From e476230f0ee46e496da0e23f8352a464530fd6ad Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Sat, 4 Mar 2017 15:30:23 +0100
Subject: arch-proxy.py: support readonly cache

---
 arch-proxy.py | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/arch-proxy.py b/arch-proxy.py
index e412364..d40cb4c 100755
--- a/arch-proxy.py
+++ b/arch-proxy.py
@@ -7,6 +7,7 @@
 # ".download" extension. If the file exists and the file is not being
 # downloaded, resume the download (Range requests).
 
+import argparse
 import http.server
 import os
 import socket
@@ -15,9 +16,6 @@ import requests
 from contextlib import closing, contextmanager
 import fcntl
 
-addr = ('', 8001)
-cache_dir = os.getcwd()
-
 DATE_FORMAT = '%a, %d %b %Y %H:%M:%S GMT'
 def text_to_epoch(text):
     return datetime.strptime(text, DATE_FORMAT).timestamp()
@@ -58,6 +56,9 @@ class RequestHandler(http.server.BaseHTTPRequestHandler):
 
     @contextmanager
     def open_write_cache(self, path):
+        if self.server.is_readonly:
+            yield None
+            return
         temp_path = path + ".download"
         try:
             with open(temp_path, 'wb') as f:
@@ -106,17 +107,19 @@ class RequestHandler(http.server.BaseHTTPRequestHandler):
             if head_only:
                 list(remote_data)  # consume yield and StopIteration
             if not head_only and remote_data:
+                cache_ok = False
                 with self.open_write_cache(path) as cache_file:
-                    if cache_file:
+                    cache_ok = cache_file is not None
+                    if cache_ok:
                         for chunk in remote_data:
                             cache_file.write(chunk)
                             yield chunk
-                    else:
-                        # Cache file unavailable, just pass all data
-                        yield from remote_data
-                        return
-                # Write was successful, now fix mtime and rename
-                self.finish_cache(mtime_pointer[0])
+                if cache_ok:
+                    # Write was successful, now fix mtime and rename
+                    self.finish_cache(mtime_pointer[0])
+                else:
+                    # Cache file unavailable, just pass all data
+                    yield from remote_data
 
     def do_GET(self):
         try:
@@ -143,19 +146,28 @@ class RequestHandler(http.server.BaseHTTPRequestHandler):
 
     def get_local_path(self):
         filename = os.path.basename(self.path)
-        return os.path.join(cache_dir, filename)
+        return os.path.join(self.server.cachedir, filename)
 
     def is_cacheable(self):
         """Whether the requested file should be cached."""
         return self.path.endswith(".pkg.tar.xz")
 
 class SomeServer(http.server.HTTPServer):
-    def __init__(self, addr, handler):
+    def __init__(self, addr, handler, args):
         self.allow_reuse_address = True
         if ':' in addr[0]:
             self.address_family = socket.AF_INET6
         super().__init__(addr, handler)
+        self.cachedir = args.cachedir
+        self.is_readonly = args.readonly
+
+parser = argparse.ArgumentParser()
+parser.add_argument("--readonly", action="store_true")
+parser.add_argument("--cachedir", default=os.getcwd())
+parser.add_argument("--port", type=int, default=8001)
 
 if __name__ == '__main__':
-    server = SomeServer(addr, RequestHandler)
+    args = parser.parse_args()
+    addr = ('', args.port)
+    server = SomeServer(addr, RequestHandler, args)
     server.serve_forever()
-- 
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