[PATCH 2/2] reset: support the --stdin option

[Johannes Schindelin <johannes.schindelin@gmx.de>]

Just like with other Git commands, this option makes it read the paths
from the standard input. It comes in handy when resetting many, many
paths at once and wildcards are not an option (e.g. when the paths are
generated by a tool).

Note: to keep things simple, we first parse the entire list and perform
the actual reset action only in a second phase.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Documentation/git-reset.txt | 10 +++++++-
 builtin/reset.c             | 56 +++++++++++++++++++++++++++++++++++++++++++--
 t/t7107-reset-stdin.sh      | 33 ++++++++++++++++++++++++++
 3 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100755 t/t7107-reset-stdin.sh

diff --git a/Documentation/git-reset.txt b/Documentation/git-reset.txt
index 25432d9..533ef69 100644
--- a/Documentation/git-reset.txt
+++ b/Documentation/git-reset.txt
@@ -8,7 +8,7 @@ git-reset - Reset current HEAD to the specified state
 SYNOPSIS
 --------
 [verse]
-'git reset' [-q] [<tree-ish>] [--] <paths>...
+'git reset' [-q] [--stdin [-z]] [<tree-ish>] [--] <paths>...
 'git reset' (--patch | -p) [<tree-ish>] [--] [<paths>...]
 'git reset' [--soft | --mixed [-N] | --hard | --merge | --keep] [-q] [<commit>]
 
@@ -97,6 +97,14 @@ OPTIONS
 --quiet::
 	Be quiet, only report errors.
 
+--stdin::
+	Instead of taking list of paths from the command line,
+	read list of paths from the standard input.  Paths are
+	separated by LF (i.e. one path per line) by default.
+
+-z::
+	Only meaningful with `--stdin`; paths are separated with
+	NUL character instead of LF.
 
 EXAMPLES
 --------
diff --git a/builtin/reset.c b/builtin/reset.c
index c04ac07..018735f 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -21,10 +21,12 @@
 #include "parse-options.h"
 #include "unpack-trees.h"
 #include "cache-tree.h"
+#include "strbuf.h"
+#include "quote.h"
 
 static const char * const git_reset_usage[] = {
 	N_("git reset [--mixed | --soft | --hard | --merge | --keep] [-q] [<commit>]"),
-	N_("git reset [-q] [<tree-ish>] [--] <paths>..."),
+	N_("git reset [-q] [--stdin [-z]] [<tree-ish>] [--] <paths>..."),
 	N_("git reset --patch [<tree-ish>] [--] [<paths>...]"),
 	NULL
 };
@@ -267,7 +269,9 @@ static int reset_refs(const char *rev, const struct object_id *oid)
 int cmd_reset(int argc, const char **argv, const char *prefix)
 {
 	int reset_type = NONE, update_ref_status = 0, quiet = 0;
-	int patch_mode = 0, unborn;
+	int patch_mode = 0, nul_term_line = 0, read_from_stdin = 0, unborn;
+	char **stdin_paths = NULL;
+	int stdin_nr = 0, stdin_alloc = 0;
 	const char *rev;
 	struct object_id oid;
 	struct pathspec pathspec;
@@ -286,6 +290,10 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 		OPT_BOOL('p', "patch", &patch_mode, N_("select hunks interactively")),
 		OPT_BOOL('N', "intent-to-add", &intent_to_add,
 				N_("record only the fact that removed paths will be added later")),
+		OPT_BOOL('z', NULL, &nul_term_line,
+			N_("paths are separated with NUL character")),
+		OPT_BOOL(0, "stdin", &read_from_stdin,
+				N_("read paths from <stdin>")),
 		OPT_END()
 	};
 
@@ -295,6 +303,44 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 						PARSE_OPT_KEEP_DASHDASH);
 	parse_args(&pathspec, argv, prefix, patch_mode, &rev);
 
+	if (read_from_stdin) {
+		strbuf_getline_fn getline_fn = nul_term_line ?
+			strbuf_getline_nul : strbuf_getline_lf;
+		int flags = PATHSPEC_PREFER_FULL |
+			PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP;
+		struct strbuf buf = STRBUF_INIT;
+		struct strbuf unquoted = STRBUF_INIT;
+
+		if (patch_mode)
+			die(_("--stdin is incompatible with --patch"));
+
+		if (pathspec.nr)
+			die(_("--stdin is incompatible with path arguments"));
+
+		if (patch_mode)
+			flags |= PATHSPEC_PREFIX_ORIGIN;
+
+		while (getline_fn(&buf, stdin) != EOF) {
+			if (!nul_term_line && buf.buf[0] == '"') {
+				strbuf_reset(&unquoted);
+				if (unquote_c_style(&unquoted, buf.buf, NULL))
+					die(_("line is badly quoted"));
+				strbuf_swap(&buf, &unquoted);
+			}
+			ALLOC_GROW(stdin_paths, stdin_nr + 1, stdin_alloc);
+			stdin_paths[stdin_nr++] = xstrdup(buf.buf);
+			strbuf_reset(&buf);
+		}
+		strbuf_release(&unquoted);
+		strbuf_release(&buf);
+
+		ALLOC_GROW(stdin_paths, stdin_nr + 1, stdin_alloc);
+		stdin_paths[stdin_nr++] = NULL;
+		parse_pathspec(&pathspec, 0, flags, prefix,
+			       (const char **)stdin_paths);
+	} else if (nul_term_line)
+		die(_("-z requires --stdin"));
+
 	unborn = !strcmp(rev, "HEAD") && get_sha1("HEAD", oid.hash);
 	if (unborn) {
 		/* reset on unborn branch: treat as reset to empty tree */
@@ -385,5 +431,11 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (!pathspec.nr)
 		remove_branch_state();
 
+	if (stdin_paths) {
+		while (stdin_nr)
+			free(stdin_paths[--stdin_nr]);
+		free(stdin_paths);
+	}
+
 	return update_ref_status;
 }
diff --git a/t/t7107-reset-stdin.sh b/t/t7107-reset-stdin.sh
new file mode 100755
index 0000000..997dc42
--- /dev/null
+++ b/t/t7107-reset-stdin.sh
@@ -0,0 +1,33 @@
+#!/bin/sh
+
+test_description='reset --stdin'
+
+. ./test-lib.sh
+
+test_expect_success 'reset --stdin' '
+	test_commit hello &&
+	git rm hello.t &&
+	test -z "$(git ls-files hello.t)" &&
+	echo hello.t | git reset --stdin &&
+	test hello.t = "$(git ls-files hello.t)"
+'
+
+test_expect_success 'reset --stdin -z' '
+	test_commit world &&
+	git rm hello.t world.t &&
+	test -z "$(git ls-files hello.t world.t)" &&
+	printf world.tQworld.tQhello.tQ | q_to_nul | git reset --stdin -z &&
+	printf "hello.t\nworld.t\n" >expect &&
+	git ls-files >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--stdin requires --mixed' '
+	echo hello.t >list &&
+	test_must_fail git reset --soft --stdin <list &&
+	test_must_fail git reset --hard --stdin <list &&
+	git reset --mixed --stdin <list
+'
+
+test_done
+
-- 
2.10.1.513.g00ef6dd