ContainerizationOS: minor fixes (#241)

While reviewing test coverage, I noticed a couple of minor issues:
 - 0 is non-negative - allow for zero memory
 - we should likely use lstat instead of stat for file info
 - we should check for empty name parameter

---------

Signed-off-by: Eric Ernst <eric_ernst@apple.com>

Sources/ContainerizationOS/BinaryInteger+Extensions.swift

@@ -16,7 +16,7 @@
 
 extension BinaryInteger {
     private func toUnsignedMemoryAmount(_ amount: UInt64) -> UInt64 {
-        guard self > 0 else {
+        guard self >= 0 else {
             fatalError("encountered negative number during conversion to memory amount")
         }
         let val = UInt64(self)

Sources/ContainerizationOS/File.swift

@@ -42,7 +42,7 @@ public struct File: Sendable {
     ///   - path: The path to the file as a string.
     public static func info(_ path: String) throws -> FileInfo {
         var st = stat()
-        guard stat(path, &st) == 0 else {
+        guard lstat(path, &st) == 0 else {
             throw Error.errno(errno)
         }
         return FileInfo(path, stat: st)

Sources/ContainerizationOS/Path.swift

@@ -33,6 +33,11 @@ public struct Path {
     }
 
     private static func lookup(_ name: String, path: String) -> URL? {
+        // Return nil for empty names
+        if name.isEmpty {
+            return nil
+        }
+
         if name.contains("/") {
             if findExec(name) {
                 return URL(fileURLWithPath: name)