@matheusbsbs / matheus-bagliano / commits / c17b229454

checkout -b <name>: correctly detect existing branch

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>

Junio C Hamano committed Jun 5, 2011 at 22:17 UTC c17b229454ac3f5d20fd0cff3a663b03c13cb38e

4 files changed +19 -1

builtin/checkout.c

+1 -1

@@ -874,7 +874,7 @@ no_reference:

874 if (strbuf_check_branch_ref(&buf, opts.new_branch))

875 die("git checkout: we do not like '%s' as a branch name.",

876 opts.new_branch);

877 - if (!get_sha1(buf.buf, rev)) {

877 + if (ref_exists(buf.buf)) {

878 opts.branch_exists = 1;

879 if (!opts.new_branch_force)

880 die("git checkout: branch %s already exists",

refs.c

@@ -1732,6 +1732,12 @@ int update_ref(const char *action, const char *refname,

1732 return 0;

1733 }

1734

1735 +int ref_exists(char *refname)

1736 +{

1737 + unsigned char sha1[20];

1738 + return !!resolve_ref(refname, sha1, 1, NULL);

1739 +}

1740 +

1741 struct ref *find_ref_by_name(const struct ref *list, const char *name)

1742 {

1743 for ( ; list; list = list->next)

refs.h

@@ -46,6 +46,7 @@ extern void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refn

46 */

47 extern void add_extra_ref(const char *refname, const unsigned char *sha1, int flags);

48 extern void clear_extra_refs(void);

49 +extern int ref_exists(char *);

51 extern int peel_ref(const char *, unsigned char *);

t/t2018-checkout-branch.sh

+11

@@ -163,4 +163,15 @@ test_expect_success 'checkout -f -B to an existing branch with mergeable changes

163 test_must_fail test_dirty_mergeable

164 '

165

166 +test_expect_success 'checkout -b <describe>' '

167 + git tag -f -m "First commit" initial initial &&

168 + git checkout -f change1 &&

169 + name=$(git describe) &&

170 + git checkout -b $name &&

171 + git diff --exit-code change1 &&

172 + echo "refs/heads/$name" >expect &&

173 + git symbolic-ref HEAD >actual &&

174 + test_cmp expect actual

175 +'

176 +

177 test_done