Change the comments to a running example of running the function with
refname set to "refs/foo/bar". Add some more explanation of the logic.
Signed-off-by: Michael Haggerty <mhagger@xxxxxxxxxxxx>
---
refs.c | 69 +++++++++++++++++++++++++++++++++++++++++++++---------------------
1 file changed, 47 insertions(+), 22 deletions(-)
diff --git a/refs.c b/refs.c
index 47e4e53..776bbce 100644
--- a/refs.c
+++ b/refs.c
@@ -876,9 +876,9 @@ static void report_refname_conflict(struct ref_entry *entry,
* operation).
*
* Two reference names conflict if one of them exactly matches the
- * leading components of the other; e.g., "foo/bar" conflicts with
- * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
- * "foo/barbados".
+ * leading components of the other; e.g., "refs/foo/bar" conflicts
+ * with both "refs/foo" and with "refs/foo/bar/baz" but not with
+ * "refs/foo/bar" or "refs/foo/barbados".
*
* skip must be sorted.
*/
@@ -891,19 +891,39 @@ static int is_refname_available(const char *refname,
int pos;
char *dirname;
+ /*
+ * For the sake of comments in this function, suppose that
+ * refname is "refs/foo/bar".
+ */
+
for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
/*
- * We are still at a leading dir of the refname; we are
- * looking for a conflict with a leaf entry.
- *
- * If we find one, we still must make sure it is
- * not in "skip".
+ * We are still at a leading dir of the refname (e.g.,
+ * "refs/foo"; if there is a reference with that name,
+ * it is a conflict, *unless* it is in skip.
*/
pos = search_ref_dir(dir, refname, slash - refname);
if (pos >= 0) {
+ /*
+ * We found a reference whose name is a proper
+ * prefix of refname; e.g., "refs/foo".
+ */
struct ref_entry *entry = dir->entries[pos];
- if (entry_matches(entry, skip))
+ if (entry_matches(entry, skip)) {
+ /*
+ * The reference we just found, e.g.,
+ * "refs/foo", is also in skip, so it
+ * is not considered a conflict.
+ * Moreover, the fact that "refs/foo"
+ * exists means that there cannot be
+ * any references anywhere under the
+ * "refs/foo/" namespace (because they
+ * would have conflicted with
+ * "refs/foo"). So we can stop looking
+ * now and return true.
+ */
return 1;
+ }
report_refname_conflict(entry, refname);
return 0;
}
@@ -911,19 +931,29 @@ static int is_refname_available(const char *refname,
/*
* Otherwise, we can try to continue our search with
- * the next component; if we come up empty, we know
- * there is nothing under this whole prefix.
+ * the next component. So try to look up the
+ * directory, e.g., "refs/foo/".
*/
pos = search_ref_dir(dir, refname, slash + 1 - refname);
- if (pos < 0)
+ if (pos < 0) {
+ /*
+ * There was no directory "refs/foo/", so
+ * there is nothing under this whole prefix,
+ * and we are OK.
+ */
return 1;
+ }
dir = get_ref_dir(dir->entries[pos]);
}
/*
- * We are at the leaf of our refname; we want to
- * make sure there are no directories which match it.
+ * We are at the leaf of our refname (e.g., "refs/foo/bar").
+ * There is no point in searching for a reference with that
+ * name, because a refname isn't considered to conflict with
+ * itself. But we still need to check for references whose
+ * names are in the "refs/foo/bar/" namespace, because they
+ * *do* conflict.
*/
len = strlen(refname);
dirname = xmallocz(len + 1);
@@ -933,9 +963,9 @@ static int is_refname_available(const char *refname,
if (pos >= 0) {
/*
- * We found a directory named "refname". It is a
- * problem iff it contains any ref that is not
- * in "skip".
+ * We found a directory named "$refname/" (e.g.,
+ * "refs/foo/bar/"). It is a problem iff it contains
+ * any ref that is not in "skip".
*/
struct ref_entry *entry = dir->entries[pos];
struct ref_dir *dir = get_ref_dir(entry);
@@ -950,11 +980,6 @@ static int is_refname_available(const char *refname,
return 0;
}
- /*
- * There is no point in searching for another leaf
- * node which matches it; such an entry would be the
- * ref we are looking for, not a conflict.
- */
return 1;
}
--
2.1.4
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