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. Also checkout
[https://git.sr.ht/~retropikzel/scheme-php](https://git.sr.ht/~retropikzel/scheme-php).

[Project](https://sr.ht/~retropikzel/scheme-cgi/)

[Repository](https://git.sr.ht/~retropikzel/scheme-cgi)

[Issue tracker](https://todo.sr.ht/~retropikzel/scheme-cgi)

## Caveats

- Works only on unix as it reads from /dev/fd/0 and /dev/random.

## Buggy on implementations

- Does not work with mit-scheme
    - For some reason mit-scheme exits when it reads eof-object from standard
    input
- STklos
    - No output for some reason

## How to use

Example using Gauche in Docker.

lighttpd.conf:

    server.document-root = "/workdir"
    server.port = 3000
    server.modules += ("mod_cgi", "mod_dirlisting")
    cgi.assign = (".scm"  => "/usr/bin/scheme-script")
    dir-listing.activate = "enable"

Dockerfile:

    FROM schemers/gauche
    RUN apt-get update && apt-get install -y --no-install-recommends lighttpd
    WORKDIR /workdir
    EXPOSE 3000
    COPY lighttpd.conf /lighttpd.conf
    RUN echo "#!/bin/sh" > /usr/bin/scheme-script
    RUN echo "exec gosh -r7 -I ./snow \$@" >> /usr/bin/scheme-script
    RUN chmod +x /usr/bin/scheme-script
    ENTRYPOINT ["/usr/sbin/lighttpd", "-D", "-f", "/lighttpd.conf"]

hello.scm:

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

    (display "Content-type: text/html")
    (display "\r\n")
    (display "\r\n")
    (display "Hello")
    (display "</br>")

    (display "Request: ")
    (write (get-request))
    (display "</br>")
    (cgi-exit)

Run:

    docker build . --tag=scheme-cgi
    docker run -it -v ${PWD}:/workdir -p 3000:3000 scheme-cgi

Then navigate with your browser to http://127.0.0.1:3000

## Documentation

### Reference

**get-request**

Returns the whole request as association list.

**get-header** _name_

Name can be symbol or a string. Returns the value of given header or #f.

**get-headers**

Returns association list of all headers.

**get-parameter** _name_

Name can be symbol or a string. Returns the value of given parameter or #f.

**get-parameters**

Returns association list of all parameters.

**get-cookie** _name_

Returns the value of given cookie or #f if.

**get-cookies**

Returns association list of all cookies.

**get-file** _filename_

Filename is a symbol or a string. Returns the path of given file from files or #f.

Uploaded files are stored in /tmp, with randomly generated prefix on their
name. They are not deleted unless cgi-exit is called. Use **move-file** to move
them into preferred location.

**get-files**

Returns association list of all files.

**move-file** _from_ _to_

Moves a file from _from_ path to _to_ path.

**get-body**

Returns the request body.

**cgi-exit**</br>
**cgi-exit** _code_

Does necessary cleanup and exits the script. Code is a number, if it is given
then that is used as exit code.

### Environment variables

**SCHEME\_CGI\_TMP\_PATH**

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