c - 出现错误 : Stack around the variable was corrupted

Question

运行以下程序但出现错误

Run-Time Check Failure #2 - Stack around the variable 'unzip' was corrupted

什么可能导致错误？下面是我的代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void fmuUnzip() {
  char fmuFileName[100], path[100],strFinal[100];
  char unzip[]="winzip32 -e -o -j";
  printf("Enter fmuFileName\n");
  gets(fmuFileName);

  printf("Enter path of the fmuFileName\n");
  gets(path);
  strcat(unzip," ");
  strcat(unzip,fmuFileName);
  strcat(unzip," ");
  strcat(unzip,path);
}

void fmuLoad() {
  fmuUnzip();
}

int main(int argc,char* argv[]) {
 fmuLoad();
}

Answer 1

这里的问题是(是)

strcat(unzip," ");   //problem starts here itself
strcat(unzip,fmuFileName);
strcat(unzip," ");
strcat(unzip,path);

因为，没有足够的内存来保存连接的字符串。本质上，您超出了分配的内存，它会调用 undefined behaviour .

当您定义一个未指定大小的数组并使用字符串对其进行初始化时，数组的有效大小将计算为字符串的长度，加上空终止符的长度。试图“猫”到那是内存溢出。

来自man page strcat()(强调我的)

The strcat() function appends the src string to the dest string, overwriting the terminating null byte ('\0') at the end of dest, and then adds a terminating null byte. The strings may not overlap, and the dest string must have enough space for the result. If dest is not large enough, program behavior is unpredictable; ....

解决方案:

定义一个足够大的目标数组来容纳连接的字符串，当然包括终止 null。

<小时/>

也就是说，gets() 是纯粹的邪恶，非常危险，因为它存在缓冲区溢出问题。您可能想使用fgets()相反。