valgrind条件跳转或移动取决于未初始化

Question

Valgrind对两行代码抛出警告，每行旁边的注释中都提到了。

警告1：

大小为8的无效写入，地址...在一个大小的块内为8个字节9已分配

data[size] = NULL;

警告2：

有条件的跳跃或移动取决于未初始化的值

for (char **ptr = data; *ptr; ptr++) { // warning -> Conditional jump or move depends on uninitialized values(s)
    free(*ptr);
}

---

这里是完整的代码，

Callee

char **getList() {
    char **list = (char *[]) {"John", "Jane", NULL};

    int size = 0;
    for (char **ptr = list; *ptr; ptr++) {
        size++;
    }

    char **data = malloc(sizeof(char *) * size + 1);
    if (data == NULL) goto exception;

    for (int i = 0; *list; list++, i++) {
        data[i] = malloc(sizeof(char) * (strlen(*list) + 1));
        if (data[i] == NULL) goto exception;
        strcpy(data[i], *list);
    }

    data[size] = NULL; // this line gives warning
    // warning -> invalid write of size 8, Address ... is 8 bytes inside a block of size 9 alloc'd
    return data;

    exception:
    fprintf(stderr, "data allocation failed.\n");
    return NULL;
}

Caller不同的文件/作用域

char **data = getList();

for (char **ptr = data; *ptr; ptr++) { // warning -> Conditional jump or move depends on uninitialized values(s)
    free(*ptr);
}
free(data);

Answer 1

基于新板的建议撰写，我没有收到strlen + memcpy评论，请提出建议。

char **getList(void) {
    const char * const list[] = {"John", "Jane", NULL};

    unsigned int size = 0;
    char **ptr;
    for (ptr = (char **) list; *ptr != NULL; ptr++) {
        size++;
    }

    char **data = malloc(sizeof(char *) * (size + 1));
    if (data == NULL) goto exception;

    ptr = (char **) list;
    for (unsigned int i = 0; *ptr != NULL; ptr++, i++) {
        data[i] = malloc(sizeof(char) * (strlen(*ptr) + 1));
        if (data[i] == NULL) goto exception;
        strcpy(data[i], *ptr);
    }

    data[size] = NULL;
    return data;

    exception:
    fprintf(stderr, "data Allocation failed.\n");
    return NULL;
}