msh-console/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;

        try{
            std::string* line=nullptr;
            struct Params p;

            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 command.
                executeCmd(p);
            };
        } catch(CommandExecutor::ExitException c) {
            exitCode=c.getCode();
        }

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

        notLoop = false;
        return exitCode;
    }

    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
            if((a=execvp(p.argv[0], p.argv)) == -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){
        if (!p.argc) return 1; //Return if the line is empty.

        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){
        return executeCmd(splitLine(&args));
    }

    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;
        sa.sa_sigaction = funcptr;
        sa.sa_flags = 0;
        sigaction(signal, &sa, 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;
    }

    struct Params Shell::splitLine(const std::string* line){
        struct Params p;
        stringToArgcArgv(*line, &(p.argc), &(p.argv));
        return p;
    }

    bool Shell::SIGINTRaised = false;

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

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