Subject: Re: [PATCH] check-ref-format: require a repository for --branch

From: Junio C Hamano <[email-masked]>
Date: Mon, 16 Oct 2017 19:45:46 +0900

Junio C Hamano <[email-masked]> writes:

> Having said that, there may still be a use case where a Porcelain
> script wants a way to see if a $name it has is appropriate as a
> branch name before it has a repository (e.g. a wrapper to "git
> clone" that wants to verify the name it is going to give to the "-b"
> option), and a check desired in such a context is different from
> (and is stricter than) feeding refs/heads/$name to the same command
> without the "--branch" option.
>
> So I think the right endgame in the longer term is:
> ...

Here is to illustrate what I mean in a patch form.  It resurrects
the gentle setup, and uses a purely textual format check when we are
outside the repository, while bypassing the @{magic} interpolation
codepath that requires us to be in a repository.  When we are in a
repository, we operate the same way as before.

Designed to be applied directly on top of 4d03f955
("check-ref-format: require a repository for --branch", 2017-07-14),
so it is missing the "'HEAD' is not a good branch name" I showed a
few days ago.

 builtin/check-ref-format.c  | 16 +++++++++++++---
 cache.h                     | 14 ++++++++++++++
 sha1_name.c                 | 22 +++++++++++++++++++---
 strbuf.h                    |  6 ++++++
 t/t1402-check-ref-format.sh | 10 +++++++++-
 5 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/builtin/check-ref-format.c b/builtin/check-ref-format.c
index 1e5f9835f0..4e62852089 100644
--- a/builtin/check-ref-format.c
+++ b/builtin/check-ref-format.c
@@ -38,12 +38,22 @@ static char *collapse_slashes(const char *refname)
 
 static int check_ref_format_branch(const char *arg)
 {
+	int nongit, malformed;
 	struct strbuf sb = STRBUF_INIT;
+	const char *name = arg;
 
-	setup_git_directory();
-	if (strbuf_check_branch_ref(&sb, arg))
+	setup_git_directory_gently(&nongit);
+
+	if (!nongit)
+		malformed = (strbuf_check_branch_ref(&sb, arg) ||
+			     !skip_prefix(sb.buf, "refs/heads/", &name));
+	else
+		malformed = check_branch_ref_format(arg);
+
+	if (malformed)
 		die("'%s' is not a valid branch name", arg);
-	printf("%s\n", sb.buf + 11);
+	printf("%s\n", name);
+	strbuf_release(&sb);
 	return 0;
 }
 
diff --git a/cache.h b/cache.h
index 52b91f5b64..3815925122 100644
--- a/cache.h
+++ b/cache.h
@@ -1444,6 +1444,20 @@ extern int parse_oid_hex(const char *hex, struct object_id *oid, const char **en
 #define INTERPRET_BRANCH_HEAD (1<<2)
 extern int interpret_branch_name(const char *str, int len, struct strbuf *,
 				 unsigned allowed);
+
+/*
+ * NEEDSWORK: declare strbuf_branchname() and strbuf_check_branch_ref()
+ * here, not in strbuf.h
+ */
+
+/*
+ * Check if a 'name' is suitable to be used as a branch name; this can
+ * be and is stricter than what check_refname_format() returns for a
+ * string that is a concatenation of "name" after "refs/heads/"; a
+ * name that begins with "-" is not allowed, for example.
+ */
+extern int check_branch_ref_format(const char *name);
+
 extern int get_oid_mb(const char *str, struct object_id *oid);
 
 extern int validate_headref(const char *ref);
diff --git a/sha1_name.c b/sha1_name.c
index 5e2ec37b65..c95080258f 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1319,15 +1319,31 @@ void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
 	strbuf_add(sb, name + used, len - used);
 }
 
-int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
+static int strbuf_check_branch_ref_format(struct strbuf *sb)
 {
-	strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
-	if (name[0] == '-')
+	if (*sb->buf == '-')
 		return -1;
 	strbuf_splice(sb, 0, 0, "refs/heads/", 11);
 	return check_refname_format(sb->buf, 0);
 }
 
+int check_branch_ref_format(const char *name)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int result;
+
+	strbuf_addstr(&sb, name);
+	result = strbuf_check_branch_ref_format(&sb);
+	strbuf_release(&sb);
+	return result;
+}
+
+int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
+{
+	strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
+	return strbuf_check_branch_ref_format(sb);
+}
+
 /*
  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
  * notably "xyz^" for "parent of xyz"
diff --git a/strbuf.h b/strbuf.h
index d785258649..3da95685b2 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -568,6 +568,12 @@ static inline void strbuf_complete_line(struct strbuf *sb)
 	strbuf_complete(sb, '\n');
 }
 
+/*
+ * NEEDSWORK: the following two functions should not be in this file;
+ * these are about refnames, and should be declared next to
+ * interpret_branch_name() in cache.h
+ */
+
 /*
  * Copy "name" to "sb", expanding any special @-marks as handled by
  * interpret_branch_name(). The result is a non-qualified branch name
diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
index 1674b061e2..2ddefb4bd1 100755
--- a/t/t1402-check-ref-format.sh
+++ b/t/t1402-check-ref-format.sh
@@ -161,10 +161,18 @@ test_expect_success 'check-ref-format --branch from subdir' '
 	test "$refname" = "$sha1"
 '
 
-test_expect_success 'check-ref-format --branch from non-repo' '
+test_expect_success 'check-ref-format --branch @{-1} from non-repo' '
 	test_must_fail nongit git check-ref-format --branch @{-1}
 '
 
+test_expect_success 'check-ref-format --branch master in non-repo' '
+	nongit git check-ref-format --branch master
+'
+
+test_expect_success 'check-ref-format --branch -naster in repo' '
+	test_must_fail git check-ref-format --branch -naster
+'
+
 valid_ref_normalized() {
 	prereq=
 	case $1 in