midx: factor out fill_pack_info()

When selecting which packfiles will be written while generating a MIDX,
the MIDX internals fill out a 'struct pack_info' with various pieces of
book-keeping.

Instead of filling out each field of the `pack_info` structure
individually in each of the two spots that modify the array of such
structures (`ctx->info`), extract a common routine that does this for
us.

This reduces the code duplication by a modest amount. But more
importantly, it zero-initializes the structure before assigning values
into it. This hardens us for a future change which will add additional
fields to this structure which (until this patch) was not
zero-initialized.

As a result, any new fields added to the `pack_info` structure need only
be updated in a single location, instead of at each spot within midx.c.

There are no functional changes in this patch.

Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: ttaylorr

midx.c

@@ -475,6 +475,17 @@ struct pack_info {
 	unsigned expired : 1;
 };
 
+static void fill_pack_info(struct pack_info *info,
+			   struct packed_git *p, const char *pack_name,
+			   uint32_t orig_pack_int_id)
+{
+	memset(info, 0, sizeof(struct pack_info));
+
+	info->orig_pack_int_id = orig_pack_int_id;
+	info->pack_name = xstrdup(pack_name);
+	info->p = p;
+}
+
 static int pack_info_compare(const void *_a, const void *_b)
 {
 	struct pack_info *a = (struct pack_info *)_a;
@@ -515,6 +526,7 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 			     const char *file_name, void *data)
 {
 	struct write_midx_context *ctx = data;
+	struct packed_git *p;
 
 	if (ends_with(file_name, ".idx")) {
 		display_progress(ctx->progress, ++ctx->pack_paths_checked);
@@ -541,27 +553,22 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 
 		ALLOC_GROW(ctx->info, ctx->nr + 1, ctx->alloc);
 
-		ctx->info[ctx->nr].p = add_packed_git(full_path,
-						      full_path_len,
-						      0);
-
-		if (!ctx->info[ctx->nr].p) {
+		p = add_packed_git(full_path, full_path_len, 0);
+		if (!p) {
 			warning(_("failed to add packfile '%s'"),
 				full_path);
 			return;
 		}
 
-		if (open_pack_index(ctx->info[ctx->nr].p)) {
+		if (open_pack_index(p)) {
 			warning(_("failed to open pack-index '%s'"),
 				full_path);
-			close_pack(ctx->info[ctx->nr].p);
-			FREE_AND_NULL(ctx->info[ctx->nr].p);
+			close_pack(p);
+			free(p);
 			return;
 		}
 
-		ctx->info[ctx->nr].pack_name = xstrdup(file_name);
-		ctx->info[ctx->nr].orig_pack_int_id = ctx->nr;
-		ctx->info[ctx->nr].expired = 0;
+		fill_pack_info(&ctx->info[ctx->nr], p, file_name, ctx->nr);
 		ctx->nr++;
 	}
 }
@@ -1321,11 +1328,6 @@ static int write_midx_internal(const char *object_dir,
 		for (i = 0; i < ctx.m->num_packs; i++) {
 			ALLOC_GROW(ctx.info, ctx.nr + 1, ctx.alloc);
 
-			ctx.info[ctx.nr].orig_pack_int_id = i;
-			ctx.info[ctx.nr].pack_name = xstrdup(ctx.m->pack_names[i]);
-			ctx.info[ctx.nr].p = ctx.m->packs[i];
-			ctx.info[ctx.nr].expired = 0;
-
 			if (flags & MIDX_WRITE_REV_INDEX) {
 				/*
 				 * If generating a reverse index, need to have
@@ -1341,10 +1343,10 @@ static int write_midx_internal(const char *object_dir,
 				if (open_pack_index(ctx.m->packs[i]))
 					die(_("could not open index for %s"),
 					    ctx.m->packs[i]->pack_name);
-				ctx.info[ctx.nr].p = ctx.m->packs[i];
 			}
 
-			ctx.nr++;
+			fill_pack_info(&ctx.info[ctx.nr++], ctx.m->packs[i],
+				       ctx.m->pack_names[i], i);
 		}
 	}