double free or corruption(fasttop) error/segmentation C 错误

Question

我正在尝试动态分配一个数组以从命令行读取用户输入。它工作 99/100 次，但如果我重复输入一堆字符，我有时会收到分段错误或双重释放或损坏（fasttop）错误。此错误相对难以重现。

我很确定错误的发生是因为我重新分配数组的方式。

while(1){
        char *buf_in;               // Holds user keyboard input
        int cnt = 0, length = 0;    // cnt stores current read buffer size, length allows input into buf_in
        char ch;
        int buf_max = 64;           // Current buffer size. Dynamically allocated

        buf_in = malloc(buf_max * sizeof(char));
        if (buf_in==NULL){
            fprintf(stderr,"Error allocating memory!\n");
            exit(EXIT_FAILURE);
        }

        do{
            if (cnt > (buf_max/2)){
                cnt = 0;
                buf_max *= 2; // Double size of buffer
                printf("Doubling buffer: %d\n",buf_max);
                buf_in = realloc(buf_in,buf_max);
                if (buf_in == NULL){
                    fprintf(stderr,"Error re-allocating memory!\n");
                    exit(EXIT_FAILURE);
                }
            }
            /* Store line-by-line into buffer */
            ch = getc(stdin);
            buf_in[length] = ch;
            length++;
            cnt++;
        }while(ch != '\n');

        /* Handles different option arguments */
        processOptions(buf_in,&opt_n_inc);

        // stdout
        fprintf(stdout,"%s",buf_in);
        fflush(stdout);

        free(buf_in);
        buf_in=NULL;
    }

Answer 1

代码似乎试图使用 "%s" 一个 char 数组而不是字符串来打印。缺少空字符 '[=14=]' 终止符。

此外，问题可能在 processOptions() 中表现出来，因为该函数调用未传递有效数据的长度。

buf_in[length] = ch;

// Add    
buf_in[length+1] = '[=10=]';

...
processOptions(buf_in,&opt_n_inc);
fprintf(stdout,"%s",buf_in);

注意：无限循环应该getc(stdin)returnEOF。更好用

int ch = getc(stdin);
if (ch == EOF) break;
buf_in[length] = ch;

double free or corruption(fasttop) error/segmentation C 错误

double free or corruption(fasttop) error/segmentation fault in C

c

segmentation-fault

realloc