linux C语言：*** glibc detected *** ./control: free():invalid pointer:-蒲公英云

linux C语言：*** glibc detected *** ./control: free():invalid pointer:

野性酷女 2023-06-19 04:24 47阅读 0赞

前言

今天遇到了一个问题，折腾好久才找到问题原因，永远不要理想化，各种困难都会浮现的，我们只需要不骄不躁，一定可以解决所有问题。

问题代码

我们先来看一下问题代码部分吧。

static char *control_process(char *verb[],char *noun[],char *result)
{ 
    int verbOpcode = 0; //verb Opcode index
    int nounOpcode = 0; //noun Opcode index 
    char *Matchverb = (char *)malloc(40*sizeof(char));
    char *Matchnoun = (char *)malloc(40*sizeof(char));
    char *Playfile = (char *)malloc(sizeof(char)*40);
    int index1 = 0;
    printf("enter the control_process \n\n");
    for(index1 =1; index1 <37;index1++)
    {     
        Matchverb = mystrstr1(result,verb[index1]);
        if(Matchverb != NULL)
        { 
            verbOpcode = index1;
            break;
        }else
        { 
            verbOpcode = 0;
        }
    }
    int index2 = 0;
    for(index2 = 1;index2 <29;index2++)
    { 
        Matchnoun = mystrstr1(result,noun[index2]);
        if(Matchnoun != NULL)
        { 
            nounOpcode = index2;
            break;
        }else
        { 
            nounOpcode=0;
        }
    }
    printf("achieve the verb and noun deal \n\n");
    sprintf(Playfile,"/mnt/card/1%02d2%02d",verbOpcode,nounOpcode);
    printf("play file is %s \n\n",Playfile);
    free(Matchverb);
    free(Matchnoun);
    return Playfile;
}

解决问题

就是这段代码，一直报错，初看确实看不到什么问题，为此我加了很多打印，最后确定问题就发生在 free(Matchverb);free(Matchnoun);这两句话，下面就讲一个一知识点，为什么free发生异常了呢？
我们在使用malloc分配内存后，指针变量获取到了地址。但是在程序中我们又给指针变量重新赋值了，因此地址发生了变化，此时我再次使用free()来释放，已经不是原来malloc分配的内存地址了，因此这就是指针地址非法。

修改方法

为了防止地址发生变化，我可以在定义两个指针变量保存malloc分配初地址，然后在释放之前将初地址重新赋值回去，这样就完美解决了。

static char *control_process(char *verb[],char *noun[],char *result)
{ 
    int verbOpcode = 0; //verb Opcode index
    int nounOpcode = 0; //noun Opcode index 
    char *Matchverb = (char *)malloc(40*sizeof(char));
    char *Matchnoun = (char *)malloc(40*sizeof(char));
    char *Playfile = (char *)malloc(sizeof(char)*40);
    char *p1 = Matchverb;
    char *p2 = Matchnoun;
    int index1 = 0;
    printf("enter the control_process \n\n");
    for(index1 =1; index1 <37;index1++)
    {     
        Matchverb = mystrstr1(result,verb[index1]);
        if(Matchverb != NULL)
        { 
            verbOpcode = index1;
            break;
        }else
        { 
            verbOpcode = 0;
        }
    }
    int index2 = 0;
    for(index2 = 1;index2 <29;index2++)
    { 
        Matchnoun = mystrstr1(result,noun[index2]);
        if(Matchnoun != NULL)
        { 
            nounOpcode = index2;
            break;
        }else
        { 
            nounOpcode=0;
        }
    }
    printf("achieve the verb and noun deal \n\n");
    sprintf(Playfile,"/mnt/card/1%02d2%02d",verbOpcode,nounOpcode);
    printf("play file is %s \n\n",Playfile);
    Matchverb = p1;
    Matchnoun = p2;
    free(Matchverb);
    free(Matchnoun);
    return Playfile;
}