C/C++: goto into the for loop

Question

I have a bit unusual situation - I want to use goto statement to jump into the loop, not to jump out from it.

There are strong reasons to do so - this code must be part of some function which makes some calculations after the first call, returns with request for new data and needs one more call to continue. Function pointers (obvious solution) can't be used because we need interoperability with code which does not support function pointers.

I want to know whether code below is safe, i.e. it will be correctly compiled by all standard-compliant C/C++ compilers (we need both C and C++).

function foo(int not_a_first_call, int *data_to_request, ...other parameters... )
{
    if( not_a_first_call )
        goto request_handler;
    for(i=0; i<n; i++)
    {
        *data_to_request = i;
        return;
request_handler:
        ...process data...
    }
}

I've studied standards, but there isn't much information about such use case. I also wonder whether replacing for by equivalent while will be beneficial from the portability point of view.

Thanks in advance.

UPD: Thanks to all who've commented!

1. to all commenters :) yes, I understand that I can't jump over initializers of local variables and that I have to save/restore i on each call.

2. about strong reasons :) This code must implement reverse communication interface. Reverse communication is a coding pattern which tries to avoid using function pointers. Sometimes it have to be used because of legacy code which expects that you will use it.

Unfortunately, r-comm-interface can't be implemented in a nice way. You can't use function pointers and you can't easily split work into several functions.

Answer 1

Seems perfectly legal.

From a draft of the C99 standard http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/n843.htm in the section on the goto statement:

[#3] EXAMPLE 1 It is sometimes convenient to jump  into  the
   middle  of  a  complicated set of statements.  The following
   outline presents one possible approach to a problem based on
   these three assumptions:

     1.  The  general initialization code accesses objects only
         visible to the current function.

     2.  The  general  initialization  code  is  too  large  to
         warrant duplication.

     3.  The  code  to  determine  the next operation is at the
         head of the loop.  (To  allow  it  to  be  reached  by
         continue statements, for example.)

           /* ... */
           goto first_time;
           for (;;) {
                   // determine next operation
                   /* ... */
                   if (need to reinitialize) {
                           // reinitialize-only code
                           /* ... */
                   first_time:
                           // general initialization code
                           /* ... */
                           continue;
                   }
                   // handle other operations
                   /* ... */
           }

Next, we look at the for loop statement:

[#1]  Except for the behavior of a continue statement in the |
   loop body, the statement

           for ( clause-1 ; expr-2 ; expr-3 ) statement

   and the sequence of statements

           {
                   clause-1 ;
                   while ( expr-2 ) {
                           statement
                           expr-3 ;
                   }
           }

Putting the two together with your problem tells you that you are jumping past

i=0;

into the middle of a while loop. You will execute

...process data...

and then

i++;

before flow of control jumps to the test in the while/for loop

i<n;