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
4000
(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");
}