/*
* tsh - A tiny shell program with job control
*
* Zhang Zichen 5110369009
*/
#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 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);
/*
* 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]; //Arguments list execve()
char buf[MAXLINE]; //Hold modified command line
int bg; //Should the job run in bg or fg?
pid_t pid; //Process id
strcpy(buf, cmdline);
bg = parseline(buf, argv);
if(argv[0] == NULL) return; //ignore empty lines
if(!builtin_cmd(argv))
{
sigset_t set;
sigemptyset(&set);
sigaddset(&set, SIGCHLD);
sigprocmask(SIG_BLOCK, &set, 0);
if((pid = fork()) == 0) //child
{
sigprocmask(SIG_UNBLOCK, &set, 0);
setpgid(0, 0);
if(execve(argv[0], argv, environ) < 0)
{
printf("%s: Command not found\n", argv[0]);
exit(0);
}
}
//parent
//printf("added!\n");
if(!addjob(jobs, pid, bg?BG:FG, cmdline))
app_error("add job error");
sigprocmask(SIG_UNBLOCK, &set, 0);
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], "jobs"))
{
listjobs(jobs);
return 1;
}
if(!strcmp(argv[0], "bg") || !strcmp(argv[0], "fg"))
{
do_bgfg(argv);
return 1;
}
if(!strcmp(argv[0], "&"))
return 1;
return 0; /* not a builtin command */
}
/*
* do_bgfg - Execute the builtin bg and fg commands
*/
void do_bgfg(char **argv)
{
//pid_t pid;
struct job_t *job;
if(argv[1] == 0)
{
printf("%s command requires PID or "
"%%jobid argument\n", argv[0
