wshell.c

/*
 * =====================================================================================
 *       Filename:  wshell.c
 *    Description:  
 *        Version:  1.0
 *        Created:  2013.10.16 17h12min19s
 *         Author:  wuyue (wy), vvuyve@gmail.com
 *        Company:  UESTC
 * =====================================================================================
 */
#include "wshell.h"
#define TRUE 1
#define MAXPIDTABLE 1024

pid_t BPTable[MAXPIDTABLE];

void sig_handler(int sig)
{
    pid_t pid;
    int i;
    for(i=0;i<MAXPIDTABLE;i++)
        if(BPTable[i] != 0) //only handler the background processes
        {
            pid = waitpid(BPTable[i],NULL,WNOHANG);
            if(pid > 0)
            {
                printf("process %d exited.\n",pid);
                BPTable[i] = 0; //clear
            }
            else if(pid < 0)
            {
	if(errno != ECHILD)
                    perror("waitpid error");
            }
            //else:do nothing.
            //Not background processses has their waitpid() in wshell.
         }
    return;
}

void proc(void)
{
    int status,i;
    char *command = NULL;
    char **parameters;
    int ParaNum;
    char prompt[MAX_PROMPT];
    struct parse_info info;
    pid_t ChdPid,ChdPid2;
    parameters = malloc(sizeof(char *)*(MAXARG+2));
    buffer = malloc(sizeof(char) * MAXLINE);
    if(parameters == NULL || buffer == NULL)
    {
        printf("Wshell error:malloc failed.\n");
        return;
    }
	//arg[0] is command
	//arg[MAXARG+1] is NULL

    if(signal(SIGCHLD,sig_handler) == SIG_ERR)
        perror("signal() error");

    while(TRUE)
    {
        int pipe_fd[2],in_fd,out_fd;
        type_prompt(prompt);
        ParaNum = read_command(&command,parameters,prompt);
        if(-1 == ParaNum)
            continue;
        ParaNum--;//count of units in buffer
        parsing(parameters,ParaNum,&info);
        if(builtin_command(command,parameters))
            continue;
        if(info.flag & IS_PIPED) //command2 is not null
        {                
            if(pipe(pipe_fd)<0)
            {
                printf("Wshell error:pipe failed.\n");
                exit(0);
            }
        }  
        if((ChdPid = fork())!=0) //wshell
        {
            if(info.flag & IS_PIPED)
            {
                if((ChdPid2=fork()) == 0) //command2
                {
                    close(pipe_fd[1]);
                    close(fileno(stdin)); 
                    dup2(pipe_fd[0], fileno(stdin));
                    close(pipe_fd[0]); 
                    execvp(info.command2,info.parameters2);
                }
                else
                {
                    close(pipe_fd[0]);
                    close(pipe_fd[1]);
                    waitpid(ChdPid2,&status,0); //wait command2
                }
            }

            if(info.flag & BACKGROUND)
            {
                printf("Child pid:%u\n",ChdPid);
                int i;
                for(i=0;i<MAXPIDTABLE;i++)
                    if(BPTable[i]==0)
                        BPTable[i] = ChdPid; //register a background process
                if(i==MAXPIDTABLE)
                    perror("Too much background processes\nThere will be zombine process");                    
            }
            else
            {          
                waitpid(ChdPid,&status,0);//wait command1
            } 
        }
        else //command1
        {
			
            if(info.flag & IS_PIPED) //command2 is not null
            {                
                if(!(info.flag & OUT_REDIRECT) && !(info.flag & OUT_REDIRECT_APPEND)) // ONLY PIPED
	           {
                    close(pipe_fd[0]);
                    close(fileno(stdout)); 
                    dup2(pipe_fd[1], fileno(stdout));
                    close(pipe_fd[1]);
                }
                else //OUT_REDIRECT and PIPED
	           {
                    close(pipe_fd[0]);
                    close(pipe_fd[1]);//send a EOF to command2
                    if(info.flag & OUT_REDIRECT)
    	               out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_TRUNC, 0666);
                    else
    	               out_fd = open(info.out_file, O_WRONLY|O_APPEND|O_TRUNC, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);	        
                }
            }
            else
            {
                if(info.flag & OUT_REDIRECT) // OUT_REDIRECT WITHOUT PIPE
	           {
                    out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_TRUNC, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);
                }
                if(info.flag & OUT_REDIRECT_APPEND) // OUT_REDIRECT_APPEND WITHOUT PIPE
	           {
                    out_fd = open(info.out_file, O_WRONLY|O_CREAT|O_APPEND, 0666);
                    close(fileno(stdout)); 
                    dup2(out_fd, fileno(stdout));
                    close(out_fd);
                }
            }
            
            if(info.flag & IN_REDIRECT)
            {
                in_fd = open(info.in_file, O_CREAT |O_RDONLY, 0666);
                close(fileno(stdin)); 
                dup2(in_fd, fileno(stdin));
                close(in_fd); 
            }
            execvp(command,parameters);
        }
    }
    free(parameters);
	free(buffer);
}

int main() {
    int i;
    //init the BPTable
    for(i=0;i<MAXPIDTABLE;i++)
        BPTable[i] = 0;
    proc();
    return 0;
}