115 lines
4.0 KiB
Scheme
115 lines
4.0 KiB
Scheme
;;; Path handler for uploading Scheme code to the SU web server -*- Scheme -*-
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;;; This is really just an handler example demonstrating how to upload code
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;;; into the server.
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;;; Copyright (c) 1995 by Olin Shivers.
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;;; Imports and non-R4RS'isms
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;;; \r and \n in string for cr and lf.
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;;; SWITCH conditional, ? for COND
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;;; HTTP request record stucture
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;;; HTTP-ERROR & reply codes
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;;; Basic path handler support
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;;; scsh syscalls
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;;; Pretty-printing P proc.
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;;; htmlout stuff
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;;; SAFE-EVAL
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;;; ERROR
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;;; INDEX
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;;; URI decoding
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;;; HTML forms
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; This path handler is suitable for receiving code entered into an
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;;; HTML text form. The Scheme code being uploaded is being POST'd to us
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;;; (from a form). See http-forms.scm for info on the format of this kind
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;;; of request. After parsing the request into the submitted string, we
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;;; parse *that* into a Scheme sexp with READ, and eval it.
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;;; (do/timeout secs thunk)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;; Run THUNK, and gun it down if it hasn't finished in SECS seconds.
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;;; Returns nothing useful, and THUNK gets executed in a subprocess,
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;;; so its side-effects are invisible, as well. This is a clever kludge --
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;;; it uses three subprocesses -- but I don't have interrupts, so I'm hosed.
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(define (do/timeout* secs thunk)
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(run (begin (let ((timer (fork (lambda () (sleep secs))))
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(worker (fork thunk)))
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(receive (process status) (wait-any)
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(ignore-errors
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(lambda ()
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(signal-process (proc:pid (if (eq? worker process)
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timer
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worker))
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signal/kill))))))))
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(define-syntax do/timeout
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(syntax-rules ()
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((do/timeout secs body ...) (do/timeout* secs (lambda () body ...)))))
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;;; The path handler for seval ops.
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(define (seval-handler path req)
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(let ((request-method (request:method req)))
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(cond
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((string=? request-method "POST") ; Could do others also.
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(let ((modern-protocol? (not (v0.9-request? req))))
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(if modern-protocol?
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(begin
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(begin-http-header #t 200)
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(write-string "Content-type: text/html\r\n\r\n")))
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(with-tag #t HEAD ()
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(newline)
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(emit-title #t "Scheme program output"))
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(newline))
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(with-tag #t BODY ()
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(newline)
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(let ((sexp (read-request-sexp req)))
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(do/timeout
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10
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(receive vals
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;; Do the computation.
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(begin (emit-header #t 2 "Output from execution")
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(newline)
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(with-tag #t PRE ()
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(newline)
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(force-output) ; In case we're gunned down.
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(eval-safely sexp)))
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;; Pretty-print the returned value(s).
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(emit-header #t 2 "Return value(s)")
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(with-tag #t PRE ()
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(for-each p vals)))))))
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(else (http-error http-reply/method-not-allowed #f req)))))
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;;; Read an HTTP request entity body from stdin. The Content-length:
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;;; element of request REQ's header tells how many bytes to this entity
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;;; is. The entity should be a URI-encoded form body. Pull out the
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;;; program=<stuff>
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;;; string, extract <stuff>, uri-decode it, parse that into an s-expression,
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;;; and return it.
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(define (read-request-sexp req)
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(cond
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((get-header (request:headers req) 'content-length) =>
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(lambda (cl-str) ; Take the first Content-length: header,
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(let* ((cl-start (string-skip cl-str char-set:whitespace)) ; skip whitespace,
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(cl (if cl-start ; & convert to
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(string->number (substring cl-str ; a number.
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cl-start
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(string-length cl-str)))
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0)) ; All whitespace?? -- WTF.
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(qs (read-string cl)) ; Read in CL chars,
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(q (parse-html-form-query qs)) ; and parse them up.
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(s (cond ((assoc "program" q) => cdr)
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(else (error "No program in entity body.")))))
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(http-log "Seval sexp:~%~s~%" s)
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(read (make-string-input-port s)))))
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(else (http-error http-reply/bad-request req
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"No Content-length: field in POST request."))))
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