[fml] Handle absolute paths on Windows (flutter#33029)

knopp · Apr 30, 2022 · b8d80cd · b8d80cd
1 parent 77c6a02
commit b8d80cd
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Showing 2 changed files with 49 additions and 4 deletions.
diff --git a/fml/file_unittest.cc b/fml/file_unittest.cc
@@ -248,6 +248,33 @@ TEST(FileTest, AtomicWriteTest) {
   ASSERT_TRUE(fml::UnlinkFile(dir.fd(), "precious_data"));
 }
 
+TEST(FileTest, IgnoreBaseDirWhenPathIsAbsolute) {
+  fml::ScopedTemporaryDirectory dir;
+
+  // Make an absolute path.
+  std::string filename = "filename.txt";
+  std::string full_path =
+      fml::paths::AbsolutePath(fml::paths::JoinPaths({dir.path(), filename}));
+
+  const std::string contents = "These are my contents.";
+  auto data = std::make_unique<fml::DataMapping>(
+      std::vector<uint8_t>{contents.begin(), contents.end()});
+
+  // Write.
+  ASSERT_TRUE(fml::WriteAtomically(dir.fd(), full_path.c_str(), *data));
+
+  // Test existence.
+  ASSERT_TRUE(fml::FileExists(dir.fd(), full_path.c_str()));
+
+  // Read and verify.
+  ASSERT_EQ(contents,
+            ReadStringFromFile(fml::OpenFile(dir.fd(), full_path.c_str(), false,
+                                             fml::FilePermission::kRead)));
+
+  // Cleanup.
+  ASSERT_TRUE(fml::UnlinkFile(dir.fd(), full_path.c_str()));
+}
+
 TEST(FileTest, EmptyMappingTest) {
   fml::ScopedTemporaryDirectory dir;
 

diff --git a/fml/platform/win/file_win.cc b/fml/platform/win/file_win.cc
@@ -34,11 +34,29 @@ static std::string GetFullHandlePath(const fml::UniqueFD& handle) {
   return WideStringToUtf8({buffer, buffer_size});
 }
 
+static bool IsAbsolutePath(const char* path) {
+  if (path == nullptr || strlen(path) == 0) {
+    return false;
+  }
+
+  auto wpath = Utf8ToWideString({path});
+  if (wpath.size() == 0) {
+    return false;
+  }
+
+  return ::PathIsRelative(wpath.c_str()) == FALSE;
+}
+
 static std::string GetAbsolutePath(const fml::UniqueFD& base_directory,
                                    const char* subpath) {
-  std::stringstream stream;
-  stream << GetFullHandlePath(base_directory) << "\\" << subpath;
-  auto path = stream.str();
+  std::string path;
+  if (IsAbsolutePath(subpath)) {
+    path = subpath;
+  } else {
+    std::stringstream stream;
+    stream << GetFullHandlePath(base_directory) << "\\" << subpath;
+    path = stream.str();
+  }
   std::replace(path.begin(), path.end(), '/', '\\');
   return path;
 }
@@ -82,7 +100,7 @@ static DWORD GetFileAttributesForUtf8Path(const char* absolute_path) {
 
 static DWORD GetFileAttributesForUtf8Path(const fml::UniqueFD& base_directory,
                                           const char* path) {
-  std::string full_path = GetFullHandlePath(base_directory) + "\\" + path;
+  std::string full_path = GetAbsolutePath(base_directory, path);
   return GetFileAttributesForUtf8Path(full_path.c_str());
 }