tag: generate useful reflog message

When tags are created with `--create-reflog` or with the option
`core.logAllRefUpdates` set to 'always', a reflog is created for them.
So far, the description of reflog entries for tags was empty, making the
reflog hard to understand. For example:
6e3a7b3 refs/tags/test@{0}:

Now, a reflog message is generated when creating a tag, following the
pattern "tag: tagging <short-sha1> (<description>)". If
GIT_REFLOG_ACTION is set, the message becomes "$GIT_REFLOG_ACTION
(<description>)" instead. If the tag references a commit object, the
description is set to the subject line of the commit, followed by its
commit date. For example:
6e3a7b3 refs/tags/test@{0}: tag: tagging 6e3a7b3398 (Git 2.12-rc0, 2017-02-03)

If the tag points to a tree/blob/tag objects, the following static
strings are taken as description:

- "tree object"
- "blob object"
- "other tag object"

Signed-off-by: Cornelius Weig <cornelius.weig@tngtech.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/tag.c b/builtin/tag.c
index 50e4ae5678c21f348c3ce0e0d0662c9d5f995847..085d8abcaff3c8ce1e4f59b0386c5550c9140504 100644 (file)
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -288,6 +288,54 @@ static void create_tag(const unsigned char *object, const char *tag,
        }
 }
 
+static void create_reflog_msg(const unsigned char *sha1, struct strbuf *sb)
+{
+       enum object_type type;
+       struct commit *c;
+       char *buf;
+       unsigned long size;
+       int subject_len = 0;
+       const char *subject_start;
+
+       char *rla = getenv("GIT_REFLOG_ACTION");
+       if (rla) {
+               strbuf_addstr(sb, rla);
+       } else {
+               strbuf_addstr(sb, _("tag: tagging "));
+               strbuf_add_unique_abbrev(sb, sha1, DEFAULT_ABBREV);
+       }
+
+       strbuf_addstr(sb, " (");
+       type = sha1_object_info(sha1, NULL);
+       switch (type) {
+       default:
+               strbuf_addstr(sb, _("object of unknown type"));
+               break;
+       case OBJ_COMMIT:
+               if ((buf = read_sha1_file(sha1, &type, &size)) != NULL) {
+                       subject_len = find_commit_subject(buf, &subject_start);
+                       strbuf_insert(sb, sb->len, subject_start, subject_len);
+               } else {
+                       strbuf_addstr(sb, _("commit object"));
+               }
+               free(buf);
+
+               if ((c = lookup_commit_reference(sha1)) != NULL)
+                       strbuf_addf(sb, ", %s", show_date(c->date, 0, DATE_MODE(SHORT)));
+               break;
+       case OBJ_TREE:
+               strbuf_addstr(sb, _("tree object"));
+               break;
+       case OBJ_BLOB:
+               strbuf_addstr(sb, _("blob object"));
+               break;
+       case OBJ_TAG:
+               strbuf_addstr(sb, _("other tag object"));
+               break;
+       }
+       strbuf_addch(sb, ')');
+}
+
 struct msg_arg {
        int given;
        struct strbuf buf;
@@ -321,6 +369,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 {
        struct strbuf buf = STRBUF_INIT;
        struct strbuf ref = STRBUF_INIT;
+       struct strbuf reflog_msg = STRBUF_INIT;
        unsigned char object[20], prev[20];
        const char *object_ref, *tag;
        struct create_tag_options opt;
@@ -473,6 +522,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
        else
                die(_("Invalid cleanup mode %s"), cleanup_arg);
 
+       create_reflog_msg(object, &reflog_msg);
+
        if (create_tag_object) {
                if (force_sign_annotate && !annotate)
                        opt.sign = 1;
@@ -483,7 +534,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
        if (!transaction ||
            ref_transaction_update(transaction, ref.buf, object, prev,
                                   create_reflog ? REF_FORCE_CREATE_REFLOG : 0,
-                                  NULL, &err) ||
+                                  reflog_msg.buf, &err) ||
            ref_transaction_commit(transaction, &err))
                die("%s", err.buf);
        ref_transaction_free(transaction);
@@ -493,5 +544,6 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
        strbuf_release(&err);
        strbuf_release(&buf);
        strbuf_release(&ref);
+       strbuf_release(&reflog_msg);
        return 0;
 }

diff --git a/t/t7004-tag.sh b/t/t7004-tag.sh
index 8b0f71a2ac15d65f977b0daa2a53ad47b64a043a..e5d3fa71296df5029993036b5459e0bc2e83b71b 100755 (executable)
--- a/t/t7004-tag.sh
+++ b/t/t7004-tag.sh
@@ -56,9 +56,25 @@ test_expect_success 'creating a tag using default HEAD should succeed' '
 '
 
 test_expect_success 'creating a tag with --create-reflog should create reflog' '
+       git log -1 \
+               --format="format:tag: tagging %h (%s, %cd)%n" \
+               --date=format:%Y-%m-%d >expected &&
        test_when_finished "git tag -d tag_with_reflog" &&
        git tag --create-reflog tag_with_reflog &&
-       git reflog exists refs/tags/tag_with_reflog
+       git reflog exists refs/tags/tag_with_reflog &&
+       sed -e "s/^.*   //" .git/logs/refs/tags/tag_with_reflog >actual &&
+       test_cmp expected actual
+'
+
+test_expect_success 'annotated tag with --create-reflog has correct message' '
+       git log -1 \
+               --format="format:tag: tagging %h (%s, %cd)%n" \
+               --date=format:%Y-%m-%d >expected &&
+       test_when_finished "git tag -d tag_with_reflog" &&
+       git tag -m "annotated tag" --create-reflog tag_with_reflog &&
+       git reflog exists refs/tags/tag_with_reflog &&
+       sed -e "s/^.*   //" .git/logs/refs/tags/tag_with_reflog >actual &&
+       test_cmp expected actual
 '
 
 test_expect_success '--create-reflog does not create reflog on failure' '