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update-ref: add support for 'symref-update' command
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 <[email protected]> Helped-by: Junio C Hamano <[email protected]> Signed-off-by: Karthik Nayak <[email protected]> Signed-off-by: Junio C Hamano <[email protected]>
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‎Documentation/git-update-ref.txt

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -65,6 +65,7 @@ performs all modifications together. Specify commands of the form:
6565
create SP <ref> SP <new-oid> LF
6666
delete SP <ref> [SP <old-oid>] LF
6767
verify SP <ref> [SP <old-oid>] LF
68+
symref-update SP <ref> SP <new-target> [SP (ref SP <old-target> | oid SP <old-oid>)] LF
6869
symref-create SP <ref> SP <new-target> LF
6970
symref-delete SP <ref> [SP <old-target>] LF
7071
symref-verify SP <ref> [SP <old-target>] LF
@@ -89,6 +90,7 @@ quoting:
8990
create SP <ref> NUL <new-oid> NUL
9091
delete SP <ref> NUL [<old-oid>] NUL
9192
verify SP <ref> NUL [<old-oid>] NUL
93+
symref-update SP <ref> NUL <new-target> [NUL (ref NUL <old-target> | oid NUL <old-oid>)] NUL
9294
symref-create SP <ref> NUL <new-target> NUL
9395
symref-delete SP <ref> [NUL <old-target>] NUL
9496
symref-verify SP <ref> [NUL <old-target>] NUL
@@ -119,6 +121,11 @@ delete::
119121
Delete <ref> after verifying it exists with <old-oid>, if
120122
given. If given, <old-oid> may not be zero.
121123

124+
symref-update::
125+
Set <ref> to <new-target> after verifying <old-target> or <old-oid>,
126+
if given. Specify a zero <old-oid> to ensure that the ref does not
127+
exist before the update.
128+
122129
verify::
123130
Verify <ref> against <old-oid> but do not change it. If
124131
<old-oid> is zero or missing, the ref must not exist.

‎builtin/update-ref.c

Lines changed: 92 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -98,6 +98,42 @@ static char *parse_next_refname(const char **next)
9898
return parse_refname(next);
9999
}
100100

101+
/*
102+
* Wrapper around parse_arg which skips the next delimiter.
103+
*/
104+
static char *parse_next_arg(const char **next)
105+
{
106+
struct strbuf arg = STRBUF_INIT;
107+
108+
if (line_termination) {
109+
/* Without -z, consume SP and use next argument */
110+
if (!**next || **next == line_termination)
111+
return NULL;
112+
if (**next != ' ')
113+
die("expected SP but got: %s", *next);
114+
} else {
115+
/* With -z, read the next NUL-terminated line */
116+
if (**next)
117+
return NULL;
118+
}
119+
/* Skip the delimiter */
120+
(*next)++;
121+
122+
if (line_termination) {
123+
/* Without -z, use the next argument */
124+
*next = parse_arg(*next, &arg);
125+
} else {
126+
/* With -z, use everything up to the next NUL */
127+
strbuf_addstr(&arg, *next);
128+
*next += arg.len;
129+
}
130+
131+
if (arg.len)
132+
return strbuf_detach(&arg, NULL);
133+
134+
strbuf_release(&arg);
135+
return NULL;
136+
}
101137

102138
/*
103139
* 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,
237273
strbuf_release(&err);
238274
}
239275

276+
static void parse_cmd_symref_update(struct ref_transaction *transaction,
277+
const char *next, const char *end)
278+
{
279+
char *refname, *new_target, *old_arg;
280+
char *old_target = NULL;
281+
struct strbuf err = STRBUF_INIT;
282+
struct object_id old_oid;
283+
int have_old_oid = 0;
284+
285+
refname = parse_refname(&next);
286+
if (!refname)
287+
die("symref-update: missing <ref>");
288+
289+
new_target = parse_next_refname(&next);
290+
if (!new_target)
291+
die("symref-update %s: missing <new-target>", refname);
292+
293+
old_arg = parse_next_arg(&next);
294+
if (old_arg) {
295+
old_target = parse_next_arg(&next);
296+
if (!old_target)
297+
die("symref-update %s: expected old value", refname);
298+
299+
if (!strcmp(old_arg, "oid")) {
300+
if (repo_get_oid(the_repository, old_target, &old_oid))
301+
die("symref-update %s: invalid oid: %s", refname, old_target);
302+
303+
have_old_oid = 1;
304+
} else if (!strcmp(old_arg, "ref")) {
305+
if (check_refname_format(old_target, REFNAME_ALLOW_ONELEVEL))
306+
die("symref-update %s: invalid ref: %s", refname, old_target);
307+
} else {
308+
die("symref-update %s: invalid arg '%s' for old value", refname, old_arg);
309+
}
310+
}
311+
312+
if (*next != line_termination)
313+
die("symref-update %s: extra input: %s", refname, next);
314+
315+
if (ref_transaction_update(transaction, refname, NULL,
316+
have_old_oid ? &old_oid : NULL,
317+
new_target,
318+
have_old_oid ? NULL : old_target,
319+
update_flags | create_reflog_flag,
320+
msg, &err))
321+
die("%s", err.buf);
322+
323+
update_flags = default_flags;
324+
free(refname);
325+
free(old_arg);
326+
free(old_target);
327+
free(new_target);
328+
strbuf_release(&err);
329+
}
330+
240331
static void parse_cmd_create(struct ref_transaction *transaction,
241332
const char *next, const char *end)
242333
{
@@ -502,6 +593,7 @@ static const struct parse_cmd {
502593
{ "create", parse_cmd_create, 2, UPDATE_REFS_OPEN },
503594
{ "delete", parse_cmd_delete, 2, UPDATE_REFS_OPEN },
504595
{ "verify", parse_cmd_verify, 2, UPDATE_REFS_OPEN },
596+
{ "symref-update", parse_cmd_symref_update, 4, UPDATE_REFS_OPEN },
505597
{ "symref-create", parse_cmd_symref_create, 2, UPDATE_REFS_OPEN },
506598
{ "symref-delete", parse_cmd_symref_delete, 2, UPDATE_REFS_OPEN },
507599
{ "symref-verify", parse_cmd_symref_verify, 2, UPDATE_REFS_OPEN },

‎t/t1400-update-ref.sh

Lines changed: 203 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1360,6 +1360,7 @@ test_expect_success 'fails with duplicate HEAD update' '
13601360
'
13611361

13621362
test_expect_success 'fails with duplicate ref update via symref' '
1363+
test_when_finished "git symbolic-ref -d refs/heads/symref2" &&
13631364
git branch target2 $A &&
13641365
git symbolic-ref refs/heads/symref2 refs/heads/target2 &&
13651366
cat >stdin <<-EOF &&
@@ -1862,6 +1863,208 @@ do
18621863
git reflog exists refs/heads/symref
18631864
'
18641865

1866+
test_expect_success "stdin $type symref-update fails with too many arguments" '
1867+
format_command $type "symref-update refs/heads/symref" "$a" "ref" "$a" "$a" >stdin &&
1868+
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
1869+
if test "$type" = "-z"
1870+
then
1871+
grep "fatal: unknown command: $a" err
1872+
else
1873+
grep "fatal: symref-update refs/heads/symref: extra input: $a" err
1874+
fi
1875+
'
1876+
1877+
test_expect_success "stdin $type symref-update fails with wrong old value argument" '
1878+
format_command $type "symref-update refs/heads/symref" "$a" "foo" "$a" "$a" >stdin &&
1879+
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
1880+
grep "fatal: symref-update refs/heads/symref: invalid arg ${SQ}foo${SQ} for old value" err
1881+
'
1882+
1883+
test_expect_success "stdin $type symref-update creates with zero old value" '
1884+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1885+
format_command $type "symref-update refs/heads/symref" "$a" "oid" "$Z" >stdin &&
1886+
git update-ref --stdin $type --no-deref <stdin &&
1887+
echo $a >expect &&
1888+
git symbolic-ref refs/heads/symref >actual &&
1889+
test_cmp expect actual
1890+
'
1891+
1892+
test_expect_success "stdin $type symref-update creates with no old value" '
1893+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1894+
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
1895+
git update-ref --stdin $type --no-deref <stdin &&
1896+
echo $a >expect &&
1897+
git symbolic-ref refs/heads/symref >actual &&
1898+
test_cmp expect actual
1899+
'
1900+
1901+
test_expect_success "stdin $type symref-update creates dangling" '
1902+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1903+
test_must_fail git rev-parse refs/heads/nonexistent &&
1904+
format_command $type "symref-update refs/heads/symref" "refs/heads/nonexistent" >stdin &&
1905+
git update-ref --stdin $type --no-deref <stdin &&
1906+
echo refs/heads/nonexistent >expect &&
1907+
git symbolic-ref refs/heads/symref >actual &&
1908+
test_cmp expect actual
1909+
'
1910+
1911+
test_expect_success "stdin $type symref-update fails with wrong old value" '
1912+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1913+
git symbolic-ref refs/heads/symref $a &&
1914+
format_command $type "symref-update refs/heads/symref" "$m" "ref" "$b" >stdin &&
1915+
test_must_fail git update-ref --stdin $type --no-deref <stdin 2>err &&
1916+
grep "fatal: verifying symref target: ${SQ}refs/heads/symref${SQ}: is at $a but expected $b" err &&
1917+
test_must_fail git rev-parse --verify -q $c
1918+
'
1919+
1920+
test_expect_success "stdin $type symref-update updates dangling ref" '
1921+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1922+
test_must_fail git rev-parse refs/heads/nonexistent &&
1923+
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
1924+
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
1925+
git update-ref --stdin $type --no-deref <stdin &&
1926+
echo $a >expect &&
1927+
git symbolic-ref refs/heads/symref >actual &&
1928+
test_cmp expect actual
1929+
'
1930+
1931+
test_expect_success "stdin $type symref-update updates dangling ref with old value" '
1932+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1933+
test_must_fail git rev-parse refs/heads/nonexistent &&
1934+
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
1935+
format_command $type "symref-update refs/heads/symref" "$a" "ref" "refs/heads/nonexistent" >stdin &&
1936+
git update-ref --stdin $type --no-deref <stdin &&
1937+
echo $a >expect &&
1938+
git symbolic-ref refs/heads/symref >actual &&
1939+
test_cmp expect actual
1940+
'
1941+
1942+
test_expect_success "stdin $type symref-update fails update dangling ref with wrong old value" '
1943+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1944+
test_must_fail git rev-parse refs/heads/nonexistent &&
1945+
git symbolic-ref refs/heads/symref refs/heads/nonexistent &&
1946+
format_command $type "symref-update refs/heads/symref" "$a" "ref" "refs/heads/wrongref" >stdin &&
1947+
test_must_fail git update-ref --stdin $type --no-deref <stdin &&
1948+
echo refs/heads/nonexistent >expect &&
1949+
git symbolic-ref refs/heads/symref >actual &&
1950+
test_cmp expect actual
1951+
'
1952+
1953+
test_expect_success "stdin $type symref-update works with right old value" '
1954+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1955+
git symbolic-ref refs/heads/symref $a &&
1956+
format_command $type "symref-update refs/heads/symref" "$m" "ref" "$a" >stdin &&
1957+
git update-ref --stdin $type --no-deref <stdin &&
1958+
echo $m >expect &&
1959+
git symbolic-ref refs/heads/symref >actual &&
1960+
test_cmp expect actual
1961+
'
1962+
1963+
test_expect_success "stdin $type symref-update works with no old value" '
1964+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1965+
git symbolic-ref refs/heads/symref $a &&
1966+
format_command $type "symref-update refs/heads/symref" "$m" >stdin &&
1967+
git update-ref --stdin $type --no-deref <stdin &&
1968+
echo $m >expect &&
1969+
git symbolic-ref refs/heads/symref >actual &&
1970+
test_cmp expect actual
1971+
'
1972+
1973+
test_expect_success "stdin $type symref-update fails with empty old ref-target" '
1974+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1975+
git symbolic-ref refs/heads/symref $a &&
1976+
format_command $type "symref-update refs/heads/symref" "$m" "ref" "" >stdin &&
1977+
test_must_fail git update-ref --stdin $type --no-deref <stdin &&
1978+
echo $a >expect &&
1979+
git symbolic-ref refs/heads/symref >actual &&
1980+
test_cmp expect actual
1981+
'
1982+
1983+
test_expect_success "stdin $type symref-update creates (with deref)" '
1984+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
1985+
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
1986+
git update-ref --stdin $type <stdin &&
1987+
echo $a >expect &&
1988+
git symbolic-ref --no-recurse refs/heads/symref >actual &&
1989+
test_cmp expect actual &&
1990+
test-tool ref-store main for-each-reflog-ent refs/heads/symref >actual &&
1991+
grep "$Z $(git rev-parse $a)" actual
1992+
'
1993+
1994+
test_expect_success "stdin $type symref-update regular ref to symref with correct old-oid" '
1995+
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/regularref" &&
1996+
git update-ref --no-deref refs/heads/regularref $a &&
1997+
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "$(git rev-parse $a)" >stdin &&
1998+
git update-ref --stdin $type <stdin &&
1999+
echo $a >expect &&
2000+
git symbolic-ref --no-recurse refs/heads/regularref >actual &&
2001+
test_cmp expect actual &&
2002+
test-tool ref-store main for-each-reflog-ent refs/heads/regularref >actual &&
2003+
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
2004+
'
2005+
2006+
test_expect_success "stdin $type symref-update regular ref to symref fails with wrong old-oid" '
2007+
test_when_finished "git update-ref -d refs/heads/regularref" &&
2008+
git update-ref --no-deref refs/heads/regularref $a &&
2009+
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "$(git rev-parse refs/heads/target2)" >stdin &&
2010+
test_must_fail git update-ref --stdin $type <stdin 2>err &&
2011+
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 &&
2012+
echo $(git rev-parse $a) >expect &&
2013+
git rev-parse refs/heads/regularref >actual &&
2014+
test_cmp expect actual
2015+
'
2016+
2017+
test_expect_success "stdin $type symref-update regular ref to symref fails with invalid old-oid" '
2018+
test_when_finished "git update-ref -d refs/heads/regularref" &&
2019+
git update-ref --no-deref refs/heads/regularref $a &&
2020+
format_command $type "symref-update refs/heads/regularref" "$a" "oid" "not-a-ref-oid" >stdin &&
2021+
test_must_fail git update-ref --stdin $type <stdin 2>err &&
2022+
grep "fatal: symref-update refs/heads/regularref: invalid oid: not-a-ref-oid" err &&
2023+
echo $(git rev-parse $a) >expect &&
2024+
git rev-parse refs/heads/regularref >actual &&
2025+
test_cmp expect actual
2026+
'
2027+
2028+
test_expect_success "stdin $type symref-update existing symref with zero old-oid" '
2029+
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/symref" &&
2030+
git symbolic-ref refs/heads/symref refs/heads/target2 &&
2031+
format_command $type "symref-update refs/heads/symref" "$a" "oid" "$Z" >stdin &&
2032+
test_must_fail git update-ref --stdin $type <stdin 2>err &&
2033+
grep "fatal: cannot lock ref ${SQ}refs/heads/symref${SQ}: reference already exists" err &&
2034+
echo refs/heads/target2 >expect &&
2035+
git symbolic-ref refs/heads/symref >actual &&
2036+
test_cmp expect actual
2037+
'
2038+
2039+
test_expect_success "stdin $type symref-update regular ref to symref (with deref)" '
2040+
test_when_finished "git symbolic-ref -d refs/heads/symref" &&
2041+
test_when_finished "git update-ref -d --no-deref refs/heads/symref2" &&
2042+
git update-ref refs/heads/symref2 $a &&
2043+
git symbolic-ref --no-recurse refs/heads/symref refs/heads/symref2 &&
2044+
format_command $type "symref-update refs/heads/symref" "$a" >stdin &&
2045+
git update-ref $type --stdin <stdin &&
2046+
echo $a >expect &&
2047+
git symbolic-ref --no-recurse refs/heads/symref2 >actual &&
2048+
test_cmp expect actual &&
2049+
echo refs/heads/symref2 >expect &&
2050+
git symbolic-ref --no-recurse refs/heads/symref >actual &&
2051+
test_cmp expect actual &&
2052+
test-tool ref-store main for-each-reflog-ent refs/heads/symref >actual &&
2053+
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
2054+
'
2055+
2056+
test_expect_success "stdin $type symref-update regular ref to symref" '
2057+
test_when_finished "git symbolic-ref -d --no-recurse refs/heads/regularref" &&
2058+
git update-ref --no-deref refs/heads/regularref $a &&
2059+
format_command $type "symref-update refs/heads/regularref" "$a" >stdin &&
2060+
git update-ref $type --stdin <stdin &&
2061+
echo $a >expect &&
2062+
git symbolic-ref --no-recurse refs/heads/regularref >actual &&
2063+
test_cmp expect actual &&
2064+
test-tool ref-store main for-each-reflog-ent refs/heads/regularref >actual &&
2065+
grep "$(git rev-parse $a) $(git rev-parse $a)" actual
2066+
'
2067+
18652068
done
18662069

18672070
test_done

‎t/t1416-ref-transaction-hooks.sh

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -163,6 +163,7 @@ test_expect_success 'hook gets all queued symref updates' '
163163
git update-ref refs/heads/branch $POST_OID &&
164164
git symbolic-ref refs/heads/symref refs/heads/main &&
165165
git symbolic-ref refs/heads/symrefd refs/heads/main &&
166+
git symbolic-ref refs/heads/symrefu refs/heads/main &&
166167
167168
test_hook reference-transaction <<-\EOF &&
168169
echo "$*" >>actual
@@ -190,17 +191,20 @@ test_expect_success 'hook gets all queued symref updates' '
190191
ref:refs/heads/main $ZERO_OID refs/heads/symref
191192
ref:refs/heads/main $ZERO_OID refs/heads/symrefd
192193
$ZERO_OID ref:refs/heads/main refs/heads/symrefc
194+
ref:refs/heads/main ref:refs/heads/branch refs/heads/symrefu
193195
committed
194196
ref:refs/heads/main $ZERO_OID refs/heads/symref
195197
ref:refs/heads/main $ZERO_OID refs/heads/symrefd
196198
$ZERO_OID ref:refs/heads/main refs/heads/symrefc
199+
ref:refs/heads/main ref:refs/heads/branch refs/heads/symrefu
197200
EOF
198201
199202
git update-ref --no-deref --stdin <<-EOF &&
200203
start
201204
symref-verify refs/heads/symref refs/heads/main
202205
symref-delete refs/heads/symrefd refs/heads/main
203206
symref-create refs/heads/symrefc refs/heads/main
207+
symref-update refs/heads/symrefu refs/heads/branch ref refs/heads/main
204208
prepare
205209
commit
206210
EOF

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