fix(logger): Do not log twice if logfile is the same as stdout redire…

…ction (#691)
Hypfer · Feb 16, 2021 · 2bd4c82 · 2bd4c82
1 parent 4bd09c8
commit 2bd4c82
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Showing 2 changed files with 31 additions and 4 deletions.
diff --git a/lib/Logger.js b/lib/Logger.js
@@ -1,6 +1,7 @@
 const {EventEmitter} = require("events");
 const fs = require("fs");
 const util = require("util");
+const Tools = require("./Tools");
 
 const LogFileOptions = Object.freeze({
     flags: "as"
@@ -46,14 +47,24 @@ class Logger {
         LogLevel = LogLevels[value];
     }
     static set LogFile(filename) {
-        if (LogFilename === filename) {
+        if (Tools.ARE_SAME_FILES(LogFilename, filename)) {
+            // We are already writing to that file
             return;
         }
+
         if (LogFile) {
             LogFile.close();
+            LogFile = null;
         }
         LogFilename = filename;
-        LogFile = fs.createWriteStream(LogFilename, LogFileOptions);
+        // Check if output is already redirected to that same file. If
+        // it is, we do not need to write to that same file, because that
+        // would lead to duplicate log entries.
+        // Setting the LogFilename anyway ensures that the UI Log still works.
+        if (!Tools.ARE_SAME_FILES(filename, "/proc/self/fd/1")) {
+            LogFilename = filename;
+            LogFile = fs.createWriteStream(LogFilename, LogFileOptions);
+        }
 
         Logger.log("info", "Set Logfile to " + filename);
     }
@@ -75,8 +86,10 @@ class Logger {
                 }
                 return util.inspect(arg);
             }).join(" ");
-            LogFile.write(logLine);
-            LogFile.write("\n");
+            if (LogFile) {
+                LogFile.write(logLine);
+                LogFile.write("\n");
+            }
             LogEventEmitter.emit("LogMessage", logLine);
         }
     }

diff --git a/lib/Tools.js b/lib/Tools.js
@@ -12,6 +12,20 @@ class Tools {
         }
     }
 
+    static ARE_SAME_FILES(filepath1, filepath2) {
+        if (filepath1 === filepath2) {
+            return true;
+        }
+
+        try {
+            const stat1 = fs.statSync(filepath1, {bigint: true});
+            const stat2 = fs.statSync(filepath2, {bigint: true});
+            return (stat1.dev === stat2.dev && stat1.ino === stat2.ino);
+        } catch (e) {
+            return false;
+        }
+    }
+
     static BUFFER_IS_GZIP(buf) {
         return Buffer.isBuffer(buf) && buf[0] === 0x1f && buf[1] === 0x8b;
     }