Merge branch 'jk/pack-header-parse-alignment-fix'

It was possible for "git unpack-objects" and "git index-pack" to
make an unaligned access, which has been corrected.

* jk/pack-header-parse-alignment-fix:
  index-pack, unpack-objects: use skip_prefix to avoid magic number
  index-pack, unpack-objects: use get_be32() for reading pack header
  parse_pack_header_option(): avoid unaligned memory writes
  packfile: factor out --pack_header argument parsing
  bswap.h: squelch potential sparse -Wcast-truncate warnings

1 files changed, 12 insertions, 18 deletions

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 7025c32fbb..6ffbb7ce35 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -380,16 +380,18 @@ static const char *open_pack_file(const char *pack_name)
 
 static void parse_pack_header(void)
 {
-	struct pack_header *hdr = fill(sizeof(struct pack_header));
+	unsigned char *hdr = fill(sizeof(struct pack_header));
 
 	/* Header consistency check */
-	if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
+	if (get_be32(hdr) != PACK_SIGNATURE)
 		die(_("pack signature mismatch"));
-	if (!pack_version_ok(hdr->hdr_version))
+	hdr += 4;
+	if (!pack_version_ok_native(get_be32(hdr)))
 		die(_("pack version %"PRIu32" unsupported"),
-			ntohl(hdr->hdr_version));
+		    get_be32(hdr));
+	hdr += 4;
 
-	nr_objects = ntohl(hdr->hdr_entries);
+	nr_objects = get_be32(hdr);
 	use(sizeof(struct pack_header));
 }
 
@@ -1956,19 +1958,11 @@ int cmd_index_pack(int argc,
 					warning(_("no threads support, ignoring %s"), arg);
 					nr_threads = 1;
 				}
-			} else if (starts_with(arg, "--pack_header=")) {
-				struct pack_header *hdr;
-				char *c;
-
-				hdr = (struct pack_header *)input_buffer;
-				hdr->hdr_signature = htonl(PACK_SIGNATURE);
-				hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
-				if (*c != ',')
-					die(_("bad %s"), arg);
-				hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
-				if (*c)
-					die(_("bad %s"), arg);
-				input_len = sizeof(*hdr);
+			} else if (skip_prefix(arg, "--pack_header=", &arg)) {
+				if (parse_pack_header_option(arg,
+							     input_buffer,
+							     &input_len) < 0)
+					die(_("bad --pack_header: %s"), arg);
 			} else if (!strcmp(arg, "-v")) {
 				verbose = 1;
 			} else if (!strcmp(arg, "--progress-title")) {