top: correct cursor positioning for all ^Z or ^C cases

Some more (very obscure) conditions where a suspension
or program end might embed the shell prompt within top
output have been uncovered beyond the 2 already known.

We had already covered some suspend/end contingencies:
1. the users were using the 'fields management' screen
2. the users were prompted for any line oriented input

However, there remained some situations where ^Z or ^C
could still produce a misplaced cursor + shell prompt:
3. the 'g' command while waiting for the window choice
4. the 'W' command if about to overwrite an old rcfile
5. the '=' command when exploiting the Inspect feature
6. the period during which any error message was shown

But, even when all those bases are covered there still
remains a remote possibility that such interrupts will
occur during a top repaint cycle. So rather than throw
yet more code at these self-inflicted problems perhaps
it is better if we just throw in the proverbial towel.

Thus, I'll take the only sane approach and restore the
results expected ever since top's inception and before
scrollback buffers entered the picture. Namely, with a
^Z or ^C the cursor will be placed on the final screen
row. That usually means it will immediately follow the
last output line but it may follow many blank lines if
the user interrupts top when *not* on the main screen.

Reference(s):
. expanded repositioning (for line oriented input)
commit 33104a2bcc321495107d72e4cfee4090b1d90f76
. introduced repositioning (for fields management)
commit 5c974ff44da4fbbb9170dd15bdd81555c62c31a9
. scrollback buffers (the cursor handling changes)
commit dedaf6e1a81738ff08ee8e8523871e12f555ad6d

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

diff --git a/top/top.c b/top/top.c
index 8978cd12ea7031f8ec529bae0367f176f61f2c5f..e2451f5bcbc5e48527f99af8a5453d6f1a3640d2 100644 (file)
--- a/top/top.c
+++ b/top/top.c
@@ -72,9 +72,8 @@ static struct termios Tty_original,    // our inherited terminal definition
                       Tty_raw;         // for unsolicited input
 static int Ttychanged = 0;
 
-        /* Last established cursor state/shape, and is re-position needed */
+        /* Last established cursor state/shape */
 static const char *Cursor_state = "";
-static int         Cursor_repos;
 
         /* Program name used in error messages and local 'rc' file name */
 static char *Myname;
@@ -351,7 +350,7 @@ static void at_eoj (void) {
    if (Ttychanged) {
       tcsetattr(STDIN_FILENO, TCSAFLUSH, &Tty_original);
       if (keypad_local) putp(keypad_local);
-      if (Cursor_repos) putp(tg2(0, Screen_rows));
+      putp(tg2(0, Screen_rows));
       putp("\n");
 #ifdef OFF_SCROLLBK
       if (exit_ca_mode) {
@@ -602,7 +601,7 @@ static void sig_paused (int dont_care_sig) {
    if (-1 == tcsetattr(STDIN_FILENO, TCSAFLUSH, &Tty_original))
       error_exit(fmtmk(N_fmt(FAIL_tty_set_fmt), strerror(errno)));
    if (keypad_local) putp(keypad_local);
-   if (Cursor_repos) putp(tg2(0, Screen_rows));
+   putp(tg2(0, Screen_rows));
    putp(Cap_curs_norm);
 #ifndef RMAN_IGNORED
    putp(Cap_smam);
@@ -1081,14 +1080,12 @@ static char *ioline (const char *prompt) {
    static char buf[MEDBUFSIZ];
    char *p;
 
-   Cursor_repos = 1;
    show_pmt(prompt);
    memset(buf, '\0', sizeof(buf));
    ioch(1, buf, sizeof(buf)-1);
 
    if ((p = strpbrk(buf, ws))) *p = '\0';
    // note: we DO produce a vaid 'string'
-   Cursor_repos = 0;
    return buf;
 } // end: ioline
 
@@ -1119,7 +1116,6 @@ static char *ioline (const char *prompt) {
    };
    static struct lin_s *anchor, *plin;
 
-   Cursor_repos = 1;
    if (!anchor) {
       anchor = alloc_c(sizeof(struct lin_s));
       anchor->str = alloc_s("");       // top-of-stack == empty str
@@ -1185,7 +1181,6 @@ static char *ioline (const char *prompt) {
       putp(tg2(beg+pos, Msg_row));
    } while (key && key != kbd_ENTER && key != kbd_ESC);
 
-   Cursor_repos = 0;
    // weed out duplicates, including empty strings (top-of-stack)...
    for (i = 0, plin = anchor; ; i++) {
 #ifdef RECALL_FIXED
@@ -2126,7 +2121,6 @@ static void fields_utility (void) {
    int i, key;
    FLG_t f;
 
-   Cursor_repos = 1;
    spewFI
 signify_that:
    putp(Cap_clr_scr);
@@ -2187,7 +2181,6 @@ signify_that:
             break;
       }
    } while (key != 'q' && key != kbd_ESC);
-   Cursor_repos = 0;
  #undef unSCRL
  #undef swapEM
  #undef spewFI