Windows JNI library: prepare for widechar WinAPI

This change:
- renames windows_error_handling.* to
windows_util.*
- moves most stuff except for the JNI method
implementations into the new windows_util
namespace
- implements a jstring to wchar string converter
- uses GetFileAttributesW in
windows_file_operations.cc

See https://github.com/bazelbuild/bazel/issues/2181

--
PiperOrigin-RevId: 141187291
MOS_MIGRATED_REVID=141187291

4 files changed, 80 insertions, 35 deletions

diff --git a/src/main/native/windows_file_operations.cc b/src/main/native/windows_file_operations.cc
index cbec4715c0..9f74293c9f 100644
--- a/src/main/native/windows_file_operations.cc
+++ b/src/main/native/windows_file_operations.cc
@@ -15,9 +15,12 @@
 #include <jni.h>
 #include <windows.h>
 
+#include <memory>
 #include <string>
 
-#include "src/main/native/windows_error_handling.h"
+#include "src/main/native/windows_util.h"
+
+namespace windows_util {
 
 // Keep in sync with j.c.g.devtools.build.lib.windows.WindowsFileOperations
 enum {
@@ -28,6 +31,9 @@ enum {
 
 // Determines whether `path` is a junction point or directory symlink.
 //
+// Uses the `GetFileAttributesW` WinAPI function.
+// `path` should be a valid Windows-style or UNC path.
+//
 // To read about differences between junction points and directory symlinks,
 // see http://superuser.com/a/343079.
 //
@@ -39,8 +45,8 @@ enum {
 //   created using "mklink" instead of "mklink /d", as such symlinks don't
 //   behave the same way as directories (e.g. they can't be listed)
 // - IS_JUNCTION_ERROR, if `path` doesn't exist or some error occurred
-int IsJunctionOrDirectorySymlink(const char* path) {
-  DWORD attrs = GetFileAttributesA(path);
+static int IsJunctionOrDirectorySymlink(const wchar_t* path) {
+  DWORD attrs = GetFileAttributesW(path);
   if (attrs == INVALID_FILE_ATTRIBUTES) {
     return IS_JUNCTION_ERROR;
   } else {
@@ -53,21 +59,26 @@ int IsJunctionOrDirectorySymlink(const char* path) {
   }
 }
 
+}  // namespace windows_util
+
 extern "C" JNIEXPORT jint JNICALL
 Java_com_google_devtools_build_lib_windows_WindowsFileOperations_nativeIsJunction(
     JNIEnv* env, jclass clazz, jstring path, jobjectArray error_msg_holder) {
-  const char* path_cstr = env->GetStringUTFChars(path, NULL);
   bool report_error =
       error_msg_holder != NULL && env->GetArrayLength(error_msg_holder) > 0;
-  int result = IsJunctionOrDirectorySymlink(path_cstr);
-  if (result == IS_JUNCTION_ERROR && report_error) {
-    std::string error_str =
-        GetLastErrorString(std::string("GetFileAttributesA(") +
-                           std::string(path_cstr) + std::string(")"));
+  std::unique_ptr<wchar_t[]> long_path(
+      windows_util::JstringToWstring(env, path));
+  int result = windows_util::IsJunctionOrDirectorySymlink(long_path.get());
+  if (result == windows_util::IS_JUNCTION_ERROR && report_error) {
+    // Getting the string's characters again in UTF8 encoding is probably
+    // easier than converting `long_path` using `wcstombs(3)`.
+    const char* path_cstr = env->GetStringUTFChars(path, NULL);
+    std::string error_str = windows_util::GetLastErrorString(
+        std::string("GetFileAttributes(") + std::string(path_cstr) +
+        std::string(")"));
+    env->ReleaseStringUTFChars(path, path_cstr);
     jstring error_msg = env->NewStringUTF(error_str.c_str());
     env->SetObjectArrayElement(error_msg_holder, 0, error_msg);
   }
-
-  env->ReleaseStringUTFChars(path, path_cstr);
   return result;
 }
diff --git a/src/main/native/windows_processes.cc b/src/main/native/windows_processes.cc
index 9210d259aa..49355430e6 100644
--- a/src/main/native/windows_processes.cc
+++ b/src/main/native/windows_processes.cc
@@ -22,7 +22,7 @@
 #include <atomic>
 #include <string>
 
-#include "src/main/native/windows_error_handling.h"
+#include "src/main/native/windows_util.h"
 
 extern "C" JNIEXPORT jint JNICALL
 Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeGetpid(
@@ -138,7 +138,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
   }
 
   if (!CreatePipe(&stdin_process, &result->stdin_, &sa, 0)) {
-    result->error_ = GetLastErrorString("CreatePipe(stdin)");
+    result->error_ = windows_util::GetLastErrorString("CreatePipe(stdin)");
     goto cleanup;
   }
 
@@ -155,12 +155,12 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
         NULL);
 
     if (stdout_process == INVALID_HANDLE_VALUE) {
-      result->error_ = GetLastErrorString("CreateFile(stdout)");
+      result->error_ = windows_util::GetLastErrorString("CreateFile(stdout)");
       goto cleanup;
     }
   } else {
     if (!CreatePipe(&result->stdout_.handle_, &stdout_process, &sa, 0)) {
-      result->error_ = GetLastErrorString("CreatePipe(stdout)");
+      result->error_ = windows_util::GetLastErrorString("CreatePipe(stdout)");
       goto cleanup;
     }
   }
@@ -180,13 +180,13 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
           NULL);
 
       if (stderr_process == INVALID_HANDLE_VALUE) {
-        result->error_ = GetLastErrorString("CreateFile(stderr)");
+        result->error_ = windows_util::GetLastErrorString("CreateFile(stderr)");
         goto cleanup;
       }
     }
   } else {
     if (!CreatePipe(&result->stderr_.handle_, &stderr_process, &sa, 0)) {
-      result->error_ = GetLastErrorString("CreatePipe(stderr)");
+      result->error_ = windows_util::GetLastErrorString("CreatePipe(stderr)");
       goto cleanup;
     }
   }
@@ -196,7 +196,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
   // allowed. Thus, we don't need to do any more setup here.
   HANDLE job = CreateJobObject(NULL, NULL);
   if (job == NULL) {
-    result->error_ = GetLastErrorString("CreateJobObject()");
+    result->error_ = windows_util::GetLastErrorString("CreateJobObject()");
     goto cleanup;
   }
 
@@ -209,8 +209,9 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
       JobObjectExtendedLimitInformation,
       &job_info,
       sizeof(job_info))) {
-      result->error_ = GetLastErrorString("SetInformationJobObject()");
-      goto cleanup;
+    result->error_ =
+        windows_util::GetLastErrorString("SetInformationJobObject()");
+    goto cleanup;
   }
 
   startup_info.hStdInput = stdin_process;
@@ -233,7 +234,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
       &process_info);
 
   if (!ok) {
-    result->error_ = GetLastErrorString("CreateProcess()");
+    result->error_ = windows_util::GetLastErrorString("CreateProcess()");
     goto cleanup;
   }
 
@@ -253,14 +254,15 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeCreateProcess(
       CloseHandle(result->job_);
       result->job_ = INVALID_HANDLE_VALUE;
     } else {
-      result->error_ = GetLastErrorString("AssignProcessToJobObject()");
+      result->error_ =
+          windows_util::GetLastErrorString("AssignProcessToJobObject()");
       goto cleanup;
     }
   }
 
   // Now that we put the process in a new job object, we can start executing it
   if (ResumeThread(thread) == -1) {
-    result->error_ = GetLastErrorString("ResumeThread()");
+    result->error_ = windows_util::GetLastErrorString("ResumeThread()");
     goto cleanup;
   }
 
@@ -325,7 +327,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeWriteStdin(
 
   if (!::WriteFile(process->stdin_, bytes + offset, length, &bytes_written,
                    NULL)) {
-    process->error_ = GetLastErrorString("WriteFile()");
+    process->error_ = windows_util::GetLastErrorString("WriteFile()");
     bytes_written = -1;
   }
 
@@ -377,7 +379,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeReadStream(
       stream->error_ = "";
       bytes_read = 0;
     } else {
-      stream->error_ = GetLastErrorString("ReadFile()");
+      stream->error_ = windows_util::GetLastErrorString("ReadFile()");
       bytes_read = -1;
     }
   } else {
@@ -394,7 +396,7 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeGetExitCode(
   NativeProcess* process = reinterpret_cast<NativeProcess*>(process_long);
   DWORD exit_code;
   if (!GetExitCodeProcess(process->process_, &exit_code)) {
-    process->error_ = GetLastErrorString("GetExitCodeProcess()");
+    process->error_ = windows_util::GetLastErrorString("GetExitCodeProcess()");
     return -1;
   }
 
@@ -471,12 +473,13 @@ Java_com_google_devtools_build_lib_windows_WindowsProcesses_nativeTerminate(
     // In theory, CloseHandle() on process->job_ would work, too, since we set
     // KILL_OBJECT_LIMIT_KILL_ON_JOB_CLOSE, but this is a little more explicit.
     if (!TerminateJobObject(process->job_, 0)) {
-      process->error_ = GetLastErrorString("TerminateJobObject()");
+      process->error_ =
+          windows_util::GetLastErrorString("TerminateJobObject()");
       return JNI_FALSE;
     }
   } else if (process->process_ != INVALID_HANDLE_VALUE) {
     if (!TerminateProcess(process->process_, 1)) {
-      process->error_ = GetLastErrorString("TerminateProcess()");
+      process->error_ = windows_util::GetLastErrorString("TerminateProcess()");
       return JNI_FALSE;
     }
   }
diff --git a/src/main/native/windows_error_handling.cc b/src/main/native/windows_util.cc
index dc14289729..b25bd2c114 100644
--- a/src/main/native/windows_error_handling.cc
+++ b/src/main/native/windows_util.cc
@@ -13,13 +13,20 @@
 // limitations under the License.
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <windows.h>
 
+#include <memory>
 #include <string>
 
-#include "src/main/native/windows_error_handling.h"
+#include "src/main/native/windows_util.h"
 
-std::string GetLastErrorString(const std::string& cause) {
+namespace windows_util {
+
+using std::string;
+using std::unique_ptr;
+
+string GetLastErrorString(const string& cause) {
   DWORD last_error = GetLastError();
   if (last_error == 0) {
     return "";
@@ -45,7 +52,19 @@ std::string GetLastErrorString(const std::string& cause) {
     buf[sizeof(buf) - 1] = 0;
   }
 
-  std::string result = std::string(message);
+  string result = string(message);
   LocalFree(message);
   return cause + ": " + result;
 }
+
+unique_ptr<wchar_t[]> JstringToWstring(JNIEnv* env, const jstring& jstr) {
+  const jsize len = env->GetStringLength(jstr);
+  const char* cstr_ptr = env->GetStringUTFChars(jstr, NULL);
+  unique_ptr<wchar_t[]> result(new wchar_t[len + 1]);
+  mbstowcs(result.get(), cstr_ptr, len);
+  result.get()[len] = L'\0';
+  env->ReleaseStringUTFChars(jstr, cstr_ptr);
+  return std::move(result);
+}
+
+}  // namespace windows_util
diff --git a/src/main/native/windows_error_handling.h b/src/main/native/windows_util.h
index efbe95e7ad..48b88be191 100644
--- a/src/main/native/windows_error_handling.h
+++ b/src/main/native/windows_util.h
@@ -14,11 +14,23 @@
 //
 // INTERNAL header file for use by C++ code in this package.
 
-#ifndef BAZEL_SRC_MAIN_NATIVE_WINDOWS_ERROR_HANDLING_H__
-#define BAZEL_SRC_MAIN_NATIVE_WINDOWS_ERROR_HANDLING_H__
+#ifndef BAZEL_SRC_MAIN_NATIVE_WINDOWS_UTIL_H__
+#define BAZEL_SRC_MAIN_NATIVE_WINDOWS_UTIL_H__
 
+#include <jni.h>
+
+#include <memory>
 #include <string>
 
-std::string GetLastErrorString(const std::string& cause);
+namespace windows_util {
+
+using std::string;
+using std::unique_ptr;
+
+string GetLastErrorString(const string& cause);
+
+unique_ptr<wchar_t[]> JstringToWstring(JNIEnv* env, const jstring& jstr);
+
+}  // namespace windows_util
 
-#endif  // BAZEL_SRC_MAIN_NATIVE_WINDOWS_ERROR_HANDLING_H__
+#endif  // BAZEL_SRC_MAIN_NATIVE_WINDOWS_UTIL_H__