commandHandler.c

#include "headers.h"
#include "commands.h"
#include "commandHandler.h"
#include "childHandler.h"

static int num_custom_commands=13;
int BACKUP_STDOUT_FILENO_1, BACKUP_STDIN_FILENO_1;
extern int numbgChilds;
//extern process bgProcess[50]; Moved to Linked List
extern Node *listptr;
process tempProcess;
char nText[PATH_MAX];

void removeWhiteSpaces(char *text){
    int start=0, end=strlen(text);
    while(text[start]==' ') start+=1;
    while(text[end]==' '){
        text[end]=='\0';
        end-=1;
    }
    int i=start, j=0;
    while(text[i]!='\0'){
        if(!(text[i]==' ' && text[i+1]==' ')){
            nText[j]=text[i];
            j++;
        }
        i++;
    }
    nText[j]='\0';
}

int isAnd(char *input){
    int i=strlen(input)-1;
    *input=*(input+i);
    while(input[i]==' ')
        i-=1;
     if(input[i]=='&'){
         input[i]=='\0';
         return 1;
     }
     return 0;
        
}

int runCommand(char **parsed, char* input){
    // Backing up file descriptors of STDIN and STDOUT 
    BACKUP_STDIN_FILENO_1=dup(STDIN_FILENO);
    BACKUP_STDOUT_FILENO_1=dup(STDOUT_FILENO);
    
    removeWhiteSpaces(input); // Stores Command without whitespaces in nText
    char* custom_commands[num_custom_commands];
    custom_commands[0]="echo";
    custom_commands[1]="ls";
    custom_commands[2]="cd";
    custom_commands[3]="history";
    custom_commands[4]="pwd";
    custom_commands[5]="pinfo";
    custom_commands[6]="setenv";
    custom_commands[7]="unsetenv";
    custom_commands[8]="jobs";
    custom_commands[9]="kjob";
    custom_commands[10]="fg";
    custom_commands[11]="bg";
    custom_commands[12]="overkill";

    int i, command_id=0;
    for(i=0;i<num_custom_commands;i++){
        if(!strcmp(parsed[0], custom_commands[i])){
            command_id=i+1;
            break;
        }
    }
    // Check for input Output Redirection
    char inpfile[PATH_MAX], opfile[PATH_MAX];
    int l=0, inp=0, op=0, opc=0, inflag=0, outflag=0;
    while(nText[l]!='\0'){
        if(nText[l]=='>'){
            if(nText[l+1]=='>'){
                opc=1;
                op=l+3;
            }else{
                op=l+2;
            }
            nText[l]='\0';
            outflag+=1;
            if(opc)
                l+=1;
        }
        if(nText[l]=='<'){
            inp=l+2;
            nText[l]='\0';
            inflag+=1;
        }
        l++;
    }
    if(outflag <=1 && inflag <=1){
        int w;
        if(inflag){
            strcpy(inpfile, &nText[inp]);
            w=strlen(inpfile)-1;
            while(inpfile[w]==' ') w--;
            inpfile[w+1]='\0';
        }if(outflag){
            strcpy(opfile, &nText[op]);
            w=strlen(opfile)-1;
            while(opfile[w]==' ') w--;
            opfile[w+1]='\0';
        }
    }else{
        printf("More than one of input or output Redirection detected. Aborting...\n");
        return -1;
    }
    
    if(inflag==1){
        int infd=open(inpfile, O_RDONLY, 0644);;
        if (dup2(infd, STDIN_FILENO) < 0) {
            perror("Unable to open input file: ");
            return -1;
        }    
    }
    if(outflag==1){
        int ofd;
        if(opc==1){
            ofd = open(opfile, O_WRONLY | O_CREAT | O_APPEND, 0644);
        }else{
            ofd = open(opfile, O_WRONLY | O_CREAT | O_TRUNC, 0644);
        }
        if (dup2(ofd, STDOUT_FILENO) < 0) {
            perror("Unable to duplicate file descriptor.");
            return -1;
        }           
    }
    // if inflag or outflag are > 1  then multiple in and out Redirection which is not supported and hence will error.
    // Making sure redirection parts aare removed from 2d array
    l=0;
    while(parsed[l]!=NULL){
        if(parsed[l][0]=='<' || parsed[l][0]=='>' ){
            parsed[l]=NULL;
            break;
        }
        l++;
    }
    // Running Commands
    if(command_id)
        runOwnCommand(command_id, &nText[strlen(custom_commands[command_id-1]) + 1 ], parsed);
    else{
        int is_and=isAnd(input);
        if(is_and){
            int i=0, j=0;
            while(parsed[i]!=NULL)
                i+=1;
            j=strlen(parsed[i-1]);
            if(j<=1)
                parsed[i-1]=NULL;
            else{
                while(parsed[i-1][j]!='&') j--;
                if(parsed[i-1][j]=='&')
                    parsed[i-1][j]='\0';
            }
        }
        int f = fork();
        if (f>0){
            if(inflag || outflag){
                // Restoring back to original
                if (dup2(BACKUP_STDOUT_FILENO_1, STDOUT_FILENO) < 0) {
                    perror("Could Not restore to original output stream");
                    exit(1);
                }    
                if (dup2(BACKUP_STDIN_FILENO_1, STDIN_FILENO) < 0) {
                    perror("Could Not restore to original input stream");
                    exit(1);
                }
            }

            if(!is_and){
                signal(SIGTTIN, SIG_IGN);
                signal(SIGTTOU, SIG_IGN);
                tcsetpgrp(STDIN_FILENO, f);                
                int status;
                do{
                    waitpid(f, &status, WUNTRACED);
                }while(!WIFEXITED(status) && !WIFSIGNALED(status) && !WIFSTOPPED(status));                
                //fflush(stdout);
                tcsetpgrp(STDIN_FILENO, getpgid(0));
                signal(SIGTTIN, SIG_DFL);
                signal(SIGTTOU, SIG_DFL);
                if (WIFSTOPPED(status)) {
                    tempProcess.id=f;
                    tempProcess.inbg=0;
                    strcpy(tempProcess.name, parsed[0]);
                    numbgChilds+=1;
                    tempProcess.num=numbgChilds;
                    printf("[%d] %d\n", numbgChilds, f);
                    createListNode(tempProcess);                        
                }
            }else{
                tempProcess.id=f;
                tempProcess.inbg=0;
                strcpy(tempProcess.name, parsed[0]);
                numbgChilds+=1;
                tempProcess.num=numbgChilds;
                printf("[%d] %d\n", numbgChilds, f);
                createListNode(tempProcess);
            }
            return 0;
        }else if(f<0){
            printf("\nFork Failed\n");
        }else {
            //if(is_and){
                setpgid(0, 0);
            //}
            //FILE *tF;
            //tF=fopen("test", "a");
            //fprintf(tF, "START:Child id=%d command=%s\n", getpid(), parsed[0]);
            //fclose(tF);
            if(execvp(parsed[0], parsed)==-1){
                printf("\nbash: %s: command not found\n", parsed[0]);
                exit(1);
            }
            //tF=fopen("test", "a");
            //fprintf(tF, "END:Child id=%d command=%s\n", getpid(), parsed[0]);
            //fclose(tF);
            exit(0);
        }
    }
    if(inflag || outflag){
        // Restoring back to original
        if (dup2(BACKUP_STDOUT_FILENO_1, STDOUT_FILENO) < 0) {
            perror("Could Not restore to original output stream");
            exit(1);
        }    
        if (dup2(BACKUP_STDIN_FILENO_1, STDIN_FILENO) < 0) {
            perror("Could Not restore to original input stream");
            exit(1);
        }
    }
}

int runOwnCommand(int command_id, char* input, char** parsed){
    switch(command_id){
        case 1: echo(input); break;
        case 2: ls(parsed); break;
        case 3: cd(input); break;
        case 4: print_history(input); break;
        case 5: pwd(); break;
        case 6: pinfo(input); break;
        case 7: csetenv(parsed); break;
        case 8: cunsetenv(parsed); break;
        case 9: printProcess(); break;
        case 10: kjob(parsed); break;
        case 11: fg(parsed); break;
        case 12: bg(parsed); break;
        case 13: 
            if(killallChilds()==1); 
                printf("No Process in bg\n");
            break;
        default: break;
    }
    return 0;
}