Return and check status from get_cur_line.

From time to time get_cur_line doesn't fetch a value
due to a timeout or, more likely, interference
from TTY input.  We have to check those situations
so as not to try to calculate with a bad value or
pass it to stty or whatever.

* basta.sh (basta.query_terminal_lines): Propagate status now
returned by get_cur_line.
(basta.prepare_term): Skip logic and return failure if
query_terminal_lines failed, since realrows contains garbage.
(basta.get_cur_line): Return success if value obtained
is a string of one or more decimal digits.
(basta.check_cursor): Improve error checking.
(basta.fullscreen_alt): Error checks.

1 files changed, 14 insertions, 9 deletions

diff --git a/basta.sh b/basta.sh
index 44c5a71..9acaa89 100644
--- a/basta.sh
+++ b/basta.sh
@@ -17,11 +17,14 @@ basta_deferred_intr=${basta_deferred_intr-}
 basta.query_terminal_lines()
 {
   local -n intovar=$1
+  local result
   local curline
   printf $'\e7\e[999;999H'
   basta.get_cur_line curline
+  result=$?
   printf $'\e8'
   intovar=$curline
+  return $result
 }
 
 basta.query_termios_lines_cols()
@@ -37,7 +40,10 @@ basta.query_termios_lines_cols()
 basta.prepare_term()
 {
   local realrows
-  basta.query_terminal_lines realrows
+
+  if ! basta.query_terminal_lines realrows; then
+    return 1
+  fi
 
   if [ -z "$basta_prev_reserved_rows" ] ; then
     basta_prev_reserved_rows=${#LC_basta_status[@]}
@@ -61,6 +67,7 @@ basta.get_cur_line()
   local IFS="[;"
   set -- $response
   intovar=$2
+  [[ "$intovar" =~ ^[0-9]+$ ]]
 }
 
 if [ $EPOCHSECONDS ] ; then
@@ -142,15 +149,13 @@ basta.check_cursor()
       local curln
       local realrows
 
-      basta.get_cur_line curln
-
-      if [ $curln ] && [ $curln -gt $basta_scroll_lines ]; then
+      if basta.get_cur_line curln && [ $curln -gt $basta_scroll_lines ]; then
         printf $'\e[%s;1H' $basta_scroll_lines
       fi
 
       basta_last_check_epoch=$now
 
-      basta.query_terminal_lines realrows
+      basta.query_terminal_lines realrows &&
       [ $LINES -eq $((realrows - $basta_prev_reserved_rows - 1)) ]
       return $?
     fi
@@ -351,10 +356,10 @@ basta.fullscreen_alt() {
   basta_deferred_intr=WINCH
   LINES=$realrows command "$@" || exit=$?
 
-  basta.query_terminal_lines realrows >&$ttyfd <&$ttyfd
-  basta.get_cur_line curline >&$ttyfd <&$ttyfd
-
-  if [ $curline -ge $(( realrows - basta_prev_reserved_rows )) ] ; then
+  if basta.query_terminal_lines realrows >&$ttyfd <&$ttyfd &&
+     basta.get_cur_line curline >&$ttyfd <&$ttyfd &&
+     [ $curline -ge $(( realrows - basta_prev_reserved_rows )) ]
+  then
     local scrolls_needed=$(( curline - realrows + basta_prev_reserved_rows ))
     printf $'\e[%s;1H' $realrows >&$ttyfd
     for (( i = 0 ; i < scrolls_needed; i++ )) ; do