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 #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(_WIN32) && !GLIB_CHECK_VERSION(2, 50, 0)
  72 /*
  73  * g_poll has a problem on Windows when using
  74  * timeouts < 10ms, so use wrapper.
  75  */
  76 #define g_poll(fds, nfds, timeout) g_poll_fixed(fds, nfds, timeout)
  77 gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
  78 #endif
  79
  80 #if defined(G_OS_UNIX)
  81 /*
  82  * Note: The fallback implementation is not MT-safe, and it returns a copy of
  83  * the libc passwd (must be g_free() after use) but not the content. Because of
  84  * these important differences the caller must be aware of, it's not #define for
  85  * GLib API substitution.
  86  */
  87 static inline struct passwd *
  88 g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
  89 {
  90 #if GLIB_CHECK_VERSION(2, 64, 0)
  91     return g_unix_get_passwd_entry(user_name, error);
  92 #else
  93     struct passwd *p = getpwnam(user_name);
  94     if (!p) {
  95         g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
  96         return NULL;
  97     }
  98     return (struct passwd *)g_memdup(p, sizeof(*p));
  99 #endif
 100 }
 101 #endif /* G_OS_UNIX */
 102
 103 #pragma GCC diagnostic pop
 104
 105 #endif