GH-48832: [R] Fix crash with zero-length POSIXct tzone attribute by shashbha14 · Pull Request #48854 · apache/arrow

shashbha14 · 2026-01-14T10:21:38Z

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

Add safety check for empty tzone attribute in InferArrowTypeFromVector to prevent out-of-bounds access when handling zero-length POSIXct vectors.

…t/Ubuntu Added Development Tool Requirements section to cpp/development.rst documenting the required versions: - clang-format 14.0.6+ - pre-commit 2.17.0+ - Ubuntu 22.04 LTS+

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 · 2026-01-14T17:14:17Z

r/tests/testthat/test-issue-48832.R

+test_that("zero-length POSIXct with empty tzone attribute handled safely", {
+  x <- as.POSIXct(character(0))
+  attr(x, "tzone") <- character(0)
+
+  # Should not crash or error
+  expect_error(type(x), NA)
+
+  # Should default to no timezone (or empty string which effectively means local/no-tz behavior in arrow)
+  # When sys.timezone is picked up it might vary, but we just check it doesn't crash.
+  # If it picks up Sys.timezone(), checking exact equality might be flaky across environments if not mocked.
+  # So we primarily check for no error.
+
+  # Also check write_parquet survival
+  tf <- tempfile() 
+  on.exit(unlink(tf))
+  expect_error(write_parquet(data.frame(x = x), tf), NA)
+  expect_true(file.exists(tf))
+})


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)

})

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

4ce1cf7

Add safety check for empty tzone attribute in InferArrowTypeFromVector to prevent out-of-bounds access when handling zero-length POSIXct vectors.

shashbha14 requested review from jonkeane and thisisnic as code owners January 14, 2026 10:21

github-actions bot added Component: R awaiting review Awaiting review labels Jan 14, 2026

apacheGH-48850: [Doc][Dev] Clarify versions of clang-format/pre-commi…

43ab06f

…t/Ubuntu Added Development Tool Requirements section to cpp/development.rst documenting the required versions: - clang-format 14.0.6+ - pre-commit 2.17.0+ - Ubuntu 22.04 LTS+

github-actions bot added the Component: Documentation label Jan 14, 2026

jonkeane requested changes Jan 14, 2026

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GH-48832: [R] Fix crash with zero-length POSIXct tzone attribute#48854

GH-48832: [R] Fix crash with zero-length POSIXct tzone attribute#48854
shashbha14 wants to merge 2 commits intoapache:mainfrom
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	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()))
	})
	})

	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)
	})

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