[英]C++ : Send an object through a named pipe
I try to send an object through a named pipe, between two process, in C++ with ifstream and ofstream. 我尝试在C ++中使用ifstream和ofstream在两个进程之间通过命名管道发送对象。 I have read and try so many things but my research has led to nothing. 我已经阅读并尝试了很多东西,但是我的研究没有结果。
I block during the serialization of my object. 我在对象序列化期间阻塞。 When I try to cast and send to my named pipe, I can not recover my object to his normale state. 当我尝试投射并发送到命名管道时,无法将对象恢复到他的正常状态。
I try something with this code but the object is not full after its passage in the named pipe : 我尝试使用此代码进行操作,但是对象在命名管道中通过后未满:
#include <string.h>
#include <iostream>
#include <unistd.h>
#include <fstream>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
class Obj {
public:
std::string text1;
std::string text2;
};
int main() {
mkfifo("fifo", 0666);
if (fork() == 0) //Receiving Side
{
std::ifstream fifo("fifo", std::ofstream::binary);
//Re-make the object
Obj *tmp = new Obj();
char *b = new char[sizeof(*tmp)];
//Receive from named pipe
fifo >> b;
//Recover the object
memcpy(&*tmp, b, sizeof(*tmp));
//Display object content
std::cout << tmp->text1 << std::endl << tmp->text2 << std::endl;
//!\ Output = "Some \n" /!\\
fifo.close();
delete tmp;
delete[] b;
}
else //Sending Side
{
std::ofstream fifo("fifo", std::ofstream::binary);
//Create the object
Obj *struct_data = new Obj();
struct_data->text1 = "Some text";
struct_data->text2 = "Some text";
char *b = new char[sizeof(*struct_data)];
//Serialize the object
memcpy((void *)b, &*struct_data, sizeof(*struct_data));
//Send to named pipe
fifo << b;
fifo.close();
wait(NULL);
delete[] b;
}
//delete struct_data;
return (0);
}
Does someone could give me a tip or en example ? 有人可以给我小费或举个例子吗?
Thanks ! 谢谢 ! :) :)
You will need to serialize your object properly. 您将需要正确序列化您的对象。 Something like this (just did one member, the rest will be left as an excercise to the reader): 这样的事情(只有一名成员,其余的留给读者练习):
#include <iostream>
#include <fstream>
#include <cstring>
#include <sys/types.h>
#include <sys/stat.h>
class Obj
{
public:
std::string text1;
std::string text2;
friend std::ostream& operator<<(std::ostream &os, const Obj& o);
friend std::istream& operator>>(std::istream &os, Obj& o);
};
std::ostream& operator<<(std::ostream &os, const Obj& o)
{
os << o.text1.length();
os << o.text1;
return os;
}
std::istream& operator>>(std::istream &is, Obj& o)
{
size_t length;
is >> length;
char* tmp = new char[length];
is.get(tmp, length+1);
o.text1 = tmp;
delete[] tmp;
return is;
}
static const char* myfifo = "myfifo";
int main(int argc, char *argv[])
{
mkfifo(myfifo, 0666);
if (argc > 1)
{
std::ifstream infifo(myfifo, std::ifstream::binary);
Obj *tmp = new Obj();
infifo >> *tmp;
infifo.close();
std::cout << "Done reading : [" << tmp->text1 << "]" << std::endl;
}
else
{
std::ofstream outfifo(myfifo, std::ofstream::binary);
Obj *struct_data = new Obj();
struct_data->text1 = "Some text1";
struct_data->text2 = "Some text2";
outfifo << *struct_data;
}
return 0;
}
For more on serialization see https://stackoverflow.com/a/26337239/2742863 有关序列化的更多信息,请参见https://stackoverflow.com/a/26337239/2742863
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