如何检查程序是否正在写入终端

这是我在代码审查上发布的问题的后续 - 终端上的彩色输出，我试图在终端上输出彩色字符串并通过isatty()调用检测它。然而，正如@Jerry棺材所指出的——

您可以使用 isatty 检查标准输出是否连接到终端，无论您要写入什么流。这意味着其余函数只有在将std::cout作为它们要写入的流传递时才能正常工作。否则，您可以在写入非 TTY 的内容时允许格式设置，并且可以在写入 TTY 内容时禁止格式化。

这是我不知道的事情（阅读为没有经验），我什至不知道cin/cout可以重定向到其他地方的事实。所以我试图阅读更多关于它的信息，并发现了一些关于 SO 的现有问题。这是我一起破解的内容：

// initialize them at start of program - mandatory
std::streambuf const *coutbuf = std::cout.rdbuf();
std::streambuf const *cerrbuf = std::cerr.rdbuf();
std::streambuf const *clogbuf = std::clog.rdbuf();

// ignore this, just checks for TERM env var
inline bool supportsColor()
    {
        if(const char *env_p = std::getenv("TERM")) {
            const char *const term[8] = {
                "xterm", "xterm-256", "xterm-256color", "vt100",
                "color", "answersi",      "cygwin",         "linux"};
            for(unsigned int i = 0; i < 8; ++i) {
                if(std::strcmp(env_p, term[i]) == 0) return true;
            }
        }
        return false;
    }
rightTerm = supportsColor();
// would make necessary checks to ensure in terminal
inline bool isTerminal(const std::streambuf *osbuf)
    {
        FILE *currentStream = nullptr;
        if(osbuf == coutbuf) {
            currentStream = stdout;
        }
        else if(osbuf == cerrbuf || osbuf == clogbuf) {
            currentStream = stderr;
        }
        else {
            return false;
        }
        return isatty(fileno(currentStream));
    }
// this would print checking rightTerm && isTerminal calls
inline std::ostream &operator<<(std::ostream &os, rang::style v)
    {
        std::streambuf const *osbuf = os.rdbuf();
        return rightTerm && isTerminal(osbuf)
                   ? os << "e[" << static_cast<int>(v) << "m"
                   : os;
    }

我的主要问题是，尽管我已经手动测试了它，但我不知道这可能会失败的情况或可能包含的错误。这是做这件事的正确方法吗？我可能缺少什么吗？

下面是一个运行示例（您还需要一个包含随机数据的in.txt）：

#include <iostream>
#include <fstream>
#include <string>
#include <unistd.h>
#include <cstdlib>
#include <cstring>
void f();
bool supportsColor();
// sample enum for foreground colors
enum class fg : unsigned char {
    def     = 39,
    black   = 30,
    red     = 31,
    green   = 32,
    yellow  = 33,
    blue    = 34,
    magenta = 35,
    cyan    = 36,
    gray    = 37
};
// initialize them at start of program - mandatory
// so that even if user redirects, we've a copy
std::streambuf const *coutbuf = std::cout.rdbuf();
std::streambuf const *cerrbuf = std::cerr.rdbuf();
std::streambuf const *clogbuf = std::clog.rdbuf();
// check if TERM supports color
bool rightTerm = supportsColor();
// Here is the implementation of isTerminal
// which checks if program is writing to Terminal or not
bool isTerminal(const std::streambuf *osbuf)
{
    FILE *currentStream = nullptr;
    if(osbuf == coutbuf) {
        currentStream = stdout;
    }
    else if(osbuf == cerrbuf || osbuf == clogbuf) {
        currentStream = stderr;
    }
    else {
        return false;
    }
    return isatty(fileno(currentStream));
}
// will check if TERM supports color and isTerminal()
inline std::ostream &operator<<(std::ostream &os, fg v)
{
    std::streambuf const *osbuf = os.rdbuf();
    return rightTerm && isTerminal(osbuf)
               ? os << "e[" << static_cast<int>(v) << "m"
               : os;
}

int main()
{
    std::cout << fg::red << "ERROR HERE! " << std::endl
              << fg::blue << "ERROR INVERSE?" << std::endl;
    std::ifstream in("in.txt");
    std::streambuf *Orig_cinbuf = std::cin.rdbuf(); // save old buf
    std::cin.rdbuf(in.rdbuf()); // redirect std::cin to in.txt!
    std::ofstream out("out.txt");
    std::streambuf *Orig_coutbuf = std::cout.rdbuf(); // save old buf
    std::cout.rdbuf(out.rdbuf()); // redirect std::cout to out.txt!
    std::string word;
    std::cin >> word;                      // input from the file in.txt
    std::cout << fg::blue << word << "  "; // output to the file out.txt
    f(); // call function
    std::cin.rdbuf(Orig_cinbuf);   // reset to standard input again
    std::cout.rdbuf(Orig_coutbuf); // reset to standard output again
    std::cin >> word;  // input from the standard input
    std::cout << word; // output to the standard input
    return 0;
}
void f()
{
    std::string line;
    while(std::getline(std::cin, line)) // input from the file in.txt
    {
        std::cout << fg::green << line << "n"; // output to the file out.txt
    }
}
bool supportsColor()
{
    if(const char *env_p = std::getenv("TERM")) {
        const char *const term[8] = {"xterm",  "xterm-256", "xterm-256color",
                                     "vt100",  "color",     "answersi",
                                     "cygwin", "linux"};
        for(unsigned int i = 0; i < 8; ++i) {
            if(std::strcmp(env_p, term[i]) == 0) return true;
        }
    }
    return false;
}

^{我也标记了c语言，尽管这是c++代码，因为相关代码是共享的黑白两个，我不想错过任何建议}