widget/gtk/GfxInfoUtils.h

   1 /* vim: se cin sw=2 ts=2 et : */
   2 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   3  *
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #ifndef WIDGET_GTK_GFXINFO_UTILS_h__
   9 #define WIDGET_GTK_GFXINFO_UTILS_h__
  10
  11 // An alternative to mozilla::Unused for use in (a) C code and (b) code where
  12 // linking with unused.o is difficult.
  13 #define MOZ_UNUSED(expr) \
  14   do {                   \
  15     if (expr) {          \
  16       (void)0;           \
  17     }                    \
  18   } while (0)
  19
  20 #define LOG_PIPE 2
  21
  22 static bool enable_logging = false;
  23 static void log(const char* format, ...) {
  24   if (!enable_logging) {
  25     return;
  26   }
  27   va_list args;
  28   va_start(args, format);
  29   vfprintf(stderr, format, args);
  30   va_end(args);
  31 }
  32
  33 static int output_pipe = 1;
  34 static void close_logging() {
  35   // we want to redirect to /dev/null stdout, stderr, and while we're at it,
  36   // any PR logging file descriptors. To that effect, we redirect all positive
  37   // file descriptors up to what open() returns here. In particular, 1 is stdout
  38   // and 2 is stderr.
  39   int fd = open("/dev/null", O_WRONLY);
  40   for (int i = 1; i < fd; i++) {
  41     if (output_pipe != i) {
  42       dup2(fd, i);
  43     }
  44   }
  45   close(fd);
  46 }
  47
  48 // C++ standard collides with C standard in that it doesn't allow casting void*
  49 // to function pointer types. So the work-around is to convert first to size_t.
  50 // http://www.trilithium.com/johan/2004/12/problem-with-dlsym/
  51 template <typename func_ptr_type>
  52 static func_ptr_type cast(void* ptr) {
  53   return reinterpret_cast<func_ptr_type>(reinterpret_cast<size_t>(ptr));
  54 }
  55
  56 #define BUFFER_SIZE_STEP 4000
  57
  58 static char* test_buf = nullptr;
  59 static int test_bufsize = 0;
  60 static int test_length = 0;
  61
  62 static void record_value(const char* format, ...) {
  63   if (!test_buf || test_length + BUFFER_SIZE_STEP / 2 > test_bufsize) {
  64     test_bufsize += BUFFER_SIZE_STEP;
  65     test_buf = (char*)realloc(test_buf, test_bufsize);
  66   }
  67   int remaining = test_bufsize - test_length;
  68
  69   // Append the new values to the buffer, not to exceed the remaining space.
  70   va_list args;
  71   va_start(args, format);
  72   int max_added = vsnprintf(test_buf + test_length, remaining, format, args);
  73   va_end(args);
  74
  75   if (max_added >= remaining) {
  76     test_length += remaining;
  77   } else {
  78     test_length += max_added;
  79   }
  80 }
  81
  82 #define record_error(str_, ...) record_value("ERROR\n" str_ "\n", ##__VA_ARGS__)
  83 #define record_warning(str_, ...) \
  84   record_value("WARNING\n" str_ "\n", ##__VA_ARGS__)
  85
  86 static void record_flush() {
  87   if (!test_buf) {
  88     return;
  89   }
  90   MOZ_UNUSED(write(output_pipe, test_buf, test_length));
  91   if (enable_logging) {
  92     MOZ_UNUSED(write(LOG_PIPE, test_buf, test_length));
  93   }
  94   free(test_buf);
  95   test_buf = nullptr;
  96 }
  97
  98 #endif /* WIDGET_GTK_GFXINFO_h__ */