include/glib-compat.h

   1 /*
   2  * GLIB Compatibility Functions
   3  *
   4  * Copyright IBM, Corp. 2013
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *  Michael Tokarev   <mjt@tls.msk.ru>
   9  *  Paolo Bonzini     <pbonzini@redhat.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  *
  14  */
  15
  16 #ifndef QEMU_GLIB_COMPAT_H
  17 #define QEMU_GLIB_COMPAT_H
  18
  19 /* Ask for warnings for anything that was marked deprecated in
  20  * the defined version, or before. It is a candidate for rewrite.
  21  */
  22 #define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_48
  23
  24 /* Ask for warnings if code tries to use function that did not
  25  * exist in the defined version. These risk breaking builds
  26  */
  27 #define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_48
  28
  29 #pragma GCC diagnostic push
  30 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  31
  32 #include <glib.h>
  33
  34 /*
  35  * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
  36  * use of functions from newer GLib via this compat header needs a little
  37  * trickery to prevent warnings being emitted.
  38  *
  39  * Consider a function from newer glib-X.Y that we want to use
  40  *
  41  *    int g_foo(const char *wibble)
  42  *
  43  * We must define a static inline function with the same signature that does
  44  * what we need, but with a "_qemu" suffix e.g.
  45  *
  46  * static inline void g_foo_qemu(const char *wibble)
  47  * {
  48  *     #if GLIB_CHECK_VERSION(X, Y, 0)
  49  *        g_foo(wibble)
  50  *     #else
  51  *        g_something_equivalent_in_older_glib(wibble);
  52  *     #endif
  53  * }
  54  *
  55  * The #pragma at the top of this file turns off -Wdeprecated-declarations,
  56  * ensuring this wrapper function impl doesn't trigger the compiler warning
  57  * about using too new glib APIs. Finally we can do
  58  *
  59  *   #define g_foo(a) g_foo_qemu(a)
  60  *
  61  * So now the code elsewhere in QEMU, which *does* have the
  62  * -Wdeprecated-declarations warning active, can call g_foo(...) as normal,
  63  * without generating warnings.
  64  */
  65
  66 #if defined(_WIN32) && !GLIB_CHECK_VERSION(2, 50, 0)
  67 /*
  68  * g_poll has a problem on Windows when using
  69  * timeouts < 10ms, so use wrapper.
  70  */
  71 #define g_poll(fds, nfds, timeout) g_poll_fixed(fds, nfds, timeout)
  72 gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
  73 #endif
  74
  75 #pragma GCC diagnostic pop
  76
  77 #endif