From db826a9c1f89f895a0f3e01e35e6b9811dc5b668 Mon Sep 17 00:00:00 2001
From: vibr <vibr>
Date: Thu, 14 Apr 2005 15:18:54 +0000
Subject: [PATCH] add comment explaining why the concept of
 http-reader-writer-body (which is used by the seval-handler only) doesn't
 work

---
 scheme/httpd/response.scm | 9 +++++++++
 scheme/httpd/seval.scm    | 6 +++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/scheme/httpd/response.scm b/scheme/httpd/response.scm
index 5ac0d48..104800e 100644
--- a/scheme/httpd/response.scm
+++ b/scheme/httpd/response.scm
@@ -46,6 +46,15 @@
   writer-body?
   (proc writer-body-proc))
 
+;; the concept of http-reader-writer-body doesn't work: status-line
+;; and headers of the response (i.e. the whole http-response record)
+;; have to be built _before_ we have seen the entity-body of the
+;; request. (Not until display-http-body hands over the iport to
+;; reader-writer-body the entity-body can be read in). If the
+;; entity-body is erroneous or if we encounter a server internal error
+;; while reading in the entity-body we are not able to send an
+;; appropriate response. (At that point of time we already sent
+;; status-line and response-headers!)
 (define-record-type http-reader-writer-body :http-reader-writer-body
   (make-reader-writer-body proc)
   reader-writer-body?
diff --git a/scheme/httpd/seval.scm b/scheme/httpd/seval.scm
index d06bd13..72cbf0a 100644
--- a/scheme/httpd/seval.scm
+++ b/scheme/httpd/seval.scm
@@ -9,6 +9,10 @@
 ;;; This is really just an handler example demonstrating how to upload code 
 ;;; into the server.
 
+;;; Besides, this handler has always been broken because it makes use
+;;; of the concept of http-reader-writer-body which is broken
+;;; itself. See response.scm.
+
 ;;; (do/timeout secs thunk)
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;; Run THUNK, and gun it down if it hasn't finished in SECS seconds.
@@ -54,7 +58,7 @@
      (time)
      "text/html"
      '()
-     (make-reader-writer-body
+     (make-reader-writer-body ;; see response.scm for an explanation why the concept of http-reader-writer-body doesn't work
       (lambda (iport oport options)
 	(with-fatal-error-handler