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663 regels
13 KiB
663 regels
13 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <string.h>
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#include <dirent.h>
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#include <signal.h>
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#include <errno.h>
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#include <fcntl.h>
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#include "yeeshell.h"
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/* record cmdline history */
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char *history[CMDLINE_HISTORY_MAX_QUANTITY];
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int cmdline_amount = 0;
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/* if true, print additional output */
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int verbose = 0;
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/* next job ID to allocate */
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int nextjid = 1;
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/* environment variable */
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extern char **environ;
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/* The job list */
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struct job_t jobs[JOBS_MAX_QUANTITY];
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int main()
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{
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char *cmdline = NULL, *pwd = NULL;
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char *args[ARGS_MAX_QUANTITY];
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int status = 1;
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pwd = (char *)calloc(PATH_MAX_SIZE, sizeof(char));
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for (int i = 0; i < CMDLINE_HISTORY_MAX_QUANTITY; i++)
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{
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history[i] = (char *)calloc(CMDLINE_MAX_SIZE, sizeof(char));
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}
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/* Install the signal handlers */
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Signal(SIGINT, sigint_handler); /* ctrl-c */
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Signal(SIGTSTP, sigtstp_handler); /* ctrl-z */
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Signal(SIGCHLD, sigchld_handler); /* Terminated or stopped child */
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Signal(SIGQUIT, sigquit_handler);
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/* initiate job list */
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initjobs(jobs);
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/* execute the shell's read, parse and execution loop */
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do
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{
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if (!getcwd(pwd, PATH_MAX_SIZE))
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{
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printf("yeeshell: The current path cannot be obtained!\n");
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exit(0);
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}
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printf("[root@yeeshell %s]# ", pwd);
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cmdline = readline();
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strcpy(history[cmdline_amount++], cmdline);
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status = execute(cmdline, args);
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free(cmdline);
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} while (status);
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for (int i = 0; i < CMDLINE_HISTORY_MAX_QUANTITY; i++)
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{
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free(history[i]);
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}
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exit(EXIT_SUCCESS);
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}
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char *readline()
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{
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char *cmdline = NULL;
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ssize_t bufsize = 0;
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getline(&cmdline, &bufsize, stdin);
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return cmdline;
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}
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int parseline(char *cmdline, char **args)
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{
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static char array[CMDLINE_MAX_SIZE]; /* holds local copy of command line */
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char *buf = array; /* ptr that traverses command line */
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char *delim; /* points to first space delimiter */
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int argc; /* number of args */
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int bg; /* background job? */
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strcpy(buf, cmdline);
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buf[strlen(buf) - 1] = ' '; /* replace trailing '\n' with space */
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while (*buf && (*buf == ' ')) /* ignore leading spaces */
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{
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buf++;
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}
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/* Build the argv list */
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argc = 0;
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if (*buf == '\'')
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{
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buf++;
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delim = strchr(buf, '\'');
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}
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else
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{
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delim = strchr(buf, ' ');
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}
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while (delim)
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{
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args[argc++] = buf;
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*delim = '\0';
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buf = delim + 1;
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while (*buf && (*buf == ' ')) /* ignore spaces */
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{
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buf++;
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}
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if (*buf == '\'')
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{
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buf++;
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delim = strchr(buf, '\'');
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}
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else
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{
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delim = strchr(buf, ' ');
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}
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}
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args[argc] = NULL;
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if (argc == 0) /* ignore blank line */
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{
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return 1;
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}
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/* should the job run in the background? */
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if ((bg = (*args[argc - 1] == '&')) != 0)
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{
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args[--argc] = NULL;
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}
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return bg;
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}
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int check_redirect(char **args, char *redirect_filename, char **redirect_args)
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{
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int i = 0, j = 0, redirect_flag = REDIRECT_NO;
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while (args[i] != NULL)
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{
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if (!strcmp(args[i], ">"))
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{
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redirect_flag = REDIRECT_OUT;
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break;
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}
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else if (!strcmp(args[i], "<"))
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{
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redirect_flag = REDIRECT_IN;
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break;
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}
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i++;
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}
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if (redirect_flag == 1) /* redirect output */
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{
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strcpy(redirect_filename, args[i + 1]);
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for (j = 0; j < i; j++)
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{
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redirect_args[j] = args[j];
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}
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}
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else if (redirect_flag == 2) /* redirect input */
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{
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redirect_filename = args[0];
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i++;
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while (args[i] != NULL)
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{
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redirect_args[j++] = args[i++];
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}
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}
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return redirect_flag;
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}
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int execute(char *cmdline, char **args)
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{
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int bg = 0, i = 0, redirect_flag = 0, fd = 1;
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pid_t pid;
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char *redirect_filename = NULL;
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redirect_filename = (char *)calloc(32, sizeof(char));
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char *redirect_args[ARGS_MAX_QUANTITY];
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sigset_t mask_all, mask_prev;
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sigprocmask(SIG_BLOCK, NULL, &mask_all);
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sigaddset(&mask_all, SIGCHLD);
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bg = parseline(cmdline, args);
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redirect_flag = check_redirect(args, redirect_filename, redirect_args);
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if (args[0] == NULL)
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{
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return 1;
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}
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if (!built_in(args))
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{
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/* Prevent child processes from ending between parent processes, that is, between addJob and deleteJob. */
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sigprocmask(SIG_BLOCK, &mask_all, &mask_prev); /* Shield SIGCHLD */
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if ((pid = fork()) == 0) /* Child process */
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{
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if (redirect_flag == 1)
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{
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fd = open(redirect_filename, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
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close(1);
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dup2(1, fd);
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}
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else if (redirect_flag == 2)
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{
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fd = open(redirect_filename, O_RDONLY, S_IRUSR);
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close(0);
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dup2(0, fd);
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}
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/* The child process inherits the parent's signal mask and will inherit it after exec,
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so it needs to restore the signal mask before executing. */
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sigprocmask(SIG_SETMASK, &mask_prev, NULL); /* Child process, unblock SIGCHLD */
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/* Set the pid of the current process to the group number of the process group it belongs to. */
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/* avoid being grouped with tsh */
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setpgid(0, 0);
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if (execvp(args[0], args) <= 0)
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{
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printf("%s: Command not found\n", args[0]);
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free(redirect_filename);
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free(redirect_args);
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exit(0);
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}
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if ((redirect_flag == 1) || (redirect_flag == 2))
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{
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close(fd);
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}
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}
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else
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{
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if (bg) /* bg task */
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{
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addjob(jobs, pid, BG, cmdline);
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}
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else /* fg task */
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{
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addjob(jobs, pid, FG, cmdline);
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}
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sigprocmask(SIG_SETMASK, &mask_prev, NULL);
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if (bg) /* Don't wait for background tasks to finish */
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{
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printf("[%d](%d)%s", pid2jid(pid), pid, cmdline);
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}
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else /* Wait for foreground tasks to finish */
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{
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waitfg(pid);
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}
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}
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}
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return 1;
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}
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int built_in(char **args)
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{
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if (!strcmp(args[0], "exit"))
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{
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exit(0);
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}
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else if (!strcmp(args[0], "cd"))
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{
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return builtin_cd(args);
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}
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else if (!strcmp(args[0], "history"))
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{
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return builtin_history(args);
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}
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else if (!strcmp(args[0], "mytop"))
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{
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return builtin_mytop(args);
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}
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else if (!strcmp(args[0], "jobs"))
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{
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return builtin_jobs(args);
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}
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else
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{
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return 0;
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}
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}
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int builtin_cd(char **args)
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{
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if (args[1] == NULL)
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{
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return 1;
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}
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else
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{
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if (chdir(args[1]) != 0)
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{
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perror("yeeshell");
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}
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return 1;
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}
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}
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int builtin_history(char **args)
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{
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int n = 0;
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if (args[1] == NULL)
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{
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n = cmdline_amount;
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}
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else
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{
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n = atoi(args[1]) < cmdline_amount ? atoi(args[1]) : cmdline_amount;
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}
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printf("ID\tCommandline\n");
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for (int i = 0; i < n; i++)
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{
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printf("%d\t%s\n", i + 1, history[i]);
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}
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return 1;
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}
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int builtin_jobs(char **args)
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{
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/* To prevent interruptions, block all signals. */
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sigset_t mask_all, mask_prev;
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sigfillset(&mask_all);
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sigprocmask(SIG_SETMASK, &mask_all, &mask_prev);
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for (int i = 0; i < JOBS_MAX_QUANTITY; i++)
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{
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if (jobs[i].pid != 0)
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{
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printf("[%d] (%d) ", jobs[i].jid, jobs[i].pid);
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switch (jobs[i].state)
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{
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case BG:
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printf("Running ");
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break;
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case FG:
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printf("Foreground ");
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break;
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case ST:
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printf("Stopped ");
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break;
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default:
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printf("listjobs: Internal error: job[%d].state=%d ",
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i, jobs[i].state);
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}
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printf("%s", jobs[i].cmdline);
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}
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}
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sigprocmask(SIG_SETMASK, &mask_prev, NULL); /* unclock */
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return 1;
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}
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int builtin_mytop(char **args)
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{
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}
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int do_bgfg(char **args)
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{
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/* initialize variables */
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struct job_t *currentJob;
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int jid;
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pid_t pid;
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sigset_t mask_all, mask_prev;
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sigfillset(&mask_all);
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sigprocmask(SIG_SETMASK, &mask_all, &mask_prev);
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/* bg or fg has the argument? */
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if (args[1] == NULL)
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{
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printf("%s command requires PID or %%jobid argument\n", args[0]);
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return 1;
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}
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/* if process by jid, gets the corresponding Job structure*/
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else if (args[1][0] == '%')
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{
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jid = atoi(args[1][1]);
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currentJob = getjobjid(jobs, jid);
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if (currentJob == NULL)
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{
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printf("%%%d: No such job\n", jid);
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return 1;
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}
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pid = currentJob->pid;
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}
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/* if process by pid, gets the corresponding Job structure */
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else
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{
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pid = atoi(args[1]);
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currentJob = getjobpid(jobs, pid);
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if (pid <= 0)
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{
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printf("%s: argument must be a PID or %%jobid\n", args[0]);
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return 1;
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}
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currentJob = getjobpid(jobs, pid);
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if (currentJob == NULL)
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{
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printf("(%d): No such process\n", pid);
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return 1;
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}
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}
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/* bg or fg? */
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if (!strcmp(args[0], "bg")) /* if bg */
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{
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currentJob->state = BG;
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printf("[%d] (%d) %s", currentJob->jid, pid, currentJob->cmdline);
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sigprocmask(SIG_SETMASK, &mask_prev, NULL);
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kill(-pid, SIGCONT); /* send the SIGCONT to the pid */
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return 1;
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}
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else if (!strcmp(args[0], "fg")) /* if fg */
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{
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currentJob->state = FG;
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sigprocmask(SIG_SETMASK, &mask_prev, NULL);
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kill(-pid, SIGCONT); /* send the SIGCONT to the pid */
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waitfg(currentJob->pid); /* Child process switched to FG, so wait for it to finish */
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return 1;
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}
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else if (!strcmp(args[0], "kill"))
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{
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sigprocmask(SIG_SETMASK, &mask_prev, NULL);
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kill(-pid, SIGQUIT);
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return 1;
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}
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return 1;
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}
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void waitfg(pid_t pid)
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{
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sigset_t m;
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sigemptyset(&m);
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while (pid == fgpid(jobs))
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{
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/* Wake up when there is a signal to check whether the foreground process PID change, */
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/* change means that the foreground process is over. */
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sigsuspend(&m);
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}
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return;
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}
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void initjobs(struct job_t *jobs)
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{
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int i;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
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clearjob(&jobs[i]);
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}
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int addjob(struct job_t *jobs, pid_t pid, int state, char *cmdline)
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{
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int i;
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if (pid < 1)
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return 0;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
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{
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if (jobs[i].pid == 0)
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{
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jobs[i].pid = pid;
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jobs[i].state = state;
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jobs[i].jid = nextjid++;
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if (nextjid > JOBS_MAX_QUANTITY)
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nextjid = 1;
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strcpy(jobs[i].cmdline, cmdline);
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if (verbose)
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{
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printf("Added job [%d] %d %s\n", jobs[i].jid, jobs[i].pid, jobs[i].cmdline);
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}
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return 1;
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}
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}
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printf("Tried to create too many jobs\n");
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return 0;
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}
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void listjobs(struct job_t *jobs)
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{
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for (int i = 0; i < JOBS_MAX_QUANTITY; i++)
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{
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if (jobs[i].pid != 0)
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{
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printf("[%d] (%d) ", jobs[i].jid, jobs[i].pid);
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switch (jobs[i].state)
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{
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case BG:
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printf("Running ");
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break;
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case FG:
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printf("Foreground ");
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break;
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case ST:
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printf("Stopped ");
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break;
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default:
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printf("listjobs: Internal error: job[%d].state=%d ", i, jobs[i].state);
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}
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printf("%s", jobs[i].cmdline);
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}
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}
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}
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int deletejob(struct job_t *jobs, pid_t pid)
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{
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int i;
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if (pid < 1)
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return 0;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
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{
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if (jobs[i].pid == pid)
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{
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clearjob(&jobs[i]);
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nextjid = maxjid(jobs) + 1;
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return 1;
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}
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}
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return 0;
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}
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void clearjob(struct job_t *job)
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{
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job->pid = 0;
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job->jid = 0;
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job->state = UNDF;
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job->cmdline[0] = '\0';
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}
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int pid2jid(pid_t pid)
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{
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int i;
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if (pid < 1)
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return 0;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
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if (jobs[i].pid == pid)
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{
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return jobs[i].jid;
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}
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return 0;
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}
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|
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pid_t fgpid(struct job_t *jobs)
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{
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for (int i = 0; i < JOBS_MAX_QUANTITY; i++)
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if (jobs[i].state == FG)
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return jobs[i].pid;
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return 0;
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}
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|
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struct job_t *getjobpid(struct job_t *jobs, pid_t pid)
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{
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int i;
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if (pid < 1)
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return NULL;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
|
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if (jobs[i].pid == pid)
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return &jobs[i];
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return NULL;
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}
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|
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struct job_t *getjobjid(struct job_t *jobs, int jid)
|
|
{
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int i;
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|
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if (jid < 1)
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return NULL;
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for (i = 0; i < JOBS_MAX_QUANTITY; i++)
|
|
if (jobs[i].jid == jid)
|
|
return &jobs[i];
|
|
return NULL;
|
|
}
|
|
|
|
int maxjid(struct job_t *jobs)
|
|
{
|
|
int i, max = 0;
|
|
|
|
for (i = 0; i < JOBS_MAX_QUANTITY; i++)
|
|
{
|
|
if (jobs[i].jid > max)
|
|
{
|
|
max = jobs[i].jid;
|
|
}
|
|
}
|
|
return max;
|
|
}
|
|
|
|
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)
|
|
fprintf(stdout, "%s: %s\n", 'Signal Error', strerror(errno));
|
|
return (old_action.sa_handler);
|
|
}
|
|
|
|
void sigchld_handler(int signal)
|
|
{
|
|
pid_t pid;
|
|
int status;
|
|
while ((pid = waitpid(-1, &status, WNOHANG | WUNTRACED)) > 0)
|
|
{
|
|
if (WIFEXITED(status)) /* Normal termination */
|
|
{
|
|
deletejob(jobs, pid);
|
|
}
|
|
if (WIFSTOPPED(status)) /* Task suspension */
|
|
{
|
|
struct job_t *job = getjobpid(jobs, pid);
|
|
int jid = pid2jid(pid);
|
|
printf("Job [%d] (%d) stopped by signal %d\n", jid, pid, WSTOPSIG(status));
|
|
job->state = ST;
|
|
}
|
|
if (WIFSIGNALED(status)) /* Task terminated */
|
|
{
|
|
int jid = pid2jid(pid);
|
|
printf("Job [%d] (%d) terminated by signal %d\n", jid, pid, WTERMSIG(status));
|
|
deletejob(jobs, pid);
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
void sigint_handler(int signal)
|
|
{
|
|
pid_t pid = fgpid(jobs);
|
|
if (pid != 0)
|
|
{
|
|
kill(-pid, signal);
|
|
}
|
|
return;
|
|
}
|
|
|
|
void sigtstp_handler(int signal)
|
|
{
|
|
pid_t pid = fgpid(jobs);
|
|
if (pid > 0)
|
|
{
|
|
kill(-pid, signal);
|
|
}
|
|
return;
|
|
}
|
|
|
|
void sigquit_handler(int signal)
|
|
{
|
|
printf("Terminating after receipt of SIGQUIT signal\n");
|
|
exit(1);
|
|
}
|