FileManager: Implement mountedVolumeURLs(includingResourceValuesForKeys:options:)

Foundation/FileManager.swift

@@ -32,10 +32,66 @@ open class FileManager : NSObject {
         }
     }
 
-    /* Returns an NSArray of NSURLs locating the mounted volumes available on the computer. The property keys that can be requested are available in NSURL.
-     */
+    /// Returns an array of URLs that identify the mounted volumes available on the device.
     open func mountedVolumeURLs(includingResourceValuesForKeys propertyKeys: [URLResourceKey]?, options: VolumeEnumerationOptions = []) -> [URL]? {
-        NSUnimplemented()
+        var urls: [URL]
+
+#if os(Linux)
+        guard let procMounts = try? String(contentsOfFile: "/proc/mounts", encoding: .utf8) else {
+            return nil
+        }
+        urls = []
+        for line in procMounts.components(separatedBy: "\n") {
+            let mountPoint = line.components(separatedBy: " ")
+            if mountPoint.count > 2 {
+                urls.append(URL(fileURLWithPath: mountPoint[1], isDirectory: true))
+            }
+        }
+#elseif canImport(Darwin)
+
+        func mountPoints(_ statBufs: UnsafePointer<statfs>, _ fsCount: Int) -> [URL] {
+            var urls: [URL] = []
+
+            for fsIndex in 0..<fsCount {
+                var fs = statBufs.advanced(by: fsIndex).pointee
+
+                if options.contains(.skipHiddenVolumes) && fs.f_flags & UInt32(MNT_DONTBROWSE) != 0 {
+                    continue
+                }
+
+                let mountPoint = withUnsafePointer(to: &fs.f_mntonname.0) { (ptr: UnsafePointer<Int8>) -> String in
+                    return string(withFileSystemRepresentation: ptr, length: strlen(ptr))
+                }
+                urls.append(URL(fileURLWithPath: mountPoint, isDirectory: true))
+            }
+            return urls
+        }
+
+        if #available(OSX 10.13, *) {
+            var statBufPtr: UnsafeMutablePointer<statfs>?
+            let fsCount = getmntinfo_r_np(&statBufPtr, MNT_WAIT)
+            guard let statBuf = statBufPtr, fsCount > 0 else {
+                return nil
+            }
+            urls = mountPoints(statBuf, Int(fsCount))
+            free(statBufPtr)
+        } else {
+            var fsCount = getfsstat(nil, 0, MNT_WAIT)
+            guard fsCount > 0 else {
+                return nil
+            }
+            let statBuf = UnsafeMutablePointer<statfs>.allocate(capacity: Int(fsCount))
+            defer { statBuf.deallocate() }
+            fsCount = getfsstat(statBuf, fsCount * Int32(MemoryLayout<statfs>.stride), MNT_WAIT)
+            guard fsCount > 0 else {
+                return nil
+            }
+            urls = mountPoints(statBuf, Int(fsCount))
+        }
+#else
+#error("Requires a platform-specific implementation")
+#endif
+        return urls
     }
 
     /* Returns an NSArray of NSURLs identifying the the directory entries. 

TestFoundation/TestFileManager.swift

@@ -34,6 +34,7 @@ class TestFileManager : XCTestCase {
             ("test_homedirectoryForUser", test_homedirectoryForUser),
             ("test_temporaryDirectoryForUser", test_temporaryDirectoryForUser),
             ("test_creatingDirectoryWithShortIntermediatePath", test_creatingDirectoryWithShortIntermediatePath),
+            ("test_mountedVolumeURLs", test_mountedVolumeURLs)
         ]
     }
 
@@ -601,4 +602,22 @@ class TestFileManager : XCTestCase {
             XCTFail("Unable to write a file to the temporary directory: \(tmpDir), err: \(error)")
         }
     }
+
+    func test_mountedVolumeURLs() {
+        guard let volumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys:[], options: []) else {
+            XCTFail("mountedVolumeURLs returned nil")
+            return
+        }
+        XCTAssertNotEqual(0, volumes.count)
+        XCTAssertTrue(volumes.contains(URL(fileURLWithPath: "/")))
+#if os(macOS)
+        // On macOS, .skipHiddenVolumes should hide 'nobrowse' volumes of which there should be at least one
+        guard let visibleVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: [], options: [.skipHiddenVolumes]) else {
+            XCTFail("mountedVolumeURLs returned nil")
+            return
+        }
+        XCTAssertTrue(visibleVolumes.count > 0)
+        XCTAssertTrue(visibleVolumes.count < volumes.count)
+#endif
+    }
 }