Allow the dtach -n mode to be used without a terminal. If a terminal is not

present when dtach is started, we now rely on whatever default terminal
settings the kernel uses.

3 files changed, 23 insertions, 3 deletions

diff --git a/dtach.h b/dtach.h
index f28099a..2ffd778 100644
--- a/dtach.h
+++ b/dtach.h
@@ -76,6 +76,7 @@
 extern char *progname, *sockname;
 extern int detach_char, no_suspend, redraw_method;
 extern struct termios orig_term;
+extern int dont_have_tty;
 
 enum
 {
diff --git a/main.c b/main.c
index 2f7eb2c..f7bc13d 100644
--- a/main.c
+++ b/main.c
@@ -44,6 +44,7 @@ int redraw_method = REDRAW_UNSPEC;
 ** it to restore the original settings.
 */
 struct termios orig_term;
+int dont_have_tty;
 
 static void
 usage()
@@ -210,10 +211,25 @@ main(int argc, char **argv)
 	/* Save the original terminal settings. */
 	if (tcgetattr(0, &orig_term) < 0)
 	{
-		printf("%s: tcgetattr: %s\n", progname, strerror(errno));
-		return 1;
+		if (errno == ENOTTY)
+		{
+			memset(&orig_term, 0, sizeof(struct termios));
+			dont_have_tty = 1;
+		}
+		else
+		{
+			printf("%s: tcgetattr: %s\n", progname,
+				strerror(errno));
+			return 1;
+		}
 	}
 
+	if (dont_have_tty && mode != 'n')
+	{
+		printf("%s: Attaching to a session requires a terminal.\n",
+			progname);
+		return 1;
+	}
 	if (mode == 'a')
 	{
 		if (argc > 0)
diff --git a/master.c b/master.c
index 1f08a6b..4b03fab 100644
--- a/master.c
+++ b/master.c
@@ -114,7 +114,10 @@ init_pty(char **argv)
 	memset(&the_pty.ws, 0, sizeof(struct winsize));
 
 	/* Create the pty process */
-	the_pty.pid = forkpty(&the_pty.fd, NULL, &the_pty.term, NULL);
+	if (!dont_have_tty)
+		the_pty.pid = forkpty(&the_pty.fd, NULL, &the_pty.term, NULL);
+	else
+		the_pty.pid = forkpty(&the_pty.fd, NULL, NULL, NULL);
 	if (the_pty.pid < 0)
 		return -1;
 	else if (the_pty.pid == 0)