c - Valgrind 多个 "invalid write/read of size 1"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如下所示的人员结构中:

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

这些人保存在一个 Persons 数组中，填充该数组的函数如下所示(total 变量是从文件中计算的 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;
}

我清理了所有使用的内存，并为临时字符串末尾的“\0”调用了内存。不确定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)

谢谢你的帮助。我查看了几个线程，其中大部分都不是对字符末尾的 '\0' 进行调用/分配。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，我找不到主题。

Answer 1

你为第二部分的分配使用了错误的长度，

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

应该在那里使用 strlen(temp2);。