lineedit: fix handling of repeating Alt-b, Alt-f, Alt-d, Alt-Backspace

These key combinations should repeat correctly when the keys are
pressed and held.

Before this change, they do this erratically - many repeats are "eaten"
because they are treated as unrecognized ESC seqs:
ESC 0x7f is treated by Alt+baskspace, but ESC 0x7f ESC 0x7f ESC 0x7f
is unrecognized.

Escape sequences corresponding to these key combinations are moved from
read_line_input to lineedit_read_key.

Also, these key sequences are now enabled regardless of whether
FEATURE_EDITING_VI is set, since Vim does not actually support these key
combinations, but they are present in readline library.

function                                             old     new   delta
static.esccmds                                        93     103     +10
read_line_input                                     3737    3687     -50

Signed-off-by: Rostislav Skudnov <rostislav@tuxera.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 30 insertions, 42 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 2cc61db40..ac049f57d 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -13,7 +13,6 @@
  *
  * This code is 'as is' with no warranty.
  */
-
 /*
  * Usage and known bugs:
  * Terminal key codes are not extensive, more needs to be added.
@@ -23,9 +22,6 @@
  * Ctrl-E also works as End.
  *
  * The following readline-like commands are not implemented:
- * ESC-b -- Move back one word
- * ESC-f -- Move forward one word
- * ESC-d -- Delete forward one word
  * CTL-t -- Transpose two characters
  *
  * lineedit does not know that the terminal escape sequences do not
@@ -2483,6 +2479,24 @@ int FAST_FUNC read_line_input(line_input_t *st, const char *prompt, char *comman
                         while (cursor > 0 && !BB_isspace(command_ps[cursor-1]))
                                 input_backspace();
                         break;
+                case KEYCODE_ALT_D: {
+                        /* Delete word forward */
+                        int nc, sc = cursor;
+                        ctrl_right();
+                        nc = cursor - sc;
+                        input_backward(nc);
+                        while (--nc >= 0)
+                                input_delete(1);
+                        break;
+                }
+                case KEYCODE_ALT_BACKSPACE: {
+                        /* Delete word backward */
+                        int sc = cursor;
+                        ctrl_left();
+                        while (sc-- > cursor)
+                                input_delete(1);
+                        break;
+                }
 #if ENABLE_FEATURE_REVERSE_SEARCH
                 case CTRL('R'):
                         ic = ic_raw = reverse_i_search();
@@ -2625,44 +2639,6 @@ int FAST_FUNC read_line_input(line_input_t *st, const char *prompt, char *comman
                                 vi_cmdmode = 1;
                                 input_backward(1);
                         }
-                        /* Handle a few ESC-<key> combinations the same way
-                         * standard readline bindings (IOW: bash) do.
-                         * Often, Alt-<key> generates ESC-<key>.
-                         */
-                        ic = lineedit_read_key(read_key_buffer, 50);
-                        switch (ic) {
-                                //case KEYCODE_LEFT: - bash doesn't do this
-                                case 'b':
-                                        ctrl_left();
-                                        break;
-                                //case KEYCODE_RIGHT: - bash doesn't do this
-                                case 'f':
-                                        ctrl_right();
-                                        break;
-                                //case KEYCODE_DELETE: - bash doesn't do this
-                                case 'd':  /* Alt-D */
-                                {
-                                        /* Delete word forward */
-                                        int nc, sc = cursor;
-                                        ctrl_right();
-                                        nc = cursor - sc;
-                                        input_backward(nc);
-                                        while (--nc >= 0)
-                                                input_delete(1);
-                                        break;
-                                }
-                                case '\b':   /* Alt-Backspace(?) */
-                                case '\x7f': /* Alt-Backspace(?) */
-                                //case 'w': - bash doesn't do this
-                                {
-                                        /* Delete word backward */
-                                        int sc = cursor;
-                                        ctrl_left();
-                                        while (sc-- > cursor)
-                                                input_delete(1);
-                                        break;
-                                }
-                        }
                         break;
 #endif /* FEATURE_COMMAND_EDITING_VI */
 
diff --git a/libbb/read_key.c b/libbb/read_key.c
index ace23defb..951786869 100644
--- a/libbb/read_key.c
+++ b/libbb/read_key.c
@@ -18,8 +18,20 @@ int64_t FAST_FUNC read_key(int fd, char *buffer, int timeout)
         /* Known escape sequences for cursor and function keys.
          * See "Xterm Control Sequences"
          * http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
+         * Array should be sorted from shortest to longest.
          */
         static const char esccmds[] ALIGN1 = {
+                '\x7f'         |0x80,KEYCODE_ALT_BACKSPACE,
+                '\b'           |0x80,KEYCODE_ALT_BACKSPACE,
+                'd'            |0x80,KEYCODE_ALT_D   ,
+        /* lineedit mimics bash: Alt-f and Alt-b are forward/backward
+         * word jumps. We cheat here and make them return ALT_LEFT/RIGHT
+         * keycodes. This way, lineedit need no special code to handle them.
+         * If we'll need to distinguish them, introduce new ALT_F/B keycodes,
+         * and update lineedit to react to them.
+         */
+                'f'            |0x80,KEYCODE_ALT_RIGHT,
+                'b'            |0x80,KEYCODE_ALT_LEFT,
                 'O','A'        |0x80,KEYCODE_UP      ,
                 'O','B'        |0x80,KEYCODE_DOWN    ,
                 'O','C'        |0x80,KEYCODE_RIGHT   ,