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_56
  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_56
  28
  29 #pragma GCC diagnostic push
  30 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  31
  32 #include <glib.h>
  33 #if defined(G_OS_UNIX)
  34 #include <glib-unix.h>
  35 #include <sys/types.h>
  36 #include <pwd.h>
  37 #endif
  38
  39 /*
  40  * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
  41  * use of functions from newer GLib via this compat header needs a little
  42  * trickery to prevent warnings being emitted.
  43  *
  44  * Consider a function from newer glib-X.Y that we want to use
  45  *
  46  *    int g_foo(const char *wibble)
  47  *
  48  * We must define a static inline function with the same signature that does
  49  * what we need, but with a "_qemu" suffix e.g.
  50  *
  51  * static inline void g_foo_qemu(const char *wibble)
  52  * {
  53  *     #if GLIB_CHECK_VERSION(X, Y, 0)
  54  *        g_foo(wibble)
  55  *     #else
  56  *        g_something_equivalent_in_older_glib(wibble);
  57  *     #endif
  58  * }
  59  *
  60  * The #pragma at the top of this file turns off -Wdeprecated-declarations,
  61  * ensuring this wrapper function impl doesn't trigger the compiler warning
  62  * about using too new glib APIs. Finally we can do
  63  *
  64  *   #define g_foo(a) g_foo_qemu(a)
  65  *
  66  * So now the code elsewhere in QEMU, which *does* have the
  67  * -Wdeprecated-declarations warning active, can call g_foo(...) as normal,
  68  * without generating warnings.
  69  */
  70
  71 #if defined(G_OS_UNIX)
  72 /*
  73  * Note: The fallback implementation is not MT-safe, and it returns a copy of
  74  * the libc passwd (must be g_free() after use) but not the content. Because of
  75  * these important differences the caller must be aware of, it's not #define for
  76  * GLib API substitution.
  77  */
  78 static inline struct passwd *
  79 g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
  80 {
  81 #if GLIB_CHECK_VERSION(2, 64, 0)
  82     return g_unix_get_passwd_entry(user_name, error);
  83 #else
  84     struct passwd *p = getpwnam(user_name);
  85     if (!p) {
  86         g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
  87         return NULL;
  88     }
  89     return (struct passwd *)g_memdup(p, sizeof(*p));
  90 #endif
  91 }
  92 #endif /* G_OS_UNIX */
  93
  94 static inline bool
  95 qemu_g_test_slow(void)
  96 {
  97     static int cached = -1;
  98     if (cached == -1) {
  99         cached = g_test_slow() || getenv("G_TEST_SLOW") != NULL;
 100     }
 101     return cached;
 102 }
 103
 104 #undef g_test_slow
 105 #undef g_test_thorough
 106 #undef g_test_quick
 107 #define g_test_slow() qemu_g_test_slow()
 108 #define g_test_thorough() qemu_g_test_slow()
 109 #define g_test_quick() (!qemu_g_test_slow())
 110
 111 #pragma GCC diagnostic pop
 112
 113 #endif