xref: /openbmc/qemu/include/glib-compat.h (revision b43047a2)
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
78