Bazel client, Windows: impl. ForEachDirectoryEntry

This is the last function we needed from
file_posix for MSYS, so now we can remove that
from the compilation.

Fixes https://github.com/bazelbuild/bazel/issues/2386
The problem originally was that I used CloseHandle
to close the HANDLE, instead of using FindClose,
so we were holding on to open directory HANDLEs,
so we couldn't rename the installation directory.

See https://github.com/bazelbuild/bazel/issues/2107

--
Change-Id: If6c1b3c99cf386d82e829dbee2323e6bce5f6b46
Reviewed-on: https://cr.bazel.build/8952
PiperOrigin-RevId: 147734165
MOS_MIGRATED_REVID=147734165

4 files changed, 88 insertions, 15 deletions

diff --git a/src/main/cpp/util/BUILD b/src/main/cpp/util/BUILD
index b044d19537..b5c7b79d54 100644
--- a/src/main/cpp/util/BUILD
+++ b/src/main/cpp/util/BUILD
@@ -27,10 +27,6 @@ cc_library(
     name = "file",
     srcs = ["file.cc"] + select({
         "//src:windows": [
-            # TODO(bazel-team): implement functions in file_windows.cc and use
-            # more and more of them under MSYS until we can completely stop
-            # using file_posix.cc at which point remove it from this list.
-            "file_posix.cc",
             "file_windows.cc",
         ],
         "//src:windows_msvc": [
diff --git a/src/main/cpp/util/file_posix.cc b/src/main/cpp/util/file_posix.cc
index b59618201b..30fd8cd9e3 100644
--- a/src/main/cpp/util/file_posix.cc
+++ b/src/main/cpp/util/file_posix.cc
@@ -34,11 +34,6 @@ namespace blaze_util {
 using std::pair;
 using std::string;
 
-// TODO(bazel-team): implement all functions in file_windows.cc, use them from
-// MSYS, remove file_posix.cc from the `srcs` of
-// //src/main/cpp/util:file when building for MSYS, and remove all
-// #ifndef __CYGWIN__ directives.
-#ifndef __CYGWIN__
 // Runs "stat" on `path`. Returns -1 and sets errno if stat fails or
 // `path` isn't a directory. If check_perms is true, this will also
 // make sure that `path` is owned by the current user and has `mode`
@@ -371,7 +366,6 @@ string GetCwd() {
 bool ChangeDirectory(const string& path) {
   return chdir(path.c_str()) == 0;
 }
-#endif  // not __CYGWIN__
 
 void ForEachDirectoryEntry(const string &path,
                            DirectoryEntryConsumer *consume) {
diff --git a/src/main/cpp/util/file_windows.cc b/src/main/cpp/util/file_windows.cc
index c92b76ba7c..26cc47df65 100644
--- a/src/main/cpp/util/file_windows.cc
+++ b/src/main/cpp/util/file_windows.cc
@@ -1074,14 +1074,44 @@ bool ChangeDirectory(const string& path) {
   return true;
 }
 
-#ifdef COMPILER_MSVC
 void ForEachDirectoryEntry(const string &path,
                            DirectoryEntryConsumer *consume) {
-  // TODO(bazel-team): implement this.
-  pdie(255, "blaze_util::ForEachDirectoryEntry is not implemented on Windows");
+  wstring wpath;
+  if (path.empty() || IsDevNull(path)) {
+    return;
+  }
+  if (!AsWindowsPath(path, &wpath)) {
+    pdie(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR,
+         "ForEachDirectoryEntry(%s): AsWindowsPath failed", path.c_str());
+  }
+
+  static const wstring kUncPrefix(L"\\\\?\\");
+  static const wstring kDot(L".");
+  static const wstring kDotDot(L"..");
+  // Always add an UNC prefix to ensure we can work with long paths.
+  if (!windows_util::HasUncPrefix(wpath.c_str())) {
+    wpath = kUncPrefix + wpath;
+  }
+  // Unconditionally add a trailing backslash. We know `wpath` has no trailing
+  // backslash because it comes from AsWindowsPath whose output is always
+  // normalized (see NormalizeWindowsPath).
+  wpath.append(L"\\");
+  WIN32_FIND_DATAW metadata;
+  HANDLE handle = ::FindFirstFileW((wpath + L"*").c_str(), &metadata);
+  if (handle == INVALID_HANDLE_VALUE) {
+    return;  // directory does not exist or is empty
+  }
+
+  do {
+    if (kDot != metadata.cFileName && kDotDot != metadata.cFileName) {
+      wstring wname = wpath + metadata.cFileName;
+      string name(WstringToCstring(/* omit prefix */ 4 + wname.c_str()).get());
+      bool is_dir = (metadata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
+      consume->Consume(name, is_dir);
+    }
+  } while (::FindNextFileW(handle, &metadata));
+  ::FindClose(handle);
 }
-#else   // not COMPILER_MSVC
-#endif  // COMPILER_MSVC
 
 string NormalizeWindowsPath(string path) {
   if (path.empty()) {
diff --git a/src/test/cpp/util/file_test.cc b/src/test/cpp/util/file_test.cc
index ab9ce916d1..4173954559 100644
--- a/src/test/cpp/util/file_test.cc
+++ b/src/test/cpp/util/file_test.cc
@@ -14,8 +14,11 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <algorithm>
+#include <map>
 #include <memory>  // unique_ptr
 #include <thread>  // NOLINT (to silence Google-internal linter)
+#include <vector>
 
 #include "src/main/cpp/util/file.h"
 #include "src/main/cpp/util/file_platform.h"
@@ -164,4 +167,54 @@ TEST(FileTest, TestRenameDirectory) {
   ASSERT_EQ(RenameDirectory(dir2, dir1), kRenameDirectoryFailureNotEmpty);
 }
 
+class CollectingDirectoryEntryConsumer : public DirectoryEntryConsumer {
+ public:
+  CollectingDirectoryEntryConsumer(const string& _rootname)
+      : rootname(_rootname) {}
+
+  void Consume(const string& name, bool is_directory) override {
+    // Strip the path prefix up to the `rootname` to ease testing on all
+    // platforms.
+    int index = name.rfind(rootname);
+    string key = (index == string::npos) ? name : name.substr(index);
+    // Replace backslashes with forward slashes (necessary on Windows only).
+    std::replace(key.begin(), key.end(), '\\', '/');
+    entries[key] = is_directory;
+  }
+
+  const string rootname;
+  std::map<string, bool> entries;
+};
+
+TEST(FileTest, ForEachDirectoryEntryTest) {
+  string tmpdir(getenv("TEST_TMPDIR"));
+  EXPECT_FALSE(tmpdir.empty());
+  // Create a directory structure:
+  //   $TEST_TMPDIR/
+  //      foo/
+  //        bar/
+  //          file3.txt
+  //        file1.txt
+  //        file2.txt
+  string rootdir(JoinPath(tmpdir, "foo"));
+  string file1(JoinPath(rootdir, "file1.txt"));
+  string file2(JoinPath(rootdir, "file2.txt"));
+  string subdir(JoinPath(rootdir, "bar"));
+  string file3(JoinPath(subdir, "file3.txt"));
+
+  EXPECT_TRUE(MakeDirectories(subdir, 0700));
+  EXPECT_TRUE(WriteFile("hello", 5, file1));
+  EXPECT_TRUE(WriteFile("hello", 5, file2));
+  EXPECT_TRUE(WriteFile("hello", 5, file3));
+
+  std::map<string, bool> expected;
+  expected["foo/file1.txt"] = false;
+  expected["foo/file2.txt"] = false;
+  expected["foo/bar"] = true;
+
+  CollectingDirectoryEntryConsumer consumer("foo");
+  ForEachDirectoryEntry(rootdir, &consumer);
+  ASSERT_EQ(consumer.entries, expected);
+}
+
 }  // namespace blaze_util