parse_pack_header_option(): avoid unaligned memory writes

In order to recreate a pack header in our in-memory buffer, we cast the
buffer to a "struct pack_header" and assign the individual fields. This
is reported to cause SIGBUS on sparc64 due to alignment issues.

We can work around this by using put_be32() which will write individual
bytes into the buffer.

Reported-by: Koakuma <koachan@protonmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/packfile.c b/packfile.c
index e2bdadc7cbd44bdb8aad076ca1fd37c7060a99de..93f771ad95c949c945554aa6ca42316dd3c27ceb 100644 (file)
--- a/packfile.c
+++ b/packfile.c
@@ -2297,17 +2297,20 @@ int is_promisor_object(const struct object_id *oid)
 
 int parse_pack_header_option(const char *in, unsigned char *out, unsigned int *len)
 {
-       struct pack_header *hdr;
+       unsigned char *hdr;
        char *c;
 
-       hdr = (struct pack_header *)out;
-       hdr->hdr_signature = htonl(PACK_SIGNATURE);
-       hdr->hdr_version = htonl(strtoul(in, &c, 10));
+       hdr = out;
+       put_be32(hdr, PACK_SIGNATURE);
+       hdr += 4;
+       put_be32(hdr, strtoul(in, &c, 10));
+       hdr += 4;
        if (*c != ',')
                return -1;
-       hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
+       put_be32(hdr, strtoul(c + 1, &c, 10));
+       hdr += 4;
        if (*c)
                return -1;
-       *len = sizeof(*hdr);
+       *len = hdr - out;
        return 0;
 }