top: attempt to provide missing xterm vim keys support

A recent issue (and merge request) reminded me of gaps
in top's alternate 'vim' navigation keys support. Some
xterm emulators do not pass the customary strings when
keys were used with the <Ctrl> and/or <Alt> modifiers.

While it was a known problem, this issue/merge request
prompted research into the root cause. As it turns out
the problem is traceable to an X resource known by the
name 'eightBitInput'. When 'true' (the default), a key
pressed in combination with <Alt> will not be preceded
by the <Esc> character. Rather, a single character was
presented (modified via an 'eightBitMeta' X resource).

The following approaches would eliminate this problem:

. start xterm thus: xterm -xrm '*eightBitInput: false'

. use: ~/.Xresources with 'Xterm*eightBitInput: false'

. build xterm with 'configure --enable-meta-sends-esc'
( apparently used for CentOS, Fedora, openSUSE, etc. )

. enable xterm's menu via 'configure --enable-toolbar'
( so the user can set the 'Meta Sends Escape' option )

Of course, none of the above steps is desirable from a
user's perspective. So, this patch will add additional
entries to the iokey function's tinfo_tab to represent
strings passed when the <Alt> key does not send <Esc>.

[ hopefully they'll be the same across all platforms ]

Lastly, this patch will also eliminate those redundant
<Atl> + '\', '/', '<' & '>' provisions, which now seem
like overkill and suffer from that same 'eightBitMeta'
xterm problem. And we might as well say goodbye to the
4 '<Alt> + arrow key' table entries (which do not seem
to currently work with any emulator which I can find).

[ what in the world was I thinking way back in 2011? ]

Reference(s):
. issue
https://gitlab.com/procps-ng/procps/issues/135
. merge request
https://gitlab.com/procps-ng/procps/merge_requests/84

Signed-off-by: Jim Warner <james.warner@comcast.net>

diff --git a/NEWS b/NEWS
index 622f81c6d7b8180480b9581784f1ad187b208e3b..9de1f35d94fb270d6834b150eead7c0071d685c1 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,7 @@ procps-ng-NEXT
   * top: preserves 'other filters' in configuration file   issue #99
   * top: can now collapse/expand forest view children      issue #99
   * top: parent %CPU time includes collapsed children
+  * top: improve xterm support for vim navigation keys     issue #135
 
 procps-ng-3.3.15
 ----------------

diff --git a/top/top.1 b/top/top.1
index 945b09076f7a558020dab52ff97920903c9287ef..afc57dba1ea75405797441e0aff1f36fd828efbd 100644 (file)
--- a/top/top.1
+++ b/top/top.1
@@ -62,7 +62,7 @@
 .
 .\" Document /////////////////////////////////////////////////////////////
 .\" ----------------------------------------------------------------------
-.TH TOP 1 "July 2018" "procps-ng" "User Commands"
+.TH TOP 1 "June 2019" "procps-ng" "User Commands"
 .\" ----------------------------------------------------------------------
 
 .\" ----------------------------------------------------------------------
@@ -198,15 +198,15 @@ motion keys like the standard \*(KAs plus the Home, End, PgUp and PgDn keys.
 If your terminal or emulator does not provide those keys, the following
 combinations are accepted as alternatives:
 .nf
-      \fI key      equivalent-key-combinations \fR
-       Up       alt +\fB \\\fR      or  alt +\fB k \fR
-       Down     alt +\fB /\fR      or  alt +\fB j \fR
-       Left     alt +\fB <\fR      or  alt +\fB h \fR
-       Right    alt +\fB >\fR      or  alt +\fB l \fR(lower case L)
-       PgUp     alt +\fB Up\fR     or  alt + ctrl +\fB k \fR
-       PgDn     alt +\fB Down\fR   or  alt + ctrl +\fB j \fR
-       Home     alt +\fB Left\fR   or  alt + ctrl +\fB h \fR
-       End      alt +\fB Right\fR  or  alt + ctrl +\fB l \fR
+      \fI key      equivalent-keys \fR
+       Left     alt +\fB h \fR
+       Down     alt +\fB j \fR
+       Up       alt +\fB k \fR
+       Right    alt +\fB l \fR
+       Home     alt + ctrl +\fB h \fR
+       PgDn     alt + ctrl +\fB j \fR
+       PgUp     alt + ctrl +\fB k \fR
+       End      alt + ctrl +\fB l \fR
 .fi
 
 The \fBUp\fR and \fBDown\fR \*(KAs have special significance when prompted

diff --git a/top/top.c b/top/top.c
index df30e0d89abca835708f0d0ec0fe3d51b85ea2ee..a2678a3720be9d4ad070d6e45c75e2a0ae50f117 100644 (file)
--- a/top/top.c
+++ b/top/top.c
@@ -1135,8 +1135,6 @@ static int ioch (int ech, char *buf, unsigned cnt) {
          * note: we support more keys than we currently need, in case
          *       we attract new consumers in the future */
 static int iokey (int action) {
-   static char buf12[CAPBUFSIZ], buf13[CAPBUFSIZ]
-      , buf14[CAPBUFSIZ], buf15[CAPBUFSIZ];
    static struct {
       const char *str;
       int key;
@@ -1145,17 +1143,16 @@ static int iokey (int action) {
       { NULL, kbd_LEFT     }, { NULL, kbd_RIGHT    }, { NULL, kbd_PGUP     },
       { NULL, kbd_PGDN     }, { NULL, kbd_HOME     }, { NULL, kbd_END      },
       { NULL, kbd_BKSP     }, { NULL, kbd_INS      }, { NULL, kbd_DEL      },
-         // next 4 destined to be meta + arrow keys...
-      { buf12, kbd_PGUP    }, { buf13, kbd_PGDN    },
-      { buf14, kbd_HOME    }, { buf15, kbd_END     },
          // remainder are alternatives for above, just in case...
          // ( the k,j,l,h entries are the vim cursor motion keys )
-      { "\033\\",   kbd_UP    }, { "\033/",    kbd_DOWN  }, /* meta+      \,/ */
-      { "\033<",    kbd_LEFT  }, { "\033>",    kbd_RIGHT }, /* meta+      <,> */
       { "\033k",    kbd_UP    }, { "\033j",    kbd_DOWN  }, /* meta+      k,j */
       { "\033h",    kbd_LEFT  }, { "\033l",    kbd_RIGHT }, /* meta+      h,l */
       { "\033\013", kbd_PGUP  }, { "\033\012", kbd_PGDN  }, /* ctrl+meta+ k,j */
-      { "\033\010", kbd_HOME  }, { "\033\014", kbd_END   }  /* ctrl+meta+ h,l */
+      { "\033\010", kbd_HOME  }, { "\033\014", kbd_END   }, /* ctrl+meta+ h,l */
+      { "\xC3\xAB", kbd_UP    }, { "\xC3\xAA", kbd_DOWN  }, /* meta+      k,j (some xterms) */
+      { "\xC3\xA8", kbd_LEFT  }, { "\xC3\xAC", kbd_RIGHT }, /* meta+      h,l (some xterms) */
+      { "\xC2\x8B", kbd_PGUP  }, { "\xC2\x8A", kbd_PGDN  }, /* ctrl+meta+ k,j (some xterms) */
+      { "\xC2\x88", kbd_HOME  }, { "\xC2\x8C", kbd_END   }  /* ctrl+meta+ h,l (some xterms) */
    };
 #ifdef TERMIOS_ONLY
    char buf[SMLBUFSIZ], *pb;
@@ -1179,10 +1176,6 @@ static int iokey (int action) {
       tinfo_tab[9].str  = tOk(key_backspace);
       tinfo_tab[10].str = tOk(key_ic);
       tinfo_tab[11].str = tOk(key_dc);
-      STRLCPY(buf12, fmtmk("\033%s", tOk(key_up)));
-      STRLCPY(buf13, fmtmk("\033%s", tOk(key_down)));
-      STRLCPY(buf14, fmtmk("\033%s", tOk(key_left)));
-      STRLCPY(buf15, fmtmk("\033%s", tOk(key_right)));
       // next is critical so returned results match bound terminfo keys
       putp(tOk(keypad_xmit));
       // ( converse keypad_local issued at pause/pgm end, just in case )
@@ -1221,7 +1214,7 @@ static int iokey (int action) {
          return tinfo_tab[i].key;
 
    // no match, so we'll return single non-escaped keystrokes only
-   if (buf[0] == '\033' && buf[1]) return 0;
+   if (buf[0] == '\033' && buf[1]) return -1;
    return buf[0];
 } // end: iokey