test-tool synthesize: add precomputed SHA-256 pack for 4 GiB + 1
Add a SHA-256 entry to the fast_packs[] table. The pack prefix and deflate block structure are identical to SHA-1 (the pack format does not encode the hash algorithm in its header). Only the suffix differs: SHA-256 OIDs are 32 bytes instead of 20, giving a 609-byte suffix compared to 513 for SHA-1, and a different pack checksum. The constants were generated by running the generic path inside a repository initialized with --object-format=sha256. Assisted-by: Claude Opus 4.6 Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
May 8, 2026 at 08:16 UTC
f549253b0b76f4f4a31ef8d5e98da72389f48189
1 file changed
+91
t/helper/test-synthesize.c
+91
@@ -246,6 +246,90 @@ static const unsigned char fast_pack_sha1_suffix[] = {
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0xe3
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};
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+/*
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+ * SHA-256 suffix: same structure, but with 32-byte OIDs and SHA-256
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+ * pack checksum (609 bytes vs 513 for SHA-1).
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+ */
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+static const unsigned char fast_pack_sha256_suffix[] = {
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+ 0xac, 0x02, 0x78, 0x01, 0x01, 0x2c, 0x00, 0xd3,
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+ 0xff, 0x31, 0x30, 0x30, 0x36, 0x34, 0x34, 0x20,
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+ 0x66, 0x69, 0x6c, 0x65, 0x00, 0x42, 0x53, 0xc1,
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+ 0x8a, 0x9f, 0x5e, 0xc3, 0xbb, 0x47, 0xb0, 0x83,
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+ 0x8a, 0x19, 0xdb, 0x31, 0xbb, 0x7b, 0x0f, 0x3b,
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+ 0x80, 0xa4, 0xbc, 0x2f, 0xaf, 0x72, 0x6b, 0xdb,
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+ 0x62, 0xaa, 0xba, 0xdd, 0xde, 0x77, 0xc6, 0x13,
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+ 0x9a, 0xc9, 0x11, 0x76, 0x61, 0xa3, 0x89, 0x49,
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+ 0xb7, 0xa1, 0x58, 0xc6, 0x1d, 0x8c, 0x33, 0x75,
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+ 0x8d, 0x7e, 0x4d, 0x8e, 0x58, 0x91, 0xf8, 0x5c,
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+ 0x57, 0xd9, 0x89, 0x9e, 0xb8, 0xd2, 0x9a, 0xd8,
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+ 0xc9
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+};
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+
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static const struct fast_pack fast_packs[] = {
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{
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.format_id = GIT_SHA1_FORMAT_ID,
@@ -253,6 +337,13 @@ static const struct fast_pack fast_packs[] = {
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.suffix_len = sizeof(fast_pack_sha1_suffix),
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.commit_oid = "aac43daf40d0377af31aa9c798a4ae8a31b55c1d",
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},
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+ {
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+ .format_id = GIT_SHA256_FORMAT_ID,
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+ .suffix = fast_pack_sha256_suffix,
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+ .suffix_len = sizeof(fast_pack_sha256_suffix),
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+ .commit_oid = "63c46ca51267b1d45be69a044bb84b4bf0559f09"
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+ "d727f861d2ae94ddebdddbc9",
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+ },
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};
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/*