msh-console/library/shell.cpp

/**
    MIT License

    Copyright (c) 2016 Claudio Maggioni

    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
*/

#include "shell.h"
namespace mshconsole {
    const std::string& Shell::getPs() const{
        return ps;
    }

    void Shell::setPs(const std::string &value){
        ps = value;
    }

    const std::string& Shell::getName() const{
        return name;
    }

    void Shell::setName(const std::string &value){
        name = value;
    }

    Shell::Shell(std::string nam, std::string ps, std::istream &i, std::ostream &o, std::ostream &e,
          void (*s)(Shell*), void (*pss)(Shell*)) : cmds(this), inputStream(i),
          outputStream(o), errorStream(e){
        shellSetup = s;
        name = nam;
        this->ps = ps;
        shellPostSetup = pss;
    }

    int Shell::launch(){
        //Forbid launching shell if it is already launched in other threads.
        static bool notLoop=false;
        if(notLoop) return -1;
        notLoop = true;

        //Launch the shell setup.
        if(shellSetup!=0) (*shellSetup)(this);

        //Run the shell loop.
        int exitCode;
        std::string* line=nullptr;
        std::vector<std::string> p;

        try{
            while(1){
                delete line;
                outputStream << ps << " "; //Print the prompt.

                //Try reading the line. if SIGINT is caught, print another time the prompt and retry.
                try{
                    line = readLine();
                }
                catch (IsUndoingLineException){
                    outputStream << "\n";
                    continue;
                }

                //Try line conversion from string to argc and argv. stringToArgcArgv() throws a std::runtime_error
                //exception if the string has unproper quotes.
                try{
                    p = splitLine(line);
                }
                catch(std::runtime_error e){
                    errorStream << name << ": error in line parsing\n";
                    errorStream << e.what() << "\n";
                    continue;
                }

                //Execute the pipe.
                executePipe(p);
            };
        } catch(CommandExecutor::ExitException c) {
            delete line;
            exitCode=c.getCode();
        }

        //Launch postSetup().
        if(shellPostSetup!=0) shellPostSetup(this);

        notLoop = false;
        return exitCode;
    }

    int Shell::executePipe(std::vector<std::string>& argv)
    {
        int newPipe[2], oldPipe[2], status;
        pid_t pid;

        std::vector<std::vector<std::string>> argvs;

        size_t c=0, i=0;
        for(; i<argv.size(); i++){
            if(argv[i]=="|"){ //Pipe reached
                if(c!=i){
                    //Write the command in the pipe std::vector
                    argvs.push_back(std::vector<std::string>(argv.begin()+c, argv.begin()+i));
                }
                c=i+1;
            }
        }
        if(c!=i){
            //Write the last command in the pipe std::vector
            argvs.push_back(std::vector<std::string>(argv.begin()+c, argv.end()));
        }
        if(argvs.size()==1){
            struct Params p;
            vectorToArgcArgv(argvs[0], &p.argc, &p.argv);
            return executeCmd(p,false);
        }
        for(size_t i=0; i<argvs.size(); i++){
            if(cmds.found(std::string(argvs[i][0]),false)){
                errorStream << name << ": non-thread command " << argv[0] << " can't be launched from a pipe" << std::endl;
                return 1;
            }
        }
        for(size_t i=0; i<argvs.size(); i++) /* For each command */
        {
            struct Params p;
            vectorToArgcArgv(argvs[i], &p.argc, &p.argv);

            /* If there still are commands to be executed */
            if(i < argvs.size()-1)
            {
                pipe(newPipe); /* just create a pipe */
            }

            pid = fork();

            if(pid == 0)  /* Child */
            {
                /* If there is a previous command */
                if(i > 0)
                {
                    close(oldPipe[1]);
                    dup2(oldPipe[0], 0); //redirect stdin to input of the pipe
                    close(oldPipe[0]);
                }

                /* If there still are commands to be executed */
                if(i < argvs.size()-1)
                {
                    close(newPipe[0]);
                    dup2(newPipe[1], 1); //redirect stdout to output of the pipe
                    close(newPipe[1]);
                }

                //Execute
                exit(executeCmd(p,true));
            }
            else if (pid < 0) {
                // Error forking
                errorStream << name <<": error in process forking.\n";
            }
            else /* Father */
            {
                /* If there is a previous command */
                if(i > 0)
                {
                    close(oldPipe[0]);
                    close(oldPipe[1]);
                }

                /* do we have a next command? */
                if(i < argvs.size()-1)
                {
                    oldPipe[0] = newPipe[0];
                    oldPipe[1] = newPipe[1];
                }

                /* wait for last command process? */
                if(i == argvs.size()-1)
                {
                    waitpid(pid, &status, 0);
                }
            }
            deleteParams(p);
        }
        return 0;
    }

    int Shell::launchCmd(const struct Params& p){
        int status;

        pid_t pid = fork();
        if (pid == 0) {
            //child process

            //execute threadCommand
            int a;

            try {
                a=cmds.launch(p, true);
                std::exit(EXIT_SUCCESS);
            }
            catch (CommandNotFoundException){}

            //execute bash command or program
            a=execvp(p.argv[0], p.argv);

            if(a == -1) {
                outputStream << name << ": execution failed. Errno is set to: "<<strerror(errno)<<"\n";
                std::exit(EXIT_FAILURE);
            }
            else std::exit(EXIT_SUCCESS);
        }
        else if (pid < 0) {
            // Error forking
            errorStream << name <<": error in process forking.\n";
        }
        else {
            // Parent process
            do {
                //wait until child finished
                waitpid(pid, &status, WUNTRACED);
            } while (!WIFEXITED(status) && !WIFSIGNALED(status));
        }
        return 1;
    }

    int Shell::executeCmd(const struct Params& p, bool isPipe){
        if (!p.argc) return 1; //Return if the line is empty.

        if(isPipe){
            if(cmds.found(p.argv[0],false)){
                errorStream << name << ": non-thread command " << p.argv[0] << " can't be launched from a pipe" << std::endl;
                return 1;
            }
        }
        else{
            try {
                //Search in non-thread commands.
                return cmds.launch(p, false);
            }
            catch(CommandNotFoundException) {}
        }
        //Execute the threadCommand or the executable.
        return launchCmd(p);
    }

    inline int Shell::executeCmd(const std::string &args){
        std::vector<std::string>a =splitLine(&args);
        return executePipe(a);
    }

    void Shell::SIGINTHandler(int,siginfo_t*, void *){
        SIGINTRaised = true;
    }

    void Shell::setShellSetup(void (*s)(Shell *)){
        shellSetup=s;
    }

    void (*Shell::getShellSetup())(Shell*) const{
        return shellSetup;
    }

    void Shell::setShellPostSetup(void (*s)(Shell *)){
        shellPostSetup=s;
    }

    void (*Shell::getShellPostSetup())(Shell*) const{
        return shellPostSetup;
    }


    struct sigaction* setHandler(unsigned signal, void (*funcptr)(int, siginfo_t*, void*)){
        struct sigaction* before = new struct sigaction();
        struct sigaction sa;
        sigset_t mask;
        sigemptyset(&mask);
        sigaddset(&mask, SIGTERM);
        sa.sa_mask=mask;
        sa.sa_sigaction = funcptr;
        sa.sa_flags = SA_RESTART;
        sigaction(signal, &sa, before);
        return before;
    }

    void restoreHandler(unsigned signal, struct sigaction* before){
        sigaction(signal, before, NULL);
        delete before;
    }

    std::string* Shell::readLine(){
        std::string* buffer = new std::string();
        struct sigaction* beforeSIGINT = setHandler(SIGINT,SIGINTHandler);
        getline(inputStream,*buffer); //Get line of input TODO: handle directional keys
        inputStream.clear();  //Clear flags. This is needed for the detection of SIGINT

        if(SIGINTRaised){
            SIGINTRaised=false;
            throw IsUndoingLineException();
        }

        restoreHandler(SIGINT, beforeSIGINT);
        return buffer;
    }

    std::vector<std::string> Shell::splitLine(const std::string* line){
        return parseStringToVector(*line);
    }

    void Shell::deleteParams(struct Params p){
        freeString(p.argc,p.argv);
    }

    bool Shell::SIGINTRaised = false;

    void Shell::addCmd(Command* cmd, bool isthread){
        cmds.add(cmd, isthread);
    }

    size_t Shell::howManyCmds() const{
        return cmds.howMany();
    }
}