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fetch: protect branches checked out in all worktrees
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Refuse to fetch into the currently checked out branch of any working
tree, not just the current one.

Fixes this previously reported bug:

https://lore.kernel.org/git/cb957174-5e9a-5603-ea9e-ac9b58a2eaad@mathema.de/

As a side effect of using find_shared_symref, we’ll also refuse the
fetch when we’re on a detached HEAD because we’re rebasing or bisecting
on the branch in question. This seems like a sensible change.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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@andersk @gitster
andersk authored and gitster committed Dec 2, 2021
1 parent c8dd491 commit 8bc1f39
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Showing 2 changed files with 58 additions and 35 deletions.
75 changes: 40 additions & 35 deletions builtin/fetch.c
View file
Expand Up @@ -28,6 +28,7 @@
#include "promisor-remote.h"
#include "commit-graph.h"
#include "shallow.h"
#include "worktree.h"

#define FORCED_UPDATES_DELAY_WARNING_IN_MS (10 * 1000)

Expand Down Expand Up @@ -848,13 +849,12 @@ static void format_display(struct strbuf *display, char code,

static int update_local_ref(struct ref *ref,
struct ref_transaction *transaction,
const char *remote,
const struct ref *remote_ref,
struct strbuf *display,
int summary_width)
const char *remote, const struct ref *remote_ref,
struct strbuf *display, int summary_width,
struct worktree **worktrees)
{
struct commit *current = NULL, *updated;
struct branch *current_branch = branch_get(NULL);
const struct worktree *wt;
const char *pretty_ref = prettify_refname(ref->name);
int fast_forward = 0;

Expand All @@ -868,16 +868,17 @@ static int update_local_ref(struct ref *ref,
return 0;
}

if (current_branch &&
!strcmp(ref->name, current_branch->name) &&
!(update_head_ok || is_bare_repository()) &&
!is_null_oid(&ref->old_oid)) {
if (!update_head_ok &&
(wt = find_shared_symref(worktrees, "HEAD", ref->name)) &&
!wt->is_bare && !is_null_oid(&ref->old_oid)) {
/*
* If this is the head, and it's not okay to update
* the head, and the old value of the head isn't empty...
*/
format_display(display, '!', _("[rejected]"),
_("can't fetch in current branch"),
wt->is_current ?
_("can't fetch in current branch") :
_("checked out in another worktree"),
remote, pretty_ref, summary_width);
return 1;
}
Expand Down Expand Up @@ -1076,7 +1077,8 @@ N_("it took %.2f seconds to check forced updates; you can use\n"
"to avoid this check\n");

static int store_updated_refs(const char *raw_url, const char *remote_name,
int connectivity_checked, struct ref *ref_map)
int connectivity_checked, struct ref *ref_map,
struct worktree **worktrees)
{
struct fetch_head fetch_head;
int url_len, i, rc = 0;
Expand Down Expand Up @@ -1205,7 +1207,8 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
strbuf_reset(&note);
if (ref) {
rc |= update_local_ref(ref, transaction, what,
rm, &note, summary_width);
rm, &note, summary_width,
worktrees);
free(ref);
} else if (write_fetch_head || dry_run) {
/*
Expand Down Expand Up @@ -1298,7 +1301,9 @@ static int check_exist_and_connected(struct ref *ref_map)
return check_connected(iterate_ref_map, &rm, &opt);
}

static int fetch_and_consume_refs(struct transport *transport, struct ref *ref_map)
static int fetch_and_consume_refs(struct transport *transport,
struct ref *ref_map,
struct worktree **worktrees)
{
int connectivity_checked = 1;
int ret;
Expand All @@ -1319,10 +1324,8 @@ static int fetch_and_consume_refs(struct transport *transport, struct ref *ref_m
}

trace2_region_enter("fetch", "consume_refs", the_repository);
ret = store_updated_refs(transport->url,
transport->remote->name,
connectivity_checked,
ref_map);
ret = store_updated_refs(transport->url, transport->remote->name,
connectivity_checked, ref_map, worktrees);
trace2_region_leave("fetch", "consume_refs", the_repository);

out:
Expand Down Expand Up @@ -1385,19 +1388,18 @@ static int prune_refs(struct refspec *rs, struct ref *ref_map,
return result;
}

static void check_not_current_branch(struct ref *ref_map)
static void check_not_current_branch(struct ref *ref_map,
struct worktree **worktrees)
{
struct branch *current_branch = branch_get(NULL);

if (is_bare_repository() || !current_branch)
return;

const struct worktree *wt;
for (; ref_map; ref_map = ref_map->next)
if (ref_map->peer_ref && !strcmp(current_branch->refname,
ref_map->peer_ref->name))
die(_("refusing to fetch into current branch %s "
"of non-bare repository"),
current_branch->refname);
if (ref_map->peer_ref &&
(wt = find_shared_symref(worktrees, "HEAD",
ref_map->peer_ref->name)) &&
!wt->is_bare)
die(_("refusing to fetch into branch '%s' "
"checked out at '%s'"),
ref_map->peer_ref->name, wt->path);
}

static int truncate_fetch_head(void)
Expand Down Expand Up @@ -1495,7 +1497,8 @@ static struct transport *prepare_transport(struct remote *remote, int deepen)
return transport;
}

static void backfill_tags(struct transport *transport, struct ref *ref_map)
static void backfill_tags(struct transport *transport, struct ref *ref_map,
struct worktree **worktrees)
{
int cannot_reuse;

Expand All @@ -1516,7 +1519,7 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map)
transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, NULL);
transport_set_option(transport, TRANS_OPT_DEPTH, "0");
transport_set_option(transport, TRANS_OPT_DEEPEN_RELATIVE, NULL);
fetch_and_consume_refs(transport, ref_map);
fetch_and_consume_refs(transport, ref_map, worktrees);

if (gsecondary) {
transport_disconnect(gsecondary);
Expand All @@ -1534,6 +1537,7 @@ static int do_fetch(struct transport *transport,
struct transport_ls_refs_options transport_ls_refs_options =
TRANSPORT_LS_REFS_OPTIONS_INIT;
int must_list_refs = 1;
struct worktree **worktrees = get_worktrees();

if (tags == TAGS_DEFAULT) {
if (transport->remote->fetch_tags == 2)
Expand Down Expand Up @@ -1589,7 +1593,7 @@ static int do_fetch(struct transport *transport,
ref_map = get_ref_map(transport->remote, remote_refs, rs,
tags, &autotags);
if (!update_head_ok)
check_not_current_branch(ref_map);
check_not_current_branch(ref_map, worktrees);

if (tags == TAGS_DEFAULT && autotags)
transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
Expand All @@ -1607,7 +1611,7 @@ static int do_fetch(struct transport *transport,
transport->url);
}
}
if (fetch_and_consume_refs(transport, ref_map)) {
if (fetch_and_consume_refs(transport, ref_map, worktrees)) {
free_refs(ref_map);
retcode = 1;
goto cleanup;
Expand Down Expand Up @@ -1656,7 +1660,7 @@ static int do_fetch(struct transport *transport,
"you need to specify exactly one branch with the --set-upstream option"));
}
}
skip:
skip:
free_refs(ref_map);

/* if neither --no-tags nor --tags was specified, do automated tag
Expand All @@ -1666,11 +1670,12 @@ static int do_fetch(struct transport *transport,
ref_map = NULL;
find_non_local_tags(remote_refs, &ref_map, &tail);
if (ref_map)
backfill_tags(transport, ref_map);
backfill_tags(transport, ref_map, worktrees);
free_refs(ref_map);
}

cleanup:
cleanup:
free_worktrees(worktrees);
return retcode;
}

Expand Down
18 changes: 18 additions & 0 deletions t/t5516-fetch-push.sh
View file
Expand Up @@ -1771,4 +1771,22 @@ test_expect_success 'denyCurrentBranch and worktrees' '
git -C cloned push origin HEAD:new-wt &&
test_must_fail git -C cloned push --delete origin new-wt
'

test_expect_success 'refuse fetch to current branch of worktree' '
test_when_finished "git worktree remove --force wt && git branch -D wt" &&
git worktree add wt &&
test_commit apple &&
test_must_fail git fetch . HEAD:wt &&
git fetch -u . HEAD:wt
'

test_expect_success 'refuse fetch to current branch of bare repository worktree' '
test_when_finished "rm -fr bare.git" &&
git clone --bare . bare.git &&
git -C bare.git worktree add wt &&
test_commit banana &&
test_must_fail git -C bare.git fetch .. HEAD:wt &&
git -C bare.git fetch -u .. HEAD:wt
'

test_done

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