teach CheckTimeZoneDatabaseAvailability how to inspect conda environm…

…ents

cpp/src/arrow/adapters/orc/adapter.cc

@@ -189,15 +189,21 @@ liborc::RowReaderOptions DefaultRowReaderOptions() {
 #ifdef ARROW_ORC_NEED_TIME_ZONE_DATABASE_CHECK
 // Proactively check timezone database availability for ORC versions older than 2.0.0
 Status CheckTimeZoneDatabaseAvailability() {
-  auto tz_dir = std::getenv("TZDIR");
-  bool is_tzdb_avaiable = tz_dir != nullptr
+  // orc >=2.0.1 will look for tzdb in $CONDA_PREFIX/share/zoneinfo,
+  // which is provided by the package `tzdata` (if installed)
+  auto conda_prefix = std::getenv("CONDA_PREFIX");
+  auto tz_dir_raw = std::getenv("TZDIR");
+  std::string tz_dir = conda_prefix != nullptr
+                        ? std::string(conda_prefix) + "/share/zoneinfo"
+                        : std::string(tz_dir_raw != nullptr ? tz_dir_raw : "");
+  bool is_tzdb_available = (!tz_dir.empty())
                               ? std::filesystem::exists(tz_dir)
                               : std::filesystem::exists("/usr/share/zoneinfo");
-  if (!is_tzdb_avaiable) {
+  if (!is_tzdb_available) {
     return Status::Invalid(
         "IANA time zone database is unavailable but required by ORC."
         " Please install it to /usr/share/zoneinfo or set TZDIR env to the installed"
-        " directory");
+        " directory. If you are using conda, simply install the package `tzdata`.");
   }
   return Status::OK();
 }