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update-ref: add support for 'symref-update' command

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Add 'symref-update' command to the '--stdin' mode of 'git-update-ref' to
allow updates of symbolic refs. The 'symref-update' command takes in a
<new-target>, which the <ref> will be updated to. If the <ref> doesn't
exist it will be created.

It also optionally takes either an `ref <old-target>` or `oid
<old-oid>`. If the <old-target> is provided, it checks to see if the
<ref> targets the <old-target> before the update. If <old-oid> is provided
it checks <ref> to ensure that it is a regular ref and <old-oid> is the
OID before the update. This by extension also means that this when a
zero <old-oid> is provided, it ensures that the ref didn't exist before.

The divergence in syntax from the regular `update` command is because if
we don't use a `(ref | oid)` prefix for the old_value, then there is
ambiguity around if the value provided should be treated as an oid or a
reference. This is more so the reason, because we allow anything
committish to be provided as an oid. While 'symref-verify' and
'symref-delete' also take in `<old-target>` we do not have this
divergence there as those commands only work with symrefs. Whereas
'symref-update' also works with regular refs and allows users to convert
regular refs to symrefs.

The command allows users to perform symbolic ref updates within a
transaction. This provides atomicity and allows users to perform a set
of operations together.

This command supports deref mode, to ensure that we can update
dereferenced regular refs to symrefs.

Helped-by: Patrick Steinhardt <ps@pks.im>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Karthik Nayak 2024-06-07 15:33:04 +02:00 committed by Junio C Hamano
parent f1dcdd6deb
commit 7dd4051b01
4 changed files with 306 additions and 0 deletions
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7
Documentation/git-update-ref.txt
View file

@ -65,6 +65,7 @@ performs all modifications together. Specify commands of the form:
create SP <ref> SP <new-oid> LF
delete SP <ref> [SP <old-oid>] LF
verify SP <ref> [SP <old-oid>] LF
symref-update SP <ref> SP <new-target> [SP (ref SP <old-target> | oid SP <old-oid>)] LF
symref-create SP <ref> SP <new-target> LF
symref-delete SP <ref> [SP <old-target>] LF
symref-verify SP <ref> [SP <old-target>] LF
@ -89,6 +90,7 @@ quoting:
create SP <ref> NUL <new-oid> NUL
delete SP <ref> NUL [<old-oid>] NUL
verify SP <ref> NUL [<old-oid>] NUL
symref-update SP <ref> NUL <new-target> [NUL (ref NUL <old-target> | oid NUL <old-oid>)] NUL
symref-create SP <ref> NUL <new-target> NUL
symref-delete SP <ref> [NUL <old-target>] NUL
symref-verify SP <ref> [NUL <old-target>] NUL
@ -119,6 +121,11 @@ delete::
Delete <ref> after verifying it exists with <old-oid>, if
given. If given, <old-oid> may not be zero.
symref-update::
Set <ref> to <new-target> after verifying <old-target> or <old-oid>,
if given. Specify a zero <old-oid> to ensure that the ref does not
exist before the update.
verify::
Verify <ref> against <old-oid> but do not change it. If
<old-oid> is zero or missing, the ref must not exist.

92
builtin/update-ref.c
View file

@ -98,6 +98,42 @@ static char *parse_next_refname(const char **next)
return parse_refname(next);
}
/*
* Wrapper around parse_arg which skips the next delimiter.
*/
static char *parse_next_arg(const char **next)
{
struct strbuf arg = STRBUF_INIT;
if (line_termination) {
/* Without -z, consume SP and use next argument */
if (!**next || **next == line_termination)
return NULL;
if (**next != ' ')
die("expected SP but got: %s", *next);
} else {
/* With -z, read the next NUL-terminated line */
if (**next)
return NULL;
}
/* Skip the delimiter */
(*next)++;
if (line_termination) {
/* Without -z, use the next argument */
*next = parse_arg(*next, &arg);
} else {
/* With -z, use everything up to the next NUL */
strbuf_addstr(&arg, *next);
*next += arg.len;
}
if (arg.len)
return strbuf_detach(&arg, NULL);
strbuf_release(&arg);
return NULL;
}
/*
* The value being parsed is <old-oid> (as opposed to <new-oid>; the
@ -237,6 +273,61 @@ static void parse_cmd_update(struct ref_transaction *transaction,
strbuf_release(&err);
}
static void parse_cmd_symref_update(struct ref_transaction *transaction,
const char *next, const char *end)
{
char *refname, *new_target, *old_arg;
char *old_target = NULL;
struct strbuf err = STRBUF_INIT;
struct object_id old_oid;
int have_old_oid = 0;
refname = parse_refname(&next);
if (!refname)
die("symref-update: missing <ref>");
new_target = parse_next_refname(&next);
if (!new_target)
die("symref-update %s: missing <new-target>", refname);
old_arg = parse_next_arg(&next);
if (old_arg) {
old_target = parse_next_arg(&next);
if (!old_target)
die("symref-update %s: expected old value", refname);
if (!strcmp(old_arg, "oid")) {
if (repo_get_oid(the_repository, old_target, &old_oid))
die("symref-update %s: invalid oid: %s", refname, old_target);
have_old_oid = 1;
} else if (!strcmp(old_arg, "ref")) {
if (check_refname_format(old_target, REFNAME_ALLOW_ONELEVEL))
die("symref-update %s: invalid ref: %s", refname, old_target);
} else {
die("symref-update %s: invalid arg '%s' for old value", refname, old_arg);
}
}
if (*next != line_termination)
die("symref-update %s: extra input: %s", refname, next);
if (ref_transaction_update(transaction, refname, NULL,
have_old_oid ? &old_oid : NULL,
new_target,
have_old_oid ? NULL : old_target,
update_flags | create_reflog_flag,
msg, &err))
die("%s", err.buf);
update_flags = default_flags;
free(refname);
free(old_arg);
free(old_target);
free(new_target);
strbuf_release(&err);
}
static void parse_cmd_create(struct ref_transaction *transaction,
const char *next, const char *end)
{
@ -502,6 +593,7 @@ static const struct parse_cmd {
{ "create", parse_cmd_create, 2, UPDATE_REFS_OPEN },
{ "delete", parse_cmd_delete, 2, UPDATE_REFS_OPEN },
{ "verify", parse_cmd_verify, 2, UPDATE_REFS_OPEN },
{ "symref-update", parse_cmd_symref_update, 4, UPDATE_REFS_OPEN },
{ "symref-create", parse_cmd_symref_create, 2, UPDATE_REFS_OPEN },
{ "symref-delete", parse_cmd_symref_delete, 2, UPDATE_REFS_OPEN },
{ "symref-verify", parse_cmd_symref_verify, 2, UPDATE_REFS_OPEN },

203
t/t1400-update-ref.sh
View file

@ -1360,6 +1360,7 @@ test_expect_success 'fails with duplicate HEAD update' '
'
test_expect_success 'fails with duplicate ref update via symref' '
test_when_finished "git symbolic-ref -d refs/heads/symref2" &&
git branch target2 $A &&
git symbolic-ref refs/heads/symref2 refs/heads/target2 &&
cat >stdin <<-EOF &&
@ -1862,6 +1863,208 @@ do
git reflog exists refs/heads/symref
'
test_expect_success "stdin $type symref-update fails with too many arguments" '
format_command $type "symref-update refs/heads/symref" "$a" "ref" "$a" "$a" >stdin &&
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
if test "$type" = "-z"
then
grep "fatal: unknown command: $a" err
else
grep "fatal: symref-update refs/heads/symref: extra input: $a" err
fi
'
test_expect_success "stdin $type symref-update fails with wrong old value argument" '
format_command $type "symref-update refs/heads/symref" "$a" "foo" "$a" "$a" >stdin &&
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
grep "fatal: symref-update refs/heads/symref: invalid arg ${SQ}foo${SQ} for old value" err
'
test_expect_success "stdin $type symref-update creates with zero old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
format_command $type "symref-update refs/heads/symref" "$a" "oid" "$Z" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $a >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update creates with no old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $a >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update creates dangling" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
test_must_fail git rev-parse refs/heads/nonexistent &&
format_command $type "symref-update refs/heads/symref" "refs/heads/nonexistent" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo refs/heads/nonexistent >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update fails with wrong old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
git symbolic-ref refs/heads/symref $a &&
format_command $type "symref-update refs/heads/symref" "$m" "ref" "$b" >stdin &&
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
grep "fatal: verifying symref target: ${SQ}refs/heads/symref${SQ}: is at $a but expected $b" err &&
test_must_fail git rev-parse --verify -q $c
'
test_expect_success "stdin $type symref-update updates dangling ref" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
test_must_fail git rev-parse refs/heads/nonexistent &&
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $a >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update updates dangling ref with old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
test_must_fail git rev-parse refs/heads/nonexistent &&
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
format_command $type "symref-update refs/heads/symref" "$a" "ref" "refs/heads/nonexistent" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $a >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update fails update dangling ref with wrong old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
test_must_fail git rev-parse refs/heads/nonexistent &&
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
format_command $type "symref-update refs/heads/symref" "$a" "ref" "refs/heads/wrongref" >stdin &&
test_must_fail git update-ref --stdin $type --no-deref <stdin &&
echo refs/heads/nonexistent >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update works with right old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
git symbolic-ref refs/heads/symref $a &&
format_command $type "symref-update refs/heads/symref" "$m" "ref" "$a" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $m >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update works with no old value" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
git symbolic-ref refs/heads/symref $a &&
format_command $type "symref-update refs/heads/symref" "$m" >stdin &&
git update-ref --stdin $type --no-deref <stdin &&
echo $m >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update fails with empty old ref-target" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
git symbolic-ref refs/heads/symref $a &&
format_command $type "symref-update refs/heads/symref" "$m" "ref" "" >stdin &&
test_must_fail git update-ref --stdin $type --no-deref <stdin &&
echo $a >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update creates (with deref)" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
git update-ref --stdin $type <stdin &&
echo $a >expect &&
git symbolic-ref --no-recurse refs/heads/symref >actual &&
test_cmp expect actual &&
test-tool ref-store main for-each-reflog-ent refs/heads/symref >actual &&
grep "$Z $(git rev-parse $a)" actual
'
test_expect_success "stdin $type symref-update regular ref to symref with correct old-oid" '
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/regularref" &&
git update-ref --no-deref refs/heads/regularref $a &&
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "$(git rev-parse $a)" >stdin &&
git update-ref --stdin $type <stdin &&
echo $a >expect &&
git symbolic-ref --no-recurse refs/heads/regularref >actual &&
test_cmp expect actual &&
test-tool ref-store main for-each-reflog-ent refs/heads/regularref >actual &&
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
'
test_expect_success "stdin $type symref-update regular ref to symref fails with wrong old-oid" '
test_when_finished "git update-ref -d refs/heads/regularref" &&
git update-ref --no-deref refs/heads/regularref $a &&
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "$(git rev-parse refs/heads/target2)" >stdin &&
test_must_fail git update-ref --stdin $type <stdin 2>err &&
grep "fatal: cannot lock ref ${SQ}refs/heads/regularref${SQ}: is at $(git rev-parse $a) but expected $(git rev-parse refs/heads/target2)" err &&
echo $(git rev-parse $a) >expect &&
git rev-parse refs/heads/regularref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update regular ref to symref fails with invalid old-oid" '
test_when_finished "git update-ref -d refs/heads/regularref" &&
git update-ref --no-deref refs/heads/regularref $a &&
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "not-a-ref-oid" >stdin &&
test_must_fail git update-ref --stdin $type <stdin 2>err &&
grep "fatal: symref-update refs/heads/regularref: invalid oid: not-a-ref-oid" err &&
echo $(git rev-parse $a) >expect &&
git rev-parse refs/heads/regularref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update existing symref with zero old-oid" '
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/symref" &&
git symbolic-ref refs/heads/symref refs/heads/target2 &&
format_command $type "symref-update refs/heads/symref" "$a" "oid" "$Z" >stdin &&
test_must_fail git update-ref --stdin $type <stdin 2>err &&
grep "fatal: cannot lock ref ${SQ}refs/heads/symref${SQ}: reference already exists" err &&
echo refs/heads/target2 >expect &&
git symbolic-ref refs/heads/symref >actual &&
test_cmp expect actual
'
test_expect_success "stdin $type symref-update regular ref to symref (with deref)" '
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
test_when_finished "git update-ref -d --no-deref refs/heads/symref2" &&
git update-ref refs/heads/symref2 $a &&
git symbolic-ref --no-recurse refs/heads/symref refs/heads/symref2 &&
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
git update-ref $type --stdin <stdin &&
echo $a >expect &&
git symbolic-ref --no-recurse refs/heads/symref2 >actual &&
test_cmp expect actual &&
echo refs/heads/symref2 >expect &&
git symbolic-ref --no-recurse refs/heads/symref >actual &&
test_cmp expect actual &&
test-tool ref-store main for-each-reflog-ent refs/heads/symref >actual &&
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
'
test_expect_success "stdin $type symref-update regular ref to symref" '
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/regularref" &&
git update-ref --no-deref refs/heads/regularref $a &&
format_command $type "symref-update refs/heads/regularref" "$a" >stdin &&
git update-ref $type --stdin <stdin &&
echo $a >expect &&
git symbolic-ref --no-recurse refs/heads/regularref >actual &&
test_cmp expect actual &&
test-tool ref-store main for-each-reflog-ent refs/heads/regularref >actual &&
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
'
done
test_done

4
t/t1416-ref-transaction-hooks.sh
View file

@ -163,6 +163,7 @@ test_expect_success 'hook gets all queued symref updates' '
git update-ref refs/heads/branch $POST_OID &&
git symbolic-ref refs/heads/symref refs/heads/main &&
git symbolic-ref refs/heads/symrefd refs/heads/main &&
git symbolic-ref refs/heads/symrefu refs/heads/main &&
test_hook reference-transaction <<-\EOF &&
echo "$*" >>actual
@ -190,10 +191,12 @@ test_expect_success 'hook gets all queued symref updates' '
ref:refs/heads/main $ZERO_OID refs/heads/symref
ref:refs/heads/main $ZERO_OID refs/heads/symrefd
$ZERO_OID ref:refs/heads/main refs/heads/symrefc
ref:refs/heads/main ref:refs/heads/branch refs/heads/symrefu
committed
ref:refs/heads/main $ZERO_OID refs/heads/symref
ref:refs/heads/main $ZERO_OID refs/heads/symrefd
$ZERO_OID ref:refs/heads/main refs/heads/symrefc
ref:refs/heads/main ref:refs/heads/branch refs/heads/symrefu
EOF
git update-ref --no-deref --stdin <<-EOF &&
@ -201,6 +204,7 @@ test_expect_success 'hook gets all queued symref updates' '
symref-verify refs/heads/symref refs/heads/main
symref-delete refs/heads/symrefd refs/heads/main
symref-create refs/heads/symrefc refs/heads/main
symref-update refs/heads/symrefu refs/heads/branch ref refs/heads/main
prepare
commit
EOF