midx: use chunk-format API in write_midx_internal()

The chunk-format API allows writing the table of contents and all chunks
using the anonymous 'struct chunkfile' type. We only need to convert our
local chunk logic to this API for the multi-pack-index writes to share
that logic with the commit-graph file writes.

Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: derrickstolee

midx.c

@@ -11,6 +11,7 @@
 #include "trace2.h"
 #include "run-command.h"
 #include "repository.h"
+#include "chunk-format.h"
 
 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
 #define MIDX_VERSION 1
@@ -21,7 +22,6 @@
 #define MIDX_HEADER_SIZE 12
 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + the_hash_algo->rawsz)
 
-#define MIDX_MAX_CHUNKS 5
 #define MIDX_CHUNK_ALIGNMENT 4
 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
@@ -799,18 +799,15 @@ static int write_midx_large_offsets(struct hashfile *f,
 static int write_midx_internal(const char *object_dir, struct multi_pack_index *m,
 			       struct string_list *packs_to_drop, unsigned flags)
 {
-	unsigned char cur_chunk, num_chunks = 0;
 	char *midx_name;
 	uint32_t i;
 	struct hashfile *f = NULL;
 	struct lock_file lk;
 	struct write_midx_context ctx = { 0 };
-	uint64_t header_size = 0;
-	uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
-	uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 	int pack_name_concat_len = 0;
 	int dropped_packs = 0;
 	int result = 0;
+	struct chunkfile *cf;
 
 	midx_name = get_midx_filename(object_dir);
 	if (safe_create_leading_directories(midx_name))
@@ -923,98 +920,35 @@ static int write_midx_internal(const char *object_dir, struct multi_pack_index *
 	if (ctx.m)
 		close_midx(ctx.m);
 
-	cur_chunk = 0;
-	num_chunks = ctx.large_offsets_needed ? 5 : 4;
-
 	if (ctx.nr - dropped_packs == 0) {
 		error(_("no pack files to index."));
 		result = 1;
 		goto cleanup;
 	}
 
-	header_size = write_midx_header(f, num_chunks, ctx.nr - dropped_packs);
-
-	chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
-	chunk_offsets[cur_chunk] = header_size + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
-
-	cur_chunk++;
-	chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + pack_name_concat_len;
-
-	cur_chunk++;
-	chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
-
-	cur_chunk++;
-	chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + ctx.entries_nr * the_hash_algo->rawsz;
-
-	cur_chunk++;
-	chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH;
-	if (ctx.large_offsets_needed) {
-		chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
-
-		cur_chunk++;
-		chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
-					   ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
-	}
-
-	chunk_ids[cur_chunk] = 0;
-
-	for (i = 0; i <= num_chunks; i++) {
-		if (i && chunk_offsets[i] < chunk_offsets[i - 1])
-			BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
-			    chunk_offsets[i - 1],
-			    chunk_offsets[i]);
-
-		if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
-			BUG("chunk offset %"PRIu64" is not properly aligned",
-			    chunk_offsets[i]);
-
-		hashwrite_be32(f, chunk_ids[i]);
-		hashwrite_be64(f, chunk_offsets[i]);
-	}
-
-	for (i = 0; i < num_chunks; i++) {
-		if (f->total + f->offset != chunk_offsets[i])
-			BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
-			    chunk_offsets[i],
-			    f->total + f->offset,
-			    chunk_ids[i]);
+	cf = init_chunkfile(f);
 
-		switch (chunk_ids[i]) {
-			case MIDX_CHUNKID_PACKNAMES:
-				write_midx_pack_names(f, &ctx);
-				break;
+	add_chunk(cf, MIDX_CHUNKID_PACKNAMES, pack_name_concat_len,
+		  write_midx_pack_names);
+	add_chunk(cf, MIDX_CHUNKID_OIDFANOUT, MIDX_CHUNK_FANOUT_SIZE,
+		  write_midx_oid_fanout);
+	add_chunk(cf, MIDX_CHUNKID_OIDLOOKUP,
+		  ctx.entries_nr * the_hash_algo->rawsz,
+		  write_midx_oid_lookup);
+	add_chunk(cf, MIDX_CHUNKID_OBJECTOFFSETS,
+		  ctx.entries_nr * MIDX_CHUNK_OFFSET_WIDTH,
+		  write_midx_object_offsets);
 
-			case MIDX_CHUNKID_OIDFANOUT:
-				write_midx_oid_fanout(f, &ctx);
-				break;
-
-			case MIDX_CHUNKID_OIDLOOKUP:
-				write_midx_oid_lookup(f, &ctx);
-				break;
-
-			case MIDX_CHUNKID_OBJECTOFFSETS:
-				write_midx_object_offsets(f, &ctx);
-				break;
-
-			case MIDX_CHUNKID_LARGEOFFSETS:
-				write_midx_large_offsets(f, &ctx);
-				break;
-
-			default:
-				BUG("trying to write unknown chunk id %"PRIx32,
-				    chunk_ids[i]);
-		}
-	}
+	if (ctx.large_offsets_needed)
+		add_chunk(cf, MIDX_CHUNKID_LARGEOFFSETS,
+			ctx.num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH,
+			write_midx_large_offsets);
 
-	if (hashfile_total(f) != chunk_offsets[num_chunks])
-		BUG("incorrect final offset %"PRIu64" != %"PRIu64,
-		    hashfile_total(f),
-		    chunk_offsets[num_chunks]);
+	write_midx_header(f, get_num_chunks(cf), ctx.nr - dropped_packs);
+	write_chunkfile(cf, &ctx);
 
 	finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
+	free_chunkfile(cf);
 	commit_lock_file(&lk);
 
 cleanup: