Created
June 14, 2018 03:41
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#include <alloca.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
struct tmpvar_hook { | |
void *ptr; | |
struct tmpvar_hook *next; | |
}; | |
static void tmpvar_hook_free(struct tmpvar_hook **hook) { | |
struct tmpvar_hook *h = *hook; | |
while (h) { | |
printf("freeing ptr %p\n", h->ptr); | |
free(h->ptr); | |
h = h->next; | |
} | |
} | |
#define TMPVAR_ALLOC_MALLOC_THRESHOLD 64 | |
#define TMPVAR_ALLOC(hook_, size_) \ | |
({ \ | |
void *__h_ptr__ = NULL; \ | |
if ((size_) <= TMPVAR_ALLOC_MALLOC_THRESHOLD) { \ | |
__h_ptr__ = alloca(size_); \ | |
printf("%zu bytes is below thresh, alloca()->%p\n", (size_), __h_ptr__); \ | |
} else { \ | |
__h_ptr__ = malloc(size_); \ | |
if (__h_ptr__) { \ | |
struct tmpvar_hook *__h_tmp__ = alloca(sizeof(struct tmpvar_hook)); \ | |
__h_tmp__->ptr = __h_ptr__; \ | |
__h_tmp__->next = hook_; \ | |
hook_ = __h_tmp__; \ | |
printf("%zu bytes is *above* thresh, malloc()->%p\n", (size_), \ | |
__h_ptr__); \ | |
} \ | |
} \ | |
__h_ptr__; \ | |
}) | |
int main(void) { | |
struct tmpvar_hook *hook __attribute__((cleanup(tmpvar_hook_free))) = NULL; | |
for (int i = 1; i < 1000; i += 10) { | |
void *ptr = TMPVAR_ALLOC(hook, i); | |
} | |
} |
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