[PATCH v2 1/6] hash-object: demonstrate a >4GB/LLP64 problem

From: Philip Oakley via GitGitGadget <gitgitgadget@gmail.com>
Date: Jun 16, 2026, 14:49 UTC
Message-ID: <9c01bac407034c6361dc54af7f11f64e8af7db0e.1781621398.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.2138.v2.git.1781621398.gitgitgadget@gmail.com>

From: Philip Oakley <philipoakley@iee.email>

On LLP64 systems, such as Windows, the size of `long`, `int`, etc. is only 32 bits (for backward compatibility). Git's use of `unsigned long` for file memory sizes in many places, rather than size_t, limits the handling of large files on LLP64 systems (commonly given as `>4GB`).

Provide a minimum test for handling a >4GB file. The `hash-object` command, with the `--literally` and without `-w` option avoids writing the object, either loose or packed. This avoids the code paths hitting the `bigFileThreshold` config test code, the zlib code, and the pack code.

Subsequent patches will walk the test's call chain, converting types to `size_t` (which is larger in LLP64 data models) where appropriate.

Signed-off-by: Philip Oakley <philipoakley@iee.email>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 t/t1007-hash-object.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/t/t1007-hash-object.sh b/t/t1007-hash-object.sh
index de076293b6..7867fd1dbf 100755
--- a/t/t1007-hash-object.sh
+++ b/t/t1007-hash-object.sh
@@ -49,6 +49,9 @@ test_expect_success 'setup' '
 
 	example sha1:ddd3f836d3e3fbb7ae289aa9ae83536f76956399
 	example sha256:b44fe1fe65589848253737db859bd490453510719d7424daab03daf0767b85ae
+
+	large5GB sha1:0be2be10a4c8764f32c4bf372a98edc731a4b204
+	large5GB sha256:dc18ca621300c8d3cfa505a275641ebab00de189859e022a975056882d313e64
 	EOF
 '
 
@@ -258,4 +261,12 @@ test_expect_success '--stdin outside of repository (uses default hash)' '
 	test_cmp expect actual
 '
 
+test_expect_failure EXPENSIVE,SIZE_T_IS_64BIT,!LONG_IS_64BIT \
+		'files over 4GB hash literally' '
+	test-tool genzeros $((5*1024*1024*1024)) >big &&
+	test_oid large5GB >expect &&
+	git hash-object --stdin --literally <big >actual &&
+	test_cmp expect actual
+'
+
 test_done

-- 
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