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c++ - "points to uninitialised byte(s)"Valgrind 错误

转载 作者:可可西里 更新时间:2023-11-01 16:27:25 27 4
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我一直在使用 Valgrind 来查找我的代码中的内存泄漏,虽然没有发现内存泄漏,但报告了一些错误,所有这些错误都源于单个函数/类方法:

==17043== ERROR SUMMARY: 10100 errors from 3 contexts (suppressed: 0 from 0)
==17043==
==17043== 100 errors in context 1 of 3:
==17043== Syscall param socketcall.sendto(msg) points to uninitialised byte(s)
==17043== at 0x5441DA2: send (send.c:28)
==17043== by 0x404C2D: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x404F1C: unix_socket::sendVectorXd(Eigen::Matrix<double, -1, 1, 0, -1, 1> const&) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x401F2A: main (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== Address 0x7feffff61 is on thread 1's stack
==17043== Uninitialised value was created by a stack allocation
==17043== at 0x404BE6: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043==
==17043==
==17043== 100 errors in context 2 of 3:
==17043== Syscall param socketcall.sendto(msg) points to uninitialised byte(s)
==17043== at 0x5441DA2: send (send.c:28)
==17043== by 0x404C2D: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x404E8A: unix_socket::sendVectorXd(Eigen::Matrix<double, -1, 1, 0, -1, 1> const&) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x401F2A: main (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== Address 0x7feffff61 is on thread 1's stack
==17043== Uninitialised value was created by a stack allocation
==17043== at 0x404BE6: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043==
==17043==
==17043== 9900 errors in context 3 of 3:
==17043== Syscall param socketcall.sendto(msg) points to uninitialised byte(s)
==17043== at 0x5441DA2: send (send.c:28)
==17043== by 0x404C2D: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x404EE8: unix_socket::sendVectorXd(Eigen::Matrix<double, -1, 1, 0, -1, 1> const&) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== by 0x401F2A: main (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043== Address 0x7feffff61 is on thread 1's stack
==17043== Uninitialised value was created by a stack allocation
==17043== at 0x404BE6: unix_socket::sendMsg(char, double) (in /home/joao/CloudPT/Bolsa/Webots/controllers/darwin-pi2/client)
==17043==
==17043== ERROR SUMMARY: 10100 errors from 3 contexts (suppressed: 0 from 0)

错误指向的 sendMsg(const char _type, const double _value)unix_socket 类的一部分:

//...
typedef struct{
char type;
double value;
} MESSAGE;

//...
int unix_socket::sendMsg(const char _type, const double _value){
MESSAGE msg;
msg.type=_type;
msg.value=_value;
int n = send(client_sock, &msg, sizeof(msg), 0);
if (n < 0) {
perror("send");
return -1;
}
c_sent=msg.type;
v_sent=msg.value;
return 0;
}

我看不出有什么问题。未初始化的值到底在哪里?或者我应该忽略 Valgrind 报告的错误?

最佳答案

查看MESSAGE 结构:

typedef struct{
char type;
double value;
} MESSAGE;

由于数据结构对齐,value 的地址可能被迫对齐到字长的倍数地址。因此,在 MESSAGE::typeMESSAGE::value 之间填充了几个未使用的字节。这些是未初始化的字节,因此由 Valgrind 报告。

作为解决方法,您可以通过 memset() 强制初始化整个结构。

MESSAGE msg;
memset(&msg, 0, sizeof(MESSAGE));
msg.type=_type;
msg.value=_value;

关于c++ - "points to uninitialised byte(s)"Valgrind 错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19364942/

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