c - 符号查找错误: undefined symbol: fclose

Question

我有以下程序，它基本上实现了 DNS 服务器。共享内存用于实现服务器缓存。我试图通过从文件中读取一些初始条目来将它们填充到缓存中。但是，当文件条目超出某个点时，我会遇到段错误。我无法自己调试该程序。

typedef struct rs{
char domainName[256];
char ip[36];
time_t timeStamp;
struct rs *cacheEnd;
} ResourceRecord;
ResourceRecord *cache, *tempCachePtr, *cacheEnd;
void create_Shared_Memory()         //Creates shared memory 
{
    int stateMemory;
    stateMemory=shmget(IPC_PRIVATE, (MAX_CACHE_SIZE)*sizeof(ResourceRecord *),IPC_CREAT|0660);
    if (stateMemory == -1)
    {
            perror("Shared memory creation");
                exit(EXIT_FAILURE);
        }
    cache=(ResourceRecord *)shmat(stateMemory,NULL,0);
    tempCachePtr = cache;
    if(shmctl(stateMemory,IPC_RMID,NULL)==-1)
    printf("ERROR CREATING CARMODEMEMORY!!!");

    if(cache==NULL)
    {
        perror("Shared memory attach ");
        shmctl(stateMemory,IPC_RMID,NULL);
        exit(EXIT_FAILURE);

    }
}

void populateCache(){
   tempCachePtr = cache+1;
   struct hostent* domainAddress;
   int i;
   ResourceRecord record;
   char * line = NULL;
   size_t fileInputLength = 0;
   ssize_t read;
   puts("Populating cache");
   FILE *fp = fopen("hosts.txt", "r");
   for(i=1;i<=40; i++){
      if((read = getline(&line, &fileInputLength, fp)) == -1){
        break;
      }
      printf("%d From file %s\n",i, line);
      strcpy(record.domainName, strtok(line, " "));
      strcpy(record.ip, strtok(NULL, "\n"));
      time(&record.timeStamp);
      *tempCachePtr = record;
      tempCachePtr++;
   }
   cacheEnd = tempCachePtr-1;
   *(cache->cacheEnd) = cacheEnd;
   fclose(fp);
}

我尝试使用 gdb 调试代码，这就是我所拥有的

symbol lookup error: /home/path/dnsserver: undefined symbol: fclose, version GLIBC_2.2.5 [Inferior 1 (process 7178) exited with code 0177]

当我尝试更改文件条目数并再次调试时:

SIGSEGV from /lib64/ld-linux-x86-64.so.2 shared memory

Answer 1

正如 Anto Jurković 所指出的，错误在于我使用 50*sizeof(ResourceRecord*) 创建共享内存，其中 sizeof(ResourceRecord*) 只有几个字节，因为它是一个指针，但 sizeof(ResourceRecord) 却很大更大(我的系统中为 8 和 312)。因此 50*sizeof(ResourceRecord*) 仅分配 400 字节内存，这显然不足以容纳 40 个 ResourceRecord 类型记录。