qemu

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glib-compat.h (4358B)

      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  */
     89 static 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  */
    115 static inline struct passwd *
    116 g_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 
    131 static inline bool
    132 qemu_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 #ifndef G_NORETURN
    151 #define G_NORETURN G_GNUC_NORETURN
    152 #endif
    153 
    154 #endif