From 59b1c525c4c7c254dce702fca0fa472616a976d2 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Wed, 22 May 2024 16:12:37 -0400
Subject: tests: Print progress outside the scroll region

---
 tests/color.sh | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)

(limited to 'tests/color.sh')

diff --git a/tests/color.sh b/tests/color.sh
index 805d2b8..ca85d28 100644
--- a/tests/color.sh
+++ b/tests/color.sh
@@ -35,3 +35,104 @@ color() {
         "$@" | "$SED" $'s/\e\\[[^m]*m//g'
     fi
 }
+
+## Status bar
+
+# Show the terminal status bar
+show_bar() {
+    if [ -z "$TTY" ]; then
+        return 1
+    fi
+
+    # Name the pipe deterministically based on the ttyname, so that concurrent
+    # tests.sh runs on the same terminal (e.g. make -jN check) cooperate
+    local pipe
+    pipe=$(printf '%s' "$TTY" | tr '/' '-')
+    pipe="${TMPDIR:-/tmp}/bfs$pipe.bar"
+
+    if mkfifo "$pipe" 2>/dev/null; then
+        # We won the race, create the background process to manage the bar
+        bar_proc "$pipe" &
+        exec {BAR}>"$pipe"
+    elif [ -p "$pipe" ]; then
+        # We lost the race, connect to the existing process.
+        # There is a small TOCTTOU race here but I don't see how to avoid it.
+        exec {BAR}>"$pipe"
+    else
+        return 1
+    fi
+}
+
+# Print to the terminal status bar
+print_bar() {
+    printf 'PRINT:%d:%s\0' $$ "$1" >&$BAR
+}
+
+# Hide the terminal status bar
+hide_bar() {
+    exec {BAR}>&-
+    unset BAR
+}
+
+# The background process that muxes multiple status bars for one TTY
+bar_proc() {
+    # Read from the pipe, write to the TTY
+    exec <"$1" >"$TTY"
+
+    # Delete the pipe when done
+    defer rm "$1"
+    # Reset the scroll region when done
+    defer printf '\e7\e[r\e8\e[J'
+
+    # Workaround for bash 4: checkwinsize is off by default.  We can turn it
+    # on, but we also have to explicitly trigger a foreground job to finish
+    # so that it will update the window size before we use $LINES
+    shopt -s checkwinsize
+    (:)
+
+    BAR_HEIGHT=0
+    resize_bar
+    # Adjust the bar when the TTY size changes
+    trap resize_bar WINCH
+
+    # Map from PID to status bar
+    local -A pid2bar
+
+    # Read commands of the form "OP:PID:STRING\0"
+    while IFS=':' read -r -d '' op pid str; do
+        # Map the pid to a bar, creating a new one if necessary
+        if [ -z "${pid2bar[$pid]:-}" ]; then
+            pid2bar["$pid"]=$((BAR_HEIGHT++))
+            resize_bar
+        fi
+        bar="${pid2bar[$pid]}"
+
+        case "$op" in
+            PRINT)
+                printf '\e7\e[%d;0f\e[K%s\e8' $((TTY_HEIGHT - bar)) "$str"
+                ;;
+        esac
+    done
+}
+
+# Resize the status bar
+resize_bar() {
+    # Bash gets $LINES from stderr, so if it's redirected use tput instead
+    TTY_HEIGHT="${LINES:-$(tput lines 2>"$TTY")}"
+
+    if ((BAR_HEIGHT == 0)); then
+        return
+    fi
+
+    # Hide the bars temporarily
+    local seq='\e7\e[r\e8\e[J'
+    # Print \eD (IND) N times to ensure N blank lines at the bottom
+    for ((i = 0; i < BAR_HEIGHT; ++i)); do
+        seq="${seq}\\eD"
+    done
+    # Go back up N lines
+    seq="${seq}\\e[${BAR_HEIGHT}A"
+    # Create the new scroll region
+    seq="${seq}\\e7\\e[;$((TTY_HEIGHT - BAR_HEIGHT))r\\e8\\e[J"
+    printf "$seq"
+}
-- 
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