aboutsummaryrefslogtreecommitdiff
path: root/include/glib-compat.h
blob: 43a562974d80e525d4146aaaaea9830b6bc5178f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/*
 * GLIB Compatibility Functions
 *
 * Copyright IBM, Corp. 2013
 *
 * Authors:
 *  Anthony Liguori   <aliguori@us.ibm.com>
 *  Michael Tokarev   <mjt@tls.msk.ru>
 *  Paolo Bonzini     <pbonzini@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */

#ifndef QEMU_GLIB_COMPAT_H
#define QEMU_GLIB_COMPAT_H

/* Ask for warnings for anything that was marked deprecated in
 * the defined version, or before. It is a candidate for rewrite.
 */
#define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_56

/* Ask for warnings if code tries to use function that did not
 * exist in the defined version. These risk breaking builds
 */
#define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_56

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"

#include <glib.h>
#if defined(G_OS_UNIX)
#include <glib-unix.h>
#include <sys/types.h>
#include <pwd.h>
#endif

/*
 * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
 * use of functions from newer GLib via this compat header needs a little
 * trickery to prevent warnings being emitted.
 *
 * Consider a function from newer glib-X.Y that we want to use
 *
 *    int g_foo(const char *wibble)
 *
 * We must define a static inline function with the same signature that does
 * what we need, but with a "_compat" suffix e.g.
 *
 * static inline void g_foo_compat(const char *wibble)
 * {
 *     #if GLIB_CHECK_VERSION(X, Y, 0)
 *        g_foo(wibble)
 *     #else
 *        g_something_equivalent_in_older_glib(wibble);
 *     #endif
 * }
 *
 * The #pragma at the top of this file turns off -Wdeprecated-declarations,
 * ensuring this wrapper function impl doesn't trigger the compiler warning
 * about using too new glib APIs. Finally we can do
 *
 *   #define g_foo(a) g_foo_compat(a)
 *
 * So now the code elsewhere in QEMU, which *does* have the
 * -Wdeprecated-declarations warning active, can call g_foo(...) as normal,
 * without generating warnings.
 */

/*
 * g_memdup2_qemu:
 * @mem: (nullable): the memory to copy.
 * @byte_size: the number of bytes to copy.
 *
 * Allocates @byte_size bytes of memory, and copies @byte_size bytes into it
 * from @mem. If @mem is %NULL it returns %NULL.
 *
 * This replaces g_memdup(), which was prone to integer overflows when
 * converting the argument from a #gsize to a #guint.
 *
 * This static inline version is a backport of the new public API from
 * GLib 2.68, kept internal to GLib for backport to older stable releases.
 * See https://gitlab.gnome.org/GNOME/glib/-/issues/2319.
 *
 * Returns: (nullable): a pointer to the newly-allocated copy of the memory,
 *          or %NULL if @mem is %NULL.
 */
static inline gpointer g_memdup2_qemu(gconstpointer mem, gsize byte_size)
{
#if GLIB_CHECK_VERSION(2, 68, 0)
    return g_memdup2(mem, byte_size);
#else
    gpointer new_mem;

    if (mem && byte_size != 0) {
        new_mem = g_malloc(byte_size);
        memcpy(new_mem, mem, byte_size);
    } else {
        new_mem = NULL;
    }

    return new_mem;
#endif
}
#define g_memdup2(m, s) g_memdup2_qemu(m, s)

#if defined(G_OS_UNIX)
/*
 * Note: The fallback implementation is not MT-safe, and it returns a copy of
 * the libc passwd (must be g_free() after use) but not the content. Because of
 * these important differences the caller must be aware of, it's not #define for
 * GLib API substitution.
 */
static inline struct passwd *
g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
{
#if GLIB_CHECK_VERSION(2, 64, 0)
    return g_unix_get_passwd_entry(user_name, error);
#else
    struct passwd *p = getpwnam(user_name);
    if (!p) {
        g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
        return NULL;
    }
    return (struct passwd *)g_memdup(p, sizeof(*p));
#endif
}
#endif /* G_OS_UNIX */

static inline bool
qemu_g_test_slow(void)
{
    static int cached = -1;
    if (cached == -1) {
        cached = g_test_slow() || getenv("G_TEST_SLOW") != NULL;
    }
    return cached;
}

#undef g_test_slow
#undef g_test_thorough
#undef g_test_quick
#define g_test_slow() qemu_g_test_slow()
#define g_test_thorough() qemu_g_test_slow()
#define g_test_quick() (!qemu_g_test_slow())

#pragma GCC diagnostic pop

#ifndef G_NORETURN
#define G_NORETURN G_GNUC_NORETURN
#endif

#endif