msh.c

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include "proto.h"

/* Constants */

#define LINELEN 1024
#define EXPANDEDLEN 200000

/* Globals */
 int last_exit_status = 0;
 int m_argc;
 int m_shifted_argc;
 char **m_argv;
 char **m_shifted_argv;

/* Prototypes */

void processline (char *line, int outFD, int waitFlag);
void print_args(char **args);

/* Shell main */

int main (int mainargc, char **mainargv)
{
    // Defining Locals
    char *promptStr;
    char   buffer [LINELEN];
    int    len;
    FILE *fp;

    m_argc = mainargc;
    m_shifted_argc = mainargc;
    m_argv = mainargv;
    m_shifted_argv = mainargv;

    if(m_argc > 1) fp = fopen(m_argv[1], "r");
    else fp = stdin;

    if(fp == NULL)
    {
        fprintf(stderr, "./msh: Can not open file %s\n", m_argv[1]);
        exit(127);
    }

    while(1)
    {
        if(fp == stdin)
        {
            if(!(promptStr = getenv("P1"))) fprintf(stderr, "%% ");
            else fprintf(stderr, promptStr);
        }

        if(fgets(buffer, LINELEN, fp) != buffer) break;

        len = strlen(buffer);
        if (buffer[len-1] == '\n') buffer[len-1] = 0;

        processline (buffer, 1, 1); //, mainargc, mainargv, shiftedMArgV);
    }

    if (!feof(fp)) perror ("read");
    if(fclose(fp) != 0) perror("close");
    return 0;       /* Also known as exit (0); */
}


void processline (char *line, int outFD, int waitFlag) //, int mainargc, char **mainargv, char **shiftedMArgV)
{
    pid_t  cpid;
    int    status;
    /* All the parsed arguments, will be passed to exec */
    /* int expanded_len = 2048;*/
    char expanded_line[EXPANDEDLEN];
    char **args;
    int command_count;
    /* int index = 0; */

    if(expand(line, expanded_line, EXPANDEDLEN)) return; //, mainargc, mainargv, shiftedMArgV)) return;

    fprintf(stderr, "strlen(expanded) = %d\n", (int)strlen(expanded_line));

    command_count = arg_parse(expanded_line, &args);

    if(!command_count) return;

    if(!exec_if_built_in(args, outFD))
    {
        /* Start a new process to do the job. */
        cpid = fork();
        if (cpid < 0) {
            perror ("fork");
            free(args);
            return;
        }

        /* Check for who we are! */
        if (cpid == 0) {
          /* We are the child! */

            /* Turning stdout into pipe output if needed */
            if((dup2(outFD, 1)) < 0)
            {
                perror("dup");
                return;
            }

            execvp(args[0], args);
            perror ("exec");
            exit (127);
            last_exit_status = 127;
        }

        /* Have the parent wait for child to complete */
        if(waitFlag)
        {
            if (wait (&status) < 0) perror ("wait");
            last_exit_status = ((WEXITSTATUS(status) || !WIFEXITED(status)) ? 127 : 0);
        }
    }
    free(args);
}


/* Procedure for testing purposes,
prints the arguments of a command array */
void print_args(char **args)
{
    int i = 0;
    char** cmd = args;

    printf("COMMANDS: ");
    while(cmd[i] != 0)
    {
        printf("'%s'\n", cmd[i]);
        i++;
    }
}