win: Only retry in UseHandler() loop on ERROR_PIPE_BUSY

This is better because now end_to_end_test.py fails immediately with

[1180:9020:20151106,145204.830:ERROR registration_protocol_win.cc:39] CreateFile: The system cannot find the file specified.  (0x2)

R=mark@chromium.org
BUG=crashpad:75

Review URL: https://codereview.chromium.org/1409693011 .

snapshot/win/end_to_end_test.py

@@ -21,6 +21,7 @@ import re
 import subprocess
 import sys
 import tempfile
+import time
 
 g_temp_dirs = []
 
@@ -101,6 +102,14 @@ def GetDumpFromProgram(out_dir, pipe_name, executable_name):
           '--database=' + test_database
       ])
 
+      # Wait until the server is ready.
+      printed = False
+      while not os.path.exists(pipe_name):
+        if not printed:
+          print 'Waiting for crashpad_handler to be ready...'
+          printed = True
+        time.sleep(0.1)
+
       subprocess.call([os.path.join(out_dir, executable_name), pipe_name])
     else:
       subprocess.call([os.path.join(out_dir, executable_name),

util/win/registration_protocol_win.cc

@@ -24,8 +24,8 @@ namespace crashpad {
 bool SendToCrashHandlerServer(const base::string16& pipe_name,
                               const crashpad::ClientToServerMessage& message,
                               crashpad::ServerToClientMessage* response) {
-  int tries = 5;
-  while (tries > 0) {
+  int tries = 0;
+  for (;;) {
     ScopedFileHANDLE pipe(
         CreateFile(pipe_name.c_str(),
                    GENERIC_READ | GENERIC_WRITE,
@@ -35,10 +35,20 @@ bool SendToCrashHandlerServer(const base::string16& pipe_name,
                    SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION,
                    nullptr));
     if (!pipe.is_valid()) {
-      Sleep(10);
-      --tries;
+      if (++tries == 5 || GetLastError() != ERROR_PIPE_BUSY) {
+        PLOG(ERROR) << "CreateFile";
+        return false;
+      }
+
+      if (!WaitNamedPipe(pipe_name.c_str(), 1000) &&
+          GetLastError() != ERROR_SEM_TIMEOUT) {
+        PLOG(ERROR) << "WaitNamedPipe";
+        return false;
+      }
+
       continue;
     }
+
     DWORD mode = PIPE_READMODE_MESSAGE;
     if (!SetNamedPipeHandleState(pipe.get(), &mode, nullptr, nullptr)) {
       PLOG(ERROR) << "SetNamedPipeHandleState";
@@ -55,7 +65,8 @@ bool SendToCrashHandlerServer(const base::string16& pipe_name,
         &bytes_read,
         nullptr);
     if (!result) {
-      PLOG(ERROR) << "TransactNamedPipe";
+      LOG(ERROR) << "TransactNamedPipe: expected " << sizeof(*response)
+                 << ", observed " << bytes_read;
       return false;
     }
     if (bytes_read != sizeof(*response)) {
@@ -64,9 +75,6 @@ bool SendToCrashHandlerServer(const base::string16& pipe_name,
     }
     return true;
   }
-
-  LOG(ERROR) << "failed to connect after retrying";
-  return false;
 }
 
 }  // namespace crashpad