53f5f96c752061448a6f5d1fc629166db2f345a3
[lttng-tools.git] / src / common / macros.h
1 /*
2 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
3 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * SPDX-License-Identifier: GPL-2.0-only
6 *
7 */
8
9 #ifndef _MACROS_H
10 #define _MACROS_H
11
12 #include <stdlib.h>
13 #include <stddef.h>
14 #include <string.h>
15 #include <common/compat/string.h>
16
17 /*
18 * Takes a pointer x and transform it so we can use it to access members
19 * without a function call. Here an example:
20 *
21 * #define GET_SIZE(x) LTTNG_REF(x)->size
22 *
23 * struct { int size; } s;
24 *
25 * printf("size : %d\n", GET_SIZE(&s));
26 *
27 * For this example we can't use something like this for compatibility purpose
28 * since this will fail:
29 *
30 * #define GET_SIZE(x) x->size;
31 *
32 * This is mostly use for the compatibility layer of lttng-tools. See
33 * poll/epoll for a good example. Since x can be on the stack or allocated
34 * memory using malloc(), we must use generic accessors for compat in order to
35 * *not* use a function to access members and not the variable name.
36 */
37 #define LTTNG_REF(x) ((typeof(*x) *)(x))
38
39 /*
40 * Memory allocation zeroed
41 */
42 static inline
43 void *zmalloc(size_t len)
44 {
45 return calloc(1, len);
46 }
47
48 #ifndef ARRAY_SIZE
49 #define ARRAY_SIZE(array) (sizeof(array) / (sizeof((array)[0])))
50 #endif
51
52 #ifndef container_of
53 #define container_of(ptr, type, member) \
54 ({ \
55 const typeof(((type *)NULL)->member) * __ptr = (ptr); \
56 (type *)((char *)__ptr - offsetof(type, member)); \
57 })
58 #endif
59
60 #ifndef max
61 #define max(a, b) ((a) > (b) ? (a) : (b))
62 #endif
63
64 #ifndef max_t
65 #define max_t(type, a, b) max((type) a, (type) b)
66 #endif
67
68 #ifndef min
69 #define min(a, b) ((a) < (b) ? (a) : (b))
70 #endif
71
72 #ifndef min_t
73 #define min_t(type, a, b) min((type) a, (type) b)
74 #endif
75
76 #ifndef LTTNG_PACKED
77 #define LTTNG_PACKED __attribute__((__packed__))
78 #endif
79
80 #ifndef LTTNG_NO_SANITIZE_ADDRESS
81 #if defined(__clang__) || defined (__GNUC__)
82 #define LTTNG_NO_SANITIZE_ADDRESS __attribute__((no_sanitize_address))
83 #else
84 #define LTTNG_NO_SANITIZE_ADDRESS
85 #endif
86 #endif
87
88 #define is_signed(type) (((type) -1) < (type) 1)
89
90 /*
91 * Align value to the next multiple of align. Returns val if it already is a
92 * multiple of align. Align must be a power of two.
93 */
94 #define ALIGN_TO(value, align) ((value + (align - 1)) & ~(align - 1))
95
96 /*
97 * LTTNG_HIDDEN: set the hidden attribute for internal functions
98 * On Windows, symbols are local unless explicitly exported,
99 * see https://gcc.gnu.org/wiki/Visibility
100 */
101 #if defined(_WIN32) || defined(__CYGWIN__)
102 #define LTTNG_HIDDEN
103 #else
104 #define LTTNG_HIDDEN __attribute__((visibility("hidden")))
105 #endif
106
107 #define member_sizeof(type, field) sizeof(((type *) 0)->field)
108
109 #define ASSERT_LOCKED(lock) assert(pthread_mutex_trylock(&lock))
110
111 /*
112 * Get an aligned pointer to a value. This is meant
113 * as a helper to pass an aligned pointer to a member in a packed structure
114 * to a function.
115 */
116 #define ALIGNED_CONST_PTR(value) (((const typeof(value) []) { value }))
117
118 /*
119 * lttng_strncpy returns 0 on success, or nonzero on failure.
120 * It checks that the @src string fits into @dst_len before performing
121 * the copy. On failure, no copy has been performed.
122 *
123 * dst_len includes the string's trailing NULL.
124 */
125 static inline
126 int lttng_strncpy(char *dst, const char *src, size_t dst_len)
127 {
128 if (lttng_strnlen(src, dst_len) >= dst_len) {
129 /* Fail since copying would result in truncation. */
130 return -1;
131 }
132 strcpy(dst, src);
133 return 0;
134 }
135
136 #endif /* _MACROS_H */
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