Description:
------------
Please regard this comment seriously, it really contains information on how to fix 25266, 22072, 30301 and many other (NOT bogus) bugs under Apache SAPI.

From bug 25266 comment by iliaa@php.net:
> Apache provides a way for PHP to detect if connection was 
> aborted ONLY and ONLY when PHP is either reading data from 
> the user or writing back data.

That is not true.

This link contains description and code (mod_perl) on how to detect disconnection without flushing data:
http://www.webreference.com/programming/perl/cookbook/chap4/5.html

My untidy but WORKING solution was to add code given below to sapi_apache_flush function and call flush() function before connection_aborted() checks WITHOUT any output. Of course, it would be perfectly logical to add it to connection_aborted function itself, but I could not find any way to call SAPI-specific function from core.

Working code is:
int fd;
struct timeval tv = {0,0};
fd_set set;

if (server_context) {
    request_rec *r = SG(server_context);

    fd = ap_bfileno(r->connection->client, B_WR);

    if (fd >= 0) {
        FD_ZERO(&set);
        FD_SET(fd, &set);
        if (select(fd + 1, &set, NULL, NULL, &tv) >= 0 && FD_ISSET(fd, &set))
        {
            php_handle_aborted_connection();
        }
    }
}