csapp-lab5 shell-lab

    /*  * tsh - A tiny shell program with job control *  * <Put your name and login ID here> */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <ctype.h>#include <signal.h>#include <sys/types.h>#include <sys/wait.h>#include <errno.h>/* Misc manifest constants */#define MAXLINE    1024   /* max line size */#define MAXARGS     128   /* max args on a command line */#define MAXJOBS      16   /* max jobs at any point in time */#define MAXJID    1<<16   /* max job ID *//* Job states */#define UNDEF 0 /* undefined */#define FG 1    /* running in foreground */#define BG 2    /* running in background */#define ST 3    /* stopped *//*  * Jobs states: FG (foreground), BG (background), ST (stopped) * Job state transitions and enabling actions: *     FG -> ST  : ctrl-z *     ST -> FG  : fg command *     ST -> BG  : bg command *     BG -> FG  : fg command * At most 1 job can be in the FG state. *//* Global variables */extern char **environ;      /* defined in libc */char prompt[] = "tsh> ";    /* command line prompt (DO NOT CHANGE) */int verbose = 0;            /* if true, print additional output */int nextjid = 1;            /* next job ID to allocate */char sbuf[MAXLINE];         /* for composing sprintf messages */struct job_t {              /* The job struct */    pid_t pid;              /* job PID */    int jid;                /* job ID [1, 2, ...] */    int state;              /* UNDEF, BG, FG, or ST */    char cmdline[MAXLINE];  /* command line */};struct job_t jobs[MAXJOBS]; /* The job list *//* End global variables *//* Function prototypes *//* Here are the functions that you will implement */void eval(char *cmdline);int builtin_cmd(char **argv);void do_bgfg(char **argv);void waitfg(pid_t pid);void sigchld_handler(int sig);void sigtstp_handler(int sig);void sigint_handler(int sig);/* Here are helper routines that we've provided for you */int paseArgument(int *isJob, const char *pj_char);int parseline(const char *cmdline, char **argv); void sigquit_handler(int sig);void clearjob(struct job_t *job);void initjobs(struct job_t *jobs);int maxjid(struct job_t *jobs); int addjob(struct job_t *jobs, pid_t pid, int state, char *cmdline);int deletejob(struct job_t *jobs, pid_t pid); pid_t fgpid(struct job_t *jobs);struct job_t *getjobpid(struct job_t *jobs, pid_t pid);struct job_t *getjobjid(struct job_t *jobs, int jid); int pid2jid(pid_t pid); void listjobs(struct job_t *jobs);void usage(void);void unix_error(char *msg);void app_error(char *msg);typedef void handler_t(int);handler_t *Signal(int signum, handler_t *handler);/* Here are error-handling wrapper functions */void Sigemptyset(sigset_t *mask);void Sigaddset(sigset_t *mask, int sign);void Sigprocmask(int how, sigset_t *mask,sigset_t *oldmask);void Setpgid(pid_t pid,pid_t gpid);pid_t Fork(void);// void Execve(const char *filename, char *const argv[], char *const envp[]);void Kill(pid_t pid,int sig);/* * main - The shell's main routine  */int main(int argc, char **argv) {    char c;    char cmdline[MAXLINE];    int emit_prompt = 1; /* emit prompt (default) */    /* Redirect stderr to stdout (so that driver will get all output     * on the pipe connected to stdout) */    dup2(1, 2);    /* Parse the command line */    while ((c = getopt(argc, argv, "hvp")) != EOF) {        switch (c) {        case 'h':             /* print help message */            usage();        break;        case 'v':             /* emit additional diagnostic info */            verbose = 1;        break;        case 'p':             /* don't print a prompt */            emit_prompt = 0;  /* handy for automatic testing */        break;        default:                usage();        }    }    /* Install the signal handlers */    /* These are the ones you will need to implement */    Signal(SIGINT,  sigint_handler);   /* ctrl-c */    Signal(SIGTSTP, sigtstp_handler);  /* ctrl-z */    Signal(SIGCHLD, sigchld_handler);  /* Terminated or stopped child */    /* This one provides a clean way to kill the shell */    Signal(SIGQUIT, sigquit_handler);     /* Initialize the job list */    initjobs(jobs);    /* Execute the shell's read/eval loop */    while (1) {        /* Read command line */        if (emit_prompt) {            printf("%s", prompt);            fflush(stdout);        }        if ((fgets(cmdline, MAXLINE, stdin) == NULL) && ferror(stdin))            app_error("fgets error");        if (feof(stdin)) { /* End of file (ctrl-d) */            fflush(stdout);            exit(0);        }        /* Evaluate the command line */        eval(cmdline);        fflush(stdout);        fflush(stdout);    }     exit(0); /* control never reaches here */}/*  * eval - Evaluate the command line that the user has just typed in *  * If the user has requested a built-in command (quit, jobs, bg or fg) * then execute it immediately. Otherwise, fork a child process and * run the job in the context of the child. If the job is running in * the foreground, wait for it to terminate and then return.  Note: * each child process must have a unique process group ID so that our * background children don't receive SIGINT (SIGTSTP) from the kernel * when we type ctrl-c (ctrl-z) at the keyboard.  */void eval(char *cmdline) {    char *argv[MAXARGS];    /* Argument list execve() */    char buf[MAXLINE];      /* Holds modified command line */    int bg;                 /* Should the job run in bg or fg */    pid_t pid;              /* process id */    sigset_t mask;    strcpy(buf, cmdline);    bg = parseline(buf, argv);    if (argv[0] == NULL) {        return;    }    if (!builtin_cmd(argv)) {        Sigemptyset(&mask);        Sigaddset(&mask, SIGCHLD);        Sigprocmask(SIG_BLOCK, &mask, NULL);        if ((pid = Fork()) == 0) {            Sigprocmask(SIG_UNBLOCK, &mask, NULL);            Setpgid(0, 0);                                      if (execve(argv[0], argv, environ) < 0) {                printf("%s: Command not found\n", argv[0]);                exit(0);            }        }         // 必须在父进程添加job以后才能取消屏蔽信号        addjob(jobs, pid, bg ? BG : FG, cmdline);        Sigprocmask(SIG_UNBLOCK, &mask, NULL);        // 根据是否是后台job决定是否等待子进程完成        if (!bg) {            waitfg(pid);        } else {           printf("[%d] (%d) %s", pid2jid(pid), pid, cmdline);        }    }    return;}/*  * parseline - Parse the command line and build the argv array. *  * Characters enclosed in single quotes are treated as a single * argument.  Return true if the user has requested a BG job, false if * the user has requested a FG job.   */int parseline(const char *cmdline, char **argv) {    static char array[MAXLINE]; /* holds local copy of command line */    char *buf = array;          /* ptr that traverses command line */    char *delim;                /* points to first space delimiter */    int argc;                   /* number of args */    int bg;                     /* background job? */    strcpy(buf, cmdline);    buf[strlen(buf)-1] = ' ';  /* replace trailing '\n' with space */    while (*buf && (*buf == ' ')) /* ignore leading spaces */       buf++;    /* Build the argv list */    argc = 0;    if (*buf == '\'') {       buf++;       delim = strchr(buf, '\'');    }    else {       delim = strchr(buf, ' ');    }    while (delim) {        argv[argc++] = buf;        *delim = '\0';        buf = delim + 1;        while (*buf && (*buf == ' ')) /* ignore spaces */           buf++;        if (*buf == '\'') {            buf++;            delim = strchr(buf, '\'');        }        else {            delim = strchr(buf, ' ');        }    }    argv[argc] = NULL;    if (argc == 0)  /* ignore blank line */       return 1;    /* should the job run in the background? */    if ((bg = (*argv[argc-1] == '&')) != 0) {       argv[--argc] = NULL;    }    return bg;}/*  * builtin_cmd - If the user has typed a built-in command then execute *    it immediately.   */int builtin_cmd(char **argv) {    if (!strcmp(argv[0], "quit"))        exit(0);    if (!strcmp(argv[0], "&"))        return 1;    if (!strcmp(argv[0], "fg") || !strcmp(argv[0], "bg")) {        do_bgfg(argv);        return 1;    }    if (!strcmp(argv[0], "jobs")) {        listjobs(jobs);        return 1;    }    return 0;     /* not a builtin command */}/*  * do_bgfg - Execute the builtin bg and fg commands * Jobs states: FG (foreground), BG (background), ST (stopped) * Job state transitions and enabling actions: *     FG -> ST  : ctrl-z *     ST -> FG  : fg command *     ST -> BG  : bg command *     BG -> FG  : fg command * At most 1 job can be in the FG state. * The bg(fg)<job> command restarts <job> by sending it a SIGCONT signal,  * and then runs it in the background(background). The <job> argument  * can be either a PID or a JID. *  * Each job can be identified by either a process ID (PID) or a job ID  * (JID), which is a positive integer assigned by tsh. JIDs should be  * denoted on the command line by the prefix ’%’.  * * For example, “%5” denotes JID 5, and “5” denotes PID 5. */void do_bgfg(char **argv) {    char* pj_char = argv[1];    int JIDorPID, number;    int bg = !strcmp(argv[0], "bg");    if (argv[1] == NULL) {        printf("%s command requires PID or %%jobid argument\n", (bg?"bg":"fg"));        return;    }    number = paseArgument(&JIDorPID, pj_char);    if (number < 0) {        printf("%s: argument must be a PID or %%jobid\n", (bg?"bg":"fg"));        return;    }    if (JIDorPID == 1) {        if (number > maxjid(jobs)) {            printf("%%%d: No such job\n", number);            return;        }        struct job_t *job = getjobjid(jobs, number);        if ((job == NULL) || job->state == UNDEF) {            printf("%%%d: No such job\n", number);            return;        }         else if (bg && (job->state == ST)) {            job->state = BG;            Kill(-(job->pid), SIGCONT);            printf("[%d] (%d) %s", number, job->pid, job->cmdline);        }        else if (!bg && (job->state == ST || job->state == BG)) {            job->state = FG;            Kill(-number, SIGCONT);            waitfg(job->pid);        }    }     else if (JIDorPID == 2) {        struct job_t *job = getjobpid(jobs, number);        if ((job == NULL) || job->state == UNDEF) {            printf("(%d): No such process\n", number);            return;        }        else if (bg && (job->state == ST)) {            job->state = BG;            Kill(-number, SIGCONT);            printf("[%d] (%d) %s", job->jid, number, job->cmdline);        }        else if (!bg && (job->state == ST || job->state == BG)) {            job->state = FG;            Kill(-number, SIGCONT);            waitfg(job->pid);        }    }      return;}/* * parse arguments to fg/bg * argument: JIDorPID *      %JID -> JIDorPID = 1 *      %PID -> JIDorPID = 2 * return: number *      0 -> not a valid number input *      positive number -> valid */int paseArgument(int *JIDorPID, const char *pj_char){    int number;    if (pj_char[0] == '%') {        number = atoi(pj_char + 1);        if (number == 0) return -1;        *JIDorPID = 1;    } else {        number = atoi(pj_char);        // printf("pid number = %d\n", number);        if (number == 0) return -1;        *JIDorPID = 2;    }    return number;}/*  * waitfg - Block until process pid is no longer the foreground process */void waitfg(pid_t pid){    while (pid == fgpid(jobs)) {        sleep(0);    }    return;}/***************** * Signal handlers *****************//*  * sigchld_handler - The kernel sends a SIGCHLD to the shell whenever *     a child job terminates (becomes a zombie), or stops because it *     received a SIGSTOP or SIGTSTP signal. The handler reaps all *     available zombie children, but doesn't wait for any other *     currently running children to terminate.   */void sigchld_handler(int sig) {    int status;    pid_t pid;    while ((pid = waitpid(-1, &status, (WNOHANG|WUNTRACED))) > 0) {        // 子进程正常终止        if (WIFEXITED(status)) {            deletejob(jobs, pid);        }        // 子进程接受了一个未捕获的信号导致terminate        if (WIFSIGNALED(status)) {            printf("Job [%d] (%d) terminated by signal %d\n", pid2jid(pid), pid, WTERMSIG(status));            deletejob(jobs, pid);        }        // 子进程当前处于stop状态        if (WIFSTOPPED(status)) {            printf("Job [%d] (%d) stopped by signal %d\n", pid2jid(pid), pid, WSTOPSIG(status));            struct job_t *job = getjobpid(jobs, pid);            if (job != NULL) {                job->state = ST;            }        }    }    if (errno != ECHILD)        unix_error("waitpid error");    return;}/*  * sigint_handler - The kernel sends a SIGINT to the shell whenver the *    user types ctrl-c at the keyboard.  Catch it and send it along *    to the foreground job.   */void sigint_handler(int sig) {    pid_t pid = fgpid(jobs);    /* 获取当前的前台job pid*/    if (pid != 0) {        Kill(-pid, SIGINT);     }    return;}/* * sigtstp_handler - The kernel sends a SIGTSTP to the shell whenever *     the user types ctrl-z at the keyboard. Catch it and suspend the *     foreground job by sending it a SIGTSTP.   */void sigtstp_handler(int sig) {    pid_t pid = fgpid(jobs);     if (pid != 0) {        struct job_t *job = getjobpid(jobs, pid);        if (job->state == ST) {         /* 已经处于stop的job不需要发送信号了 */            return;        }        else {            Kill(-pid, SIGTSTP);        }    }    return;}/********************* * End signal handlers *********************//*********************************************** * Helper routines that manipulate the job list **********************************************//* clearjob - Clear the entries in a job struct */void clearjob(struct job_t *job) {    job->pid = 0;    job->jid = 0;    job->state = UNDEF;    job->cmdline[0] = '\0';}/* initjobs - Initialize the job list */void initjobs(struct job_t *jobs) {    int i;    for (i = 0; i < MAXJOBS; i++)    clearjob(&jobs[i]);}/* maxjid - Returns largest allocated job ID */int maxjid(struct job_t *jobs) {    int i, max=0;    for (i = 0; i < MAXJOBS; i++)    if (jobs[i].jid > max)        max = jobs[i].jid;    return max;}/* addjob - Add a job to the job list */int addjob(struct job_t *jobs, pid_t pid, int state, char *cmdline) {    int i;    if (pid < 1)    return 0;    for (i = 0; i < MAXJOBS; i++) {    if (jobs[i].pid == 0) {        jobs[i].pid = pid;        jobs[i].state = state;        jobs[i].jid = nextjid++;        if (nextjid > MAXJOBS)        nextjid = 1;        strcpy(jobs[i].cmdline, cmdline);        if(verbose){            printf("Added job [%d] %d %s\n", jobs[i].jid, jobs[i].pid, jobs[i].cmdline);            }            return 1;    }    }    printf("Tried to create too many jobs\n");    return 0;}/* deletejob - Delete a job whose PID=pid from the job list */int deletejob(struct job_t *jobs, pid_t pid) {    int i;    if (pid < 1)    return 0;    for (i = 0; i < MAXJOBS; i++) {    if (jobs[i].pid == pid) {        clearjob(&jobs[i]);        nextjid = maxjid(jobs)+1;        return 1;    }    }    return 0;}/* fgpid - Return PID of current foreground job, 0 if no such job */pid_t fgpid(struct job_t *jobs) {    int i;    for (i = 0; i < MAXJOBS; i++)    if (jobs[i].state == FG)        return jobs[i].pid;    return 0;}/* getjobpid  - Find a job (by PID) on the job list */struct job_t *getjobpid(struct job_t *jobs, pid_t pid) {    int i;    if (pid < 1)    return NULL;    for (i = 0; i < MAXJOBS; i++)    if (jobs[i].pid == pid)        return &jobs[i];    return NULL;}/* getjobjid  - Find a job (by JID) on the job list */struct job_t *getjobjid(struct job_t *jobs, int jid) {    int i;    if (jid < 1)    return NULL;    for (i = 0; i < MAXJOBS; i++)    if (jobs[i].jid == jid)        return &jobs[i];    return NULL;}/* pid2jid - Map process ID to job ID */int pid2jid(pid_t pid) {    int i;    if (pid < 1)    return 0;    for (i = 0; i < MAXJOBS; i++)    if (jobs[i].pid == pid) {            return jobs[i].jid;        }    return 0;}/* listjobs - Print the job list */void listjobs(struct job_t *jobs) {    int i;    for (i = 0; i < MAXJOBS; i++) {    if (jobs[i].pid != 0) {        printf("[%d] (%d) ", jobs[i].jid, jobs[i].pid);        switch (jobs[i].state) {        case BG:             printf("Running ");            break;        case FG:             printf("Foreground ");            break;        case ST:             printf("Stopped ");            break;        default:            printf("listjobs: Internal error: job[%d].state=%d ",                i, jobs[i].state);        }        printf("%s", jobs[i].cmdline);    }    }}/****************************** * end job list helper routines ******************************//*********************** * Other helper routines ***********************//* * usage - print a help message */void usage(void) {    printf("Usage: shell [-hvp]\n");    printf("   -h   print this message\n");    printf("   -v   print additional diagnostic information\n");    printf("   -p   do not emit a command prompt\n");    exit(1);}/* * unix_error - unix-style error routine */void unix_error(char *msg){    fprintf(stdout, "%s: %s\n", msg, strerror(errno));    exit(1);}/* * app_error - application-style error routine */void app_error(char *msg){    fprintf(stdout, "%s\n", msg);    exit(1);}/* * Signal - wrapper for the sigaction function */handler_t *Signal(int signum, handler_t *handler) {    struct sigaction action, old_action;    action.sa_handler = handler;      sigemptyset(&action.sa_mask); /* block sigs of type being handled */    action.sa_flags = SA_RESTART; /* restart syscalls if possible */    if (sigaction(signum, &action, &old_action) < 0)    unix_error("Signal error");    return (old_action.sa_handler);}/* * sigquit_handler - The driver program can gracefully terminate the *    child shell by sending it a SIGQUIT signal. */void sigquit_handler(int sig) {    printf("Terminating after receipt of SIGQUIT signal\n");    exit(1);}void Sigprocmask(int how, sigset_t *set, sigset_t *oldset){    if (sigprocmask(how, set, oldset) < 0)    unix_error("Sigprocmask error");    return;}void Sigemptyset(sigset_t *set){    if (sigemptyset(set) < 0)    unix_error("Sigemptyset error");    return;}void Sigaddset(sigset_t *set, int signum){    if (sigaddset(set, signum) < 0)    unix_error("Sigaddset error");    return;}void Setpgid(pid_t pid, pid_t pgid) {    if (setpgid(pid, pgid) < 0) {        unix_error("eval: setpgid failed.\n");    }}pid_t Fork(void) {    pid_t pid;    if ((pid = fork()) < 0)    unix_error("Fork error");    return pid;}void Kill(pid_t pid, int signum) {    int rc;    if ((rc = kill(pid, signum)) < 0)        unix_error("Kill error");}