From 53c231f4518a6707b08020187a7c1699023deb87 Mon Sep 17 00:00:00 2001
From: Joannis Orlandos <joannis@orlandos.nl>
Date: Sat, 28 Dec 2024 08:50:00 +0100
Subject: [PATCH] Follow symlinks when reading a file's attributes (#642)

* Follow symlinks when reading a file's attributes

* Fix up the formatting
---
 Sources/Hummingbird/Files/FileIO.swift        | 16 +++++++-
 .../Hummingbird/Files/LocalFileSystem.swift   | 10 ++---
 .../FileMiddlewareTests.swift                 | 38 +++++++++++++++++++
 3 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/Sources/Hummingbird/Files/FileIO.swift b/Sources/Hummingbird/Files/FileIO.swift
index 46620188..d0c727ff 100644
--- a/Sources/Hummingbird/Files/FileIO.swift
+++ b/Sources/Hummingbird/Files/FileIO.swift
@@ -42,7 +42,7 @@ public struct FileIO: Sendable {
         chunkLength: Int = NonBlockingFileIO.defaultChunkSize
     ) async throws -> ResponseBody {
         do {
-            let stat = try await fileIO.lstat(path: path)
+            let stat = try await fileIO.stat(path: path)
             guard stat.st_size > 0 else { return .init() }
             return self.readFile(path: path, range: 0...numericCast(stat.st_size - 1), context: context, chunkLength: chunkLength)
         } catch {
@@ -67,7 +67,7 @@ public struct FileIO: Sendable {
         chunkLength: Int = NonBlockingFileIO.defaultChunkSize
     ) async throws -> ResponseBody {
         do {
-            let stat = try await fileIO.lstat(path: path)
+            let stat = try await fileIO.stat(path: path)
             guard stat.st_size > 0 else { return .init() }
             let fileRange: ClosedRange<Int> = 0...numericCast(stat.st_size - 1)
             let range = range.clamped(to: fileRange)
@@ -144,3 +144,15 @@ public struct FileIO: Sendable {
         }
     }
 }
+
+extension NonBlockingFileIO {
+    func stat(path: String) async throws -> stat {
+        let stat = try await self.lstat(path: path)
+        if stat.st_mode & S_IFMT == S_IFLNK {
+            let realPath = try await self.readlink(path: path)
+            return try await self.lstat(path: realPath)
+        } else {
+            return stat
+        }
+    }
+}
diff --git a/Sources/Hummingbird/Files/LocalFileSystem.swift b/Sources/Hummingbird/Files/LocalFileSystem.swift
index 2ab4937a..d0099fb0 100644
--- a/Sources/Hummingbird/Files/LocalFileSystem.swift
+++ b/Sources/Hummingbird/Files/LocalFileSystem.swift
@@ -89,16 +89,16 @@ public struct LocalFileSystem: FileProvider {
     /// - Returns: File attributes
     public func getAttributes(id path: FileIdentifier) async throws -> FileAttributes? {
         do {
-            let lstat = try await self.fileIO.fileIO.lstat(path: path)
-            let isFolder = (lstat.st_mode & S_IFMT) == S_IFDIR
+            let stat = try await self.fileIO.fileIO.stat(path: path)
+            let isFolder = (stat.st_mode & S_IFMT) == S_IFDIR
             #if os(Linux)
-            let modificationDate = Double(lstat.st_mtim.tv_sec) + (Double(lstat.st_mtim.tv_nsec) / 1_000_000_000.0)
+            let modificationDate = Double(stat.st_mtim.tv_sec) + (Double(stat.st_mtim.tv_nsec) / 1_000_000_000.0)
             #else
-            let modificationDate = Double(lstat.st_mtimespec.tv_sec) + (Double(lstat.st_mtimespec.tv_nsec) / 1_000_000_000.0)
+            let modificationDate = Double(stat.st_mtimespec.tv_sec) + (Double(stat.st_mtimespec.tv_nsec) / 1_000_000_000.0)
             #endif
             return .init(
                 isFolder: isFolder,
-                size: numericCast(lstat.st_size),
+                size: numericCast(stat.st_size),
                 modificationDate: Date(timeIntervalSince1970: modificationDate)
             )
         } catch {
diff --git a/Tests/HummingbirdTests/FileMiddlewareTests.swift b/Tests/HummingbirdTests/FileMiddlewareTests.swift
index 7ff9cf02..3d5aa906 100644
--- a/Tests/HummingbirdTests/FileMiddlewareTests.swift
+++ b/Tests/HummingbirdTests/FileMiddlewareTests.swift
@@ -16,6 +16,7 @@ import Foundation
 import HTTPTypes
 import Hummingbird
 import HummingbirdTesting
+import NIOPosix
 import XCTest
 
 final class FileMiddlewareTests: XCTestCase {
@@ -317,6 +318,43 @@ final class FileMiddlewareTests: XCTestCase {
         }
     }
 
+    func testSymlink() async throws {
+        let router = Router()
+        router.middlewares.add(FileMiddleware(".", searchForIndexHtml: true))
+        let app = Application(responder: router.buildResponder())
+
+        let text = "Test file contents"
+        let data = Data(text.utf8)
+        let fileURL = URL(fileURLWithPath: "test.html")
+        XCTAssertNoThrow(try data.write(to: fileURL))
+        defer { XCTAssertNoThrow(try FileManager.default.removeItem(at: fileURL)) }
+
+        let fileIO = NonBlockingFileIO(threadPool: .singleton)
+
+        try await app.test(.router) { client in
+            try await client.execute(uri: "/test.html", method: .get) { response in
+                XCTAssertEqual(String(buffer: response.body), text)
+            }
+
+            try await client.execute(uri: "/", method: .get) { response in
+                XCTAssertEqual(String(buffer: response.body), "")
+            }
+
+            try await fileIO.symlink(path: "index.html", to: "test.html")
+
+            do {
+                try await client.execute(uri: "/", method: .get) { response in
+                    XCTAssertEqual(String(buffer: response.body), text)
+                }
+
+                try await fileIO.unlink(path: "index.html")
+            } catch {
+                try await fileIO.unlink(path: "index.html")
+                throw error
+            }
+        }
+    }
+
     func testOnThrowCustom404() async throws {
         let router = Router()
         router.middlewares.add(FileMiddleware(".", searchForIndexHtml: true))