Re: [PATCH 1/2] Allow pack header preprocessing before unpack-objects/index-pack.

[Nicolas Pitre <nico@cam.org>]

On Tue, 31 Oct 2006, Shawn Pearce wrote:

> However if the caller consumes the pack header from the input stream
> then its no longer available for unpack-objects or index-pack --stdin,
> both of which need the version and object count to process the stream.
> 
> This change introduces --pack_header=ver,cnt as a command line option
> that the caller can supply to indicate it has already consumed the
> pack header and what version and object count were found in that
> header.  As this option is only meant for low level applications
> such as receive-pack we are not documenting it at this time.

This breaks index-pack, and unpack-objects with OBJ_OFS_DELTA, if 
--pack-header is used.  The header is not accounted in the pack's offset 
and therefore every object's offset is wrong.

What about this patch instead?  This makes things much simpler IMHO.

diff --git a/builtin-unpack-objects.c b/builtin-unpack-objects.c
index 74a90c1..e6d7574 100644
--- a/builtin-unpack-objects.c
+++ b/builtin-unpack-objects.c
@@ -371,6 +371,21 @@ int cmd_unpack_objects(int argc, const c
 				recover = 1;
 				continue;
 			}
+			if (!strncmp(arg, "--pack_header=", 14)) {
+				struct pack_header *hdr;
+				char *c;
+
+				hdr = (struct pack_header *)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);
+				len = sizeof(*hdr);
+				continue;
+			}
 			usage(unpack_usage);
 		}
 
diff --git a/index-pack.c b/index-pack.c
index b37dd78..a3b55f9 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -841,6 +841,19 @@ int main(int argc, char **argv)
 				keep_msg = "";
 			} else if (!strncmp(arg, "--keep=", 7)) {
 				keep_msg = arg + 7;
+			} else if (!strncmp(arg, "--pack_header=", 14)) {
+				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 (!strcmp(arg, "-v")) {
 				verbose = 1;
 			} else if (!strcmp(arg, "-o")) {