Swap child and parent: prevent pplog immediate interrupt

.github/workflows/ci.yaml

@@ -43,3 +43,10 @@ jobs:
         with:
           files: ./coverage.txt
           verbose: true
+defaults:
+  run:
+    # NOTE: some of behavioral-tests requires tty... but
+    #
+    # GitHub Actions run without a TTY device. This is a workaround to get one,
+    # based on https://github.com/actions/runner/issues/241#issuecomment-2019042651
+    shell: 'script --return --quiet --log-out /dev/null --command "bash -e {0}"'

behavioral-tests/ctrl-c-graceful/custom-fake-server.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+child_pid=
+
+xtrap() {
+    echo "Getting SIGNAL $1. Exiting"
+    kill -9 $child_pid
+    exit
+}
+
+trap "xtrap SIGINT" 2 # graceful shutdown handler
+
+echo "Arguments: $@"
+
+(
+    # pretending someone kills process
+    for i in "$@"; do
+      echo "Working hard on ${i}..."
+      sleep 5
+    done
+) &
+
+child_pid=$!
+
+wait

behavioral-tests/ctrl-c-graceful/custom-run.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# emulate terminal: run command in separate process group
+set -m
+(
+  go run ../../cmd/... ./custom-fake-server.sh ARG1 ARG2 ARG3 > output.log
+) &
+set +m
+child_pgid=${!}
+
+sleep 1 # allow to work a little
+kill -2 -${child_pgid} # emulate user's ctrl-C
+
+wait ${child_pgid}
+
+echo "ok"

behavioral-tests/ctrl-c-graceful/expected.log

@@ -0,0 +1,3 @@
+INVALID JSON: "Arguments: ARG1 ARG2 ARG3"
+INVALID JSON: "Working hard on ARG1..."
+INVALID JSON: "Getting SIGNAL SIGINT. Exiting"

cmd/pplog/main.go

@@ -7,6 +7,7 @@ import (
 	"io/fs"
 	"os"
 	"os/exec"
+	"os/signal"
 	"path"
 	"runtime/debug"
 	"strings"
@@ -178,10 +179,29 @@ func main() {
 		showBuildInfo()
 		return
 	}
-	if flag.NArg() >= 1 {
-		runSubprocessMode()
-	} else {
-		runPipeMode()
+	interrupt := make(chan os.Signal, 1)
+	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)
+
+	done := make(chan struct{})
+	go func() {
+		if flag.NArg() >= 1 {
+			runSubprocessMode()
+		} else {
+			runPipeMode()
+		}
+		close(done)
+	}()
+
+	select {
+	case <-interrupt:
+		deb("interrupt, allow target to shutdown gracefully...")
+	case <-done:
+	}
+
+	select {
+	case <-interrupt:
+		deb("second interrupt, exit immediately")
+	case <-done:
 	}
 }