Don't delete an initiator of pruning (#556)

* Don't delete an initiator of pruning

Sometimes people have an image that is greater than half of the disk itself. In that case such image will be pulled and prunned right away.

This change makes sure that an image that is being cloned from is not pruned right away.

* Resolve symbolic links

Sources/tart/Commands/Clone.swift

@@ -53,7 +53,7 @@ struct Clone: AsyncParsableCommand {
       // APFS is doing copy-on-write so the above cloning operation (just copying files on disk)
       // is not actually claiming new space until the VM is started and it writes something to disk.
       // So once we clone the VM let's try to claim a little bit of space for the VM to run.
-      try Prune.reclaimIfNeeded(UInt64(sourceVM.sizeBytes()))
+      try Prune.reclaimIfNeeded(UInt64(sourceVM.sizeBytes()), sourceVM)
     }, onCancel: {
       try? FileManager.default.removeItem(at: tmpVMDir.baseURL)
     })

Sources/tart/Commands/Prune.swift

@@ -77,7 +77,7 @@ struct Prune: AsyncParsableCommand {
     try prunablesToDelete.forEach { try $0.delete() }
   }
 
-  static func reclaimIfNeeded(_ requiredBytes: UInt64) throws {
+  static func reclaimIfNeeded(_ requiredBytes: UInt64, _ initiator: Prunable? = nil) throws {
     SentrySDK.configureScope { scope in
       scope.setContext(value: ["requiredBytes": requiredBytes], key: "Prune")
     }
@@ -114,10 +114,10 @@ struct Prune: AsyncParsableCommand {
       return
     }
 
-    try Prune.reclaimIfPossible(requiredBytes - volumeAvailableCapacityCalculated)
+    try Prune.reclaimIfPossible(requiredBytes - volumeAvailableCapacityCalculated, initiator)
   }
 
-  private static func reclaimIfPossible(_ reclaimBytes: UInt64) throws {
+  private static func reclaimIfPossible(_ reclaimBytes: UInt64, _ initiator: Prunable? = nil) throws {
     let transaction = SentrySDK.startTransaction(name: "Pruning cache", operation: "prune", bindToScope: true)
     defer { transaction.finish() }
 
@@ -141,6 +141,11 @@ struct Prune: AsyncParsableCommand {
         break
       }
 
+      if prunable.url == initiator?.url.resolvingSymlinksInPath() {
+        // do not prune the initiator
+        continue
+      }
+
       try SentrySDK.span?.setData(value: prunable.sizeBytes(), key: prunable.url.path)
 
       cacheReclaimedBytes += try prunable.sizeBytes()