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checkout -b <name>: correctly detect existing branch

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When create a new branch, we fed "refs/heads/<proposed name>" as a string
to get_sha1() and expected it to fail when a branch already exists.

The right way to check if a ref exists is to check with resolve_ref().

A naïve solution that might appear attractive but does not work is to
forbid slashes in get_describe_name() but that will not work. A describe
name is is in the form of "ANYTHING-g<short sha1>", and that ANYTHING part
comes from a original tag name used in the repository the user ran the
describe command. A sick user could have a confusing hierarchical tag
whose name is "refs/heads/foobar" (stored as refs/tags/refs/heads/foobar")
to generate a describe name "refs/heads/foobar-6-g02ac983", and we should
be able to use that name to refer to the object whose name is 02ac983.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano 2011-06-05 22:17:04 -07:00
parent 02ac98374e
commit c17b229454
4 changed files with 19 additions and 1 deletions
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2
builtin/checkout.c
View File

@ -874,7 +874,7 @@ no_reference:
if (strbuf_check_branch_ref(&buf, opts.new_branch)) if (strbuf_check_branch_ref(&buf, opts.new_branch))
die("git checkout: we do not like '%s' as a branch name.", die("git checkout: we do not like '%s' as a branch name.",
opts.new_branch); opts.new_branch);
if (!get_sha1(buf.buf, rev)) { if (ref_exists(buf.buf)) {
opts.branch_exists = 1; opts.branch_exists = 1;
if (!opts.new_branch_force) if (!opts.new_branch_force)
die("git checkout: branch %s already exists", die("git checkout: branch %s already exists",

6
refs.c
View File

@ -1732,6 +1732,12 @@ int update_ref(const char *action, const char *refname,
return 0; return 0;
} }
int ref_exists(char *refname)
{
unsigned char sha1[20];
return !!resolve_ref(refname, sha1, 1, NULL);
}
struct ref *find_ref_by_name(const struct ref *list, const char *name) struct ref *find_ref_by_name(const struct ref *list, const char *name)
{ {
for ( ; list; list = list->next) for ( ; list; list = list->next)

1
refs.h
View File

@ -46,6 +46,7 @@ extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refn
*/ */
extern void add_extra_ref(const char *refname, const unsigned char *sha1, int flags); extern void add_extra_ref(const char *refname, const unsigned char *sha1, int flags);
extern void clear_extra_refs(void); extern void clear_extra_refs(void);
extern int ref_exists(char *);
extern int peel_ref(const char *, unsigned char *); extern int peel_ref(const char *, unsigned char *);

11
t/t2018-checkout-branch.sh
View File

@ -163,4 +163,15 @@ test_expect_success 'checkout -f -B to an existing branch with mergeable changes
test_must_fail test_dirty_mergeable test_must_fail test_dirty_mergeable
' '
test_expect_success 'checkout -b <describe>' '
git tag -f -m "First commit" initial initial &&
git checkout -f change1 &&
name=$(git describe) &&
git checkout -b $name &&
git diff --exit-code change1 &&
echo "refs/heads/$name" >expect &&
git symbolic-ref HEAD >actual &&
test_cmp expect actual
'
test_done test_done