Web lists-archives.com

[PATCH 1/2] read-tree --reset: add --protect-untracked




From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>

Currently there is no way to get git to discard changes to the
worktree without overwriting untracked files. `reset --hard`,
`checkout --force`, `checkout <rev> :/` and `read-tree --reset -u`
will all overwrite untracked files. unpack_trees() has known how to
avoid overwriting untracked files since commit fcc387db9b ("read-tree
-m -u: do not overwrite or remove untracked working tree files.",
2006-05-17) in response to concerns about lost files [1] but those
protections do not apply to --reset. This patch adds an
--protect-untracked option for read-tree/unpack_trees() to apply the
same protections with --reset. It does not change the behavior of any
of the porcelain commands but paves the way for adding options or
changing the default for those in future.

Note the actual change in unpack-trees.c is quite simple, the majority
of this patch is converting existing callers to use the new
unpack_trees_reset_type enum.

[1] https://public-inbox.org/git/8aa486160605161500m1dd8428cj@xxxxxxxxxxxxxx/

Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
---

Notes:
    adding --protect-untracked to the invocation of
    test_submodule_forced_switch() in t1013 fixes the known breakage of
    tests 57 & 58 but breaks test 64 which relies on forcing. I'm not sure
    that the expected results of 57 & 58 are correct if we're forcing.

 Documentation/git-read-tree.txt | 10 +++++++--
 builtin/am.c                    |  8 ++++---
 builtin/checkout.c              |  2 +-
 builtin/read-tree.c             | 12 +++++++++++
 builtin/rebase.c                |  2 +-
 builtin/reset.c                 |  2 +-
 builtin/stash.c                 |  7 ++++---
 t/lib-read-tree.sh              | 11 ++++++++++
 t/t1005-read-tree-reset.sh      | 37 +++++++++++++++++++++++++++++++--
 unpack-trees.c                  |  3 ++-
 unpack-trees.h                  | 10 +++++++--
 11 files changed, 88 insertions(+), 16 deletions(-)

diff --git a/Documentation/git-read-tree.txt b/Documentation/git-read-tree.txt
index d271842608..67864c6bbc 100644
--- a/Documentation/git-read-tree.txt
+++ b/Documentation/git-read-tree.txt
@@ -40,12 +40,18 @@ OPTIONS
 --reset::
 	Same as -m, except that unmerged entries are discarded instead
 	of failing. When used with `-u`, updates leading to loss of
-	working tree changes will not abort the operation.
+	working tree changes will not abort the operation and
+	untracked files will be overwritten. Use `--protect-untracked`
+	to avoid overwriting untracked files.
 
 -u::
 	After a successful merge, update the files in the work
 	tree with the result of the merge.
 
+--protect-untracked::
+	Prevent `--reset` `-u` from overwriting untracked files. Requires
+	`--reset` and `-u` (`-m` never overwrites untracked files).
+
 -i::
 	Usually a merge requires the index file as well as the
 	files in the working tree to be up to date with the
@@ -89,7 +95,7 @@ OPTIONS
 	existed in the original index file.
 
 --exclude-per-directory=<gitignore>::
-	When running the command with `-u` and `-m` options, the
+	When using `-u` with `-m` or `--reset` `--protect-untracked` options, the
 	merge result may need to overwrite paths that are not
 	tracked in the current branch.  The command usually
 	refuses to proceed with the merge to avoid losing such a
diff --git a/builtin/am.c b/builtin/am.c
index 912d9821b1..a92394b682 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1854,7 +1854,8 @@ static void am_resolve(struct am_state *state)
  * true, any unmerged entries will be discarded. Returns 0 on success, -1 on
  * failure.
  */
-static int fast_forward_to(struct tree *head, struct tree *remote, int reset)
+static int fast_forward_to(struct tree *head, struct tree *remote,
+			   enum unpack_trees_reset_type reset)
 {
 	struct lock_file lock_file = LOCK_INIT;
 	struct unpack_trees_options opts;
@@ -1942,7 +1943,8 @@ static int clean_index(const struct object_id *head, const struct object_id *rem
 
 	read_cache_unmerged();
 
-	if (fast_forward_to(head_tree, head_tree, 1))
+	if (fast_forward_to(head_tree, head_tree,
+			    UNPACK_RESET_OVERWRITE_UNTRACKED))
 		return -1;
 
 	if (write_cache_as_tree(&index, 0, NULL))
@@ -1952,7 +1954,7 @@ static int clean_index(const struct object_id *head, const struct object_id *rem
 	if (!index_tree)
 		return error(_("Could not parse object '%s'."), oid_to_hex(&index));
 
-	if (fast_forward_to(index_tree, remote_tree, 0))
+	if (fast_forward_to(index_tree, remote_tree, UNPACK_NO_RESET))
 		return -1;
 
 	if (merge_tree(remote_tree))
diff --git a/builtin/checkout.c b/builtin/checkout.c
index ffa776c6e1..e9e70018f9 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -506,7 +506,7 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 	opts.head_idx = -1;
 	opts.update = worktree;
 	opts.skip_unmerged = !worktree;
-	opts.reset = 1;
+	opts.reset = UNPACK_RESET_OVERWRITE_UNTRACKED;
 	opts.merge = 1;
 	opts.fn = oneway_merge;
 	opts.verbose_update = o->show_progress;
diff --git a/builtin/read-tree.c b/builtin/read-tree.c
index 5c9c082595..23735adde9 100644
--- a/builtin/read-tree.c
+++ b/builtin/read-tree.c
@@ -114,6 +114,7 @@ static int git_read_tree_config(const char *var, const char *value, void *cb)
 int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 {
 	int i, stage = 0;
+	int protect_untracked = -1;
 	struct object_id oid;
 	struct tree_desc t[MAX_UNPACK_TREES];
 	struct unpack_trees_options opts;
@@ -140,6 +141,8 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		  PARSE_OPT_NONEG },
 		OPT_BOOL('u', NULL, &opts.update,
 			 N_("update working tree with merge result")),
+		OPT_BOOL(0, "protect-untracked", &protect_untracked,
+			 N_("do not overwrite untracked files")),
 		{ OPTION_CALLBACK, 0, "exclude-per-directory", &opts,
 		  N_("gitignore"),
 		  N_("allow explicitly ignored files to be overwritten"),
@@ -209,8 +212,17 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	if ((opts.update || opts.index_only) && !opts.merge)
 		die("%s is meaningless without -m, --reset, or --prefix",
 		    opts.update ? "-u" : "-i");
+	if (protect_untracked >= 0) {
+		if (!opts.reset || !opts.update)
+			die("-%s-protect-untracked requires --reset and -u",
+			    protect_untracked ? "" : "-no");
+		opts.reset = UNPACK_RESET_PROTECT_UNTRACKED;
+	}
 	if ((opts.dir && !opts.update))
 		die("--exclude-per-directory is meaningless unless -u");
+	if (opts.dir && opts.reset == UNPACK_RESET_OVERWRITE_UNTRACKED)
+		warning("--exclude-per-directory without --preserve-untracked "
+			"has no effect");
 	if (opts.merge && !opts.index_only)
 		setup_work_tree();
 
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 2e41ad5644..feb30a71f5 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -398,7 +398,7 @@ static int reset_head(struct object_id *oid, const char *action,
 	unpack_tree_opts.update = 1;
 	unpack_tree_opts.merge = 1;
 	if (!detach_head)
-		unpack_tree_opts.reset = 1;
+		unpack_tree_opts.reset = UNPACK_RESET_OVERWRITE_UNTRACKED;
 
 	if (repo_read_index_unmerged(the_repository) < 0) {
 		ret = error(_("could not read index"));
diff --git a/builtin/reset.c b/builtin/reset.c
index 26ef9a7bd0..a39dd92fb2 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -70,7 +70,7 @@ static int reset_index(const struct object_id *oid, int reset_type, int quiet)
 		opts.update = 1;
 		/* fallthrough */
 	default:
-		opts.reset = 1;
+		opts.reset = UNPACK_RESET_OVERWRITE_UNTRACKED;
 	}
 
 	read_cache_unmerged();
diff --git a/builtin/stash.c b/builtin/stash.c
index 2a8e6d09b4..175d1b62d3 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -227,7 +227,8 @@ static int clear_stash(int argc, const char **argv, const char *prefix)
 	return do_clear_stash();
 }
 
-static int reset_tree(struct object_id *i_tree, int update, int reset)
+static int reset_tree(struct object_id *i_tree, int update,
+		      enum unpack_trees_reset_type reset)
 {
 	int nr_trees = 1;
 	struct unpack_trees_options opts;
@@ -461,7 +462,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	}
 
 	if (has_index) {
-		if (reset_tree(&index_tree, 0, 0))
+		if (reset_tree(&index_tree, 0, UNPACK_NO_RESET))
 			return -1;
 	} else {
 		struct strbuf out = STRBUF_INIT;
@@ -471,7 +472,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 			return -1;
 		}
 
-		if (reset_tree(&c_tree, 0, 1)) {
+		if (reset_tree(&c_tree, 0, UNPACK_RESET_OVERWRITE_UNTRACKED)) {
 			strbuf_release(&out);
 			return -1;
 		}
diff --git a/t/lib-read-tree.sh b/t/lib-read-tree.sh
index b95f485606..22f516d91f 100644
--- a/t/lib-read-tree.sh
+++ b/t/lib-read-tree.sh
@@ -39,3 +39,14 @@ read_tree_u_must_fail () {
 	test_cmp pre-dry-run-wt post-dry-run-wt &&
 	test_must_fail git read-tree "$@"
 }
+
+read_tree_u_must_fail_save_err () {
+	git ls-files -s >pre-dry-run &&
+	git diff-files -p >pre-dry-run-wt &&
+	test_must_fail git read-tree -n "$@" &&
+	git ls-files -s >post-dry-run &&
+	git diff-files -p >post-dry-run-wt &&
+	test_cmp pre-dry-run post-dry-run &&
+	test_cmp pre-dry-run-wt post-dry-run-wt &&
+	test_must_fail git read-tree "$@" 2>actual-err
+}
diff --git a/t/t1005-read-tree-reset.sh b/t/t1005-read-tree-reset.sh
index 83b09e1310..6c9dd6805b 100755
--- a/t/t1005-read-tree-reset.sh
+++ b/t/t1005-read-tree-reset.sh
@@ -19,15 +19,48 @@ test_expect_success 'setup' '
 	git add df &&
 	echo content >new &&
 	git add new &&
-	git commit -m two
+	git commit -m two &&
+	git ls-files >expect-two
 '
 
-test_expect_success 'reset should work' '
+test_expect_success '--protect-untracked option sanity checks' '
+	read_tree_u_must_fail --reset --protect-untracked HEAD &&
+	read_tree_u_must_fail --reset --no-protect-untracked HEAD &&
+	read_tree_u_must_fail -m -u --protect-untracked HEAD &&
+	read_tree_u_must_fail -m -u --no-protect-untracked
+'
+
+test_expect_success 'reset should reset worktree' '
+	echo changed >df &&
 	read_tree_u_must_succeed -u --reset HEAD^ &&
 	git ls-files >actual &&
 	test_cmp expect actual
 '
 
+test_expect_success 'reset --protect-untracked protects untracked file' '
+	echo changed >new &&
+	read_tree_u_must_fail_save_err -u --reset --protect-untracked HEAD &&
+	echo "error: Untracked working tree file '\'new\'' would be overwritten by merge." >expected-err &&
+	test_cmp expected-err actual-err
+'
+
+test_expect_success 'reset --protect-untracked protects untracked directory' '
+	rm new &&
+	mkdir new &&
+	echo untracked >new/untracked &&
+	read_tree_u_must_fail_save_err -u --reset --protect-untracked HEAD &&
+	echo "error: Updating '\'new\'' would lose untracked files in it" >expected-err &&
+	test_cmp expected-err actual-err
+'
+
+test_expect_success 'reset --protect-untracked resets' '
+	rm -rf new &&
+	echo changed >df/file &&
+	read_tree_u_must_succeed -u --reset --protect-untracked HEAD &&
+	git ls-files >actual-two &&
+	test_cmp expect-two actual-two
+'
+
 test_expect_success 'reset should remove remnants from a failed merge' '
 	read_tree_u_must_succeed --reset -u HEAD &&
 	git ls-files -s >expect &&
diff --git a/unpack-trees.c b/unpack-trees.c
index 50189909b8..b1722730fe 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -1917,7 +1917,8 @@ static int verify_absent_1(const struct cache_entry *ce,
 	int len;
 	struct stat st;
 
-	if (o->index_only || o->reset || !o->update)
+	if (o->index_only || o->reset == UNPACK_RESET_OVERWRITE_UNTRACKED ||
+	    !o->update)
 		return 0;
 
 	len = check_leading_path(ce->name, ce_namelen(ce));
diff --git a/unpack-trees.h b/unpack-trees.h
index d344d7d296..732b262c4d 100644
--- a/unpack-trees.h
+++ b/unpack-trees.h
@@ -41,9 +41,15 @@ void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
  */
 void clear_unpack_trees_porcelain(struct unpack_trees_options *opts);
 
+enum unpack_trees_reset_type {
+	UNPACK_NO_RESET = 0,
+	UNPACK_RESET_OVERWRITE_UNTRACKED,
+	UNPACK_RESET_PROTECT_UNTRACKED
+};
+
 struct unpack_trees_options {
-	unsigned int reset,
-		     merge,
+	enum unpack_trees_reset_type reset;
+	unsigned int merge,
 		     update,
 		     clone,
 		     index_only,
-- 
2.21.0