diff options
| author | Derrick Stolee <dstolee@microsoft.com> | 2021-03-30 16:10:54 +0300 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2021-03-30 22:57:46 +0300 |
| commit | cd42415fb4c9680f308ebf8f9f85ba90ae6014be (patch) | |
| tree | 8937e603c8fc93ff887578f6053817c6148ae5c4 | |
| parent | 836e25c51b20c1f1d122dc17a1c57dad15ff5854 (diff) | |
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 <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
| -rw-r--r-- | Documentation/technical/index-format.txt | 12 | ||||
| -rw-r--r-- | read-cache.c | 9 |
2 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt index 3b74c05647..65da0daaa5 100644 --- a/Documentation/technical/index-format.txt +++ b/Documentation/technical/index-format.txt @@ -392,3 +392,15 @@ The remaining data of each directory block is grouped by type: in this block of entries. - 32-bit count of cache entries in this block + +== Sparse Directory Entries + + When using sparse-checkout in cone mode, some entire directories within + the index can be summarized by pointing to a tree object instead of the + entire expanded list of paths within that tree. An index containing such + entries is a "sparse index". Index format versions 4 and less were not + implemented with such entries in mind. Thus, for these versions, an + index containing sparse directory entries will include this extension + with signature { 's', 'd', 'i', 'r' }. Like the split-index extension, + tools should avoid interacting with a sparse index unless they understand + this extension. 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 |