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>

3 files changed, 68 insertions, 80 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 20fc7329f..bdafcf5a6 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1463,46 +1463,46 @@ unsigned long long bb_makedev(unsigned major, unsigned minor) FAST_FUNC;
  * yet doesn't represent any valid Unicode character.
  * Also, -1 is reserved for error indication and we don't use it. */
 enum {
-        KEYCODE_UP       =  -2,
-        KEYCODE_DOWN     =  -3,
-        KEYCODE_RIGHT    =  -4,
-        KEYCODE_LEFT     =  -5,
-        KEYCODE_HOME     =  -6,
-        KEYCODE_END      =  -7,
-        KEYCODE_INSERT   =  -8,
-        KEYCODE_DELETE   =  -9,
-        KEYCODE_PAGEUP   = -10,
-        KEYCODE_PAGEDOWN = -11,
-        // -12 is reserved for Alt/Ctrl/Shift-TAB
+        KEYCODE_UP        =  -2,
+        KEYCODE_DOWN      =  -3,
+        KEYCODE_RIGHT     =  -4,
+        KEYCODE_LEFT      =  -5,
+        KEYCODE_HOME      =  -6,
+        KEYCODE_END       =  -7,
+        KEYCODE_INSERT    =  -8,
+        KEYCODE_DELETE    =  -9,
+        KEYCODE_PAGEUP    = -10,
+        KEYCODE_PAGEDOWN  = -11,
+        KEYCODE_BACKSPACE = -12, /* Used only if Alt/Ctrl/Shifted */
+        KEYCODE_D         = -13, /* Used only if Alted */
 #if 0
-        KEYCODE_FUN1     = -13,
-        KEYCODE_FUN2     = -14,
-        KEYCODE_FUN3     = -15,
-        KEYCODE_FUN4     = -16,
-        KEYCODE_FUN5     = -17,
-        KEYCODE_FUN6     = -18,
-        KEYCODE_FUN7     = -19,
-        KEYCODE_FUN8     = -20,
-        KEYCODE_FUN9     = -21,
-        KEYCODE_FUN10    = -22,
-        KEYCODE_FUN11    = -23,
-        KEYCODE_FUN12    = -24,
-#endif
-        /* Be sure that last defined value is small enough
-         * to not interfere with Alt/Ctrl/Shift bits.
-         * So far we do not exceed -31 (0xfff..fffe1),
-         * which gives us three upper bits in LSB to play with.
+        KEYCODE_FUN1      = ,
+        KEYCODE_FUN2      = ,
+        KEYCODE_FUN3      = ,
+        KEYCODE_FUN4      = ,
+        KEYCODE_FUN5      = ,
+        KEYCODE_FUN6      = ,
+        KEYCODE_FUN7      = ,
+        KEYCODE_FUN8      = ,
+        KEYCODE_FUN9      = ,
+        KEYCODE_FUN10     = ,
+        KEYCODE_FUN11     = ,
+        KEYCODE_FUN12     = ,
+#endif
+        /* ^^^^^ Be sure that last defined value is small enough.
+         * Current read_key() code allows going up to -32 (0xfff..fffe0).
+         * This gives three upper bits in LSB to play with:
+         * KEYCODE_foo values are 0xfff..fffXX, lowest XX bits are: scavvvvv,
+         * s=0 if SHIFT, c=0 if CTRL, a=0 if ALT,
+         * vvvvv bits are the same for same key regardless of "shift bits".
          */
-        //KEYCODE_SHIFT_TAB  = (-12)         & ~0x80,
-        //KEYCODE_SHIFT_...  = KEYCODE_...   & ~0x80,
-        //KEYCODE_CTRL_UP    = KEYCODE_UP    & ~0x40,
-        //KEYCODE_CTRL_DOWN  = KEYCODE_DOWN  & ~0x40,
-        KEYCODE_CTRL_RIGHT = KEYCODE_RIGHT & ~0x40,
-        KEYCODE_CTRL_LEFT  = KEYCODE_LEFT  & ~0x40,
-        //KEYCODE_ALT_UP     = KEYCODE_UP    & ~0x20,
-        //KEYCODE_ALT_DOWN   = KEYCODE_DOWN  & ~0x20,
-        KEYCODE_ALT_RIGHT  = KEYCODE_RIGHT & ~0x20,
-        KEYCODE_ALT_LEFT   = KEYCODE_LEFT  & ~0x20,
+        //KEYCODE_SHIFT_...   = KEYCODE_...   & ~0x80,
+        KEYCODE_CTRL_RIGHT    = KEYCODE_RIGHT & ~0x40,
+        KEYCODE_CTRL_LEFT     = KEYCODE_LEFT  & ~0x40,
+        KEYCODE_ALT_RIGHT     = KEYCODE_RIGHT & ~0x20,
+        KEYCODE_ALT_LEFT      = KEYCODE_LEFT  & ~0x20,
+        KEYCODE_ALT_BACKSPACE = KEYCODE_BACKSPACE & ~0x20,
+        KEYCODE_ALT_D         = KEYCODE_D     & ~0x20,
 
         KEYCODE_CURSOR_POS = -0x100, /* 0xfff..fff00 */
         /* How long is the longest ESC sequence we know?
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   ,