Fix Linux compatibility: replace CFAbsoluteTimeGetCurrent and stderr

Author: DePasqualeOrg

Sources/FileLock/FileLock.swift

@@ -14,7 +14,11 @@ private func logInfo(_ message: String) {
 }
 #else
 private func logInfo(_ message: String) {
-    fputs("[FileLock] \(message)\n", stderr)
+    // Use fd 2 directly to avoid concurrency warning on `stderr` global variable
+    let line = "[FileLock] \(message)\n"
+    line.utf8.withContiguousStorageIfAvailable { buffer in
+        _ = write(2, buffer.baseAddress, buffer.count)
+    }
 }
 #endif
 
@@ -549,7 +553,7 @@ public final class FileLock: Sendable {
         // for ownership tracking. Non-owning tasks should NOT affect the counter.
         // The counter is set to 1 on successful acquisition via recordAcquisition.
         let fd = try openLockFile()
-        let startTime = CFAbsoluteTimeGetCurrent()
+        let startTime = Date().timeIntervalSinceReferenceDate
 
         var attempt = 0
         do {
@@ -577,7 +581,7 @@ public final class FileLock: Sendable {
 
                     // Check if we've exceeded max retries (nil means infinite)
                     if let max = maxRetries, attempt >= max {
-                        let elapsed = CFAbsoluteTimeGetCurrent() - startTime
+                        let elapsed = Date().timeIntervalSinceReferenceDate - startTime
                         throw FileLockError.acquisitionFailed(
                             lockPath,
                             attempts: attempt + 1,
@@ -587,7 +591,7 @@ public final class FileLock: Sendable {
 
                     // Log progress periodically
                     if attempt > 0, attempt % Self.logInterval == 0 {
-                        let elapsed = CFAbsoluteTimeGetCurrent() - startTime
+                        let elapsed = Date().timeIntervalSinceReferenceDate - startTime
                         logInfo("Waiting for lock on \(self.lockPath.lastPathComponent) (elapsed: \(String(format: "%.1f", elapsed))s)")
                     }