xserver: install default X error handler

Xlib's default error handler prints the error and calls exit(1). Tests that
accidentally trigger an error thus quit without cleaning up properly.

Install a default error handler that prints the basic info and continue with
the test. Clients that expect to trigger errors should set a custom error
handler.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Chase Douglas <chase.douglas@ubuntu.com>

3 files changed, 130 insertions, 0 deletions

diff --git a/include/xorg/gtest/xorg-gtest-xserver.h b/include/xorg/gtest/xorg-gtest-xserver.h
index 8bf7996..11fc93d 100644
--- a/include/xorg/gtest/xorg-gtest-xserver.h
+++ b/include/xorg/gtest/xorg-gtest-xserver.h
@@ -265,6 +265,19 @@ class XServer : public xorg::testing::Process {
      */
     static void RegisterXIOErrorHandler();
 
+    /**
+     * Install a default XErrorHandler. That error handler will cause a test
+     * failure if called.
+     *
+     * This function is called automatically by XServer::Start(). Usually,
+     * you will not need to call this function unless your test does not
+     * instantiate and Start() an XServer object.
+     *
+     * This function will only install a new error handler if the currently
+     * installed XErrorHandler is not the default handler used by Xlib.
+     */
+    static void RegisterXErrorHandler();
+
   private:
     struct Private;
     std::auto_ptr<Private> d_;
diff --git a/src/xserver.cpp b/src/xserver.cpp
index ad018a1..2aff401 100644
--- a/src/xserver.cpp
+++ b/src/xserver.cpp
@@ -394,6 +394,40 @@ const std::string& xorg::testing::XServer::GetVersion(void) {
   return d_->version;
 }
 
+static int _x_error_handler(Display *dpy, XErrorEvent *err)
+{
+  std::stringstream error;
+  switch(err->error_code) {
+    case BadRequest: error << "BadRequest"; break;
+    case BadValue: error << "BadValue"; break;
+    case BadWindow: error << "BadWindow"; break;
+    case BadPixmap: error << "BadPixmap"; break;
+    case BadAtom: error << "BadAtom"; break;
+    case BadCursor: error << "BadCursor"; break;
+    case BadFont: error << "BadFont"; break;
+    case BadMatch: error << "BadMatch"; break;
+    case BadDrawable: error << "BadDrawable"; break;
+    case BadAccess: error << "BadAccess"; break;
+    case BadAlloc: error << "BadAlloc"; break;
+    case BadColor: error << "BadColor"; break;
+    case BadGC: error << "BadGC"; break;
+    case BadIDChoice: error << "BadIDChoice"; break;
+    case BadName: error << "BadName"; break;
+    case BadLength: error << "BadLength"; break;
+    case BadImplementation: error << "BadImplementation"; break;
+    default:
+      error << err->error_code;
+      break;
+  }
+
+  ADD_FAILURE() << "XError received: " << error.str() << ", request " <<
+    (int)err->request_code << "(" << (int)err->minor_code << "), detail: "
+    << err->resourceid << "\nThis error handler is likely to be triggered "
+    "more than once.\nCheck the first error for the real error";
+  return 0;
+}
+
+
 static int _x_io_error_handler(Display *dpy) _X_NORETURN;
 static int _x_io_error_handler(Display *dpy)
 {
@@ -409,6 +443,15 @@ void xorg::testing::XServer::RegisterXIOErrorHandler()
     XSetIOErrorHandler(old_handler);
 }
 
+void xorg::testing::XServer::RegisterXErrorHandler()
+{
+  XErrorHandler old_handler;
+  old_handler = XSetErrorHandler(_x_error_handler);
+
+  if (old_handler != _XDefaultError)
+    XSetErrorHandler(old_handler);
+}
+
 void xorg::testing::XServer::Start(const std::string &program) {
   TestStartup();
 
@@ -494,6 +537,7 @@ void xorg::testing::XServer::Start(const std::string &program) {
   signal(SIGUSR1 ,SIG_IGN);
 
   RegisterXIOErrorHandler();
+  RegisterXErrorHandler();
 }
 
 bool xorg::testing::XServer::Terminate(unsigned int timeout) {
diff --git a/test/xserver-test.cpp b/test/xserver-test.cpp
index cdf0bd9..32792e6 100644
--- a/test/xserver-test.cpp
+++ b/test/xserver-test.cpp
@@ -6,6 +6,7 @@
 #include <stdexcept>
 
 #include <xorg/gtest/xorg-gtest.h>
+#include <gtest/gtest-spi.h>
 #include <X11/extensions/XInput2.h>
 
 using namespace xorg::testing;
@@ -213,6 +214,78 @@ TEST(XServer, IOErrorException)
   }, XIOError);
 }
 
+TEST(XServer, ErrorHandler)
+{
+  XORG_TESTCASE("Start a server, trigger a BadColor error and expect a "
+                 "failure from the default error handler\n");
+
+  pid_t pid = fork();
+
+  if (pid == 0) {
+    EXPECT_NONFATAL_FAILURE({
+      XServer server;
+      server.SetOption("-logfile", LOGFILE_DIR "/xorg-error-handler-test.log");
+      server.SetOption("-config", DUMMY_CONF_PATH);
+      server.SetOption("-noreset", "");
+      server.Start();
+      ASSERT_EQ(server.GetState(), Process::RUNNING);
+      ::Display *dpy = XOpenDisplay(server.GetDisplayString().c_str());
+      ASSERT_TRUE(dpy != NULL);
+      XColor color;
+      XQueryColor(dpy, 0, &color);
+      XSync(dpy, False);
+    }, "BadColor");
+    exit(0);
+  }
+
+  /* if the Xlib default error handler triggers, child calls exit(1) */
+  int status;
+  ASSERT_EQ(waitpid(pid, &status, 0), pid);
+  ASSERT_TRUE(WIFEXITED(status));
+  ASSERT_EQ(WEXITSTATUS(status), 0);
+}
+
+static bool error_handler_triggered = false;
+
+static int _test_error_handler(Display *dpy, XErrorEvent *error) {
+  error_handler_triggered = true;
+  if (error->error_code != BadColor)
+    ADD_FAILURE() << "Error handler triggered with wrong error code\n";
+  return 0;
+}
+
+TEST(XServer, NondefaultErrorHandler)
+{
+  XORG_TESTCASE("Set a custom error handler, start a server, trigger a "
+                "BadColor error and expect the custom error handler to be "
+                "triggered\n");
+
+  pid_t pid = fork();
+
+  if (pid == 0) {
+    XSetErrorHandler(_test_error_handler);
+
+    XServer server;
+    server.SetOption("-logfile", LOGFILE_DIR "/xorg-error-handler-test.log");
+    server.SetOption("-config", DUMMY_CONF_PATH);
+    server.SetOption("-noreset", "");
+    server.Start();
+    ASSERT_EQ(server.GetState(), Process::RUNNING);
+    ::Display *dpy = XOpenDisplay(server.GetDisplayString().c_str());
+    ASSERT_TRUE(dpy != NULL);
+    XColor color;
+    XQueryColor(dpy, 0, &color);
+    XSync(dpy, False);
+    exit(error_handler_triggered ? 0 : 1);
+  }
+
+  /* if the Xlib default error handler triggers, child calls exit(1) */
+  int status;
+  ASSERT_EQ(waitpid(pid, &status, 0), pid);
+  ASSERT_TRUE(WIFEXITED(status));
+  ASSERT_EQ(WEXITSTATUS(status), 0);
+}
+
 TEST(XServer, KeepAlive)
 {
   XORG_TESTCASE("If XORG_GTEST_XSERVER_KEEPALIVE is set,\n"