git check-ref-format --print

Tolerating empty path components in ref names means each ref does
not have a unique name.  This creates difficulty for porcelains
that want to see if two branches are equal.  Add a helper associating
to each ref a canonical name.

If a user asks a porcelain to create a ref "refs/heads//master",
the porcelain can run "git check-ref-format --print refs/heads//master"
and only deal with "refs/heads/master" from then on.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-check-ref-format.txt b/Documentation/git-check-ref-format.txt
index 0b7982ea76633e45b8d3073cd275ea74a757c0eb..211ae1c3fadeb4436725a9cce80cd8583fd2a140 100644 (file)
--- a/Documentation/git-check-ref-format.txt
+++ b/Documentation/git-check-ref-format.txt
@@ -9,6 +9,7 @@ SYNOPSIS
 --------
 [verse]
 'git check-ref-format' <refname>
+'git check-ref-format' --print <refname>
 'git check-ref-format' [--branch] <branchname-shorthand>
 
 DESCRIPTION
@@ -63,16 +64,28 @@ reference name expressions (see linkgit:git-rev-parse[1]):
 
 . at-open-brace `@{` is used as a notation to access a reflog entry.
 
+With the `--print` option, if 'refname' is acceptable, it prints the
+canonicalized name of a hypothetical reference with that name.  That is,
+it prints 'refname' with any extra `/` characters removed.
+
 With the `--branch` option, it expands a branch name shorthand and
 prints the name of the branch the shorthand refers to.
 
-EXAMPLE
--------
-
-git check-ref-format --branch @{-1}::
-
-Print the name of the previous branch.
+EXAMPLES
+--------
 
+* Print the name of the previous branch:
++
+------------
+$ git check-ref-format --branch @{-1}
+------------
+
+* Determine the reference name to use for a new branch:
++
+------------
+$ ref=$(git check-ref-format --print "refs/heads/$newbranch") ||
+die "we do not like '$newbranch' as a branch name."
+------------
 
 GIT
 ---

diff --git a/builtin-check-ref-format.c b/builtin-check-ref-format.c
index f9381e07eaeda673e91ef6250eca4027c5ba0278..b97b61a0a4d957d6e2cb59eb314e49c06c8d70d8 100644 (file)
--- a/builtin-check-ref-format.c
+++ b/builtin-check-ref-format.c
@@ -17,6 +17,16 @@ int cmd_check_ref_format(int argc, const char **argv, const char *prefix)
                printf("%s\n", sb.buf + 11);
                exit(0);
        }
+       if (argc == 3 && !strcmp(argv[1], "--print")) {
+               char *refname = xmalloc(strlen(argv[2]) + 1);
+
+               if (check_ref_format(argv[2]))
+                       exit(1);
+               if (normalize_path_copy(refname, argv[2]))
+                       die("Could not normalize ref name '%s'", argv[2]);
+               printf("%s\n", refname);
+               exit(0);
+       }
        if (argc != 2)
                usage("git check-ref-format refname");
        return !!check_ref_format(argv[1]);

diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
index 382bc6e823516adcbc231e3075c731d59dd27b29..eb45afb018f6e3849204b44cce06ae1a4e2e29aa 100644 (file)
--- a/t/t1402-check-ref-format.sh
+++ b/t/t1402-check-ref-format.sh
@@ -41,4 +41,21 @@ test_expect_success "check-ref-format --branch @{-1}" '
        refname2=$(git check-ref-format --branch @{-2}) &&
        test "$refname2" = master'
 
+valid_ref_normalized() {
+       test_expect_success "ref name '$1' simplifies to '$2'" "
+               refname=\$(git check-ref-format --print '$1') &&
+               test \"\$refname\" = '$2'"
+}
+invalid_ref_normalized() {
+       test_expect_success "check-ref-format --print rejects '$1'" "
+               test_must_fail git check-ref-format --print '$1'"
+}
+
+valid_ref_normalized 'heads/foo' 'heads/foo'
+valid_ref_normalized 'refs///heads/foo' 'refs/heads/foo'
+invalid_ref_normalized 'foo'
+invalid_ref_normalized 'heads/foo/../bar'
+invalid_ref_normalized 'heads/./foo'
+invalid_ref_normalized 'heads\foo'
+
 test_done