log: refactor "rev.pending" code in cmd_show()

Refactor the juggling of "rev.pending" and our replacement for it
amended in the preceding commit so that:

 * We use an "unsigned int" instead of an "int" for "i", this matches
   the types of "struct rev_info" itself.

 * We don't need the "count" and "objects" variables introduced in
   5d7eeee2ac6 (git-show: grok blobs, trees and tags, too, 2006-12-14).

   They were originally added since we'd clobber rev.pending in the
   loop without restoring it. Since the preceding commit we are
   restoring it when we handle OBJ_COMMIT, so the main for-loop can
   refer to "rev.pending" didrectly.

 * We use the "memcpy a &blank" idiom introduced in
   5726a6b4012 (*.c *_init(): define in terms of corresponding *_INIT
   macro, 2021-07-01).

   This is more obvious than relying on us enumerating all of the
   relevant members of the "struct object_array" that we need to
   clear.

 * We comment on why we don't need an object_array_clear() here, see
   the analysis in [1].

1. https://lore.kernel.org/git/YuQtJ2DxNKX%2Fy70N@coredump.intra.peff.net/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/log.c b/builtin/log.c
index b4b1d9746178a988735cbaab9c7ea199d35ca0d9..9b937d59b83dc29691d9cb940223c981f38ff7bf 100644 (file)
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -668,10 +668,10 @@ 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;
+       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 +698,10 @@ 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;
        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 < rev.pending.nr && !ret; i++) {
+               struct object *o = rev.pending.objects[i].item;
+               const char *name = rev.pending.objects[i].name;
                switch (o->type) {
                case OBJ_BLOB:
                        ret = show_blob_object(&o->oid, &rev, name);
@@ -726,7 +724,7 @@ 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;
+                       rev.pending.objects[i].item = o;
                        i--;
                        break;
                }
@@ -745,12 +743,19 @@ int cmd_show(int argc, const char **argv, const char *prefix)
                case OBJ_COMMIT:
                {
                        struct object_array old;
+                       struct object_array blank = OBJECT_ARRAY_INIT;
 
                        memcpy(&old, &rev.pending, sizeof(old));
-                       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);
+
+                       /*
+                        * No need for
+                        * object_array_clear(&pending). It was
+                        * cleared already in prepare_revision_walk()
+                        */
                        memcpy(&rev.pending, &old, sizeof(rev.pending));
                        break;
                }