TASK

打造一个绝无伦比的 xxx-super-shell (xxx 是你的名字)，它能实现下面这些功能：

  • 实现管道（也就是 |）
  • 实现输入输出重定向（也就是 < > >>）
  • 要求在管道组合命令的两端实现重定向运算符

PLAN

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# 需要实现的功能
cat < 1.txt | grep -C 10 abc | grep -Lefd | tac >> 2.txt
# 不需要实现的功能
cat < 1.txt | grep -C 10 abc > test1.txt | test2.txt > grep -L efd | tac >> 2.txt
  • 实现后台运行（也就是 &）
  • 实现 cd，要求支持能切换到绝对路径、相对路径和支持 cd -
  • 屏蔽一些信号（如 ctrl + c 不能终止）
  • 界面美观
  • 开发过程记录、总结、发布在个人博客中
    要求：
  • 不得出现内存泄漏、内存越界等错误 - 学会如何使用 gdb 进行调试，使用 valgrind 等工具进行检测

ish.cpp

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#include"shell.hpp"
#define DB 1    // DB为1时,进入debug模式 不屏蔽信号
int main()
{
    ish sh;
    Prompt pr;
    Command cmd;
    void show();
    show();
    if(!DB)nosignal();
    system("clear"); 
    while(true)
    {
        pr.PrintPrompt();
        sh.GetCommand();
        cmd.Process();
        sh.LineClear();
    }

    return -1;
}

shell.hpp

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#include<iostream>
#include<string>
#include<vector>
#include<unistd.h>
#include<sys/ioctl.h>
#include<signal.h>
#include<string.h>
#include<sys/wait.h>
#include<fcntl.h>
#include<pwd.h>

using namespace std;

void nosignal();
vector<string> split(string,char);
vector<char*>fromStoC(vector<string>);
bool isRedirect(string);

class ish
{
friend vector<string>split(string,char);
friend bool isRedirect(string);

public:
    void GetCommand();
    void LineClear();
    bool iscd();

    ish()
    {
        char path[64];
        realpath(".",path);
        wdPath = path;
        setenv("OWD",".",1);
        char hostname[64];
        gethostname(hostname,64);
        hostName = hostname;
        int userid = getuid();
        struct passwd * pwd = getpwuid(userid);
        userName = pwd->pw_name;
    }

protected:
    string hostName;
    string userName;
    string gitHEAD = "master";
    static string wdPath;
    static string line;
    static vector<string>argv;
    static vector<int *>fds;
    static int ExeCount;
    static bool pipeError;
    int PromptLen;
    static bool isError;
};

class Prompt: public ish
{
public:
    void PrintPrompt();
    Prompt()
    {
        failed = "\e[100m\e[31m ✘\e[39m";
        isError = false;
    }

private:
    string colors;
    string output;
    string failed;
};

class Command: public Prompt
{
public:
    bool isClear();
    void isExit();
    void ExeCommand();
    void Process();
};

using.cpp

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#include"shell.hpp"
void show()
{
    string showName[9];
    showName[0] = "      __                                               __         ";
    showName[1] = "     /\\ \\                                  __         /\\ \\        ";
    showName[2] = "  ___\\ \\ \\___         ___ ___   __  __    /\\_\\    ____\\ \\ \\___    ";
    showName[3] = " / __`\\ \\  _ `\\     /' __` __`\\/\\ \\/\\ \\   \\/\\ \\  /',__\\ \\  _ `\\  ";
    showName[4] = "/\\ \\L\\ \\ \\ \\ \\ \\    /\\ \\/\\ \\/\\ \\ \\ \\_\\ \\   \\ \\ \\/\\__, `\\ \\ \\ \\ \\ ";
    showName[5] = "\\ \\____/\\ \\_\\ \\_\\   \\ \\_\\ \\_\\ \\_\\/`____ \\   \\ \\_\\/\\____/ \\ \\_\\ \\_\\";
    showName[6] = " \\/___/  \\/_/\\/_/    \\/_/\\/_/\\/_/`/___/> \\   \\/_/\\/___/   \\/_/\\/_/";
    showName[7] = "                                    /\\___/                        ";
    showName[8] = "                                    \\/__/                         ";

    for(int i = 0;i<9;i++)
    {
        printf("\e[9%dm",i);
        cout<<showName[i]<<endl;
        usleep(110000);
    }
    cout<<"输入 '?' 以获取帮助"<<endl;
    cout<<"请按任意键继续";
    getchar();
}

string ish::wdPath;
string ish::line;
vector<string> ish::argv;
bool ish::isError = false;
int ish::ExeCount = 0;
vector<int *> ish::fds;
bool ish::pipeError = false; 
void help();
vector<string> split(string s,char ch)
{
    vector<string>result;
    int pos = 0;
    while (s[pos]==ch)
        pos++;
    
    while (pos< s.size())
    {
        int n = 0;
        while (s[pos+n]!=ch&&pos+n<s.size())
        {
            n++;
        }
        result.push_back(s.substr(pos,n));
        pos += n;
        while (s[pos] ==ch&&pos<s.size())
        {
            pos++;
        }
    }
    return result;
}

vector<char *> fromStoC(vector<string>s)
{
    vector<char *>c;
    for(int i = 0;i<s.size();i++)
    {
        char * buf = new char[s[i].size()];
        strcpy(buf,s[i].c_str());
        c.push_back(buf);
    }
    return c;
}

void nosignal()
{
    signal(SIGINT,SIG_IGN);
}

bool isRedirect(string str)
{
    if(str.find('<')==-1&&str.find('>')==-1)
        return 0;
    return 1;
}

void Prompt::PrintPrompt()
{
    output = "\e[100m" + (string)" " + userName + "@" + hostName + " " + (string)"\e[90m" + (string)"\e[104m" + "" + " " + wdPath + " " + "\e[43m" + "\e[34m" + "" + "\e[33m" + "  " + gitHEAD + " ± " + "\e[33m" + "\e[49m" + "" + "\e[39m\e[0m";
    isError ? (cout<< failed + output << " ") : cout << output << " ";
    isError = false;
}

void ish::GetCommand()
{
    FLAG:
    getline(cin,line);  // get a line of command
    int pos = 0;
    while (line[pos] == ' ')
    {
        pos ++;
    }
    line = line.substr(pos);
    argv = split(line,' ');
    if(line.empty())
    {
        Prompt news;
        news.PrintPrompt();
        goto FLAG;
    }
}

void ish::LineClear()
{
    line.clear();
}

bool Command::isClear()
{
    if(line == "clear"||line == "cls")
    {    
        system("clear");
        return true;
    }
    return false;
}

void Command::isExit()
{
    if(line == "exit")
        exit(EXIT_SUCCESS);
}

bool isH(string line)
{
    if(line=="?")
    {
        help();
        return true;
    }
    if(line=="!")
    {
        show();
        return true;
    }
    return false;
}

void Command::Process()
{
    if(isH(line))
        return;
    vector<int *>vpipes;
    vector<string>v = split(line,'|');
    if(v.size()==1)
    {
        argv = split(v[0],' ');
        ExeCommand();
    }
    else
    {
        if(v.size()==0)
        {
            cout<<"ish: | 解析错误"<<endl;
            isError = 1;
            return;
        }
        for(int i = 0;i<v.size()-1;i++)
        {
            int * fd = new int[2];
            pipe(fd);
            fds.push_back(fd);
        }

        for(int i = 0;i<v.size();i++)
        {
            argv = split(v[i],' ');
            ExeCommand();

            if(ExeCount != 0)close(fds[ExeCount-1][0]);
            if(ExeCount != fds.size())close(fds[ExeCount][1]);    

            ExeCount ++;
        }
        ExeCount = 0;
        fds.clear();
    }
}

void Command::ExeCommand()
{
    vector<char *>ar = fromStoC(argv);

    if(isClear()||iscd())
        return;
    isExit();

    pid_t pid = fork();
    
    if(pid == 0)
    {
        if(ExeCount != 0)dup2(fds[ExeCount-1][0],0);
        if(ExeCount != fds.size())dup2(fds[ExeCount][1],1);
        
        if(isRedirect(line))
        {
            if(argv.size()<3)
            {
                cout<<"ish: 重定向 解析错误"<<endl;
                isError = 1;
                return;
            }
            for(int i = 0;i<argv.size();i++)
            {
                if(argv[i]=="<")
                {
                    int fd = open(argv[i+1].data(),O_RDONLY);
                    dup2(fd,0);
                    ar.erase(ar.begin()+i);
                    close(fd);
                }
                if(argv[i]==">")
                {
                    int fd = open(argv[i+1].data(),O_RDWR|O_CREAT|O_TRUNC,S_IRUSR|S_IWUSR);
                    dup2(fd,1);
                    ar.erase(ar.begin()+i);
                    ar.erase(ar.begin()+i+1);
                    close(fd);
                }
                if(argv[i]==">>")
                {
                    int fd = open(argv[i+1].data(),O_RDWR|O_APPEND|O_CREAT,S_IRUSR|S_IWUSR);
                    dup2(fd,1);
                    ar.erase(ar.begin()+i);
                    ar.erase(ar.begin()+i+1);
                    close(fd);
                }
            }
        }

        ar.push_back(NULL);

        if(strcmp(ar[0],"ls")==0)
        {
            ar.pop_back();
            ar.push_back((char *)"--color=auto");
            ar.push_back(NULL);
        }

        if(execvp(ar[0],ar.data())==-1)
        {
            isError = true;
            cout<<"ish: command not found: "<<argv[0]<<endl;
            return;
        }
    }
    wait(&pid);
}

bool ish::iscd()
{
    if(argv[0]!="cd")
        return 0;
    
    char * homepath = getenv("HOME");
    if(argv[0] == "cd"&&argv.size()==1)
        argv.push_back(homepath);

    
    if(argv[1]=="-")
    {
        char * lpath = getenv("OWD");
        cout<<lpath<<endl;
        if(chdir(lpath)==-1)
        {
            isError = true;
        }
        wdPath = lpath;
        return 1;
    }
    char rp[1000];
    realpath(argv[1].c_str(),rp);
    if(chdir(argv[1].c_str())==-1)
    {
        cout<<"cd: path not found"<<endl;
        isError = true;
        return 1;
    }
    
    setenv("OWD",wdPath.c_str(),1);
    wdPath = rp;

    return 1;
}

void help()
{
    cout<<"你知道吗？输入!可以观看炫酷的动画。"<<endl;
}