Description:
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due to network issue, or stopped by user
the content submitted by user maybe incomplete;
there should be a way to check it.
it's serious if the admins submit a incomplete post data. that will do unrecoverable damage.

i'd like if there's a function:
int content_is_complete()
which
  return strlen(content) == Content-Length;


yes, we can do '<input type=hidden value=1 name=complete></form>', and do isset($_POST['complete'])
but this is not easy for those html-designers to add it each <form> by hand

'<input type=submit name=submit>', and do isset($_POST['submit']), but not all "submit" is the last element of form