Initial add

Signed-off-by: Matt Butcher <matt.butcher@microsoft.com>

Author: technosophos

.gitignore

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+/*.wasm
+target/
+_scratch/

LICENSE.txt

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+The MIT License (MIT)
+
+Copyright (c) Microsoft Corporation. All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE

Makefile

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+# These are for both `run` (implicit) and `test` (explicit)
+PATH_INFO ?= /static/fileserver.gr
+X_MATCHED_ROUTE ?= /static/...
+
+.PHONY: run
+run:
+	PATH_INFO=${PATH_INFO} X_MATCHED_ROUTE=${X_MATCHED_ROUTE} \
+	grain fileserver.gr
+
+.PHONY: build
+build:
+	grain compile fileserver.gr
+
+.PHONY: test
+test:build
+test:
+	wasmtime --dir . --env PATH_INFO=${PATH_INFO} \
+	--env X_MATCHED_ROUTE=${X_MATCHED_ROUTE} \
+	fileserver.gr.wasm

README.md

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+# Fileserver-gr
+
+A [Wagi](https://github.com/deislabs/wagi) static fileserver written in Grain.
+
+> DeisLabs is experimenting with many WASM technologies right now.
+> This is one of a multitude of projects designed to test the limits
+> of WebAssembly as a cloud-based runtime. This code is not stable or
+> production ready.
+
+## Building and Running Locally
+
+You will need the [Grain](https://grain-lang.org) toolkit to work with this repo.
+
+To run:
+
+```console
+$ make run 
+```
+
+To compile:
+
+```console
+$ make build
+```
+
+To run test (Wasmtime required):
+
+```
+$ make test
+```
+
+## Running in Wagi
+
+Here is an example `modules.toml` for [Wagi](https://github.com/deislabs/wagi):
+
+```toml
+[[module]]
+route = "/static/..."
+module = "/path/to/fileserver/fileserver.gr.wasm"
+volumes = {"/" = "/path/to/fileserver"}
+```
+
+The above configures Wagi to map the path `/static/...` to the `fileserver.gr.wasm` module. Then it serves all of the files in this project.
+
+Assuming you have Wagi running on `http://localhost:3000`, you can then run this command:
+
+```console
+$ curl -v localhost:3000/static/fileserver.gr
+*   Trying 127.0.0.1...
+* TCP_NODELAY set
+* Connected to localhost (127.0.0.1) port 3000 (#0)
+> GET /static/fileserver.gr HTTP/1.1
+> Host: localhost:3000
+> User-Agent: curl/7.64.1
+> Accept: */*
+> 
+< HTTP/1.1 200 OK
+< content-type: text/plain
+< content-length: 1522
+< date: Thu, 03 Jun 2021 16:44:05 GMT
+< 
+// This is a simple Wagi static file server.
+
+import Env from "./env"
+import Map from "map"
+// The rest of the source of fileserver.gr
+```
+
+The fileserver took `/static/filserver.gr`, removed the `/static/` part from the front, and then loaded `fileserver.gr` from the directory mounted in the `modules.toml`. Note that any subdirectories are also served. So `/static/foo/bar` would translate to the path `foo/bar` inside of the WebAssembly module (which in the example above would fully resolve to "/path/to/fileserver/foo/bar").

env.gr

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+import Process from "sys/process"
+import Map from "map"
+import Array from "array"
+import String from "string"
+import Option from "option"
+
+// Split an environment variable at the first equals sign.
+let splitEnvVar = (item) => {
+    let offsetOpt = String.indexOf("=", item)
+
+    // For now, fail if the env var is malformed.
+    let offset = Option.unwrap(offsetOpt)
+
+    let key = String.slice(0, offset, item)
+    let val = String.slice(offset+1, String.length(item), item)
+    (key, val)
+}
+
+export let envMap = () =>  {
+    let parsed = Map.make()
+    let env = Process.env()
+    let pairs = Array.map(splitEnvVar,env)
+
+    Array.forEach((item) => {
+        let (k, v) = item
+        Map.set(k, v, parsed)
+    }, pairs)
+    parsed
+}
+
+

fileserver.gr

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+// This is a simple Wagi static file server.
+
+import Env from "./env"
+import Map from "map"
+import Option from "option"
+import File from "sys/file"
+import String from "string"
+
+let serve = (path) => {
+    File.fdWrite(File.stderr, "Loading file ")
+    File.fdWrite(File.stderr, path)
+    File.fdWrite(File.stderr, "\n")
+
+    // Open file
+    // TODO: This throws an error when something goes wrong.
+    // But Grain 0.3 does not have a try/catch yet.
+    // When we figure out how, we need to catch the error here
+    // and do a 404 or 500.
+    let input = File.pathOpen(
+        File.pwdfd,
+        [],
+        path,
+        [],
+        [File.FdRead],
+        [],
+        [],   
+    )
+
+    File.fdWrite(File.stdout, "Content-Type: text/plain\n\n")
+    
+    // Pipe output to STDOUT
+    let rec pipe = (in, out) => {
+        let (d, len) = File.fdRead(in, 1024)
+        File.fdWrite(out, d)
+        if (len > 0) {
+            pipe(in, out)
+        }
+    }
+    pipe(input, File.stdout)
+    File.fdClose(input)
+}
+
+let guestpath = (env) => {
+    let req = Option.unwrap(Map.get("PATH_INFO", env))
+    let mut base = Option.unwrap(Map.get("X_MATCHED_ROUTE", env))
+    let dots = String.indexOf("/...", base)
+    if (Option.isSome(dots) ) {
+        base = String.slice(0, Option.unwrap(dots), base)
+    }
+    String.slice(String.length(base) + 1, String.length(req), req)
+}
+
+let notFound = () => {
+    File.fdWrite(File.stdout, "Status: 404\n\nNot Found")
+}
+
+let kv = Env.envMap()
+let pathInfo = guestpath(kv)
+serve(pathInfo)