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util: add safe_container_of() macro definition

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This commit is contained in:
Bert Belder 2017-09-25 17:51:43 +02:00
parent bb23a2b9f0
commit 1e24f44238
2 changed files with 18 additions and 0 deletions
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11
src/util.c Normal file
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@ -0,0 +1,11 @@
#include <stdint.h>
#include <stdlib.h>
#include "util.h"
void* _util_safe_container_of_helper(void* ptr, size_t offset) {
if (ptr == NULL)
return NULL;
else
return (char*) ptr - offset;
}

7
src/util.h
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@ -3,6 +3,8 @@
#include <stddef.h>
#include "internal.h"
#ifndef _SSIZE_T_DEFINED
#define SSIZE_T_DEFINED
typedef intptr_t ssize_t;
@ -10,6 +12,9 @@ typedef intptr_t ssize_t;
#define array_count(a) (sizeof(a) / (sizeof((a)[0])))
#define safe_container_of(ptr, type, member) \
((type*) _util_safe_container_of_helper((ptr), offsetof(type, member)))
#define container_of(ptr, type, member) \
((type*) ((char*) (ptr) -offsetof(type, member)))
@ -21,4 +26,6 @@ typedef intptr_t ssize_t;
(unused)) int __static_assert_##__LINE__[(condition) ? 1 : -1];
#endif
EPOLL_INTERNAL void* _util_safe_container_of_helper(void* ptr, size_t offset);
#endif /* EPOLL_UTIL_H_ */