qtwasmserver to serve assets from the provided path parameter

qtwasmserver accepts a positional path argument which tells where to
serve the assets from. The argument wasn't actually used, and this
resulted in always using the cwd.

In addition add a check for the path directory existence. Otherwise
this becomes only visible as a 404 Not Found error.

Amends: 156e5c8

Pick-to: 6.9
Fixes: QTBUG-134393
Change-Id: Iacfafe8a2fb2409169b09a17dbc9ffed0ad16fdf
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

Author: Juha Vuolle

util/wasm/qtwasmserver/qtwasmserver.py

@@ -15,6 +15,7 @@
 from http import HTTPStatus
 from http.server import SimpleHTTPRequestHandler, ThreadingHTTPServer
 from subprocess import run
+from functools import partial
 
 import brotli
 import netifaces as ni
@@ -155,7 +156,7 @@ def select_http_handler_class(compression_mode, address):
             return CompressionHttpRequesthandler
 
 
-# Serve cwd from http(s)://address:port, with certificates from certdir if set
+# Serve serve_path from http(s)://address:port, with certificates from certdir if set
 def serve_on_thread(
     address,
     port,
@@ -164,12 +165,13 @@ def serve_on_thread(
     cert_key_file,
     compression_mode,
     cross_origin_isolation,
+    serve_path,
 ):
     handler = select_http_handler_class(compression_mode, address)
     handler.cross_origin_isolation = cross_origin_isolation
 
     try:
-        httpd = ThreadingHTTPServer((address, port), handler)
+        httpd = ThreadingHTTPServer((address, port), partial(handler, directory=serve_path))
     except Exception as e:
         print(f"\n### Error starting HTTP server: {e}\n")
         exit(1)
@@ -243,6 +245,10 @@ def main():
     serve_path = args.path
     cross_origin_isolation = args.cross_origin_isolation
 
+    if not os.path.isdir(serve_path):
+        print(f"The provided path '{serve_path}' does not exist or is not a directory")
+        exit(1)
+
     compression_mode = CompressionMode.AUTO
     if args.compress_always:
         compression_mode = CompressionMode.ALWAYS
@@ -285,6 +291,7 @@ def main():
             cert_key_file,
             compression_mode,
             cross_origin_isolation,
+            serve_path,
         )
 
     if has_certificate:
@@ -298,6 +305,7 @@ def main():
                 cert_key_file,
                 compression_mode,
                 cross_origin_isolation,
+                serve_path,
             )