From cd42415fb4c9680f308ebf8f9f85ba90ae6014be Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Tue, 30 Mar 2021 13:10:54 +0000 Subject: sparse-index: add 'sdir' index extension The index format does not currently allow for sparse directory entries. This violates some expectations that older versions of Git or third-party tools might not understand. We need an indicator inside the index file to warn these tools to not interact with a sparse index unless they are aware of sparse directory entries. Add a new _required_ index extension, 'sdir', that indicates that the index may contain sparse directory entries. This allows us to continue to use the differences in index formats 2, 3, and 4 before we create a new index version 5 in a later change. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- read-cache.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'read-cache.c') diff --git a/read-cache.c b/read-cache.c index dd3980c12b..b8f092d1b7 100644 --- a/read-cache.c +++ b/read-cache.c @@ -47,6 +47,7 @@ #define CACHE_EXT_FSMONITOR 0x46534D4E /* "FSMN" */ #define CACHE_EXT_ENDOFINDEXENTRIES 0x454F4945 /* "EOIE" */ #define CACHE_EXT_INDEXENTRYOFFSETTABLE 0x49454F54 /* "IEOT" */ +#define CACHE_EXT_SPARSE_DIRECTORIES 0x73646972 /* "sdir" */ /* changes that can be kept in $GIT_DIR/index (basically all extensions) */ #define EXTMASK (RESOLVE_UNDO_CHANGED | CACHE_TREE_CHANGED | \ @@ -1763,6 +1764,10 @@ static int read_index_extension(struct index_state *istate, case CACHE_EXT_INDEXENTRYOFFSETTABLE: /* already handled in do_read_index() */ break; + case CACHE_EXT_SPARSE_DIRECTORIES: + /* no content, only an indicator */ + istate->sparse_index = 1; + break; default: if (*ext < 'A' || 'Z' < *ext) return error(_("index uses %.4s extension, which we do not understand"), @@ -3020,6 +3025,10 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile, if (err) return -1; } + if (istate->sparse_index) { + if (write_index_ext_header(&c, &eoie_c, newfd, CACHE_EXT_SPARSE_DIRECTORIES, 0) < 0) + return -1; + } /* * CACHE_EXT_ENDOFINDEXENTRIES must be written as the last entry before the SHA1 -- cgit v1.3