[Storage] Improve how GetFile handles paths (#1782)

* [Storage] Improve how GetFile handles paths

* Update based on feedback

* Update storage_reference_ios.mm

* Update storage_reference_ios.mm

* Revert "Update storage_reference_ios.mm"

This reverts commit c429475.

Author: a-maurice

release_build_files/readme.md

@@ -613,6 +613,10 @@ workflow use only during the development of your app, not for publicly shipping
 code.
 
 ## Release Notes
+### Upcoming
+-   Changes
+    - Storage (iOS): Handle absolute paths being provided to GetFile. (#1724)
+
 ### 13.0.0
 -   Changes
     - General (Android): Update to Firebase Android BoM version 34.0.0.

storage/integration_test/src/integration_test.cc

@@ -657,6 +657,28 @@ TEST_F(FirebaseStorageTest, TestPutFileAndGetFile) {
     EXPECT_NE(future.result(), nullptr);
     EXPECT_EQ(*future.result(), kSimpleTestFile.size());
 
+    std::vector<char> buffer(kSimpleTestFile.size());
+    FILE* file = fopen(path.c_str(), "rb");
+    EXPECT_NE(file, nullptr);
+    size_t bytes_read = std::fread(&buffer[0], 1, kSimpleTestFile.size(), file);
+    EXPECT_EQ(bytes_read, kSimpleTestFile.size());
+    fclose(file);
+    EXPECT_EQ(memcmp(&kSimpleTestFile[0], &buffer[0], buffer.size()), 0);
+  }
+  // Test GetFile without the file prefix to ensure we can download to a file.
+  {
+    std::string path = PathForResource() + kGetFileTestFile;
+    // Try the direct path, which should also work.
+    std::string file_path = path;
+
+    LogDebug("Saving to local file: %s", path.c_str());
+
+    firebase::Future<size_t> future =
+        RunWithRetry<size_t>([&]() { return ref.GetFile(file_path.c_str()); });
+    WaitForCompletion(future, "GetFile");
+    EXPECT_NE(future.result(), nullptr);
+    EXPECT_EQ(*future.result(), kSimpleTestFile.size());
+
     std::vector<char> buffer(kSimpleTestFile.size());
     FILE* file = fopen(path.c_str(), "rb");
     EXPECT_NE(file, nullptr);

storage/src/ios/storage_reference_ios.mm

@@ -142,7 +142,25 @@
   // Cache a copy of the impl and storage, in case this is destroyed before the thread runs.
   FIRStorageReference* my_impl = impl();
   StorageInternal* storage = storage_;
-  NSURL* local_file_url = [NSURL URLWithString:@(path)];
+  NSString* path_string = @(path);
+  if (path_string.length == 0) {
+    future_impl->Complete(handle, kErrorUnknown, "Path cannot be empty.");
+    return GetFileLastResult();
+  }
+  NSURL* local_file_url = nil;
+  if ([path_string hasPrefix:@"file://"]) {
+    // If it starts with the prefix, load it assuming a URL string.
+    local_file_url = [NSURL URLWithString:path_string];
+  } else {
+    // Otherwise, assume it is a file path.
+    local_file_url = [NSURL fileURLWithPath:path_string];
+  }
+  // If we still failed to convert the path, error out.
+  if (local_file_url == nil) {
+    future_impl->Complete(handle, kErrorUnknown,
+      "Unable to convert provided path to valid URL");
+    return GetFileLastResult();
+  }
   util::DispatchAsyncSafeMainQueue(^() {
       FIRStorageDownloadTask *download_task;
       {