less: reuse former vi's key reading code. Improve SIGWINCH handling.

function                                             old     new   delta
less_main                                           2056    2097     +41
getch_nowait                                         248     273     +25
read_key                                             310     321     +11
static.esccmds                                        61      69      +8
count_lines                                           72      74      +2
less_gets                                            166     142     -24
less_getch                                           172      43    -129
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 6/5 up/down: 91/-170)           Total: -79 bytes
   text    data     bss     dec     hex filename

1 files changed, 11 insertions, 6 deletions

diff --git a/libbb/read_key.c b/libbb/read_key.c
index 598bd94f5..614e2f9e0 100644
--- a/libbb/read_key.c
+++ b/libbb/read_key.c
@@ -33,14 +33,16 @@ int FAST_FUNC read_key(int fd, smalluint *nbuffered, char *buffer)
                 '[','B'        |0x80,KEYCODE_DOWN    ,
                 '[','C'        |0x80,KEYCODE_RIGHT   ,
                 '[','D'        |0x80,KEYCODE_LEFT    ,
-                '[','H'        |0x80,KEYCODE_HOME    ,
-                '[','F'        |0x80,KEYCODE_END     ,
-                '[','1','~'    |0x80,KEYCODE_HOME    ,
+                '[','H'        |0x80,KEYCODE_HOME    , /* xterm */
+                '[','F'        |0x80,KEYCODE_END     , /* xterm */
+                '[','1','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
                 '[','2','~'    |0x80,KEYCODE_INSERT  ,
                 '[','3','~'    |0x80,KEYCODE_DELETE  ,
-                '[','4','~'    |0x80,KEYCODE_END     ,
+                '[','4','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
                 '[','5','~'    |0x80,KEYCODE_PAGEUP  ,
                 '[','6','~'    |0x80,KEYCODE_PAGEDOWN,
+                '[','7','~'    |0x80,KEYCODE_HOME    , /* vt100? linux vt? or what? */
+                '[','8','~'    |0x80,KEYCODE_END     , /* vt100? linux vt? or what? */
 #if 0
                 '[','1','1','~'|0x80,KEYCODE_FUN1    ,
                 '[','1','2','~'|0x80,KEYCODE_FUN2    ,
@@ -58,7 +60,9 @@ int FAST_FUNC read_key(int fd, smalluint *nbuffered, char *buffer)
                 0
         };
 
-        n = *nbuffered;
+        n = 0;
+        if (nbuffered)
+                n = *nbuffered;
         if (n == 0) {
                 /* If no data, block waiting for input. If we read more
                  * than the minimal ESC sequence size, the "n=0" below
@@ -141,6 +145,7 @@ int FAST_FUNC read_key(int fd, smalluint *nbuffered, char *buffer)
          * by now. */
 
  ret:
-        *nbuffered = n;
+        if (nbuffered)
+                *nbuffered = n;
         return c;
 }