refs: properly apply exclude patterns to namespaced refs

Reference namespaces allow commands like git-upload-pack(1) to serve
different sets of references to the client depending on which namespace
is enabled, which is for example useful in fork networks. Namespaced
refs are stored with a `refs/namespaces/$namespace` prefix, but all the
user will ultimately see is a stripped version where that prefix is
removed.

The way that this interacts with "transfer.hideRefs" is not immediately
obvious: the hidden refs can either apply to the stripped references, or
to the non-stripped ones that still have the namespace prefix. In fact,
the "transfer.hideRefs" machinery does the former and applies to the
stripped reference by default, but rules can have "^" prefixed to switch
this behaviour to instead match against the full reference name.

Namespaces are exclusively handled at the generic "refs" layer, the
respective backends have no clue that such a thing even exists. This
also has the consequence that they cannot handle hiding references as
soon as reference namespaces come into play because they neither know
whether a namespace is active, nor do they know how to strip references
if they are active.

Handling such exclude patterns in `refs_for_each_namespaced_ref()` and
`refs_for_each_fullref_in_prefixes()` is broken though, as both support
that the user passes both namespaces and exclude patterns. In the case
where both are set we will exclude references with unstripped names,
even though we really wanted to exclude references based on their
stripped names.

This only surfaces when:

  - A repository uses reference namespaces.

  - "transfer.hideRefs" is active.

  - The namespaced references are packed into the "packed-refs" file.

None of our tests exercise this scenario, and thus we haven't ever hit
it. While t5509 exercises both (1) and (2), it does not happen to hit
(3). It is trivial to demonstrate the bug though by explicitly packing
refs in the tests, and then we indeed surface the breakage.

Fix this bug by prefixing exclude patterns with the namespace in the
generic layer. The newly introduced function will be used outside of
"refs.c" in the next patch, so we add a declaration to "refs.h".

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/refs.c b/refs.c
index ceb72d4bd740b9496f284c2d654b69eb9eafe33d..b3a367ea12cb1b795d1f9c3ca04f5fece6630c30 100644 (file)
--- a/refs.c
+++ b/refs.c
@@ -1517,6 +1517,19 @@ const char **hidden_refs_to_excludes(const struct strvec *hide_refs)
        return hide_refs->v;
 }
 
+const char **get_namespaced_exclude_patterns(const char **exclude_patterns,
+                                            const char *namespace,
+                                            struct strvec *out)
+{
+       if (!namespace || !*namespace || !exclude_patterns || !*exclude_patterns)
+               return exclude_patterns;
+
+       for (size_t i = 0; exclude_patterns[i]; i++)
+               strvec_pushf(out, "%s%s", namespace, exclude_patterns[i]);
+
+       return out->v;
+}
+
 const char *find_descendant_ref(const char *dirname,
                                const struct string_list *extras,
                                const struct string_list *skip)
@@ -1634,11 +1647,19 @@ int refs_for_each_namespaced_ref(struct ref_store *refs,
                                 const char **exclude_patterns,
                                 each_ref_fn fn, void *cb_data)
 {
-       struct strbuf buf = STRBUF_INIT;
+       struct strvec namespaced_exclude_patterns = STRVEC_INIT;
+       struct strbuf prefix = STRBUF_INIT;
        int ret;
-       strbuf_addf(&buf, "%srefs/", get_git_namespace());
-       ret = do_for_each_ref(refs, buf.buf, exclude_patterns, fn, 0, 0, cb_data);
-       strbuf_release(&buf);
+
+       exclude_patterns = get_namespaced_exclude_patterns(exclude_patterns,
+                                                          get_git_namespace(),
+                                                          &namespaced_exclude_patterns);
+
+       strbuf_addf(&prefix, "%srefs/", get_git_namespace());
+       ret = do_for_each_ref(refs, prefix.buf, exclude_patterns, fn, 0, 0, cb_data);
+
+       strvec_clear(&namespaced_exclude_patterns);
+       strbuf_release(&prefix);
        return ret;
 }
 
@@ -1719,6 +1740,7 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
                                      const char **exclude_patterns,
                                      each_ref_fn fn, void *cb_data)
 {
+       struct strvec namespaced_exclude_patterns = STRVEC_INIT;
        struct string_list prefixes = STRING_LIST_INIT_DUP;
        struct string_list_item *prefix;
        struct strbuf buf = STRBUF_INIT;
@@ -1730,6 +1752,10 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
                strbuf_addstr(&buf, namespace);
        namespace_len = buf.len;
 
+       exclude_patterns = get_namespaced_exclude_patterns(exclude_patterns,
+                                                          namespace,
+                                                          &namespaced_exclude_patterns);
+
        for_each_string_list_item(prefix, &prefixes) {
                strbuf_addstr(&buf, prefix->string);
                ret = refs_for_each_fullref_in(ref_store, buf.buf,
@@ -1739,6 +1765,7 @@ int refs_for_each_fullref_in_prefixes(struct ref_store *ref_store,
                strbuf_setlen(&buf, namespace_len);
        }
 
+       strvec_clear(&namespaced_exclude_patterns);
        string_list_clear(&prefixes, 0);
        strbuf_release(&buf);
        return ret;

diff --git a/refs.h b/refs.h
index f8b919a138868ed20e4fb344f5a9caf925c92755..3f774e96d1887ed6639ea124669483c43fba8905 100644 (file)
--- a/refs.h
+++ b/refs.h
@@ -859,6 +859,15 @@ int ref_is_hidden(const char *, const char *, const struct strvec *);
  */
 const char **hidden_refs_to_excludes(const struct strvec *hide_refs);
 
+/*
+ * Prefix all exclude patterns with the namespace, if any. This is required
+ * because exclude patterns apply to the stripped reference name, not the full
+ * reference name with the namespace.
+ */
+const char **get_namespaced_exclude_patterns(const char **exclude_patterns,
+                                            const char *namespace,
+                                            struct strvec *out);
+
 /* Is this a per-worktree ref living in the refs/ namespace? */
 int is_per_worktree_ref(const char *refname);
 

diff --git a/t/t5509-fetch-push-namespaces.sh b/t/t5509-fetch-push-namespaces.sh
index 05090feaf9289843214cdaba4813fd50a7deec77..98e8352b6ccbeb4767f8aebdccc58fc8f5e51886 100755 (executable)
--- a/t/t5509-fetch-push-namespaces.sh
+++ b/t/t5509-fetch-push-namespaces.sh
@@ -96,6 +96,7 @@ test_expect_success 'hide namespaced refs with transfer.hideRefs' '
 '
 
 test_expect_success 'check that transfer.hideRefs does not match unstripped refs' '
+       git -C pushee pack-refs --all &&
        GIT_NAMESPACE=namespace \
                git -C pushee -c transfer.hideRefs=refs/namespaces/namespace/refs/tags \
                ls-remote "ext::git %s ." >actual &&