Michael Haggerty <mhagger@xxxxxxxxxxxx> writes:
> 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.
I initially had a hard time understanding what these two "running"s
were before reading the changes. They all look good.
Thanks.
> 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;
> }
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