[v2,02/11] sparse-checkout: create 'init' subcommand

Commit Message

Johannes Schindelin via GitGitGadget Sept. 19, 2019, 2:43 p.m. UTC

From: Derrick Stolee <[e-mail]>

Getting started with a sparse-checkout file can be daunting. Help
users start their sparse enlistment using 'git sparse-checkout init'.
This will set 'core.sparseCheckout=true' in their config, write
an initial set of patterns to the sparse-checkout file, and update
their working directory.

Using 'git read-tree' to clear directories does not work cleanly
on Windows, so manually delete directories that are tracked by Git
before running read-tree.

The use of running another process for 'git read-tree' is likely
suboptimal, but that can be improved in a later change, if valuable.

Signed-off-by: Derrick Stolee <[e-mail]>
---
 Documentation/git-sparse-checkout.txt |  7 +++
 builtin/sparse-checkout.c             | 69 ++++++++++++++++++++++++++-
 t/t1091-sparse-checkout-builtin.sh    | 41 ++++++++++++++++
 3 files changed, 116 insertions(+), 1 deletion(-)

Comments

Elijah Newren Oct. 5, 2019, 7:34 p.m. UTC | #1

On Thu, Sep 19, 2019 at 3:06 PM Derrick Stolee via GitGitGadget
<[e-mail]> wrote:
>
> From: Derrick Stolee <[e-mail]>
>
> Getting started with a sparse-checkout file can be daunting. Help
> users start their sparse enlistment using 'git sparse-checkout init'.
> This will set 'core.sparseCheckout=true' in their config, write
> an initial set of patterns to the sparse-checkout file, and update
> their working directory.

...and ensure extensions.worktreeConfig is set to true.

> Using 'git read-tree' to clear directories does not work cleanly
> on Windows, so manually delete directories that are tracked by Git
> before running read-tree.

I thought you said you fixed this?  It appears to no longer be part of
the patch, so I'm guessing you just forgot to remove this comment from
the commit message?

> The use of running another process for 'git read-tree' is likely
> suboptimal, but that can be improved in a later change, if valuable.

I think it would also be worth mentioning that not only is a
subprocess suboptimal, but the behavior of `git read-tree -mu HEAD` is
itself suboptimal for a sparse-checkout.  (We either need more error
checking e.g. when the user is in the middle of a rebase or merge or
cherry-pick and have conflicted entries with a more focused error
message for the user, or we need a command that won't abort if the
conflicts aren't in the paths we're trying to remove from or bring
back to the working tree.)


Patch looks good to me, assuming the caveats of using `git read-tree
-mu HEAD` are better documented -- and hopefully addressed at some
point.  You addressed all my other feedback on this patch from the RFC
series.

Patch

diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt
index cdef451642..9707ef93b1 100644
--- a/Documentation/git-sparse-checkout.txt
+++ b/Documentation/git-sparse-checkout.txt
@@ -26,6 +26,13 @@  COMMANDS
 'list'::
 	Provide a list of the contents in the sparse-checkout file.
 
+'init'::
+	Enable the `core.sparseCheckout` setting. If the
+	sparse-checkout file does not exist, then populate it with
+	patterns that match every file in the root directory and
+	no other directories, then will remove all directories tracked
+	by Git. Add patterns to the sparse-checkout file to
+	repopulate the working directory.
 
 SPARSE CHECKOUT
 ----------------
diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index eed9625a05..895479970d 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -8,7 +8,7 @@ 
 #include "strbuf.h"
 
 static char const * const builtin_sparse_checkout_usage[] = {
-	N_("git sparse-checkout [list]"),
+	N_("git sparse-checkout [init|list]"),
 	NULL
 };
 
@@ -59,6 +59,71 @@  static int sparse_checkout_list(int argc, const char **argv)
 	return 0;
 }
 
+static int update_working_directory(void)
+{
+	struct argv_array argv = ARGV_ARRAY_INIT;
+	int result = 0;
+	argv_array_pushl(&argv, "read-tree", "-m", "-u", "HEAD", NULL);
+
+	if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
+		error(_("failed to update index with new sparse-checkout paths"));
+		result = 1;
+	}
+
+	argv_array_clear(&argv);
+	return result;
+}
+
+static int sc_enable_config(void)
+{
+	struct argv_array argv = ARGV_ARRAY_INIT;
+
+	if (git_config_set_gently("extensions.worktreeConfig", "true")) {
+		error(_("failed to set extensions.worktreeConfig setting"));
+		return 1;
+	}
+
+	argv_array_pushl(&argv, "config", "--worktree", "core.sparseCheckout", "true", NULL);
+
+	if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
+		error(_("failed to enable core.sparseCheckout"));
+		return 1;
+	}
+
+	return 0;
+}
+
+static int sparse_checkout_init(int argc, const char **argv)
+{
+	struct pattern_list pl;
+	char *sparse_filename;
+	FILE *fp;
+	int res;
+
+	if (sc_enable_config())
+		return 1;
+
+	memset(&pl, 0, sizeof(pl));
+
+	sparse_filename = get_sparse_checkout_filename();
+	res = add_patterns_from_file_to_list(sparse_filename, "", 0, &pl, NULL);
+
+	/* If we already have a sparse-checkout file, use it. */
+	if (res >= 0) {
+		free(sparse_filename);
+		goto reset_dir;
+	}
+
+	/* initial mode: all blobs at root */
+	fp = fopen(sparse_filename, "w");
+	free(sparse_filename);
+	fprintf(fp, "/*\n!/*/\n");
+	fclose(fp);
+
+reset_dir:
+	return update_working_directory();
+}
+
 int cmd_sparse_checkout(int argc, const char **argv, const char *prefix)
 {
 	static struct option builtin_sparse_checkout_options[] = {
@@ -79,6 +144,8 @@  int cmd_sparse_checkout(int argc, const char **argv, const char *prefix)
 	if (argc > 0) {
 		if (!strcmp(argv[0], "list"))
 			return sparse_checkout_list(argc, argv);
+		if (!strcmp(argv[0], "init"))
+			return sparse_checkout_init(argc, argv);
 	}
 
 	usage_with_options(builtin_sparse_checkout_usage,
diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
index 46e7b2dded..a6c6b336c9 100755
--- a/t/t1091-sparse-checkout-builtin.sh
+++ b/t/t1091-sparse-checkout-builtin.sh
@@ -47,5 +47,46 @@  test_expect_success 'git sparse-checkout list (populated)' '
 	test_cmp expect list
 '
 
+test_expect_success 'git sparse-checkout init' '
+	git -C repo sparse-checkout init &&
+	cat >expect <<-EOF &&
+		/*
+		!/*/
+	EOF
+	test_cmp expect repo/.git/info/sparse-checkout &&
+	git -C repo config --list >config &&
+	test_i18ngrep "core.sparsecheckout=true" config &&
+	ls repo >dir  &&
+	echo a >expect &&
+	test_cmp expect dir
+'
+
+test_expect_success 'git sparse-checkout list after init' '
+	git -C repo sparse-checkout list >actual &&
+	cat >expect <<-EOF &&
+		/*
+		!/*/
+	EOF
+	test_cmp expect actual
+'
+
+test_expect_success 'init with existing sparse-checkout' '
+	echo "*folder*" >> repo/.git/info/sparse-checkout &&
+	git -C repo sparse-checkout init &&
+	cat >expect <<-EOF &&
+		/*
+		!/*/
+		*folder*
+	EOF
+	test_cmp expect repo/.git/info/sparse-checkout &&
+	ls repo >dir  &&
+	cat >expect <<-EOF &&
+		a
+		folder1
+		folder2
+	EOF
+	test_cmp expect dir
+'
+
 test_done