[PATCH 3/6] log: make the intent of cmd_show()'s "rev.pending" juggling clearer

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Adjust code added in 5d7eeee2ac6 (git-show: grok blobs, trees and
tags, too, 2006-12-14) to use the "memcpy a &blank" idiom introduced
in 5726a6b4012 (*.c *_init(): define in terms of corresponding *_INIT
macro, 2021-07-01).

Now the types in play are guaranteed to correspond, i.e. we used "int"
here for the "count" before, but the corresponding "nr" is an
"unsigned int". By using a "blank" object we almost entirely bypass
that, we'll only need to declare our own "unsigned int i".

There are no functional changes here aside from potential overflow
guard rails, the structure only has these three members ("nr", "alloc"
and "objects"), but now we're obviously future-proof against assuming
that.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/log.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 88a5e98875a..e0f40798d45 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -668,10 +668,12 @@ static void show_setup_revisions_tweak(struct rev_info *rev,
 int cmd_show(int argc, const char **argv, const char *prefix)
 {
 	struct rev_info rev;
-	struct object_array_entry *objects;
+	struct object_array blank = OBJECT_ARRAY_INIT;
+	struct object_array cp = OBJECT_ARRAY_INIT;
+	unsigned int i;
 	struct setup_revision_opt opt;
 	struct pathspec match_all;
-	int i, count, ret = 0;
+	int ret = 0;
 
 	init_log_defaults();
 	git_config(git_log_config, NULL);
@@ -698,12 +700,11 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 	if (!rev.no_walk)
 		return cmd_log_deinit(cmd_log_walk(&rev), &rev);
 
-	count = rev.pending.nr;
-	objects = rev.pending.objects;
+	memcpy(&cp, &rev.pending, sizeof(rev.pending));
 	rev.diffopt.no_free = 1;
-	for (i = 0; i < count && !ret; i++) {
-		struct object *o = objects[i].item;
-		const char *name = objects[i].name;
+	for (i = 0; i < cp.nr && !ret; i++) {
+		struct object *o = cp.objects[i].item;
+		const char *name = cp.objects[i].name;
 		switch (o->type) {
 		case OBJ_BLOB:
 			ret = show_blob_object(&o->oid, &rev, name);
@@ -726,7 +727,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 			if (!o)
 				ret = error(_("could not read object %s"),
 					    oid_to_hex(oid));
-			objects[i].item = o;
+			cp.objects[i].item = o;
 			i--;
 			break;
 		}
@@ -743,8 +744,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 			rev.shown_one = 1;
 			break;
 		case OBJ_COMMIT:
-			rev.pending.nr = rev.pending.alloc = 0;
-			rev.pending.objects = NULL;
+			memcpy(&rev.pending, &blank, sizeof(rev.pending));
 			add_object_array(o, name, &rev.pending);
 			ret = cmd_log_walk_no_free(&rev);
 			break;
-- 
2.37.0.932.g7b7031e73bc