Re: [PATCH 12/16] sha1_file: add for_each iterators for loose and packed objects

We typically iterate over the reachable objects in a
repository by starting at the tips and walking the graph.
There's no easy way to iterate over all of the objects,
including unreachable ones. Let's provide a way of doing so.

Signed-off-by: Jeff King <redacted>
---
  cache.h     | 11 +++++++++++
  sha1_file.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  2 files changed, 73 insertions(+)

diff --git a/cache.h b/cache.h
index 7abe7f6..3826b4b 100644
--- a/cache.h
+++ b/cache.h

@@ -1270,6 +1270,17 @@ int for_each_loose_file_in_objdir(const char *path,
  				  each_loose_subdir_fn subdir_cb,
  				  void *data);

+/*
+ * Iterate over loose and packed objects in both the local
+ * repository and any alternates repositories.
+ */
+typedef int each_packed_object_fn(const unsigned char *sha1,
+				  struct packed_git *pack,
+				  uint32_t pos,
+				  void *data);
+extern int for_each_loose_object(each_loose_object_fn, void *);
+extern int for_each_packed_object(each_packed_object_fn, void *);
+
  struct object_info {
  	/* Request */
  	enum object_type *typep;

diff --git a/sha1_file.c b/sha1_file.c
index 9fdad47..d017289 100644
--- a/sha1_file.c
+++ b/sha1_file.c

@@ -3313,3 +3313,65 @@ int for_each_loose_file_in_objdir(const char *path,
  	strbuf_release(&buf);
  	return r;
  }
+
+struct loose_alt_odb_data {
+	each_loose_object_fn *cb;
+	void *data;
+};
+
+static int loose_from_alt_odb(struct alternate_object_database *alt,
+			      void *vdata)
+{
+	struct loose_alt_odb_data *data = vdata;
+	return for_each_loose_file_in_objdir(alt->base,
+					     data->cb, NULL, NULL,
+					     data->data);
+}
+
+int for_each_loose_object(each_loose_object_fn cb, void *data)
+{
+	struct loose_alt_odb_data alt;
+	int r;
+
+	r = for_each_loose_file_in_objdir(get_object_directory(),
+					  cb, NULL, NULL, data);
+	if (r)
+		return r;
+
+	alt.cb = cb;
+	alt.data = data;
+	return foreach_alt_odb(loose_from_alt_odb, &alt);
+}
+
+int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)