HTTPTransport test: Deal with limited-size pipe buffers

HTTPTransport.Upload33k failed on Windows due to WinHTTP timing out. The
test server, http_transport_test_server.py, writes the entire request to
a stdout pipe, to be received by crashpad_util_test. crashpad_util_test
is also the HTTP client, and it does not attempt to read from this pipe
until the HTTP transaction is complete. http_transport_test_server.py
must not write to stdout until the transaction is complete, otherwise,
there is a risk of deadlock if the pipe buffer fills up. The new
Upload33k test sends a large request, which was filling up the pipe
buffer on Windows.

This also adds an Upload33k_LengthUnknown test variant to exercise a
large POST when the length is not known ahead of time. This more closely
matches how Crashpad crash uploads are done on OS X.

TEST=crashpad_util_test HTTPTransport.*
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/1286173007 .

util/net/http_transport_test.cc

@@ -278,7 +278,7 @@ TEST(HTTPTransport, UnchunkedPlainText) {
   test.Run();
 }
 
-TEST(HTTPTransport, Upload33k) {
+void RunUpload33k(bool has_content_length) {
   // On OS X, NSMutableURLRequest winds up calling into a CFReadStream’s Read()
   // callback with a 32kB buffer. Make sure that it’s able to get everything
   // when enough is available to fill this buffer, requiring more than one
@@ -290,8 +290,10 @@ TEST(HTTPTransport, Upload33k) {
 
   HTTPHeaders headers;
   headers[kContentType] = "application/octet-stream";
-  headers[kContentLength] =
-      base::StringPrintf("%" PRIuS, request_string.size());
+  if (has_content_length) {
+    headers[kContentLength] =
+        base::StringPrintf("%" PRIuS, request_string.size());
+  }
   HTTPTransportTestFixture test(headers, body_stream.Pass(), 200,
       [](HTTPTransportTestFixture* fixture, const std::string& request) {
         size_t body_start = request.rfind("\r\n");
@@ -300,6 +302,15 @@ TEST(HTTPTransport, Upload33k) {
   test.Run();
 }
 
+TEST(HTTPTransport, Upload33k) {
+  RunUpload33k(true);
+}
+
+TEST(HTTPTransport, Upload33k_LengthUnknown) {
+  // The same as Upload33k, but without declaring Content-Length ahead of time.
+  RunUpload33k(false);
+}
+
 }  // namespace
 }  // namespace test
 }  // namespace crashpad

util/net/http_transport_test_server.py

@@ -59,6 +59,14 @@ class BufferedReadFile(object):
 
 
 class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
+  # Everything to be written to stdout is collected into this string. It can’t
+  # be written to stdout until after the HTTP transaction is complete, because
+  # stdout is a pipe being read by a test program that’s also the HTTP client.
+  # The test program expects to complete the entire HTTP transaction before it
+  # even starts reading this script’s stdout. If the stdout pipe buffer fills up
+  # during an HTTP transaction, deadlock would result.
+  raw_request = ''
+
   response_code = 500
   response_body = ''
 
@@ -69,9 +77,7 @@ class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
     BaseHTTPServer.BaseHTTPRequestHandler.handle_one_request(self)
 
   def do_POST(self):
-    writer = sys.stdout
-
-    writer.write(self.rfile.buffer)
+    RequestHandler.raw_request = self.rfile.buffer
     self.rfile.buffer = ''
 
     if self.headers.get('Transfer-Encoding', '') == 'Chunked':
@@ -80,15 +86,14 @@ class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
       length = int(self.headers.get('Content-Length', -1))
       body = self.rfile.read(length)
 
+    RequestHandler.raw_request += body
+
     self.send_response(self.response_code)
     self.end_headers()
     if self.response_code == 200:
       self.wfile.write(self.response_body)
       self.wfile.write('\r\n')
 
-    writer.write(body)
-    writer.flush()
-
   def handle_chunked_encoding(self):
     """This parses a "Transfer-Encoding: Chunked" body in accordance with
     RFC 7230 §4.1. This returns the result as a string.
@@ -146,5 +151,9 @@ def Main():
   # Handle the request.
   server.handle_request()
 
+  # Share the entire request with the test program, which will validate it.
+  sys.stdout.write(RequestHandler.raw_request)
+  sys.stdout.flush()
+
 if __name__ == '__main__':
   Main()