From b1bee31d6196eb9ce4b74be7b818c9cff31fc4ec Mon Sep 17 00:00:00 2001
From: Joachim Wiberg <troglobit@gmail.com>
Date: Wed, 7 Apr 2021 10:07:26 +0200
Subject: [PATCH] Helper functions for setting TTY in raw and cooked mode

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
---
 src/util.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/util.h |  4 ++++
 2 files changed, 68 insertions(+)

diff --git a/src/util.c b/src/util.c
index de880c0d..745ff95a 100644
--- a/src/util.c
+++ b/src/util.c
@@ -41,6 +41,22 @@
 #include <lite/lite.h>		/* strlcat() */
 #include "util.h"
 
+#ifdef HAVE_TERMIOS_H
+/*
+ * This flag is used on *BSD when calling tcsetattr() to prevent it
+ * from changing speed, duplex, parity.  GNU says we should use the
+ * CIGNORE flag to c_cflag, but that doesn't exist so ... we rely on
+ * our initial tcgetattr() and prey that nothing changes on the TTY
+ * before we exit and restore with tcsetattr()
+ */
+#ifndef TCSASOFT
+#define TCSASOFT 0
+#endif
+
+static struct termios ttold;
+static struct termios ttnew;
+#endif
+
 int   ttrows  = 24;
 int   ttcols  = 80;
 char *prognm  = NULL;
@@ -308,6 +324,54 @@ int ttinit(void)
 
 	return ttcols;
 }
+
+/*
+ * This function sets the terminal to RAW mode, as defined for the current
+ * shell.  This is called both by ttopen() above and by spawncli() to
+ * get the current terminal settings and then change them to what
+ * mg expects.	Thus, tty changes done while spawncli() is in effect
+ * will be reflected in mg.
+ */
+int ttraw(void)
+{
+	if (tcgetattr(0, &ttold) == -1) {
+		fprintf(stderr, "%s: failed querying tty attrs: %s\n",
+			prognm, strerror(errno));
+		return 1;
+	}
+
+	(void)memcpy(&ttnew, &ttold, sizeof(ttnew));
+	/* Set terminal to 'raw' mode and ignore a 'break' */
+	ttnew.c_cc[VMIN] = 1;
+	ttnew.c_cc[VTIME] = 0;
+	ttnew.c_iflag |= IGNBRK;
+	ttnew.c_iflag &= ~(BRKINT | PARMRK | INLCR | IGNCR | ICRNL | IXON);
+	ttnew.c_oflag &= ~OPOST;
+	ttnew.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
+
+	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &ttnew) == -1) {
+		fprintf(stderr, "%s: failed setting tty in raw mode: %s\n",
+			prognm, strerror(errno));
+		return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * This function restores all terminal settings to their default values,
+ * in anticipation of exiting or suspending the editor.
+ */
+int ttcooked(void)
+{
+	if (tcsetattr(0, TCSASOFT | TCSADRAIN, &ttold) == -1) {
+		fprintf(stderr, "%s: failed restoring tty to cooked mode: %s\n",
+			prognm, strerror(errno));
+		return 1;
+	}
+
+	return 0;
+}
 #endif /* HAVE_TERMIOS_H */
 
 /**
diff --git a/src/util.h b/src/util.h
index 5f038fc7..9d37d24e 100644
--- a/src/util.h
+++ b/src/util.h
@@ -62,8 +62,12 @@ char *sanitize     (char *arg, size_t len);
 
 #ifdef HAVE_TERMIOS_H
 int     ttinit     (void);
+int     ttraw      (void);
+int     ttcooked   (void);
 #else
 #define ttinit()   ttcols
+#define ttraw()    0
+#define ttcooked() 0
 #endif
 
 static inline char *strterm(char *str, size_t len)