Windows, JNI: move around sources

Move the Windows JNI C++ sources to a separate
package and separate namespace.

This no-op refactoring allows other build rules
than Bazel's client library to depend on file I/O
and/or JNI functionality.

A follow-up commit will split the
//src/main/native/windows:processes library into
:jni-processes and :jni-file.

Change-Id: I33c5f8ebd8961cc440db3b4a95ff78024d7c1d74
PiperOrigin-RevId: 160404298

1 files changed, 186 insertions, 0 deletions

diff --git a/src/main/native/windows/file.cc b/src/main/native/windows/file.cc
new file mode 100644
index 0000000000..b5dc5974c8
--- /dev/null
+++ b/src/main/native/windows/file.cc
@@ -0,0 +1,186 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// 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.
+
+#include <windows.h>
+
+#include <memory>
+#include <sstream>
+#include <string>
+
+#include "src/main/native/windows/file.h"
+#include "src/main/native/windows/util.h"
+
+namespace bazel {
+namespace windows {
+
+using std::string;
+using std::unique_ptr;
+using std::wstring;
+
+int IsJunctionOrDirectorySymlink(const WCHAR* path) {
+  DWORD attrs = ::GetFileAttributesW(path);
+  if (attrs == INVALID_FILE_ATTRIBUTES) {
+    return IS_JUNCTION_ERROR;
+  } else {
+    if ((attrs & FILE_ATTRIBUTE_DIRECTORY) &&
+        (attrs & FILE_ATTRIBUTE_REPARSE_POINT)) {
+      return IS_JUNCTION_YES;
+    } else {
+      return IS_JUNCTION_NO;
+    }
+  }
+}
+
+bool GetLongPath(const WCHAR* path, unique_ptr<WCHAR[]>* result) {
+  DWORD size = ::GetLongPathNameW(path, NULL, 0);
+  if (size == 0) {
+    return false;
+  }
+  result->reset(new WCHAR[size]);
+  ::GetLongPathNameW(path, result->get(), size);
+  return true;
+}
+
+HANDLE OpenDirectory(const WCHAR* path, bool read_write) {
+  return ::CreateFileW(
+      /* lpFileName */ path,
+      /* dwDesiredAccess */
+      read_write ? (GENERIC_READ | GENERIC_WRITE) : GENERIC_READ,
+      /* dwShareMode */ 0,
+      /* lpSecurityAttributes */ NULL,
+      /* dwCreationDisposition */ OPEN_EXISTING,
+      /* dwFlagsAndAttributes */ FILE_FLAG_OPEN_REPARSE_POINT |
+          FILE_FLAG_BACKUP_SEMANTICS,
+      /* hTemplateFile */ NULL);
+}
+
+#pragma pack(push, 4)
+typedef struct _JunctionDescription {
+  typedef struct _Header {
+    DWORD ReparseTag;
+    WORD ReparseDataLength;
+    WORD Reserved;
+  } Header;
+
+  typedef struct _WriteDesc {
+    WORD SubstituteNameOffset;
+    WORD SubstituteNameLength;
+    WORD PrintNameOffset;
+    WORD PrintNameLength;
+  } WriteDesc;
+
+  Header header;
+  WriteDesc write;
+  WCHAR PathBuffer[ANYSIZE_ARRAY];
+} JunctionDescription;
+#pragma pack(pop)
+
+string CreateJunction(const wstring& junction_name,
+                      const wstring& junction_target) {
+  const wstring target = HasUncPrefix(junction_target.c_str())
+                             ? junction_target.substr(4)
+                             : junction_target;
+  // The entire JunctionDescription cannot be larger than
+  // MAXIMUM_REPARSE_DATA_BUFFER_SIZE bytes.
+  //
+  // The structure's layout is:
+  //   [JunctionDescription::Header]
+  //   [JunctionDescription::WriteDesc]
+  //   ---- start of JunctionDescription::PathBuffer ----
+  //   [4 WCHARs]             : "\??\" prefix
+  //   [target.size() WCHARs] : junction target name
+  //   [1 WCHAR]              : null-terminator
+  //   [target.size() WCHARs] : junction target displayed name
+  //   [1 WCHAR]              : null-terminator
+  // The sum of these must not exceed MAXIMUM_REPARSE_DATA_BUFFER_SIZE.
+  // We can rearrange this to get the limit for target.size().
+  static const size_t kMaxJunctionTargetLen =
+      ((MAXIMUM_REPARSE_DATA_BUFFER_SIZE - sizeof(JunctionDescription::Header) -
+        sizeof(JunctionDescription::WriteDesc) -
+        /* one "\??\" prefix */ sizeof(WCHAR) * 4 -
+        /* two null terminators */ sizeof(WCHAR) * 2) /
+       /* two copies of the string are stored */ 2) /
+      sizeof(WCHAR);
+  if (target.size() > kMaxJunctionTargetLen) {
+    std::stringstream error;
+    error << "junction target is too long (" << target.size()
+          << " characters, limit: " << kMaxJunctionTargetLen << ")";
+    return error.str();
+  }
+  const wstring name = HasUncPrefix(junction_name.c_str())
+                           ? junction_name
+                           : (wstring(L"\\\\?\\") + junction_name);
+
+  // Junctions are directories, so create one
+  if (!::CreateDirectoryW(name.c_str(), NULL)) {
+    return string("CreateDirectoryW failed");
+  }
+
+  AutoHandle handle(OpenDirectory(name.c_str(), true));
+  if (!handle.IsValid()) {
+    return string("OpenDirectory failed");
+  }
+
+  char reparse_buffer_bytes[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
+  JunctionDescription* reparse_buffer =
+      reinterpret_cast<JunctionDescription*>(reparse_buffer_bytes);
+  memset(reparse_buffer_bytes, 0, MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
+
+  // "\??\" is meaningful to the kernel, it's a synomym for the "\DosDevices\"
+  // object path. (NOT to be confused with "\\?\" which is meaningful for the
+  // Win32 API.) We need to use this prefix to tell the kernel where the reparse
+  // point is pointing to.
+  memcpy(reparse_buffer->PathBuffer, L"\\??\\", 4 * sizeof(WCHAR));
+  memcpy(reparse_buffer->PathBuffer + 4, target.c_str(),
+         target.size() * sizeof(WCHAR));
+
+  // In addition to their target, junctions also have another string which is a
+  // user-visible name of where the junction points, as listed by "dir". This
+  // can be any string and won't affect the usability of the junction.
+  // MKLINK uses the target path without the "\??\" prefix as the display name,
+  // so let's do that here too. This is also in line with how UNIX behaves.
+  // Using a dummy or fake display name would be pure evil, it would make the
+  // output of `dir` look like:
+  //   2017-01-18  01:37 PM    <JUNCTION>     juncname [dummy string]
+  memcpy(reparse_buffer->PathBuffer + 4 + target.size() + 1, target.c_str(),
+         target.size() * sizeof(WCHAR));
+
+  reparse_buffer->write.SubstituteNameOffset = 0;
+  reparse_buffer->write.SubstituteNameLength =
+      (4 + target.size()) * sizeof(WCHAR);
+  reparse_buffer->write.PrintNameOffset =
+      reparse_buffer->write.SubstituteNameLength +
+      /* null-terminator */ sizeof(WCHAR);
+  reparse_buffer->write.PrintNameLength = target.size() * sizeof(WCHAR);
+
+  reparse_buffer->header.ReparseTag = IO_REPARSE_TAG_MOUNT_POINT;
+  reparse_buffer->header.ReparseDataLength =
+      sizeof(JunctionDescription::WriteDesc) +
+      reparse_buffer->write.SubstituteNameLength +
+      reparse_buffer->write.PrintNameLength +
+      /* 2 null-terminators */ (2 * sizeof(WCHAR));
+  reparse_buffer->header.Reserved = 0;
+
+  DWORD bytes_returned;
+  if (!::DeviceIoControl(handle, FSCTL_SET_REPARSE_POINT, reparse_buffer,
+                         reparse_buffer->header.ReparseDataLength +
+                             sizeof(JunctionDescription::Header),
+                         NULL, 0, &bytes_returned, NULL)) {
+    return string("DeviceIoControl(FSCTL_SET_REPARSE_POINT) failed");
+  }
+  return "";
+}
+
+}  // namespace windows
+}  // namespace bazel