HW1: 初始化 RasShell 和簡單的命令列解析

5 files changed, 135 insertions, 10 deletions

diff --git a/hw1/configure.ac b/hw1/configure.ac
index 40a8113..e37e45c 100644
--- a/hw1/configure.ac
+++ b/hw1/configure.ac
@@ -32,5 +32,12 @@ AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_CHECK_FUNCS([setgroups initgroups getdtablesize])
 
+# Misc options.
+AC_ARG_WITH([motd],
+		[AS_HELP_STRING([--with-motd=FILE],
+		[Set FILE as default message of the day @<:@default=/etc/motd@:>@])],
+		[with_motd="$withval"], [with_motd="/etc/motd"])
+AC_DEFINE_UNQUOTED([ETC_MOTD], ["$with_motd"], [Message of the day])
+
 AC_CONFIG_FILES([Makefile])
 AC_OUTPUT
diff --git a/hw1/connection.c b/hw1/connection.c
index b7bd650..4ca17b2 100644
--- a/hw1/connection.c
+++ b/hw1/connection.c
@@ -54,16 +54,14 @@ int ras_conn_init (
 	conn->domain = domain;
 	conn->perm = perm;
 	conn->id = id;
-	conn->pid = getpid ();
-	conn->name = xsprintf ("%s-%d (%s-%s) [%d]",
+	conn->name = xsprintf ("%s-%d (%s-%s)",
 		name, conn->id,
 		domain == AF_LOCAL ? "unix" :
 		domain == AF_INET ? "ipv4" :
 		domain == AF_INET6 ? "ipv6" : "unknown",
 		perm == RAS_CONN_PERM_RESTRICTED ? "restricted" :
 		perm == RAS_CONN_PERM_REGULAR ? "regular" :
-		perm == RAS_CONN_PERM_ADMIN ? "admin" : "unknown",
-		conn->pid);
+		perm == RAS_CONN_PERM_ADMIN ? "admin" : "unknown");
 	conn->fd_is_set = false;
 
 	return 0;
@@ -98,10 +96,10 @@ void ras_conn_log (RasConn* conn, const char* format, ...) {
 	fcntl (conn->log_fd, F_SETLKW, &lock_info);
 
 	fprintf (conn->log,
-		"%04d-%02d-%02d %02d:%02d:%02d %s: ",
+		"%04d-%02d-%02d %02d:%02d:%02d %s [%d]: ",
 		tmd.tm_year + 1900, tmd.tm_mon + 1, tmd.tm_mday,
 		tmd.tm_hour, tmd.tm_min, tmd.tm_sec,
-		conn->name);
+		conn->name, getpid ());
 	vfprintf (conn->log, format, ap);
 	putc ('\n', conn->log);
 
diff --git a/hw1/connection.h b/hw1/connection.h
index 6ad4442..015619b 100644
--- a/hw1/connection.h
+++ b/hw1/connection.h
@@ -18,7 +18,6 @@ typedef struct {
 	int id;
 	int fd;
 	int fd_is_set  : 1;
-	pid_t pid;
 	char* name;
 	FILE* log;
 	char* log_file;
diff --git a/hw1/session.c b/hw1/session.c
index b8e122e..4c4db13 100644
--- a/hw1/session.c
+++ b/hw1/session.c
@@ -222,6 +222,8 @@ int ras_session_start_shell (RasSession* session) {
 	const int noshell_len = STATIC_STRLEN (noshell_msg);
 	const char nopty_msg[] = "Error: Cannot allocate a pseudo-tty.\n";
 	const int nopty_len = STATIC_STRLEN (nopty_msg);
+	const char nosid_msg[] = "Error: Cannot start a new session.\n";
+	const int nosid_len = STATIC_STRLEN (nosid_msg);
 	int sockpair[2]; /* parent = 0, child = 1 */
 	char* slave_dev = NULL;
 
@@ -258,6 +260,7 @@ int ras_session_start_shell (RasSession* session) {
 			close (session->shell_stdio);
 			return -1;
 		}
+		ras_session_log (session, "new pseudo-tty is %s", slave_dev);
 	} else {
 		if (socketpair (AF_LOCAL, SOCK_STREAM, 0, sockpair) < 0) {
 			write (RAS_CONN (session)->fd, noshell_msg, noshell_len);
@@ -289,6 +292,8 @@ int ras_session_start_shell (RasSession* session) {
 		FD_SET (child, &rset);
 		FD_SET (sock, &rset);
 
+		ras_session_log (session, "child started with pid %d", session->shell_pid);
+
 		while (!child_terminated) {
 			rresult = rset;
 			if (select (nfds, &rresult, NULL, NULL, NULL) >= 0) {
@@ -320,6 +325,11 @@ int ras_session_start_shell (RasSession* session) {
 		/* child process */
 		int child_stdio;
 
+		if (setsid () < 0) {
+			write (RAS_CONN (session)->fd, nosid_msg, nosid_len);
+			ras_session_log (session, "cannot setsid: %s", strerror (errno));
+		}
+
 		if (slave_dev != NULL) {
 			child_stdio = open (slave_dev, O_RDWR);
 			if (child_stdio < 0) {
@@ -338,6 +348,8 @@ int ras_session_start_shell (RasSession* session) {
 			child_stdio = sockpair[1];
 		}
 
+		ras_session_log (session, "shell environment is OK, closing log file");
+
 		ras_socktool_reset_signals ();
 
 		ras_socktool_close_except (child_stdio);
@@ -346,8 +358,13 @@ int ras_session_start_shell (RasSession* session) {
 		dup2 (child_stdio, STDERR_FILENO);
 		close (child_stdio);
 
-		char* argv[] = { "-ras-shell", NULL };
-		exit (ras_shell_main (1, argv));
+		if (RAS_CONN (session)->perm == RAS_CONN_PERM_RESTRICTED) {
+			char* argv[] = { "-ras-shell", "-r", NULL };
+			exit (ras_shell_main (2, argv));
+		} else {
+			char* argv[] = { "-ras-shell", NULL };
+			exit (ras_shell_main (1, argv));
+		}
 	}
 
 	return 0;
diff --git a/hw1/shell.c b/hw1/shell.c
index 1060054..c21669b 100644
--- a/hw1/shell.c
+++ b/hw1/shell.c
@@ -2,10 +2,114 @@
 # include "config.h"
 #endif
 
+#include "basic-array.h"
+#include "basic-list.h"
+#include "xwrap.h"
+
+#include <errno.h>
+#include <inttypes.h>
+#include <locale.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
+#include <string.h>
+#include <time.h>
 #include <unistd.h>
 
+typedef struct {
+	char*    name;             /* This is argv[0]. Do not modify or free it. */
+	uint64_t count;
+	List*    saved_list;
+	char*    saved_tmpdir;
+	int      attr_login  : 1;  /* login shell */
+	int      attr_rshell : 1;  /* restricted shell */
+} RasShell;
+
+int ras_shell_init (RasShell* shell, int argc, char* argv[]) {
+	shell->attr_login = argv[0][0] == '-';
+	shell->attr_rshell = false;
+
+	for (int i = 1; i < argc; i++) {
+		if (argv[i][0] != '-') {
+			fprintf (stderr, "%s: %s: unknown argument\n", argv[0], argv[i]);
+			return -1;
+		}
+		for (int j = 1; argv[i][j] != '\0'; j++) {
+			switch (argv[i][j]) {
+				case 'r':
+					shell->attr_rshell = true;
+					break;
+				case 'l':
+					shell->attr_login = true;
+					break;
+				case 'h':
+				case '?':
+				case '-':
+					printf (
+						"Usage: %s [-hlr]\n"
+						"  -h  View this help message\n"
+						"  -l  Make ras-shell be a login shell\n"
+						"  -r  Make ras-shell be a restricted shell\n",
+						argv[0]);
+					return -1;
+					break;
+				default:
+					fprintf (stderr, "%s: -%c: unknown option\n", argv[0], argv[i][j]);
+					return -1;
+			}
+		}
+	}
+
+	char* tmpdir = xstrcat ("/tmp/", argv[0], "-XXXXXX", NULL);
+	if (mkdtemp (tmpdir) < 0) {
+		fprintf (stderr, "%s: mkdtemp: %s\n", argv[0], strerror (errno));
+		free (tmpdir);
+		return -1;
+	}
+
+	shell->name = argv[0];
+	shell->count = 1;
+	shell->saved_list = list_create ();
+	shell->saved_tmpdir = tmpdir;
+
+	return 0;
+}
+
+void ras_shell_destroy (RasShell* shell) {
+	list_free (shell->saved_list);
+	free (shell->saved_tmpdir);
+}
+
 int ras_shell_main (int argc, char* argv[]) {
-	printf ("Hello World\n");
+	setlocale (LC_ALL, "");
+	tzset ();
+
+	RasShell shell;
+	if (ras_shell_init (&shell, argc, argv) < 0) {
+		return 1;
+	}
+
+	if (shell.attr_login) {
+		FILE* motd_fp;
+		int c;
+		puts ("Welcome! This is remote access system (RAS) login shell.");
+		motd_fp = fopen (ETC_MOTD, "r");
+		if (motd_fp == NULL) {
+			fprintf (stderr, "%s: fail to open " ETC_MOTD ": %s", argv[0], strerror (errno));
+		} else {
+			while ((c = getc (motd_fp)) != EOF) {
+				putchar (c);
+			}
+			fclose (motd_fp);
+		}
+	}
+
+	if (shell.attr_rshell) {
+		puts ("Note: This is a restricted shell. Some command may be disabled.");
+	}
+
+	ras_shell_destroy (&shell);
+
 	return 0;
 }