built-in add -i: re-implement add-untracked in C

This is yet another command, ported to C. It builds nicely on the
support functions introduced for other commands, with the notable
difference that only names are displayed for untracked files, no
file type or diff summary.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

add-interactive.c

@@ -7,6 +7,7 @@
 #include "refs.h"
 #include "string-list.h"
 #include "lockfile.h"
+#include "dir.h"
 
 struct add_i_state {
 	struct repository *r;
@@ -560,6 +561,7 @@ static int is_valid_prefix(const char *prefix, size_t prefix_len)
 struct print_file_item_data {
 	const char *modified_fmt, *color, *reset;
 	struct strbuf buf, name, index, worktree;
+	unsigned only_names:1;
 };
 
 static void print_file_item(int i, int selected, struct string_list_item *item,
@@ -583,6 +585,12 @@ static void print_file_item(int i, int selected, struct string_list_item *item,
 		highlighted = d->name.buf;
 	}
 
+	if (d->only_names) {
+		printf("%c%2d: %s", selected ? '*' : ' ', i + 1,
+		       highlighted ? highlighted : item->string);
+		return;
+	}
+
 	render_adddel(&d->worktree, &c->worktree, _("nothing"));
 	render_adddel(&d->index, &c->index, _("unchanged"));
 
@@ -762,6 +770,88 @@ static int run_revert(struct add_i_state *s, const struct pathspec *ps,
 	return res;
 }
 
+static int get_untracked_files(struct repository *r,
+			       struct prefix_item_list *files,
+			       const struct pathspec *ps)
+{
+	struct dir_struct dir = { 0 };
+	size_t i;
+	struct strbuf buf = STRBUF_INIT;
+
+	if (repo_read_index(r) < 0)
+		return error(_("could not read index"));
+
+	prefix_item_list_clear(files);
+	setup_standard_excludes(&dir);
+	add_pattern_list(&dir, EXC_CMDL, "--exclude option");
+	fill_directory(&dir, r->index, ps);
+
+	for (i = 0; i < dir.nr; i++) {
+		struct dir_entry *ent = dir.entries[i];
+
+		if (index_name_is_other(r->index, ent->name, ent->len)) {
+			strbuf_reset(&buf);
+			strbuf_add(&buf, ent->name, ent->len);
+			add_file_item(&files->items, buf.buf);
+		}
+	}
+
+	strbuf_release(&buf);
+	return 0;
+}
+
+static int run_add_untracked(struct add_i_state *s, const struct pathspec *ps,
+		      struct prefix_item_list *files,
+		      struct list_and_choose_options *opts)
+{
+	struct print_file_item_data *d = opts->list_opts.print_item_data;
+	int res = 0, fd;
+	size_t count, i;
+	struct lock_file index_lock;
+
+	if (get_untracked_files(s->r, files, ps) < 0)
+		return -1;
+
+	if (!files->items.nr) {
+		printf(_("No untracked files.\n"));
+		goto finish_add_untracked;
+	}
+
+	opts->prompt = N_("Add untracked");
+	d->only_names = 1;
+	count = list_and_choose(s, files, opts);
+	d->only_names = 0;
+	if (count <= 0)
+		goto finish_add_untracked;
+
+	fd = repo_hold_locked_index(s->r, &index_lock, LOCK_REPORT_ON_ERROR);
+	if (fd < 0) {
+		res = -1;
+		goto finish_add_untracked;
+	}
+
+	for (i = 0; i < files->items.nr; i++) {
+		const char *name = files->items.items[i].string;
+		if (files->selected[i] &&
+		    add_file_to_index(s->r->index, name, 0) < 0) {
+			res = error(_("could not stage '%s'"), name);
+			break;
+		}
+	}
+
+	if (!res &&
+	    write_locked_index(s->r->index, &index_lock, COMMIT_LOCK) < 0)
+		res = error(_("could not write index"));
+
+	if (!res)
+		printf(Q_("added %d path\n",
+			  "added %d paths\n", count), (int)count);
+
+finish_add_untracked:
+	putchar('\n');
+	return res;
+}
+
 static int run_help(struct add_i_state *s, const struct pathspec *unused_ps,
 		    struct prefix_item_list *unused_files,
 		    struct list_and_choose_options *unused_opts)
@@ -858,6 +948,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 		{ "status", run_status },
 		{ "update", run_update },
 		{ "revert", run_revert },
+		{ "add untracked", run_add_untracked },
 		{ "help", run_help },
 	};
 	struct prefix_item_list commands = PREFIX_ITEM_LIST_INIT;