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fix hanging of write on Windows

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When using File::Write(), Var size in int64_t is casted to DWORD(unsigned long). When Var size is out of DWORD range, casted value will be zero. Before calling into File::Write() on Windows, validate the size.

Bug: https://github.com/dart-lang/sdk/issues/40339
Change-Id: I36fade62dfa3025f418405cb3e45c286dd6b7db1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/134440
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Zichang Guo <zichangguo@google.com>
This commit is contained in:
Zichang Guo 2020-02-06 19:58:52 +00:00 committed by commit-bot@chromium.org
parent c33935faa8
commit eb075dcc21
2 changed files with 22 additions and 2 deletions
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9
runtime/bin/file_win.cc
View file

@ -146,10 +146,15 @@ int64_t File::Read(void* buffer, int64_t num_bytes) {
int64_t File::Write(const void* buffer, int64_t num_bytes) {
int fd = handle_->fd();
ASSERT(fd >= 0);
// TODO(zichangguo): num_bytes from signed integer to unsigned integer.
ASSERT(fd >= 0 && num_bytes >= 0);
HANDLE handle = reinterpret_cast<HANDLE>(_get_osfhandle(fd));
// On Windows, int64_t is much larger than required size DWORD(unsigned long).
// Limit the size to be a valid DWORD(unsigned long).
COMPILE_ASSERT(sizeof(uint32_t) == sizeof(DWORD));
DWORD bytes_to_write = num_bytes > MAXDWORD ? MAXDWORD : num_bytes;
DWORD written = 0;
BOOL result = WriteFile(handle, buffer, num_bytes, &written, NULL);
BOOL result = WriteFile(handle, buffer, bytes_to_write, &written, NULL);
if (!result) {
return -1;
}

15
tests/standalone_2/io/file_write_as_test.dart
View file

@ -4,6 +4,7 @@
import 'dart:async';
import 'dart:io';
import 'dart:typed_data';
import "package:async_helper/async_helper.dart";
import "package:expect/expect.dart";
@ -27,6 +28,19 @@ testWriteAsStringSync(dir) {
Expect.equals('$data$data', f.readAsStringSync());
}
testWriteWithLargeList(dir) {
var f;
if (Platform.isWindows) {
f = File('NUL');
} else {
f = File('/dev/null');
}
// 0x100000000 exceeds the maximum of unsigned long.
// This should no longer hang.
// Issue: https://github.com/dart-lang/sdk/issues/40339
f.writeAsBytesSync(Uint8List(0x100000000));
}
Future testWriteAsBytes(dir) {
var completer = new Completer();
var f = new File('${dir.path}/bytes.txt');
@ -73,6 +87,7 @@ main() {
var tempDir = Directory.systemTemp.createTempSync('dart_file_write_as');
testWriteAsBytesSync(tempDir);
testWriteAsStringSync(tempDir);
testWriteWithLargeList(tempDir);
testWriteAsBytes(tempDir).then((_) {
return testWriteAsString(tempDir);
}).then((_) {