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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
union sptr_u {
uint8_t base[1];
uint32_t offset;
};
typedef union sptr_u sptr_t;
struct s {
uint8_t name1_len;
uint8_t name2_len;
uint8_t name3_len;
sptr_t name1;
sptr_t name2;
sptr_t name3;
};
static void sptr_set(sptr_t *sptr, void *ptr)
{
sptr->offset = (uint8_t *)ptr - sptr->base;
printf("sptr->base : %p\n", sptr->base);
printf("sptr->offset : %u\n", sptr->offset);
}
static void *sptr_get(sptr_t *sptr)
{
return sptr->base + sptr->offset;
}
int main(void)
{
static const char * const names[] = { "toor", "foobar", "baz" };
struct s *s = malloc(sizeof(struct s) +
strlen(names[0]) + strlen(names[1]) +
strlen(names[2]) + 3);
char *p = (char *)(s) + sizeof(struct s);
printf("s : %p\n", s);
s->name1_len = strlen(names[0]);
sptr_set(&s->name1, p);
p = stpcpy(p, names[0]);
p++;
s->name2_len = strlen(names[1]);
sptr_set(&s->name2, p);
p = stpcpy(p, names[1]);
p++;
s->name3_len = strlen(names[2]);
sptr_set(&s->name3, p);
p = stpcpy(p, names[2]);
printf("name1 : %s\n", (const char *)sptr_get(&s->name1));
printf("name2 : %s\n", (const char *)sptr_get(&s->name2));
printf("name3 : %s\n", (const char *)sptr_get(&s->name3));
free(s);
exit(EXIT_SUCCESS);
}
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