R7RS Scheme library for Common Gateway Interface

If you dont know what CGI is, in short server runs your Scheme script and
displays it's output as a webpage.

## Installation

    snow-chibi --impls=$SCHEME retropikzel.cgi


## Documentation

(**handle-request** options thunk)

Options must be association list. Thunk must be procedure taking arguments:

- request
    - Full request
- headers
    - Request headers
- parameters
    - Request parameters
        - The ?foo=bar&baz=1 part parsed
- cookies
    - Request cookies
- body
    - Request body
- files
    - Request files

Whatever thunk writes to (current-output-port) is sent back as response.


### Environment variables

**SCM_CGI_TMPDIR**

Path to where uploaded files are stored. Default is /tmp.


## Usage examples

These files are shared among all examples. We will be usign Gauche for examples,
but you can comment out your preferred implementation or copy just that exec
line from scheme-script. (Without the #)

scheme-script:

    #!/bin/sh
    #exec capy --r7rs --script "$@"
    #exec chibi-scheme "$@"
    #exec csi -quiet -batch "$@"
    #exec icyc -s "$@"
    #exec gsi /home/youruser/.gambit_userlib/ "$@"
    exec gosh "$@"
    #exec kawa --r7rs -Dkawa.import.path=/usr/local/share/kawa/lib/*.sld "$@"
    #exec loko --program "$@"
    #exec mit-scheme --batch-mode --load "$@"
    #exec racket -I r7rs --script "$@"
    #exec sash -r7 "$@"
    #exec skint "$@"
    #exec stklos "$@"
    #exec tr7i "$@"

hello.scm:

    (import (scheme base)
            (scheme write)
            (retropikzel cgi))

    (handle-request
     '()
     (lambda (request headers parameters cookies body files)
      (display "Content-type: text/html\r\n")
      (display "\r\n")
      (display "Hello</br>")
      (write request)))


### Usage lighttpd example

Debian/Ubuntu/Mint:

    apt-get install lighttpd

Files in any (same) directory.

lighttpd.conf:

    var.basedir = env.PWD
    server.document-root = basedir
    server.port = 3000
    server.modules += ("mod_cgi", "mod_dirlisting")
    cgi.assign = (".scm"  => basedir + "/scheme-script")
    dir-listing.activate = "enable"

run:

    chmod +x scheme-cript
    lighttpd -D -f lighttpd.conf

Then navigate with your browser to http://127.0.0.1:3000/hello.scm


### Usage apache2 example

Debian/Ubuntu/Mint:

    apt-get install apache2
    a2enmod cgi
    systemctl restart apache

Only hello.scm in /var/lib/cgi-bin/

Add shebang line as first line of hello.scm, for example:

    #!/usr/local/bin/gosh

run:

    chmod +x /var/lib/cgi-bin/hello.scm

Then navigate with your browser to http://127.0.0.1/cgi-bin/hello.scm

If your server does not have cgi-bin directory you can try adding it

    mkdir cgi-bin

cgi-bin/.htaccess:

    Options +ExecCGI
    SetHandler cgi-script


That should work in any other dir too, but you propably want to make it treat
only .scm files as cgi scripts.

    SetHandler cgi-script "scm"