LXR qemu/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 "_compat" suffix e.g.
  50 *
  51 * static inline void g_foo_compat(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_compat(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/*
  72 * g_memdup2_qemu:
  73 * @mem: (nullable): the memory to copy.
  74 * @byte_size: the number of bytes to copy.
  75 *
  76 * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it
  77 * from @mem. If @mem is %NULL it returns %NULL.
  78 *
  79 * This replaces g_memdup(), which was prone to integer overflows when
  80 * converting the argument from a #gsize to a #guint.
  81 *
  82 * This static inline version is a backport of the new public API from
  83 * GLib 2.68, kept internal to GLib for backport to older stable releases.
  84 * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319.
  85 *
  86 * Returns: (nullable): a pointer to the newly-allocated copy of the memory,
  87 *          or %NULL if @mem is %NULL.
  88 */
  89static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size)
  90{
  91#if GLIB_CHECK_VERSION(2, 68, 0)
  92    return g_memdup2(mem, byte_size);
  93#else
  94    gpointer new_mem;
  95
  96    if (mem && byte_size != 0) {
  97        new_mem = g_malloc(byte_size);
  98        memcpy(new_mem, mem, byte_size);
  99    } else {
 100        new_mem = NULL;
 101    }
 102
 103    return new_mem;
 104#endif
 105}
 106#define g_memdup2(m, s) g_memdup2_qemu(m, s)
 107
 108#if defined(G_OS_UNIX)
 109/*
 110 * Note: The fallback implementation is not MT-safe, and it returns a copy of
 111 * the libc passwd (must be g_free() after use) but not the content. Because of
 112 * these important differences the caller must be aware of, it's not #define for
 113 * GLib API substitution.
 114 */
 115static inline struct passwd *
 116g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
 117{
 118#if GLIB_CHECK_VERSION(2, 64, 0)
 119    return g_unix_get_passwd_entry(user_name, error);
 120#else
 121    struct passwd *p = getpwnam(user_name);
 122    if (!p) {
 123        g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
 124        return NULL;
 125    }
 126    return (struct passwd *)g_memdup(p, sizeof(*p));
 127#endif
 128}
 129#endif /* G_OS_UNIX */
 130
 131static inline bool
 132qemu_g_test_slow(void)
 133{
 134    static int cached = -1;
 135    if (cached == -1) {
 136        cached = g_test_slow() || getenv("G_TEST_SLOW") != NULL;
 137    }
 138    return cached;
 139}
 140
 141#undef g_test_slow
 142#undef g_test_thorough
 143#undef g_test_quick
 144#define g_test_slow() qemu_g_test_slow()
 145#define g_test_thorough() qemu_g_test_slow()
 146#define g_test_quick() (!qemu_g_test_slow())
 147
 148#pragma GCC diagnostic pop
 149
 150#endif
 151