[PATCH v4 3/7] bulk-checkin: refactor deflate routine to accept a `bulk_checkin_source`

[Taylor Blau <me@ttaylorr.com>]

Prepare for a future change where we will want to use a routine very
similar to the existing `deflate_blob_to_pack()` but over arbitrary
sources (i.e. either open file-descriptors, or a location in memory).

Extract out a common "deflate_obj_to_pack()" routine that acts on a
bulk_checkin_source, instead of a (int, size_t) pair. Then rewrite
`deflate_blob_to_pack()` in terms of it.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 bulk-checkin.c | 52 ++++++++++++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/bulk-checkin.c b/bulk-checkin.c
index 7e6b52112e..28bc8d5ab4 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -285,30 +285,23 @@ static void prepare_to_stream(struct bulk_checkin_packfile *state,
 		die_errno("unable to write pack header");
 }
 
-static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
-				struct object_id *result_oid,
-				int fd, size_t size,
-				const char *path, unsigned flags)
+
+static int deflate_obj_to_pack(struct bulk_checkin_packfile *state,
+			       struct object_id *result_oid,
+			       struct bulk_checkin_source *source,
+			       enum object_type type,
+			       off_t seekback,
+			       unsigned flags)
 {
-	off_t seekback, already_hashed_to;
+	off_t already_hashed_to = 0;
 	git_hash_ctx ctx;
 	unsigned char obuf[16384];
 	unsigned header_len;
 	struct hashfile_checkpoint checkpoint = {0};
 	struct pack_idx_entry *idx = NULL;
-	struct bulk_checkin_source source = {
-		.type = SOURCE_FILE,
-		.fd = fd,
-		.size = size,
-		.path = path,
-	};
 
-	seekback = lseek(fd, 0, SEEK_CUR);
-	if (seekback == (off_t) -1)
-		return error("cannot find the current offset");
-
-	header_len = format_object_header((char *)obuf, sizeof(obuf),
-					  OBJ_BLOB, size);
+	header_len = format_object_header((char *)obuf, sizeof(obuf), type,
+					  source->size);
 	the_hash_algo->init_fn(&ctx);
 	the_hash_algo->update_fn(&ctx, obuf, header_len);
 	the_hash_algo->init_fn(&checkpoint.ctx);
@@ -317,8 +310,6 @@ static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
 	if ((flags & HASH_WRITE_OBJECT) != 0)
 		CALLOC_ARRAY(idx, 1);
 
-	already_hashed_to = 0;
-
 	while (1) {
 		prepare_to_stream(state, flags);
 		if (idx) {
@@ -327,7 +318,7 @@ static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
 			crc32_begin(state->f);
 		}
 		if (!stream_obj_to_pack(state, &ctx, &already_hashed_to,
-					&source, OBJ_BLOB, flags))
+					source, type, flags))
 			break;
 		/*
 		 * Writing this object to the current pack will make
@@ -339,7 +330,7 @@ static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
 		hashfile_truncate(state->f, &checkpoint);
 		state->offset = checkpoint.offset;
 		flush_bulk_checkin_packfile(state);
-		if (bulk_checkin_source_seek_to(&source, seekback) == (off_t)-1)
+		if (bulk_checkin_source_seek_to(source, seekback) == (off_t)-1)
 			return error("cannot seek back");
 	}
 	the_hash_algo->final_oid_fn(result_oid, &ctx);
@@ -361,6 +352,25 @@ static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
 	return 0;
 }
 
+static int deflate_blob_to_pack(struct bulk_checkin_packfile *state,
+				struct object_id *result_oid,
+				int fd, size_t size,
+				const char *path, unsigned flags)
+{
+	struct bulk_checkin_source source = {
+		.type = SOURCE_FILE,
+		.fd = fd,
+		.size = size,
+		.path = path,
+	};
+	off_t seekback = lseek(fd, 0, SEEK_CUR);
+	if (seekback == (off_t) -1)
+		return error("cannot find the current offset");
+
+	return deflate_obj_to_pack(state, result_oid, &source, OBJ_BLOB,
+				   seekback, flags);
+}
+
 void prepare_loose_object_bulk_checkin(void)
 {
 	/*
-- 
2.42.0.405.g86fe3250c2