From 9fe4c9e5d0566c1c579b3853b6695ae513379221 Mon Sep 17 00:00:00 2001
From: Kentaro Hayashi <hayashi@clear-code.com>
Date: Mon, 19 Feb 2024 18:20:33 +0900
Subject: [PATCH] msi: guard duplicated instance

Before:

  Even though fluentdwinsvc is running, you can execute duplicated
  Fluentd instance.
  It may cause inconsistency of buffer or pos file.

After:

  Guard duplicated Fluentd instance when the following conditions are
  met:

  * fluentdwinsvc service is running
  * fluentd.conf is specified in fluentdopt registry value

  and

  * A) duplicated fluentd.conf is specified with -c ... option
    or
  * B) fluentd.bat is executed without arguments

Signed-off-by: Kentaro Hayashi <hayashi@clear-code.com>
---
 fluent-package/msi/assets/fluentd.bat      | 34 ++++++++++++++++++++++
 fluent-package/msi/update-from-v4-test.ps1 | 17 +++++++++++
 2 files changed, 51 insertions(+)

diff --git a/fluent-package/msi/assets/fluentd.bat b/fluent-package/msi/assets/fluentd.bat
index d3ca83a87..f21c0dad3 100644
--- a/fluent-package/msi/assets/fluentd.bat
+++ b/fluent-package/msi/assets/fluentd.bat
@@ -14,12 +14,46 @@ set PATH=%FLUENT_PACKAGE_TOPDIR%;%PATH%
 set "FLUENT_CONF=%FLUENT_PACKAGE_TOPDIR%/etc/fluent/fluentd.conf"
 set "FLUENT_PLUGIN=%FLUENT_PACKAGE_TOPDIR%/etc/fluent/plugin"
 set "FLUENT_PACKAGE_VERSION=%FLUENT_PACKAGE_TOPDIR%/bin/fluent-package-version.rb"
+set FLUENT_CONF_CLI=
+set /a n=0
+set /a conf_index=0
 for %%p in (%*) do (
     if "%%p"=="--version" (
         ruby "%FLUENT_PACKAGE_VERSION%"
         goto last
     )
+    if "%%p"=="-c" (
+        set /a conf_index=n+1
+    )
+    if !n! equ !conf_index! (
+        set FLUENT_CONF_CLI="%%p"
+    )
+    set /a n=n+1
 )
+
+@rem Abort if the fluentdwinsvc service is running and conflict with -c ...:
+sc query fluentdwinsvc | findstr RUNNING > nul
+if !ERRORLEVEL! neq 0 (
+    goto noguard
+)
+@rem extract fluentdopt from registry: (e.g. fluentdopt REG_SZ -c ...)
+for /f "usebackq delims=" %%v in (`reg query HKLM\SYSTEM\CurrentControlSet\Services\fluentdwinsvc /v fluentdopt ^| findstr fluentdopt`) do set FLUENTDOPT=%%v
+if not "!FLUENT_CONF_CLI!"=="" (
+    echo "!FLUENTDOPT:\=/!" | findstr /C:!FLUENT_CONF_CLI:\=/! > nul
+    if !ERRORLEVEL! equ 0 (
+   	    echo Error: can't start duplicate Fluentd instance with same !FLUENT_CONF_CLI!
+	    exit /b 2
+    )
+)
+if not "!FLUENT_CONF!"=="" (
+    echo "!FLUENTDOPT:\=/!" | findstr /C:!FLUENT_CONF! > nul
+    if !ERRORLEVEL! equ 0 (
+   	    echo Error: can't start duplicate Fluentd instance with same !FLUENT_CONF!
+	    exit /b 2
+    )
+)
+
+:noguard
 "%FLUENT_PACKAGE_TOPDIR%/bin/fluentd" %*
 endlocal
 
diff --git a/fluent-package/msi/update-from-v4-test.ps1 b/fluent-package/msi/update-from-v4-test.ps1
index 91cf4259a..9836a6596 100644
--- a/fluent-package/msi/update-from-v4-test.ps1
+++ b/fluent-package/msi/update-from-v4-test.ps1
@@ -50,3 +50,20 @@ $output_files_after_sleep = Get-ChildItem "C:\\opt\\td-agent\\output"
 If ($output_files_after_sleep.Count -le $output_files.Count) {
     [Environment]::Exit(1)
 }
+
+# Test: The previous config works as before
+Start-Process "C:\\opt\\fluent\\fluentd.bat" -ArgumentList "/c", "c:\\opt\\fluent\\etc\\fluent\\fluentd.conf" -Wait -NoNewWindow
+$exitcode = $LASTEXITCODE
+if ($exitcode -ne 2) {
+    Write-Host "Failed to abort when it is conflict with running fluentdwinsvc"
+    [Environment]::Exit(1)
+}
+Write-Host "Succeeded to abort if trying to launch duplicated Fluentd instance"
+
+Start-Process "C:\\opt\\fluent\\fluentd.bat" -Wait -NoNewWindow
+$exitcode = $LASTEXITCODE
+if ($exitcode -ne 2) {
+    Write-Host "Failed to abort without arguments when it is conflict with running fluentdwinsvc"
+    [Environment]::Exit(1)
+}
+Write-Host "Succeeded to abort if trying to launch duplicated Fluentd instance without arguments"