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restore: avoid sparse index expansion 

Teach update_some() to handle sparse directory entries at the tree
level rather than expanding the entire sparse index. When iterating a
source tree during checkout/restore operations:

 - If a directory matches a sparse directory entry with the same OID,
   skip it entirely (no change needed).

 - If the OID differs and we are in non-overlay mode (e.g., restore
   --staged), update the sparse directory entry's OID in place. This
   is semantically correct because non-overlay mode removes paths not
   in the source tree anyway.

 - In overlay mode (e.g., checkout <tree> -- .), fall through to
   recursive descent so individual file entries are preserved
   correctly.

Also switch from index_name_pos() to index_name_pos_sparse() for
individual file lookups to avoid triggering ensure_full_index() when
the file is already individually tracked in the index.

Update the test expectation in t1092 to assert that 'restore --staged'
no longer expands the sparse index.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
main
Derrick Stolee 2026-05-26 20:26:34 +00:00 committed by Junio C Hamano
parent ca7b9ae340
commit 105aacd072
2 changed files with 63 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
builtin/checkout.c
View File

@ -31,6 +31,7 @@
#include "revision.h"
#include "sequencer.h"
#include "setup.h"
#include "sparse-index.h"
#include "strvec.h"
#include "submodule.h"
#include "symlinks.h"
@ -141,15 +142,65 @@ static int post_checkout_hook(struct commit *old_commit, struct commit *new_comm
return run_hooks_opt(the_repository, "post-checkout", &opt);
}

/*
* Handle a tree object and determine if we need to recurse into the
* tree (READ_TREE_RECURSIVE) or skip it (0).
*/
static int try_update_sparse_directory(const struct object_id *oid,
struct strbuf *base,
const char *pathname,
int overlay_mode)
{
struct strbuf dirpath = STRBUF_INIT;
struct cache_entry *old;
int pos, result = READ_TREE_RECURSIVE;

if (!the_repository->index->sparse_index)
return result;

strbuf_addbuf(&dirpath, base);
strbuf_addstr(&dirpath, pathname);
strbuf_addch(&dirpath, '/');

pos = index_name_pos_sparse(the_repository->index,
dirpath.buf, dirpath.len);
if (pos < 0)
goto cleanup;

old = the_repository->index->cache[pos];
if (!S_ISSPARSEDIR(old->ce_mode))
goto cleanup;

if (oideq(oid, &old->oid)) {
/* Tree content already matches; no need to descend. */
result = 0;
} else if (!overlay_mode) {
/*
* In non-overlay mode (e.g., restore --staged), replace the
* sparse directory OID directly since files not present in
* the source tree should be removed anyway.
*/
oidcpy(&old->oid, oid);
old->ce_flags |= CE_UPDATE;
result = 0;
}

cleanup:
strbuf_release(&dirpath);
return result;
}

static int update_some(const struct object_id *oid, struct strbuf *base,
const char *pathname, unsigned mode, void *context UNUSED)
const char *pathname, unsigned mode, void *context)
{
int len;
struct cache_entry *ce;
int pos;
int overlay_mode = context ? *((int *)context) : 1;

if (S_ISDIR(mode))
return READ_TREE_RECURSIVE;
return try_update_sparse_directory(oid, base, pathname,
overlay_mode);

len = base->len + strlen(pathname);
ce = make_empty_cache_entry(the_repository->index, len);
@ -165,7 +216,7 @@ static int update_some(const struct object_id *oid, struct strbuf *base,
* entry in place. Whether it is UPTODATE or not, checkout_entry will
* do the right thing.
*/
pos = index_name_pos(the_repository->index, ce->name, ce->ce_namelen);
pos = index_name_pos_sparse(the_repository->index, ce->name, ce->ce_namelen);
if (pos >= 0) {
struct cache_entry *old = the_repository->index->cache[pos];
if (ce->ce_mode == old->ce_mode &&
@ -182,10 +233,11 @@ static int update_some(const struct object_id *oid, struct strbuf *base,
return 0;
}

static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
static int read_tree_some(struct tree *tree, const struct pathspec *pathspec,
int overlay_mode)
{
read_tree(the_repository, tree,
pathspec, update_some, NULL);
pathspec, update_some, &overlay_mode);

/* update the index with the given tree's info
* for all args, expanding wildcards, and exit
@ -580,7 +632,8 @@ static int checkout_paths(const struct checkout_opts *opts,
return error(_("index file corrupt"));

if (opts->source_tree)
read_tree_some(opts->source_tree, &opts->pathspec);
read_tree_some(opts->source_tree, &opts->pathspec,
opts->overlay_mode);
if (opts->merge)
unmerge_index(the_repository->index, &opts->pathspec, CE_MATCHED);


8
t/t1092-sparse-checkout-compatibility.sh
View File

@ -2608,19 +2608,19 @@ test_expect_success 'restore --staged with wildcards' '
test_all_match git diff --cached
'

test_expect_success 'sparse-index is expanded: restore --staged' '
test_expect_success 'sparse-index is not expanded: restore --staged' '
init_repos &&

git -C sparse-index checkout -b restore-staged-exp base &&
git -C sparse-index reset --soft update-folder1 &&
ensure_expanded restore --staged .
ensure_not_expanded restore --staged .
'

test_expect_success 'sparse-index is expanded: restore --source --staged' '
test_expect_success 'sparse-index is not expanded: restore --source --staged' '
init_repos &&

git -C sparse-index checkout -b restore-source-staged base &&
ensure_expanded restore --source update-folder1 --staged .
ensure_not_expanded restore --source update-folder1 --staged .
'

test_done