ORC-1684: [C++] Find tzdb without TZDIR when in conda-environments

c++/src/Timezone.cc

@@ -656,10 +656,18 @@ namespace orc {
  epoch_ = utcEpoch - getVariant(utcEpoch).gmtOffset;
  }
 
- const char* getTimezoneDirectory() {
+ std::string getTimezoneDirectory() {
  const char* dir = getenv("TZDIR");
  if (!dir) {
- dir = DEFAULT_TZDIR;
+ // this is present if we're in an activated conda environment
+ const char* condaPrefix = getenv("CONDA_PREFIX");
+ if (condaPrefix) {
+ std::string condaDir(condaPrefix);
+ condaDir += "/share/zoneinfo";
+ return condaDir;
+ } else {
+ dir = DEFAULT_TZDIR;
+ }
  }
  return dir;
  }

c++/test/TestTimezone.cc

@@ -21,6 +21,7 @@
 #include "wrap/gmock.h"
 #include "wrap/gtest-wrapper.h"
 
+#include <algorithm>
 #include <cstdlib>
 #include <iostream>
 #include <vector>
@@ -421,20 +422,61 @@ namespace orc {
  }
 
  TEST(TestTimezone, testMissingTZDB) {
- const char* tzDirBackup = std::getenv("TZDIR");
- if (tzDirBackup != nullptr) {
+ const char* tzDir = std::getenv("TZDIR");
+ std::string tzDirBackup;
+ if (tzDir != nullptr) {
+ // std::string creates a deepcopy of buffer, which avoids that
+ // unsetting environment variable wrecks pointer to tzDir
+ tzDirBackup = tzDir;
  ASSERT_TRUE(delEnv("TZDIR"));
  }
  ASSERT_TRUE(setEnv("TZDIR", "/path/to/wrong/tzdb"));
  EXPECT_THAT([]() { getTimezoneByName("America/Los_Angeles"); },
  testing::ThrowsMessage<TimezoneError>(testing::HasSubstr(
  "Time zone file /path/to/wrong/tzdb/America/Los_Angeles does not exist."
  " Please install IANA time zone database and set TZDIR env.")));
- if (tzDirBackup != nullptr) {
- ASSERT_TRUE(setEnv("TZDIR", tzDirBackup));
+ if (!tzDirBackup.empty()) {
+ ASSERT_TRUE(setEnv("TZDIR", tzDirBackup.c_str()));
  } else {
  ASSERT_TRUE(delEnv("TZDIR"));
  }
  }
 
+ TEST(TestTimezone, testTzdbFromCondaEnv) {
+ const char* tzDir = std::getenv("TZDIR");
+ // test only makes sense if TZDIR exists
+ if (tzDir != nullptr) {
+ std::string tzDirBackup = tzDir;
+ ASSERT_TRUE(delEnv("TZDIR"));
+
+ // remove "/share/zoneinfo" from TZDIR (as set through TZDATA_DIR in CI) to
+ // get the equivalent of CONDA_PREFIX, relative to the location of the tzdb
+ std::string condaPrefix(tzDirBackup);
+ condaPrefix += "/../..";
+ ASSERT_TRUE(setEnv("CONDA_PREFIX", condaPrefix.c_str()));
+
+ // small test sample to ensure tzbd loads with CONDA_PREFIX, even without TZDIR
+ const Timezone* zrh = &getTimezoneByName("Europe/Zurich");
+ EXPECT_EQ("CET", getVariantFromZone(*zrh, "2024-03-31 00:59:59"));
+ EXPECT_EQ("CEST", getVariantFromZone(*zrh, "2024-03-31 01:00:00"));
+ EXPECT_EQ("CEST", getVariantFromZone(*zrh, "2024-10-27 00:59:59"));
+ EXPECT_EQ("CET", getVariantFromZone(*zrh, "2024-10-27 01:00:00"));
+
+ // CONDA_PREFIX contains backslashes on windows; test that this doesn't blow up
+ std::replace(condaPrefix.begin(), condaPrefix.end(), '/', '\\');
+ ASSERT_TRUE(setEnv("CONDA_PREFIX", condaPrefix.c_str()));
+
+ // as above, but different timezone to avoid hitting cache
+ const Timezone* syd = &getTimezoneByName("Australia/Sydney");
+ EXPECT_EQ("AEDT", getVariantFromZone(*syd, "2024-04-06 15:59:59"));
+ EXPECT_EQ("AEST", getVariantFromZone(*syd, "2024-04-06 16:00:00"));
+ EXPECT_EQ("AEST", getVariantFromZone(*syd, "2024-10-05 15:59:59"));
+ EXPECT_EQ("AEDT", getVariantFromZone(*syd, "2024-10-05 16:00:00"));
+
+ // restore state of environment variables
+ ASSERT_TRUE(delEnv("CONDA_PREFIX"));
+ ASSERT_TRUE(setEnv("TZDIR", tzDirBackup.c_str()));
+ }
+ }
+
 } // namespace orc