION  cannot  fail,  UNDO  is   not  necessary  and
oldadmin_status is not really used, therefore I suppose that there is no
real bug. But looking at at.c, I  see that this is the same logic. There
is only  one instance of  oldarp_row, therefore, writing  several values
while one of them is failing will lead to undo only one.

Please, correct me if I am wrong.

Another  question:  what is  the  best  way to  pass  an  object to  the
write_method? For example,  if I need some expensive  processing to find
an  object,  I  would  like  to  not redo  it  in  write_method.  Since,
write_method is always immediatly called after the var_* method, I could
put a pointer  to my object in some global variable.  Is there a cleaner
way?  For example, using  the statP  pointer (I  don't need  the current
value)?

BTW, why is there a lookup before each action? I mean, the workflow is:

var_atEntry lookups the entry and sets write_method.
write_arp is called with action == RESERVE1
var_atEntry lookups the entry and sets write_method.
write_arp is called with action == RESERVE2
var_atEntry lookups the entry and sets write_method.
write_arp is called with action == ACTION
var_atEntry lookups the entry and sets write_method.
write_arp is called with action == COMMIT
var_atEntry lookups the entry and sets write_method.
write_arp is called with action == FREE

The workflow could be more efficient with:
var_atEntry lookups the entry and sets write_method.
write_arp is called with action == RESERVE1
write_arp is called with action == RESERVE2
write_arp is called with action == ACTION
write_arp is called with action == COMMIT
write_arp is called with action == FREE

Why is  var_atEntry called  so many times  while always giving  the same
result?
-- 
I AM NOT LICENSED TO DO ANYTHING
I AM NOT LICENSED TO DO ANYTHING
I AM NOT LICENSED TO DO ANYTHING
-+- Bart Simpson on chalkboard in episode 4F08

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