Operating_System/fun_2.c

#include <string.h>
#include<fcntl.h> 
//#include "fun.h"

static int num = 0;
static char storage[MAXLINE][MAXLINE];

void history(char *cmdline)
{
    strcpy(storage[num], cmdline);
    num++;
}

void print_history(char *argv)
{
    int i = 0;
    if(argv == NULL)
    {
        for(; i<num; i++)
            puts(storage[i]);
        return;
    }
    i = num - atoi(argv);
    if(i < 0)
    {
        i = 0;
    }
    for(; i<num; i++)
        puts(storage[i]);
}


void shell_pip(char **prog1, char **prog2)
{
    int des_p[2];
    if(pipe(des_p) == -1)
    {
        perror("Pipe failed");
        exit(1);
    }
    if(fork() == 0)
    {
        close(1);
        dup(des_p[1]);
        close(des_p[0]);
        close(des_p[1]);
        execvp(prog1[0], prog1);
        perror("execvp of prog1 failed");
        exit(1);
    }
    if(fork() == 0)
    {
        close(0);
        dup(des_p[0]);
        close(des_p[1]);
        close(des_p[0]);
        execvp(prog2[0], prog2);
        perror("execvp of prog2 failed");
        exit(1);
    }
    close(des_p[0]);
    close(des_p[1]);
    wait(0);
    wait(0);
}

int Is_pipe(char **argv)
{
    int i = 0;
    int Ispipe = 0;
    char *cmd_0[MAXLINE];
    char *cmd_1[MAXLINE];
    while (argv[i]!=NULL)
    {
        if (argv[i][0] == '|')
        {
            Ispipe = 1;
        }
        i++;
    }
    if(Ispipe == 0)
    {
        return 0;
    }
    i = 0;
    while (argv[i][0] != '|')
    {
        cmd_0[i] = argv[i];
        i++;
    }
    cmd_0[i] = NULL;
    i++;
    int j = 0;
    while (argv[i]!=NULL)
    {
        cmd_1[j] = argv[i];
        i++;
        j++;
    }    
    cmd_1[j] = NULL;      
    shell_pip(cmd_0, cmd_1);
    return 1;
}


void shell_direct(char **prog1, char **prog2, char Isopen)
{    
    int fd;
if(Isopen == '>')
{
    if(fork() == 0)
    {   
        if( (fd=open(prog2[0],O_RDWR | O_CREAT | O_NOCTTY | O_NDELAY))<0 )
        {
            perror("open");
            exit(0);
        }
        close(1);
        dup(fd);
        close(fd);
        execvp(prog1[0], prog1);
        remove(prog2[0]);
        exit(0);
    }
    wait(0);
    if(fork() == 0)
    {   
        if( (fd=open(prog1[0],O_RDWR | O_NOCTTY | O_NDELAY))<0 )
        {
            exit(0);
        }
        close(0);
        dup(fd);
        close(fd);
        execvp(prog2[0], prog2);
        exit(0);
    }
    wait(0);
}
    if(Isopen == '<')
    {
        if(fork() == 0)
        {   
            if( (fd=open(prog2[0],O_RDWR | O_NOCTTY | O_NDELAY))<0 )
            {
                perror("open");
                exit(0);
            }
            close(0);
            dup(fd);
            close(fd);
            execvp(prog1[0], prog1);
            exit(0);
        }
        wait(0);
    }
    return;
}

int Is_redirect(char **argv)
{
    int i = 0;
    char Isopen = '0';
    char *cmd_0[MAXLINE];
    char *cmd_1[MAXLINE];
    while (argv[i]!=NULL)
    {
        if (argv[i][0] == '>')
        {
            Isopen = '>';
        }
        if (argv[i][0] == '<')
        {
            Isopen = '<';
        }
        i++;
    }
    if(Isopen == '0')
    {
        return 0;
    }
    i = 0;
    while (argv[i][0] != '>' && argv[i][0] != '<')
    {
        cmd_0[i] = argv[i];
        i++;
    }
    cmd_0[i] = NULL;
    i++;
    int j = 0;
    while (argv[i]!=NULL)
    {
        cmd_1[j] = argv[i];
        i++;
        j++;
    }    
    cmd_1[j] = NULL;

    shell_direct(cmd_0, cmd_1, Isopen);
    return 1;
}