我遇到了分段错误我不明白的方式

Question

我的任务是创建一个编译器 我现在在这里列出了两个产生问题的函数。 下面我给出了它给出的输出 当我连续调用 cond3AC 函数时

s_3AC * e1 = cond3AC (tree-> childrens [0]);

我得到分段错误

如果您尝试跟踪打印，我会正确分配并正确返回所有内容。

s_3AC* Exp3AC(node *tree){
     if(!strcmp("&&", tree->token) || !strcmp("||", tree->token) || !strcmp("==", tree->token) || !strcmp("!=", tree->token)|| 
        !strcmp(">", tree->token) || !strcmp(">=", tree->token) || !strcmp("<", tree->token) || !strcmp("<=", tree->token)){           
        red();
        printf("######## check now the e2 ########## \n");
        printf("check token right: %s\n",tree->childrens[1]->token);
        s_3AC* e2 = cond3AC(tree->childrens[1]);
        printf("e2 -> %s\n", e2->code);

        purple();
        printf("######## check now the e1 ########## %s\n", tree->childrens[0]->token);
        printf("check token left: %s\n",tree->childrens[0]->token);
        /* send left side to evaluate*/
        s_3AC* e1 = cond3AC(tree->childrens[0]);
        printf("e1 -> %s", e1->code); 
        reset();
        s_3AC* node = (s_3AC*)malloc(sizeof(s_3AC) * 1);
        node->code = (char*)malloc(sizeof(char) * (strlen(tree->token) + strlen(e1->code) + strlen(e2->code) + 1));
        strcat(node->code,e1->code);
        strcat(node->code,tree->token);
        strcat(node->code,e2->code);

        node->var = NULL;
        node->falsel = NULL;
        node->truel = NULL;
        return node;

    }else{
        s_3AC* node = (s_3AC*)malloc(sizeof(s_3AC));
        printf("SUCCESS\n");
        node->code = strdup(tree->token);
        node->var = strdup(tree->token);
        node->truel = NULL;
        node->falsel = NULL;

    return node;
}

s_3AC* cond3AC(node *tree){
    printf("OKOKOK\n");
    printf("tree->token: %s\n",tree->token);
    if(is_kind_of_type(tree->token)){
        char *code = (char*)malloc(sizeof(char) * (strlen(tree->childrens[0]->token) + 1));
         printf("tree->token after the if: %s\n",tree->token);
        strcat(code, tree->childrens[0]->token);

        s_3AC* node = (s_3AC*)malloc(sizeof(s_3AC) * 1);
        node->code = strdup(code);
        node->var = NULL;
        node->truel = NULL;
        node->falsel = NULL;
        return node;
    }
    s_3AC* check = Exp3AC(tree);
    printf("ˆˆˆˆcheck->codeˆˆˆˆ: %s\n", check->code);
    return check;
}

输出：

    ######## check now the e2 ########## 
check token right: int
OKOKOK
tree->token: int
tree->token after the if: int
e2 -> 23
######## check now the e1 ########## a
check token left: a
OKOKOK
tree->token: a
SUCCESS
ˆˆˆˆcheck->codeˆˆˆˆ: a
zsh: segmentation fault  ./Part3 < test.t

Answer 1

考虑这些代码行：

node->code = (char*)malloc(sizeof(char) * (strlen(tree->token) + strlen(e1->code) + strlen(e2->code) + 1));
strcat(node->code,e1->code);
strcat(node->code,tree->token);
strcat(node->code,e2->code);

分配的内存尚未初始化，第一个 strcat 期望有一个有效的 C 字符串（一个空字符串）。该函数将在内存中搜索，直到找到开始追加的字符串终止符，这可能超出了内存分配。

把第一个strcat改成strcpy这样

node->code = (char*)malloc(sizeof(char) * (strlen(tree->token) + strlen(e1->code) + strlen(e2->code) + 1));
strcpy(node->code,e1->code);
strcat(node->code,tree->token);
strcat(node->code,e2->code);