[6.0.x] URL path bug fixes (#969)

* (133878310) URL.fileSystemPath should drop all trailing slashes (#852)

* (133882014) URL(filePath: path, directoryHint: .notDirectory) should strip trailing slashes (#867)

* (137129292) URL(filePath:) should not treat "~" as absolute (#961)

* (137068266) URL.fileSystemPath should strip leading slash for Windows drive letters (#964)

* (137287143) URL path extension APIs should strip trailing slashes (#965)

Author: jrflat

Sources/FoundationEssentials/String/String+Path.swift

@@ -194,7 +194,11 @@ extension String {
         guard let lastDot = self.utf8.lastIndex(of: dot) else {
             return self
         }
-        return String(self[..<lastDot])
+        var result = String(self[..<lastDot])
+        if utf8.last == ._slash {
+            result += "/"
+        }
+        return result
     }
 
     private func validatePathExtension(_ pathExtension: String) -> Bool {
@@ -214,7 +218,16 @@ extension String {
         guard validatePathExtension(pathExtension) else {
             return self
         }
-        return self + ".\(pathExtension)"
+        var result = self._droppingTrailingSlashes
+        guard result != "/" else {
+            // Path was all slashes
+            return self + ".\(pathExtension)"
+        }
+        result += ".\(pathExtension)"
+        if utf8.last == ._slash {
+            result += "/"
+        }
+        return result
     }
 
     internal var pathExtension: String {
@@ -366,7 +379,7 @@ extension String {
         return String(cString: output)
     }
 
-    #if !NO_FILESYSTEM
+#if !NO_FILESYSTEM
     internal static func homeDirectoryPath(forUser user: String? = nil) -> String {
 #if os(Windows)
         if let user {
@@ -529,8 +542,10 @@ extension String {
 #else
         return "/tmp/"
 #endif
-#endif
+#endif // os(Windows)
     }
+#endif // !NO_FILESYSTEM
+
     /// Replaces any number of sequential `/`
     /// characters with /
     /// NOTE: Internal so it's testable
@@ -569,7 +584,7 @@ extension String {
         }
     }
 
-    private var _droppingTrailingSlashes: String {
+    internal var _droppingTrailingSlashes: String {
         guard !self.isEmpty else {
             return self
         }
@@ -579,7 +594,9 @@ extension String {
         }
         return String(self[...lastNonSlash])
     }
-    
+
+#if !NO_FILESYSTEM
+
     static var NETWORK_PREFIX: String { #"\\"# }
 
     private var _standardizingPath: String {
@@ -616,7 +633,8 @@ extension String {
     var standardizingPath: String {
         expandingTildeInPath._standardizingPath
     }
-    #endif // !NO_FILESYSTEM
+
+#endif // !NO_FILESYSTEM
 
     // _NSPathComponents
     var pathComponents: [String] {

Sources/FoundationEssentials/URL/URL.swift

@@ -1319,13 +1319,32 @@ public struct URL: Equatable, Sendable, Hashable {
         }
     }
 
-    private static func fileSystemPath(for urlPath: String) -> String {
-        var result = urlPath
-        if result.count > 1 && result.utf8.last == UInt8(ascii: "/") {
-            _ = result.popLast()
+    private static func windowsPath(for posixPath: String) -> String {
+        let utf8 = posixPath.utf8
+        guard utf8.count >= 4 else {
+            return posixPath
+        }
+        // "C:\" is standardized to "/C:/" on initialization
+        let array = Array(utf8)
+        if array[0] == ._slash,
+           array[1].isAlpha,
+           array[2] == ._colon,
+           array[3] == ._slash {
+            return String(Substring(utf8.dropFirst()))
         }
+        return posixPath
+    }
+
+    private static func fileSystemPath(for urlPath: String) -> String {
         let charsToLeaveEncoded: Set<UInt8> = [._slash, 0]
-        return Parser.percentDecode(result, excluding: charsToLeaveEncoded) ?? ""
+        guard let posixPath = Parser.percentDecode(urlPath._droppingTrailingSlashes, excluding: charsToLeaveEncoded) else {
+            return ""
+        }
+        #if os(Windows)
+        return windowsPath(for: posixPath)
+        #else
+        return posixPath
+        #endif
     }
 
     var fileSystemPath: String {
@@ -2026,55 +2045,65 @@ extension URL {
 
 #if !NO_FILESYSTEM
     private static func isDirectory(_ path: String) -> Bool {
-#if !FOUNDATION_FRAMEWORK
+        #if os(Windows)
+        let path = path.replacing(._slash, with: ._backslash)
+        #endif
+        #if !FOUNDATION_FRAMEWORK
         var isDirectory: Bool = false
         _ = FileManager.default.fileExists(atPath: path, isDirectory: &isDirectory)
         return isDirectory
-#else
+        #else
         var isDirectory: ObjCBool = false
         _ = FileManager.default.fileExists(atPath: path, isDirectory: &isDirectory)
         return isDirectory.boolValue
-#endif
+        #endif
     }
 #endif // !NO_FILESYSTEM
 
     /// Checks if a file path is absolute and standardizes the inputted file path on Windows
+    /// Assumes the path only contains `/` as the path separator
     internal static func isAbsolute(standardizing filePath: inout String) -> Bool {
+        if filePath.utf8.first == ._slash {
+            return true
+        }
         #if os(Windows)
-        var isAbsolute = false
         let utf8 = filePath.utf8
-        if utf8.first == ._backslash {
-            // Either an absolute path or a UNC path
-            isAbsolute = true
-        } else if utf8.count >= 3 {
-            // Check if this is a drive letter
-            let first = utf8.first!
-            let secondIndex = utf8.index(after: utf8.startIndex)
-            let second = utf8[secondIndex]
-            let thirdIndex = utf8.index(after: secondIndex)
-            let third = utf8[thirdIndex]
-            isAbsolute = (
-                first.isAlpha
-                && (second == ._colon || second == ._pipe)
-                && third == ._backslash
-            )
-
-            if isAbsolute {
-                // Standardize to "\[drive-letter]:\..."
-                if second == ._pipe {
-                    var filePathArray = Array(utf8)
-                    filePathArray[1] = ._colon
-                    filePathArray.insert(._backslash, at: 0)
-                    filePath = String(decoding: filePathArray, as: UTF8.self)
-                } else {
-                    filePath = "\\" + filePath
-                }
+        guard utf8.count >= 3 else {
+            return false
+        }
+        // Check if this is a drive letter
+        let first = utf8.first!
+        let secondIndex = utf8.index(after: utf8.startIndex)
+        let second = utf8[secondIndex]
+        let thirdIndex = utf8.index(after: secondIndex)
+        let third = utf8[thirdIndex]
+        let isAbsolute = (
+            first.isAlpha
+            && (second == ._colon || second == ._pipe)
+            && third == ._slash
+        )
+        if isAbsolute {
+            // Standardize to "/[drive-letter]:/..."
+            if second == ._pipe {
+                var filePathArray = Array(utf8)
+                filePathArray[1] = ._colon
+                filePathArray.insert(._slash, at: 0)
+                filePath = String(decoding: filePathArray, as: UTF8.self)
+            } else {
+                filePath = "/" + filePath
             }
         }
-        #else
-        let isAbsolute = filePath.utf8.first == UInt8(ascii: "/") || filePath.utf8.first == UInt8(ascii: "~")
-        #endif
         return isAbsolute
+        #else // os(Windows)
+        #if !NO_FILESYSTEM
+        // Expand the tilde if present
+        if filePath.utf8.first == UInt8(ascii: "~") {
+            filePath = filePath.expandingTildeInPath
+        }
+        #endif
+        // Make sure the expanded path is absolute
+        return filePath.utf8.first == ._slash
+        #endif // os(Windows)
     }
 
     /// Initializes a newly created file URL referencing the local file or directory at path, relative to a base URL.
@@ -2111,10 +2140,9 @@ extension URL {
         }
 
         #if os(Windows)
-        let slash = UInt8(ascii: "\\")
-        var filePath = path.replacing(UInt8(ascii: "/"), with: slash)
+        // Convert any "\" to "/" before storing the URL parse info
+        var filePath = path.replacing(._backslash, with: ._slash)
         #else
-        let slash = UInt8(ascii: "/")
         var filePath = path
         #endif
 
@@ -2126,41 +2154,31 @@ extension URL {
         }
         #endif
 
-        func absoluteFilePath() -> String {
-            guard !isAbsolute, let baseURL else {
-                return filePath
-            }
-            let basePath = baseURL.path()
-            #if os(Windows)
-            let urlPath = filePath.replacing(UInt8(ascii: "\\"), with: UInt8(ascii: "/"))
-            return URL.fileSystemPath(for: basePath.merging(relativePath: urlPath)).replacing(UInt8(ascii: "/"), with: UInt8(ascii: "\\"))
-            #else
-            return URL.fileSystemPath(for: basePath.merging(relativePath: filePath))
-            #endif
-        }
-
         let isDirectory: Bool
         switch directoryHint {
         case .isDirectory:
             isDirectory = true
         case .notDirectory:
+            filePath = filePath._droppingTrailingSlashes
             isDirectory = false
         case .checkFileSystem:
             #if !NO_FILESYSTEM
+            func absoluteFilePath() -> String {
+                guard !isAbsolute, let baseURL else {
+                    return filePath
+                }
+                let absolutePath = baseURL.path().merging(relativePath: filePath)
+                return URL.fileSystemPath(for: absolutePath)
+            }
             isDirectory = URL.isDirectory(absoluteFilePath())
             #else
-            isDirectory = filePath.utf8.last == slash
+            isDirectory = filePath.utf8.last == ._slash
             #endif
         case .inferFromPath:
-            isDirectory = filePath.utf8.last == slash
+            isDirectory = filePath.utf8.last == ._slash
         }
 
-        #if os(Windows)
-        // Convert any "\" back to "/" before storing the URL parse info
-        filePath = filePath.replacing(UInt8(ascii: "\\"), with: UInt8(ascii: "/"))
-        #endif
-
-        if !filePath.isEmpty && filePath.utf8.last != UInt8(ascii: "/") && isDirectory {
+        if isDirectory && !filePath.isEmpty && filePath.utf8.last != ._slash {
             filePath += "/"
         }
         var components = URLComponents()
@@ -2438,6 +2456,9 @@ extension URL {
         guard var filePath = path else {
             return nil
         }
+        #if os(Windows)
+        filePath = filePath.replacing(._backslash, with: ._slash)
+        #endif
         guard URL.isAbsolute(standardizing: &filePath) else {
             return nil
         }

Tests/FoundationEssentialsTests/StringTests.swift

@@ -812,6 +812,19 @@ final class StringTests : XCTestCase {
         }
     }
 
+    func testAppendingPathExtension() {
+        XCTAssertEqual("".appendingPathExtension("foo"), ".foo")
+        XCTAssertEqual("/".appendingPathExtension("foo"), "/.foo")
+        XCTAssertEqual("//".appendingPathExtension("foo"), "//.foo")
+        XCTAssertEqual("/path".appendingPathExtension("foo"), "/path.foo")
+        XCTAssertEqual("/path.zip".appendingPathExtension("foo"), "/path.zip.foo")
+        XCTAssertEqual("/path/".appendingPathExtension("foo"), "/path.foo/")
+        XCTAssertEqual("/path//".appendingPathExtension("foo"), "/path.foo/")
+        XCTAssertEqual("path".appendingPathExtension("foo"), "path.foo")
+        XCTAssertEqual("path/".appendingPathExtension("foo"), "path.foo/")
+        XCTAssertEqual("path//".appendingPathExtension("foo"), "path.foo/")
+    }
+
     func testDeletingPathExtenstion() {
         XCTAssertEqual("".deletingPathExtension(), "")
         XCTAssertEqual("/".deletingPathExtension(), "/")
@@ -834,6 +847,15 @@ final class StringTests : XCTestCase {
         XCTAssertEqual("/foo.bar/bar.baz/baz.zip".deletingPathExtension(), "/foo.bar/bar.baz/baz")
         XCTAssertEqual("/.././.././a.zip".deletingPathExtension(), "/.././.././a")
         XCTAssertEqual("/.././.././.".deletingPathExtension(), "/.././.././.")
+
+        XCTAssertEqual("path.foo".deletingPathExtension(), "path")
+        XCTAssertEqual("path.foo.zip".deletingPathExtension(), "path.foo")
+        XCTAssertEqual("/path.foo".deletingPathExtension(), "/path")
+        XCTAssertEqual("/path.foo.zip".deletingPathExtension(), "/path.foo")
+        XCTAssertEqual("path.foo/".deletingPathExtension(), "path/")
+        XCTAssertEqual("path.foo//".deletingPathExtension(), "path/")
+        XCTAssertEqual("/path.foo/".deletingPathExtension(), "/path/")
+        XCTAssertEqual("/path.foo//".deletingPathExtension(), "/path/")
     }
 
     func test_dataUsingEncoding() {