toolkit/xre/nsX11ErrorHandler.cpp

   1 /* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsX11ErrorHandler.h"
   7
   8 #include "prenv.h"
   9 #include "nsXULAppAPI.h"
  10 #include "nsExceptionHandler.h"
  11 #include "nsDebug.h"
  12
  13 #include "mozilla/X11Util.h"
  14 #include <X11/Xlib.h>
  15
  16 #define BUFSIZE 2048 // What Xlib uses with XGetErrorDatabaseText
  17
  18 extern "C" {
  19 int
  20 X11Error(Display *display, XErrorEvent *event) {
  21   // Get an indication of how long ago the request that caused the error was
  22   // made.
  23   unsigned long age = NextRequest(display) - event->serial;
  24
  25   // Get a string to represent the request that caused the error.
  26   nsAutoCString message;
  27   if (event->request_code < 128) {
  28     // Core protocol request
  29     message.AppendInt(event->request_code);
  30   } else {
  31     // Extension request
  32
  33     // man XSetErrorHandler says "the error handler should not call any
  34     // functions (directly or indirectly) on the display that will generate
  35     // protocol requests or that will look for input events" so we use another
  36     // temporary Display to request extension information.  This assumes on
  37     // the DISPLAY environment variable has been set and matches what was used
  38     // to open |display|.
  39     Display *tmpDisplay = XOpenDisplay(nullptr);
  40     if (tmpDisplay) {
  41       int nExts;
  42       char** extNames = XListExtensions(tmpDisplay, &nExts);
  43       int first_error;
  44       if (extNames) {
  45         for (int i = 0; i < nExts; ++i) {
  46           int major_opcode, first_event;
  47           if (XQueryExtension(tmpDisplay, extNames[i],
  48                               &major_opcode, &first_event, &first_error)
  49               && major_opcode == event->request_code) {
  50             message.Append(extNames[i]);
  51             message.Append('.');
  52             message.AppendInt(event->minor_code);
  53             break;
  54           }
  55         }
  56
  57         XFreeExtensionList(extNames);
  58       }
  59       XCloseDisplay(tmpDisplay);
  60
  61 #if (MOZ_WIDGET_GTK == 2)
  62       // GDK2 calls XCloseDevice the devices that it opened on startup, but
  63       // the XI protocol no longer ensures that the devices will still exist.
  64       // If they have been removed, then a BadDevice error results.  Ignore
  65       // this error.
  66       if (message.EqualsLiteral("XInputExtension.4") &&
  67           event->error_code == first_error + 0) {
  68         return 0;
  69       }
  70 #endif
  71     }
  72   }
  73
  74   char buffer[BUFSIZE];
  75   if (message.IsEmpty()) {
  76     buffer[0] = '\0';
  77   } else {
  78     XGetErrorDatabaseText(display, "XRequest", message.get(), "",
  79                           buffer, sizeof(buffer));
  80   }
  81
  82   nsAutoCString notes;
  83   if (buffer[0]) {
  84     notes.Append(buffer);
  85   } else {
  86     notes.AppendLiteral("Request ");
  87     notes.AppendInt(event->request_code);
  88     notes.Append('.');
  89     notes.AppendInt(event->minor_code);
  90   }
  91
  92   notes.AppendLiteral(": ");
  93
  94   // Get a string to describe the error.
  95   XGetErrorText(display, event->error_code, buffer, sizeof(buffer));
  96   notes.Append(buffer);
  97
  98   // For requests where Xlib gets the reply synchronously, |age| will be 1
  99   // and the stack will include the function making the request.  For
 100   // asynchronous requests, the current stack will often be unrelated to the
 101   // point of making the request, even if |age| is 1, but sometimes this may
 102   // help us count back to the point of the request.  With XSynchronize on,
 103   // the stack will include the function making the request, even though
 104   // |age| will be 2 for asynchronous requests because XSynchronize is
 105   // implemented by an empty request from an XSync, which has not yet been
 106   // processed.
 107   if (age > 1) {
 108     // XSynchronize returns the previous "after function".  If a second
 109     // XSynchronize call returns the same function after an enable call then
 110     // synchronization must have already been enabled.
 111     if (XSynchronize(display, True) == XSynchronize(display, False)) {
 112       notes.AppendLiteral("; sync");
 113     } else {
 114       notes.AppendLiteral("; ");
 115       notes.AppendInt(uint32_t(age));
 116       notes.AppendLiteral(" requests ago");
 117     }
 118   }
 119
 120 #ifdef MOZ_CRASHREPORTER
 121   switch (XRE_GetProcessType()) {
 122   case GeckoProcessType_Default:
 123   case GeckoProcessType_Plugin:
 124   case GeckoProcessType_Content:
 125     CrashReporter::AppendAppNotesToCrashReport(notes);
 126     break;
 127   default:
 128     ; // crash report notes not supported.
 129   }
 130 #endif
 131
 132 #ifdef DEBUG
 133   // The resource id is unlikely to be useful in a crash report without
 134   // context of other ids, but add it to the debug console output.
 135   notes.AppendLiteral("; id=0x");
 136   notes.AppendInt(uint32_t(event->resourceid), 16);
 137 #ifdef MOZ_X11
 138   // Actually, for requests where Xlib gets the reply synchronously,
 139   // MOZ_X_SYNC=1 will not be necessary, but we don't have a table to tell us
 140   // which requests get a synchronous reply.
 141   if (!PR_GetEnv("MOZ_X_SYNC")) {
 142     notes.AppendLiteral("\nRe-running with MOZ_X_SYNC=1 in the environment may give a more helpful backtrace.");
 143   }
 144 #endif
 145 #endif
 146
 147 #ifdef MOZ_WIDGET_QT
 148   // We should not abort here if MOZ_X_SYNC is not set
 149   // until http://bugreports.qt.nokia.com/browse/QTBUG-4042
 150   // not fixed, just print error value
 151   if (!PR_GetEnv("MOZ_X_SYNC")) {
 152     fprintf(stderr, "XError: %s\n", notes.get());
 153     return 0; // temporary workaround for bug 161472
 154   }
 155 #endif
 156
 157   NS_RUNTIMEABORT(notes.get());
 158   return 0; // not reached
 159 }
 160 }
 161
 162 #if (MOZ_WIDGET_GTK != 3)
 163 void
 164 InstallX11ErrorHandler()
 165 {
 166   XSetErrorHandler(X11Error);
 167
 168   Display *display = mozilla::DefaultXDisplay();
 169   NS_ASSERTION(display, "No X display");
 170   if (PR_GetEnv("MOZ_X_SYNC")) {
 171     XSynchronize(display, True);
 172   }
 173 }
 174 #endif