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[PATCH 3/5] pack-objects: clamp negative window size to 0

From
Jeff King <peff@peff.net>
Date
May 1, 2021, 14:03 UTC
Message-ID
<YI1fubjvQQlrPz9D@coredump.intra.peff.net>
In-Reply-To
<YI1fbERSuS7Y3LKh@coredump.intra.peff.net>

A negative window size makes no sense, and the code in find_deltas() is not prepared to handle it. If you pass "-1", for example, we end up generate a 0-length array of "struct unpacked", but our loop assumes it has at least one entry in it (and we end up reading garbage memory).

We could complain to the user about this, but it's more forgiving to just clamp it to 0, which means "do not find any deltas at all". The 0-case is already tested earlier in the script, so we'll make sure this does the same thing.

Reported-by: Yiyuan guo <yguoaz@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/pack-objects.c | 2 ++
 t/t5300-pack-object.sh | 5 +++++
 2 files changed, 7 insertions(+)
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6d13cd3e1a..ea7a5b3ba5 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -3871,6 +3871,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			(1U << OE_Z_DELTA_BITS) - 1);
 		cache_max_small_delta_size = (1U << OE_Z_DELTA_BITS) - 1;
 	}
+	if (window < 0)
+		window = 0;
 
 	strvec_push(&rp, "pack-objects");
 	if (thin) {
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 887e2d8d88..5c5e53f0be 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -613,4 +613,9 @@ test_expect_success '--stdin-packs with broken links' '
 	)
 '
 
+test_expect_success 'negative window clamps to 0' '
+	git pack-objects --progress --window=-1 neg-window <obj-list 2>stderr &&
+	check_deltas stderr = 0
+'
+
 test_done
-- 
2.31.1.875.g5dccece0aa
Previous: Jeff KingNext: Derrick Stolee
Message 6 of 15 in “pack-objects: better handling of negative options”
  1. 0/5 pack-objects: better handling of negative optionsJeff King, May 1, 2021
  2. 1/5 t5300: modernize basic testsJeff King, May 1, 2021
  3. Junio C HamanoMay 3, 2021
  4. Jeff KingMay 3, 2021
  5. 2/5 t5300: check that we produced expected number of deltasJeff King, May 1, 2021
  6. 3/5 pack-objects: clamp negative window size to 0Jeff King, May 1, 2021
  7. Derrick StoleeMay 3, 2021
  8. Jeff KingMay 3, 2021
  9. René ScharfeMay 4, 2021
  10. Jeff KingMay 4, 2021
  11. Ævar Arnfjörð BjarmasonMay 5, 2021
  12. René ScharfeMay 5, 2021
  13. 4/5 t5316: check behavior of pack-objects --depth=0Jeff King, May 1, 2021
  14. 5/5 pack-objects: clamp negative depth to 0Jeff King, May 1, 2021
  15. Derrick StoleeMay 3, 2021

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