libbb: consolidate the code to set termios unbuffered mode

function                                             old     new   delta
set_termios_to_raw                                     -     116    +116
count_lines                                           72      74      +2
powertop_main                                       1458    1430     -28
top_main                                             943     914     -29
more_main                                            759     714     -45
fsck_minix_main                                     2969    2921     -48
conspy_main                                         1197    1135     -62
rawmode                                               99      36     -63
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/6 up/down: 118/-275)         Total: -157 bytes

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

2 files changed, 38 insertions, 1 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 31e392147..2a5d4e704 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -2325,7 +2325,7 @@ int FAST_FUNC read_line_input(line_input_t *st, const char *prompt, char *comman
         /* ~ECHO, ~ECHONL: turn off echoing, including newline echoing */
         /* ~ISIG: turn off INTR (ctrl-C), QUIT, SUSP */
         new_settings.c_lflag &= ~(ICANON | ECHO | ECHONL | ISIG);
-        /* reads would block only if < 1 char is available */
+        /* reads will block only if < 1 char is available */
         new_settings.c_cc[VMIN] = 1;
         /* no timeout (reads block forever) */
         new_settings.c_cc[VTIME] = 0;
diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 45650edba..98d3531d6 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -311,6 +311,43 @@ 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)
+{
+//TODO: lineedit, microcom and less might be adapted to use this too:
+// grep for "tcsetattr"
+
+        struct termios newterm;
+
+        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);
+        if (flags & TERMIOS_CLEAR_ISIG) {
+                /* dont recognize INT/QUIT/SUSP chars */
+                newterm.c_lflag &= ~ISIG;
+        }
+        /* reads will block only if < 1 char is available */
+        newterm.c_cc[VMIN] = 1;
+        /* no timeout (reads block forever) */
+        newterm.c_cc[VTIME] = 0;
+        if (flags & TERMIOS_RAW_CRNL) {
+                /* dont convert CR to NL on input */
+                newterm.c_iflag &= ~(IXON | ICRNL);
+                /* dont convert NL to CR on output */
+                newterm.c_oflag &= ~(ONLCR);
+        }
+        if (flags & TERMIOS_RAW_INPUT) {
+                /* dont convert anything on input */
+                newterm.c_iflag &= ~(BRKINT|INLCR|ICRNL|IXON|IXOFF|IUCLC|IXANY|IMAXBEL);
+        }
+
+        return tcsetattr(fd, TCSANOW, &newterm);
+}
+
 pid_t FAST_FUNC safe_waitpid(pid_t pid, int *wstat, int options)
 {
         pid_t r;