1 files changed, 40 insertions, 15 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 1b3a1667b..0dfb3e2d9 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 output processing (reqd for OLCUC and *NL* 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: input XON/XOFF chars are not special */
                 /* 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);
 }