Riff off the getfsstat implementation for OpenBSD.

The mac OS implementation is close to what is required for OpenBSD but
requires tweaking. Instead of trying to unify the two implementations
with #if branches, just riff off the mac OS implementation and create a
new platform specific implementation.

Author: 3405691582

Sources/Foundation/FileManager+POSIX.swift

@@ -70,6 +70,32 @@ extension FileManager {
             }
             urls = mountPoints(statBuf, Int(fsCount))
         }
+#elseif os(OpenBSD)
+        func mountPoints(_ statBufs: UnsafePointer<statfs>, _ fsCount: Int) -> [URL] {
+            var urls: [URL] = []
+
+            for fsIndex in 0..<fsCount {
+                var fs = statBufs.advanced(by: fsIndex).pointee
+
+                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
+        }
+
+            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, Int(fsCount) * MemoryLayout<statfs>.stride, MNT_WAIT)
+            guard fsCount > 0 else {
+                return nil
+            }
+            urls = mountPoints(statBuf, Int(fsCount))
 #else
 #error("Requires a platform-specific implementation")
 #endif