Check for closed ports when writing chunks and give a hint to the user1.2.2

This makes it a bit more obvious what happened in cases like #1838,
reported by Woodrow E Douglass.

While at it, add some more test cases for this particular case, but
also for retry-attempts, as this is also affected when retry is
allowed for non-idempotent requests (which is pretty uncommon, but
possible)

1 files changed, 9 insertions, 1 deletions

diff --git a/http-client.scm b/http-client.scm
index 0dd9dff..58d045d 100644
--- a/http-client.scm
+++ b/http-client.scm
@@ -751,8 +751,16 @@
                                            (open-input-file (cdr chunk))
                                            ;; Should be a port otherwise
                                            (cdr chunk))))
+                                (when (port-closed? p)
+                                  (raise (http-client-error 'call-with-input-request*
+                                                            (conc "At least one port for the multipart body has been already "
+                                                                  "consumed and closed. This may be due to a retry or a redirect. "
+                                                                  "Hint: use 'data:' or limit max-retry-attempts and "
+                                                                  "max-redirect-depth to zero and catch the resulting exception")
+                                                            (list p)
+                                                            'port-already-consumed 'port p)))
                                 (handle-exceptions exn
-                                  (begin (close-input-port p) (raise exn))
+                                    (begin (close-input-port p) (raise exn))
                                   (sendfile p output-port))
                                 (close-input-port p))
                               (display chunk output-port)))