index-pack, unpack-objects: use get_be32() for reading pack header
Both of these commands read the incoming pack into a static unsigned char buffer in BSS, and then parse it by casting the start of the buffer to a struct pack_header. This can result in SIGBUS on some platforms if the compiler doesn't place the buffer in a position that is properly aligned for 4-byte integers. This reportedly happens with unpack-objects (but not index-pack) on sparc64 when compiled with clang (but not gcc). But we are definitely in the wrong in both spots; since the buffer's type is unsigned char, we can't depend on larger alignment. When it works it is only because we are lucky. We'll fix this by switching to get_be32() to read the headers (just like the last few commits similarly switched us to put_be32() for writing into the same buffer). It would be nice to factor this out into a common helper function, but the interface ends up quite awkward. Either the caller needs to hardcode how many bytes we'll need, or it needs to pass us its fill()/use() functions as pointers. So I've just fixed both spots in the same way; this is not code that is likely to be repeated a third time (most of the pack reading code uses an mmap'd buffer, which should be properly aligned). I did make one tweak to the shared code: our pack_version_ok() macro expects us to pass the big-endian value we'd get by casting. We can introduce a "native" variant which uses the host integer ordering. Reported-by: Koakuma <koachan@protonmail.com> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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committed by
Junio C Hamano

parent
4f02f4d68d
commit
f1299bff26
@ -576,15 +576,16 @@ static void unpack_one(unsigned nr)
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static void unpack_all(void)
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{
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int i;
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struct pack_header *hdr = fill(sizeof(struct pack_header));
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unsigned char *hdr = fill(sizeof(struct pack_header));
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nr_objects = ntohl(hdr->hdr_entries);
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if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
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if (get_be32(hdr) != PACK_SIGNATURE)
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die("bad pack file");
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if (!pack_version_ok(hdr->hdr_version))
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hdr += 4;
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if (!pack_version_ok_native(get_be32(hdr)))
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die("unknown pack file version %"PRIu32,
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ntohl(hdr->hdr_version));
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get_be32(hdr));
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hdr += 4;
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nr_objects = get_be32(hdr);
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use(sizeof(struct pack_header));
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if (!quiet)
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