Fix simulator putfile posix error

FirebaseStorage/CHANGELOG.md

@@ -1,4 +1,7 @@
 # Unreleased
+- [fixed] Fixed an issue where `putFile` could fail on the iOS Simulator with `POSIX errno 40`
+  (`EMSGSIZE`) due to a QUIC bug in background sessions, and improved error formatting
+  for `NSPOSIXErrorDomain` errors. (#16351)
 - [fixed] Fixed a race condition in Storage task cancellation and improved Swift 6 strict
   concurrency compliance for `StorageTask`. (#16353)
 - [fixed] Fixed a crash that could occur when parsing malformed `gs://` URLs, and improved

FirebaseStorage/Sources/Internal/StorageFetcherService.swift

@@ -63,6 +63,11 @@ actor StorageFetcherService {
     if let _fetcherService {
       _fetcherService.testBlock = testBlock
     }
+    for bucketMap in fetcherServiceMap.values {
+      for fetcherService in bucketMap.values {
+        fetcherService.testBlock = testBlock
+      }
+    }
   }
 
   private var testBlock: GTMSessionFetcherTestBlock?

FirebaseStorage/Sources/StorageError.swift

@@ -77,9 +77,23 @@ public let StorageErrorDomain: String = "FIRStorageErrorDomain"
     case 404: StorageError.objectNotFound(
         object: ref.path.object ?? "<object-entity-internal-error>", serverError: errorDictionary
       )
-    default: StorageError.unknown(
-        message: "Unexpected \(serverError.code) code from backend", serverError: errorDictionary
-      )
+    default:
+      { () -> StorageError in
+        if serverError.domain == NSPOSIXErrorDomain {
+          let errorCode = Int32(truncatingIfNeeded: serverError.code)
+          var buffer = [CChar](repeating: 0, count: 128)
+          _ = strerror_r(errorCode, &buffer, buffer.count)
+          return StorageError.unknown(
+            message: "POSIX errno \(serverError.code) (\(String(cString: buffer)))",
+            serverError: errorDictionary
+          )
+        } else {
+          return StorageError.unknown(
+            message: "Unexpected \(serverError.code) code from backend",
+            serverError: errorDictionary
+          )
+        }
+      }()
     }
     return storageError as NSError
   }

FirebaseStorage/Sources/StorageUploadTask.swift

@@ -112,9 +112,13 @@ import Foundation
           uploadFetcher.uploadFileURL = fileURL
           uploadFetcher.comment = "File UploadTask"
 
-          if !GULAppEnvironmentUtil.supportsBackgroundURLSessionUploads() {
+          #if targetEnvironment(simulator)
             uploadFetcher.useBackgroundSession = false
-          }
+          #else
+            if !GULAppEnvironmentUtil.supportsBackgroundURLSessionUploads() {
+              uploadFetcher.useBackgroundSession = false
+            }
+          #endif
         }
         uploadFetcher.maxRetryInterval = self.reference.storage.maxUploadRetryInterval
 

FirebaseStorage/Tests/Integration/StoragePOSIXErrorTest.swift

@@ -0,0 +1,40 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+@testable import FirebaseStorage
+import Foundation
+#if COCOAPODS
+  import GTMSessionFetcher
+#else
+  import GTMSessionFetcherCore
+#endif
+import XCTest
+
+@available(iOS 13.0, macOS 10.15, macCatalyst 13.0, tvOS 13.0, watchOS 6.0, *)
+class StoragePOSIXErrorTest: StorageIntegrationCommon {
+  func testPutFileWithPOSIXError40() async throws {
+    let ref = storage.reference(withPath: "ios/public/testPOSIX40")
+
+    let data = try XCTUnwrap("Hello".data(using: .utf8))
+    let tmpDirURL = URL(fileURLWithPath: NSTemporaryDirectory())
+    let fileURL = tmpDirURL.appendingPathComponent(#function + "hello.txt")
+    try data.write(to: fileURL, options: .atomicWrite)
+    defer {
+      try? FileManager.default.removeItem(at: fileURL)
+    }
+
+    let metadata = try await ref.putFileAsync(from: fileURL)
+    XCTAssertEqual(metadata.size, Int64(data.count))
+  }
+}

FirebaseStorage/Tests/Unit/StoragePutFileTests.swift

@@ -0,0 +1,59 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+@testable import FirebaseStorage
+import Foundation
+#if COCOAPODS
+  import GTMSessionFetcher
+#else
+  import GTMSessionFetcherCore
+#endif
+import XCTest
+
+class StoragePutFileTests: StorageTestHelpers {
+  func testPutFileWithPOSIXError40UpdatesExistingFetcherService() async throws {
+    // Initialize storage *before* setting the testBlock to verify that
+    // `StorageFetcherService.updateTestBlock` correctly updates pre-existing instances.
+    let storageInstance = storage()
+    let ref = storageInstance.reference(withPath: "ios/public/testPOSIX40")
+
+    let testBlock: GTMSessionFetcherTestBlock = { fetcher, response in
+      let error = NSError(domain: NSPOSIXErrorDomain, code: 40, userInfo: nil)
+      response(nil, nil, error)
+    }
+    await StorageFetcherService.shared.updateTestBlock(testBlock)
+    addTeardownBlock {
+      await StorageFetcherService.shared.updateTestBlock(nil)
+    }
+
+    let data = try XCTUnwrap("Hello".data(using: .utf8))
+    let tmpDirURL = URL(fileURLWithPath: NSTemporaryDirectory())
+    let fileURL = tmpDirURL.appendingPathComponent(#function + "hello.txt")
+    try data.write(to: fileURL, options: .atomicWrite)
+    defer {
+      try? FileManager.default.removeItem(at: fileURL)
+    }
+
+    do {
+      _ = try await ref.putFileAsync(from: fileURL)
+      XCTFail("Unexpected success")
+    } catch let error as NSError {
+      XCTAssertEqual(error.domain, StorageErrorDomain)
+      XCTAssertEqual(error.code, StorageErrorCode.unknown.rawValue)
+      let message = error.localizedDescription
+      XCTAssertTrue(message.contains("POSIX errno 40 (Message too long)"),
+                    "Error message should contain 'POSIX errno 40 (Message too long)', but got \(message)")
+    }
+  }
+}

FirebaseStorage/Tests/Unit/StorageTests.swift

@@ -256,6 +256,20 @@ class StorageTests: XCTestCase {
     XCTAssertEqual(storage.maxOperationRetryInterval, 8)
   }
 
+  func testPOSIXErrorFormatting() throws {
+    let app = try getApp(bucket: "bucket")
+    let storage = Storage.storage(app: app)
+    let ref = storage.reference(withPath: "ios/public/testPOSIX40")
+    let posixError = NSError(domain: NSPOSIXErrorDomain, code: 40, userInfo: nil)
+    let storageError = StorageErrorCode.error(withServerError: posixError, ref: ref)
+    XCTAssertEqual(storageError.domain, StorageErrorDomain)
+    XCTAssertEqual(storageError.code, StorageErrorCode.unknown.rawValue)
+    XCTAssertEqual(
+      storageError.userInfo[NSLocalizedDescriptionKey] as? String,
+      "POSIX errno 40 (Message too long)"
+    )
+  }
+
   // MARK: Private Helpers
 
   // Cache the app associated with each Storage bucket