less,microcom,lineedit: use common routine to set raw termios

function                                             old     new   delta
get_termios_and_make_raw                               -     139    +139
xget1                                                 39       8     -31
read_line_input                                     3912    3867     -45
less_main                                           2525    2471     -54
set_termios_to_raw                                   116      36     -80
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/4 up/down: 139/-210)          Total: -71 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 40 insertions, 15 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 1b3a1667b..d7647704e 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -311,40 +311,65 @@ int FAST_FUNC tcsetattr_stdin_TCSANOW(const struct termios *tp)
 	return tcsetattr(STDIN_FILENO, TCSANOW, tp);
 }
 
-int FAST_FUNC set_termios_to_raw(int fd, struct termios *oldterm, int flags)
+int FAST_FUNC get_termios_and_make_raw(int fd, struct termios *newterm, struct termios *oldterm, int flags)
 {
-//TODO: lineedit, microcom, slattach, less might be adapted to use this too:
-// grep for "tcsetattr"
-
-	struct termios newterm;
+//TODO: slattach, shell read might be adapted to use this too: grep for "tcsetattr", "[VTIME] = 0"
+	int r;
 
-	tcgetattr(fd, oldterm);
-	newterm = *oldterm;
+	memset(oldterm, 0, sizeof(*oldterm)); /* paranoia */
+	r = tcgetattr(fd, oldterm);
+	*newterm = *oldterm;
 
 	/* Turn off buffered input (ICANON)
 	 * Turn off echoing (ECHO)
 	 * and separate echoing of newline (ECHONL, normally off anyway)
 	 */
-	newterm.c_lflag &= ~(ICANON | ECHO | ECHONL);
+	newterm->c_lflag &= ~(ICANON | ECHO | ECHONL);
 	if (flags & TERMIOS_CLEAR_ISIG) {
 		/* dont recognize INT/QUIT/SUSP chars */
-		newterm.c_lflag &= ~ISIG;
+		newterm->c_lflag &= ~ISIG;
 	}
 	/* reads will block only if < 1 char is available */
-	newterm.c_cc[VMIN] = 1;
+	newterm->c_cc[VMIN] = 1;
 	/* no timeout (reads block forever) */
-	newterm.c_cc[VTIME] = 0;
+	newterm->c_cc[VTIME] = 0;
 	if (flags & TERMIOS_RAW_CRNL) {
+/* IXON, IXOFF, and IXANY:
+ * IXOFF=1: sw flow control is enabled on input queue:
+ * tty transmits a STOP char when input queue is close to full
+ * and transmits a START char when input queue is nearly empty.
+ * IXON=1: sw flow control is enabled on output queue:
+ * tty will stop sending if STOP char is received,
+ * and resume sending if START is received, or if any char
+ * is received and IXANY=1.
+ */
+		/* IXON=0: XON/XOFF chars are treated as normal chars (why we do this?) */
 		/* dont convert CR to NL on input */
-		newterm.c_iflag &= ~(IXON | ICRNL);
-		/* dont convert NL to CR on output */
-		newterm.c_oflag &= ~(ONLCR);
+		newterm->c_iflag &= ~(IXON | ICRNL);
+		/* dont convert NL to CR+NL on output */
+		newterm->c_oflag &= ~(ONLCR);
+		/* Maybe clear more c_oflag bits? usually, only OPOST and ONLCR are set.
+		 * OPOST  Enable implementation-defined output processing (is this reqd for all other bits to work?)
+		 * OLCUC  Map lowercase characters to uppercase on output.
+		 * OCRNL  Map CR to NL on output.
+		 * ONOCR  Don't output CR at column 0.
+		 * ONLRET Don't output CR.
+		 */
 	}
 	if (flags & TERMIOS_RAW_INPUT) {
+		/* IXOFF=0: disable sending XON/XOFF if input buf is full */
+		/* IXON=0: XON/XOFF chars are treated as normal chars */
 		/* dont convert anything on input */
-		newterm.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
+		newterm->c_iflag &= ~(IXOFF|IXON|IXANY|BRKINT|INLCR|ICRNL|IUCLC|IMAXBEL);
 	}
+	return r;
+}
+
+int FAST_FUNC set_termios_to_raw(int fd, struct termios *oldterm, int flags)
+{
+	struct termios newterm;
 
+	get_termios_and_make_raw(fd, &newterm, oldterm, flags);
 	return tcsetattr(fd, TCSANOW, &newterm);
 }