サンプル

struct structure {
unsigned int len;
unsigned char *ptr;
};

void function(struct structure *s)
{
char type = 'c';

s->len = 2;
s->ptr = (unsigned char *) malloc(s->len + 1);

strcpy((char *)s->ptr + 1, "st");
s->ptr[0] = type;
free(s->ptr);
}

void foo(){
char *character = (char *) malloc(5 * sizeof(char));
strcpy(character, "st");
free(character);
}

ソリューション

割り振りが正常に行われたことを確認してから参照を使用します。割り振りが失敗すると、malloc() は NULL を戻します。

struct structure {
unsigned int len;
unsigned char *ptr;
};

void function(struct structure *s)
{
char type = 'c';

s->len = 2;
s->ptr = (unsigned char *) malloc(s->len + 1);

if (!s->ptr) {
fprintf(stderr, "Malloc failure: unable to allocate memory.");
exit(EXIT_FAILURE);
}

strcpy((char *)s->ptr + 1, "st");
s->ptr[0] = type;
free(s->ptr);
}

void foo(){
char *character = (char *) malloc(5 * sizeof(char));

if (NULL == character) {
fprintf(stderr, "Malloc failure: unable to allocate memory.");
exit(EXIT_FAILURE);
}

strcpy(character, "st");
free(character);
}