Valgrind 多个“大小为 1 的无效写入/读取”错误

Question

我的程序从文件中读取人员并将他们的信息保存到一个 Person 结构中，如下所示：

struct person
{
    char *fname;
    char *lname;
    int id;
};
typedef struct person Person;

这些人被保存在一个 Persons 数组中，填充该数组的函数如下所示（total 变量是从文件中统计的 Persons 总数）：

Person* fillArray(int total, FILE *fin)
{
    rewind(fin);
    int i;
    char temp[50];
    char temp2[50];
    Person *p = (Person*) calloc(total, sizeof(Person));
    for(i = 0; i < total; i++)
    {
        fscanf(fin, "%s", temp);
        p[i].fname = (char *) calloc(strlen(temp)+1, sizeof(char));
        strcpy(p[i].fname, temp);
        fscanf(fin, "%s", temp2);
        p[i].lname = (char *) calloc(strlen(temp)+1, sizeof(char));
        strcpy(p[i].lname, temp2);
        fscanf(fin, "%d", &(p + i)->id);
    }
    return p;
}

我清理了所有已使用的内存，并为临时字符串末尾的 '\0' 分配了内存。不知道为什么会出现这些错误：

HEAP SUMMARY:
==4736==     in use at exit: 0 bytes in 0 blocks
==4736==   total heap usage: 8 allocs, 8 frees, 414 bytes allocated
==4736== 
==4736== All heap blocks were freed -- no leaks are possible
==4736== 
==4736== ERROR SUMMARY: 10 errors from 2 contexts (suppressed: 0 from 0)
==4736== 
==4736== 3 errors in context 1 of 2:
==4736== Invalid write of size 1
==4736==    at 0x402C6E8: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4736==    by 0x804898E: fillArray (cscd240_s13_lab11Functions.c:30)
==4736==    by 0x8048731: main (cscd240_s13_lab11Tester.c:13)
==4736==  Address 0x41ef24f is 3 bytes after a block of size 4 alloc'd
==4736==    at 0x402A5E6: calloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4736==    by 0x804896A: fillArray (cscd240_s13_lab11Functions.c:29)
==4736==    by 0x8048731: main (cscd240_s13_lab11Tester.c:13)
==4736== 
==4736== 
==4736== 7 errors in context 2 of 2:
==4736== Invalid write of size 1
==4736==    at 0x402C6C3: strcpy (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4736==    by 0x804898E: fillArray (cscd240_s13_lab11Functions.c:30)
==4736==    by 0x8048731: main (cscd240_s13_lab11Tester.c:13)
==4736==  Address 0x41ef24c is 0 bytes after a block of size 4 alloc'd
==4736==    at 0x402A5E6: calloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==4736==    by 0x804896A: fillArray (cscd240_s13_lab11Functions.c:29)
==4736==    by 0x8048731: main (cscd240_s13_lab11Tester.c:13)
==4736== 
==4736== ERROR SUMMARY: 10 errors from 2 contexts (suppressed: 0 from 0)

感谢您的帮助。我已经查看了几个线程，其中大多数不是关于字符末尾的 '\0' 的 calloc/mallocing 。我这样做了，但是当我使用 qsort() 对 Person 数组进行排序时，我仍然会遇到这些错误以及更多错误。如果这与之前提出的问题相同，我深表歉意，我找不到该主题。

Answer 1

你在分配第二部分时使用了错误的长度，

fscanf(fin, "%s", temp2);
p[i].lname = (char *) calloc(strlen(temp)+1, sizeof(char));
strcpy(p[i].lname, temp2);

那里应该使用strlen(temp2);。