From 770f389b2d4b7a8f22d6350bed32effa74bd2253 Mon Sep 17 00:00:00 2001 From: Karthik Nayak Date: Wed, 17 Sep 2025 17:25:13 +0200 Subject: refs/files: handle F/D conflicts in case-insensitive FS When using the files-backend on case-insensitive filesystems, there is possibility of hitting F/D conflicts when creating references within a single transaction, such as: - 'refs/heads/foo' - 'refs/heads/Foo/bar' Ideally such conflicts are caught in `refs_verify_refnames_available()` which is responsible for checking F/D conflicts within a given transaction. This utility function is shared across the reference backends. As such, it doesn't consider the issues of using a case-insensitive file system, which only affects the files-backend. While one solution would be to make the function aware of such issues, this feels like leaking implementation details of file-backend specific issues into the utility function. So opt for the more simpler option, of lowercasing all references sent to this function when on a case-insensitive filesystem and operating on the files-backend. To do this, simply use a `struct strbuf` to convert the refname to lowercase and append it to the list of refnames to be checked. Since we use a `struct strbuf` and the memory is cleared right after, make sure that the string list duplicates all provided string. Without this change, the user would simply be left with a repository with '.lock' files which were created in the 'prepare' phase of the transaction, as the 'commit' phase would simply abort and not do the necessary cleanup. Reported-by: Junio C Hamano Signed-off-by: Karthik Nayak Signed-off-by: Junio C Hamano --- refs/files-backend.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'refs') diff --git a/refs/files-backend.c b/refs/files-backend.c index d1af5d6bc7..bfdf85121a 100644 --- a/refs/files-backend.c +++ b/refs/files-backend.c @@ -906,8 +906,23 @@ retry: * If the ref did not exist and we are creating it, we have to * make sure there is no existing packed ref that conflicts * with refname. This check is deferred so that we can batch it. + * + * For case-insensitive filesystems, we should also check for F/D + * conflicts between 'foo' and 'Foo/bar'. So let's lowercase + * the refname. */ - item = string_list_append(refnames_to_check, refname); + if (ignore_case) { + struct strbuf lower = STRBUF_INIT; + + strbuf_addstr(&lower, refname); + strbuf_tolower(&lower); + + item = string_list_append_nodup(refnames_to_check, + strbuf_detach(&lower, NULL)); + } else { + item = string_list_append(refnames_to_check, refname); + } + item->util = xmalloc(sizeof(update_idx)); memcpy(item->util, &update_idx, sizeof(update_idx)); } @@ -2832,7 +2847,7 @@ static int files_transaction_prepare(struct ref_store *ref_store, "ref_transaction_prepare"); size_t i; int ret = 0; - struct string_list refnames_to_check = STRING_LIST_INIT_NODUP; + struct string_list refnames_to_check = STRING_LIST_INIT_DUP; char *head_ref = NULL; int head_type; struct files_transaction_backend_data *backend_data; -- cgit v1.3