fixing issue #8345 RocksDB does not work when using UNC network paths (#9384)

Summary:
Fix https://github.com/facebook/rocksdb/issues/8345
RocksDB does not work with network filesystem paths on Windows, e.g. "\\hostname\folder\..."

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9384

Reviewed By: mrambacher

Differential Revision: D33830622

Pulled By: riversand963

fbshipit-source-id: 2a99dc3c94415eb1460e110784b97d71600218f1

HISTORY.md

@@ -1,6 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
 ### Bug Fixes
+* Fixed bug which caused rocksdb failure in the situation when rocksdb was accessible using UNC path
 * Fixed a race condition when 2PC is disabled and WAL tracking in the MANIFEST is enabled. The race condition is between two background flush threads trying to install flush results, causing a WAL deletion not tracked in the MANIFEST. A future DB open may fail.
 * Fixed a heap use-after-free race with DropColumnFamily.
 * Fixed a bug that `rocksdb.read.block.compaction.micros` cannot track compaction stats (#9722).

db/filename_test.cc

@@ -171,6 +171,69 @@ TEST_F(FileNameTest, Construction) {
   ASSERT_EQ(kMetaDatabase, type);
 }
 
+TEST_F(FileNameTest, NormalizePath) {
+  // No leading slash
+  const std::string sep = std::string(1, kFilePathSeparator);
+
+  std::string expected = "FOLDER" + sep + "filename.ext";
+  std::string given = "FOLDER" + sep + "filename.ext";
+
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // Two chars /a
+
+  expected = sep + "a";
+  given = expected;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // Two chars a/
+  expected = "a" + sep;
+  given = expected;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // Server only
+  expected = sep + sep + "a";
+  given = expected;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // Two slashes after character
+  expected = "a" + sep;
+  given = "a" + sep + sep;
+
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // slash only   /
+  expected = sep;
+  given = expected;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // UNC only   //
+  expected = sep;
+  given = sep + sep;
+
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // 3 slashesy   //
+  expected = sep + sep;
+  given = sep + sep + sep;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // 3 slashes   //
+  expected = sep + sep + "a" + sep;
+  given = sep + sep + sep + "a" + sep;
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // 2 separators in the middle
+  expected = "a" + sep + "b";
+  given = "a" + sep + sep + "b";
+  ASSERT_EQ(expected, NormalizePath(given));
+
+  // UNC with duplicate slashes
+  expected = sep + sep + "SERVER" + sep + "a" + sep + "b" + sep + "c";
+  given = sep + sep + "SERVER" + sep + "a" + sep + sep + "b" + sep + "c";
+  ASSERT_EQ(expected, NormalizePath(given));
+}
+
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

file/filename.cc

@@ -491,6 +491,12 @@ Status GetInfoLogFiles(const std::shared_ptr<FileSystem>& fs,
 
 std::string NormalizePath(const std::string& path) {
   std::string dst;
+
+  if (path.length() > 2 && path[0] == kFilePathSeparator &&
+      path[1] == kFilePathSeparator) {  // Handle UNC names
+    dst.append(2, kFilePathSeparator);
+  }
+
   for (auto c : path) {
     if (!dst.empty() && (c == kFilePathSeparator || c == '/') &&
         (dst.back() == kFilePathSeparator || dst.back() == '/')) {