【问题标题】:Valgrind Invalid read of sizeValgrind 读取大小无效
【发布时间】:2017-04-09 22:28:05
【问题描述】:

首先,我查看了其他类似的问题,但它们对我没有帮助。我有以下 Valgrind 输出:

我的代码:

int f_gozlemZamaniFarki(long long t1,long long t2)
{
    char *time1 = (char*)calloc(12,sizeof(char));
    char *time2 = (char*)calloc(12,sizeof(char));

    *time1 = '\0';
    *time2 = '\0';

    sprintf(time1,"%lli",t1);
    sprintf(time2,"%lli",t2);

    int year,month,day,hour,minute,timeDif;
    int status = 0;

    struct tm tm1;
    struct tm tm2;

    time_t timeF = NULL;
    time_t timeS = NULL;

    if(sscanf(time1,"%4d%2d%2d%2d%2d",&year,&month,&day,&hour,&minute) != EOF)
    {
        tm1.tm_year = year - 1900;
        tm1.tm_mon = month;
        tm1.tm_mdmonth = day;
        tm1.tm_hour = hour;
        tm1.tm_min = minute;
        tm1.tm_sec = 0;
        timeF = mktime(&tm1);
    }

    if(sscanf(time2,"%4d%2d%2d%2d%2d",&year,&month,&day,&hour,&minute) != EOF)
    {
        tm2.tm_year = year - 1900;
        tm2.tm_mon = month;
        tm2.tm_mdmonth = day;
        tm2.tm_hour = hour;
        tm2.tm_min = minute;
        tm2.tm_sec = 0;
        timeS = mktime(&tm2);
    }

    timeDif = (timeF - timeS) / 60;

    if ((timeDif < 0) || (timeDif > 59))
    {
        status = 1;
    }

    free(time1);
    free(time2);

    return status;
}

valngrid 输出

==12726== Invalid read of size 1
==12726==  Address 0x1786dccc is 0 bytes after a block of size 12 alloc'd
==12726==    at 0x4C2AE45: calloc (vg_replace_malloc.c:711)
==12726==    by 0x405171: f_gozlemZamaniFarki (in /home/aws/bin/awsdDataWriter)
==12726== Conditional jump or move depends on uninitialised value(s)
==12726==  Uninitialised value was created by a stack allocation
==12726==    at 0x405150: f_gozlemZamaniFarki (in /home/aws/bin/awsdDataWriter)

我所有的变量都已初始化(我希望如此),所以我不明白为什么 Valgrind 对我大喊大叫。 你有什么建议让代码正确并犯错误吗?

【问题讨论】:

  • sizeof(char) 在 C 中保证为 1。
  • 神奇人物12有什么意义?
  • 尝试char *time1 = (char*)calloc(12,sizeof(char));-> char *time1 = (char*)calloc(13,sizeof(char)); 并告诉我们问题是否仍然存在。
  • 请使用调试选项编译您的程序,以便 valgrind 可以告诉您分配发生的行。而且,不,并非所有变量都已初始化,tm1tm2 没有。

标签: c gcc memory c99


【解决方案1】:

我更改了这些行,解决了我的问题。

char *time1 = (char*)calloc(13,sizeof(char));
char *time1 = (char*)calloc(13,sizeof(char));

//*time1 = '\0';
//*time2 = '\0';

【讨论】:

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