1st attemption of pipe

result.txt

@@ -1,10 +1,10 @@
-total 52
-drwxr-xr-x   4 root root   120 Mar 16 22:47 .
-dr-xr-x---. 14 root root  4096 Mar 16 15:20 ..
-drwxr-xr-x   8 root root   201 Mar 16 22:04 .git
+total 56
+drwxr-xr-x   4 root root   120 Mar 16 23:39 .
+dr-xr-x---. 14 root root  4096 Mar 16 23:39 ..
+drwxr-xr-x   8 root root   201 Mar 16 22:49 .git
 -rw-r--r--   1 root root    46 Mar 10 17:40 README.md
--rwx------   1 root root     0 Mar 16 22:47 result.txt
+-rwx------   1 root root     0 Mar 16 23:39 result.txt
 drwxr-xr-x   2 root root    64 Mar 16 11:27 .vscode
--rwxr-xr-x   1 root root 23728 Mar 16 22:46 yeeshell
--rw-r--r--   1 root root 13535 Mar 16 22:46 yeeshell.c
--rw-r--r--   1 root root  3914 Mar 16 22:44 yeeshell.h
+-rwxr-xr-x   1 root root 27936 Mar 16 23:39 yeeshell
+-rw-r--r--   1 root root 15053 Mar 16 23:38 yeeshell.c
+-rw-r--r--   1 root root  4043 Mar 16 23:36 yeeshell.h

yeeshell.c

@@ -168,93 +168,172 @@ int check_redirect(char **args, char *redirect_filename, char **redirect_args)
 	return redirect_flag;
 }
 
+int check_pipe(char **args, char **pipe_arg_1, char **pipe_arg_2)
+{
+	int pipe_flag = 0, i = 0, j = 0;
+
+	while (args[i] != NULL)
+	{
+		if (!strcmp(args[i], "|"))
+		{
+			pipe_flag = 1;
+			break;
+		}
+		pipe_arg_1[j++] = args[i++];
+	}
+
+	j = 0;
+	i++;
+	while (args[i] != NULL)
+	{
+		pipe_arg_2[j++] = args[i++];
+	}
+	return pipe_flag;
+}
+
 int execute(char *cmdline, char **args)
 {
-	int bg = 0, i = 0, redirect_flag = 0, fd = 1;
+	int bg = 0, i = 0, redirect_flag = 0, fd = 1, pipe_num = 0;
 	pid_t pid;
 	char *redirect_filename = NULL;
-	redirect_filename = (char *)calloc(REDIRECT_FILENAME_MAX_SIZE, sizeof(char));
 	char *redirect_args[ARGS_MAX_QUANTITY];
+	char *pipe_arg_1[ARGS_MAX_QUANTITY];
+	char *pipe_arg_2[ARGS_MAX_QUANTITY];
+
+	redirect_filename = (char *)calloc(REDIRECT_FILENAME_MAX_SIZE, sizeof(char));
 	memset(redirect_args, NULL, sizeof(redirect_args));
+
 	sigset_t mask_all, mask_prev;
 	sigprocmask(SIG_BLOCK, NULL, &mask_all);
 	sigaddset(&mask_all, SIGCHLD);
+
 	bg = parseline(cmdline, args);
 	redirect_flag = check_redirect(args, redirect_filename, redirect_args);
+	pipe_num = check_pipe(args, pipe_arg_1, pipe_arg_2);
 
 	if (args[0] == NULL)
 	{
 		return 1;
 	}
-	if (!built_in(args))
+	if (pipe_num == 0)
 	{
-		/* Prevent child processes from ending between parent processes, that is, between addJob and deleteJob. */
-		sigprocmask(SIG_BLOCK, &mask_all, &mask_prev); /* Shield SIGCHLD */
-
-		if ((pid = fork()) == 0) /* Child process */
+		if (!built_in(args)) /* built-in cmd? */
 		{
-			if (redirect_flag == 1)
-			{
-				fd = open(redirect_filename, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
-				close(1);
-				dup(fd);
-			}
-			else if (redirect_flag == 2)
+			/* Prevent child processes from ending between parent processes, that is, between addJob and deleteJob. */
+			sigprocmask(SIG_BLOCK, &mask_all, &mask_prev); /* Shield SIGCHLD */
+
+			if ((pid = fork()) == 0) /* Child process */
 			{
-				fd = open(redirect_filename, O_RDONLY, S_IRUSR);
-				close(0);
-				dup(fd);
-			}
+				if (redirect_flag == 1) /* redirect? */
+				{
+					fd = open(redirect_filename, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
+					close(1);
+					dup(fd);
+				}
+				else if (redirect_flag == 2)
+				{
+					fd = open(redirect_filename, O_RDONLY, S_IRUSR);
+					close(0);
+					dup(fd);
+				}
 
-			/* The child process inherits the parent's signal mask and will inherit it after exec, 
-            so it needs to restore the signal mask before executing. */
-			sigprocmask(SIG_SETMASK, &mask_prev, NULL); /* Child process, unblock SIGCHLD */
+				/* The child process inherits the parent's signal mask and will inherit it after exec, 
+           		 so it needs to restore the signal mask before executing. */
+				sigprocmask(SIG_SETMASK, &mask_prev, NULL); /* Child process, unblock SIGCHLD */
 
-			/* Set the pid of the current process to the group number of the process group it belongs to. */
-			/* avoid being grouped with tsh */
-			setpgid(0, 0);
+				/* Set the pid of the current process to the group number of the process group it belongs to. */
+				/* avoid being grouped with tsh */
+				setpgid(0, 0);
 
-			if ((redirect_flag == 1) || (redirect_flag == 2))
-			{
+				if ((redirect_flag == 1) || (redirect_flag == 2))
+				{
 
-				if (execvp(redirect_args[0], redirect_args) <= 0)
+					if (execvp(redirect_args[0], redirect_args) <= 0)
+					{
+						printf("%s: Command not found\n", args[0]);
+						exit(0);
+					}
+					close(fd);
+				}
+				else
 				{
-					printf("%s: Command not found\n", args[0]);
-					exit(0);
+					if (execvp(args[0], args) <= 0)
+					{
+						printf("%s: Command not found\n", args[0]);
+						exit(0);
+					}
 				}
-				close(fd);
 			}
 			else
 			{
-				if (execvp(args[0], args) <= 0)
+				if (bg) /* bg task */
+				{
+					addjob(jobs, pid, BG, cmdline);
+				}
+				else /* fg task */
+				{
+					addjob(jobs, pid, FG, cmdline);
+				}
+
+				sigprocmask(SIG_SETMASK, &mask_prev, NULL);
+
+				if (bg) /* Don't wait for background tasks to finish */
 				{
-					printf("%s: Command not found\n", args[0]);
-					exit(0);
+					printf("[%d](%d)%s", pid2jid(pid), pid, cmdline);
+				}
+				else /* Wait for foreground tasks to finish */
+				{
+					waitfg(pid);
 				}
 			}
 		}
-		else
+	}
+	else
+	{
+		int fds[2];
+		pid_t prog_1, prog_2;
+		sigprocmask(SIG_BLOCK, &mask_all, &mask_prev);
+
+		if ((prog_1 = fork()) == 0) /* Child process 1 */
 		{
-			if (bg) /* bg task */
-			{
-				addjob(jobs, pid, BG, cmdline);
-			}
-			else /* fg task */
-			{
-				addjob(jobs, pid, FG, cmdline);
-			}
+			dup2(fds[1], 1);
+			dup2(fds[1], 2);
+			close(fds[0]);
+			close(fds[1]);
 
 			sigprocmask(SIG_SETMASK, &mask_prev, NULL);
+			setpgid(0, 0);
 
-			if (bg) /* Don't wait for background tasks to finish */
+			if (execvp(pipe_arg_1[0], pipe_arg_1) <= 0)
 			{
-				printf("[%d](%d)%s", pid2jid(pid), pid, cmdline);
+				printf("%s: Command not found\n", pipe_arg_1[0]);
+				exit(0);
 			}
-			else /* Wait for foreground tasks to finish */
+			_exit(127);
+		}
+
+		if ((prog_2 = fork()) == 0) /* Child process 1 */
+		{
+			dup2(fds[0], 0);
+			close(fds[0]);
+			close(fds[1]);
+
+			sigprocmask(SIG_SETMASK, &mask_prev, NULL);
+			setpgid(0, 0);
+
+			if (execvp(pipe_arg_2[0], pipe_arg_2) <= 0)
 			{
-				waitfg(pid);
+				printf("%s: Command not found\n", pipe_arg_2[0]);
+				exit(0);
 			}
+			_exit(127);
 		}
+
+		close(fds[0]);
+		close(fds[1]);
+
+		waitfg(prog_1);
+		waitfg(prog_2);
 	}
 	return 1;
 }

yeeshell.h

@@ -38,6 +38,9 @@ int parseline(char *cmdline, char **args);
 /* check_redirect - check if the command contains redirection */
 int check_redirect(char **args, char *redirect_filename, char **redirect_args);
 
+/* check_redirect - check if the command contains pipe */
+int check_pipe(char **args, char **pipe_arg_1, char **pipe_arg_2);
+
 /* execute - Execute the command line */
 int execute(char *cmdline, char **args);