linux单线程切换屏蔽stdout小组件

#ifndef PRINT_H
#define PRINT_H

#include <stdio.h>
class ReplaceStdout
{
public:
    ReplaceStdout();
    ~ReplaceStdout();
    bool isOK() { return _ok; }
private:
    bool _ok;
};
void print(const char* format, ...);
#endif

 

#include "print.h"
#include <stdarg.h>
#include <algorithm>

const static char* name = "/dev/null";
static FILE* std_file = fopen(name, "w");

bool replace()
{
    if (std_file) {
        fflush(stdout);
        std::swap(stdout->_fileno, std_file->_fileno);
        return true;
    }
    return false;
}

ReplaceStdout::ReplaceStdout():
    _ok(replace())
{
}

ReplaceStdout::~ReplaceStdout()
{
    replace();
}

void print(const char* format, ...)
{
    va_list args;
    va_start(args, format);
    vfprintf(1 == stdout->_fileno ? stdout : std_file,
            format, args);
    va_end(args);
}

 

#include "print.h"

int main(int argc, char* argv[])
{
    ReplaceStdout replace;
    printf("printf hello\n");
    print("print hello\n");
    //{ ReplaceStdout replace; }
    ReplaceStdout recover;
    printf("printf world\n");
    print("print world\n");
    return 0;
}