GH-48832: [R] Fix crash with zero-length POSIXct tzone attribute

[shashbha14]

Rationale for this change

Fixes crash when writing zero-length POSIXct vectors with empty tzone attributes to Parquet in R 4.5.2.

What changes are included in this PR?

• Added length check for tzone attribute in InferArrowTypeFromVector (both INTSXP and REALSXP specializations)
• Added regression test in test-issue-48832.R

Are these changes tested?

Yes, new test case reproduces the issue and verifies the fix.

Closes #48832

• GitHub Issue: [R] arrow::write_parquet error with zero-length datetimes in R 4.5.2 #48832

[jonkeane]

Thanks for submitting the change. The devtooling documentation should go in a separate PR IMO.

Would you mind moving the tests to where we test other examples of POSIXct? The approach to solve it looks solid, but CI will determine if we are good.

[jonkeane]

Would you mind putting this test in somewhere around

arrow/r/tests/testthat/test-Array.R

Lines 279 to 325 in 962d051

	test_that("array supports POSIXct (ARROW-3340)", {
	times <- lubridate::ymd_hms("2018-10-07 19:04:05") + 1:10
	expect_array_roundtrip(times, timestamp("us", "UTC"))
	times[5] <- NA
	expect_array_roundtrip(times, timestamp("us", "UTC"))
	times2 <- lubridate::ymd_hms("2018-10-07 19:04:05", tz = "America/New_York") + 1:10
	expect_array_roundtrip(times2, timestamp("us", "America/New_York"))
	})
	test_that("array uses local timezone for POSIXct without timezone", {
	withr::with_envvar(c(TZ = ""), {
	times <- strptime("2019-02-03 12:34:56", format = "%Y-%m-%d %H:%M:%S") + 1:10
	expect_equal(attr(times, "tzone"), NULL)
	expect_array_roundtrip(times, timestamp("us", Sys.timezone()))
	# Also test the INTSXP code path
	skip("Ingest_POSIXct only implemented for REALSXP")
	times_int <- as.integer(times)
	attributes(times_int) <- attributes(times)
	expect_array_roundtrip(times_int, timestamp("us", ""))
	})
	# If there is a timezone set, we record that
	withr::with_timezone("Pacific/Marquesas", {
	times <- strptime("2019-02-03 12:34:56", format = "%Y-%m-%d %H:%M:%S") + 1:10
	expect_equal(attr(times, "tzone"), "Pacific/Marquesas")
	expect_array_roundtrip(times, timestamp("us", "Pacific/Marquesas"))
	times_with_tz <- strptime(
	"2019-02-03 12:34:56",
	format = "%Y-%m-%d %H:%M:%S",
	tz = "Asia/Katmandu"
	) +
	1:10
	expect_equal(attr(times, "tzone"), "Asia/Katmandu")
	expect_array_roundtrip(times, timestamp("us", "Asia/Katmandu"))
	})
	# and although the TZ is NULL in R, we set it to the Sys.timezone()
	withr::with_timezone(NA, {
	times <- strptime("2019-02-03 12:34:56", format = "%Y-%m-%d %H:%M:%S") + 1:10
	expect_equal(attr(times, "tzone"), NULL)
	expect_array_roundtrip(times, timestamp("us", Sys.timezone()))
	})
	})

and possibly for the parquet section, put it somewhere near

arrow/r/tests/testthat/test-parquet.R

Lines 119 to 153 in 962d051

	test_that("write_parquet() can truncate timestamps", {
	tab <- Table$create(x1 = as.POSIXct("2020/06/03 18:00:00", tz = "UTC"))
	expect_type_equal(tab$x1, timestamp("us", "UTC"))
	tf <- tempfile()
	on.exit(unlink(tf))
	write_parquet(tab, tf, coerce_timestamps = "ms", allow_truncated_timestamps = TRUE)
	new <- read_parquet(tf, as_data_frame = FALSE)
	expect_type_equal(new$x1, timestamp("ms", "UTC"))
	expect_equal(as.data.frame(tab), as.data.frame(new))
	})
	test_that("make_valid_parquet_version()", {
	expect_equal(
	make_valid_parquet_version("1.0"),
	ParquetVersionType$PARQUET_1_0
	)
	expect_equal(
	make_valid_parquet_version("2.4"),
	ParquetVersionType$PARQUET_2_4
	)
	expect_equal(
	make_valid_parquet_version("2.6"),
	ParquetVersionType$PARQUET_2_6
	)
	expect_equal(
	make_valid_parquet_version("latest"),
	ParquetVersionType$PARQUET_2_6
	)
	expect_equal(make_valid_parquet_version(1), ParquetVersionType$PARQUET_1_0)
	expect_equal(make_valid_parquet_version(1.0), ParquetVersionType$PARQUET_1_0)
	expect_equal(make_valid_parquet_version(2.4), ParquetVersionType$PARQUET_2_4)
	})