From afbc2e07647affd4b1341d8891e5ceb70d276bfa Mon Sep 17 00:00:00 2001
From: Nikolay Edigaryev <edigaryev@gmail.com>
Date: Thu, 22 Sep 2022 18:24:14 +0400
Subject: [PATCH] tart ip: keep waiting for the /var/db/dhcpd_leases file to
 appear (#254)

---
 Sources/tart/Commands/IP.swift               |  4 ++--
 Sources/tart/MACAddressResolver/Leases.swift | 15 +++++++++++----
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/Sources/tart/Commands/IP.swift b/Sources/tart/Commands/IP.swift
index 23ffa54..7e5f234 100644
--- a/Sources/tart/Commands/IP.swift
+++ b/Sources/tart/Commands/IP.swift
@@ -44,10 +44,10 @@ struct IP: AsyncParsableCommand {
     let waitUntil = Calendar.current.date(byAdding: .second, value: Int(secondsToWait), to: Date.now)!
 
     repeat {
-      if let ip = try Leases().resolveMACAddress(macAddress: vmMACAddress) {
+      if let leases = try Leases(), let ip = try leases.resolveMACAddress(macAddress: vmMACAddress) {
         return ip
       }
-      
+
       // wait a second
       try await Task.sleep(nanoseconds: 1_000_000_000)
     } while Date.now < waitUntil
diff --git a/Sources/tart/MACAddressResolver/Leases.swift b/Sources/tart/MACAddressResolver/Leases.swift
index 1ae5cfc..477fabb 100644
--- a/Sources/tart/MACAddressResolver/Leases.swift
+++ b/Sources/tart/MACAddressResolver/Leases.swift
@@ -19,14 +19,21 @@ enum LeasesError: Error {
 class Leases {
   private let leases: [MACAddress : Lease]
 
-  convenience init() throws {
+  convenience init?() throws {
     try self.init(URL(fileURLWithPath: "/var/db/dhcpd_leases"))
   }
 
-  convenience init(_ fromURL: URL) throws {
-    let fileContents = try String(contentsOf: fromURL, encoding: .utf8)
+  convenience init?(_ fromURL: URL) throws {
+    do {
+      let urlContents = try String(contentsOf: fromURL, encoding: .utf8)
+      try self.init(urlContents)
+    } catch {
+      if error.isFileNotFound() {
+        return nil
+      }
 
-    try self.init(fileContents)
+      throw error
+    }
   }
 
   init(_ fromString: String) throws {