Merge branch 'js/add-p-leftover-bits'

The final leg of rewriting "add -i/-p" in C.

* js/add-p-leftover-bits:
  ci: include the built-in `git add -i` in the `linux-gcc` job
  built-in add -p: handle Escape sequences more efficiently
  built-in add -p: handle Escape sequences in interactive.singlekey mode
  built-in add -p: respect the `interactive.singlekey` config setting
  terminal: add a new function to read a single keystroke
  terminal: accommodate Git for Windows' default terminal
  terminal: make the code of disable_echo() reusable
  built-in add -p: handle diff.algorithm
  built-in add -p: support interactive.diffFilter
  t3701: adjust difffilter test

7 files changed, 326 insertions, 9 deletions

diff --git a/add-interactive.c b/add-interactive.c
index 577cef3842..4a9bf85cac 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -52,6 +52,24 @@ void init_add_i_state(struct add_i_state *s, struct repository *r)
 		diff_get_color(s->use_color, DIFF_FILE_OLD));
 	init_color(r, s, "new", s->file_new_color,
 		diff_get_color(s->use_color, DIFF_FILE_NEW));
+
+	FREE_AND_NULL(s->interactive_diff_filter);
+	git_config_get_string("interactive.difffilter",
+			      &s->interactive_diff_filter);
+
+	FREE_AND_NULL(s->interactive_diff_algorithm);
+	git_config_get_string("diff.algorithm",
+			      &s->interactive_diff_algorithm);
+
+	git_config_get_bool("interactive.singlekey", &s->use_single_key);
+}
+
+void clear_add_i_state(struct add_i_state *s)
+{
+	FREE_AND_NULL(s->interactive_diff_filter);
+	FREE_AND_NULL(s->interactive_diff_algorithm);
+	memset(s, 0, sizeof(*s));
+	s->use_color = -1;
 }
 
 /*
@@ -1152,6 +1170,7 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&print_file_item_data.worktree);
 	strbuf_release(&header);
 	prefix_item_list_clear(&commands);
+	clear_add_i_state(&s);
 
 	return res;
 }
diff --git a/add-interactive.h b/add-interactive.h
index b2f23479c5..693f125e8e 100644
--- a/add-interactive.h
+++ b/add-interactive.h
@@ -15,9 +15,13 @@ struct add_i_state {
 	char context_color[COLOR_MAXLEN];
 	char file_old_color[COLOR_MAXLEN];
 	char file_new_color[COLOR_MAXLEN];
+
+	int use_single_key;
+	char *interactive_diff_filter, *interactive_diff_algorithm;
 };
 
 void init_add_i_state(struct add_i_state *s, struct repository *r);
+void clear_add_i_state(struct add_i_state *s);
 
 struct repository;
 struct pathspec;
diff --git a/add-patch.c b/add-patch.c
index 46c6c183d5..d8dafa8168 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -6,6 +6,7 @@
 #include "pathspec.h"
 #include "color.h"
 #include "diff.h"
+#include "compat/terminal.h"
 
 enum prompt_mode_type {
 	PROMPT_MODE_CHANGE = 0, PROMPT_DELETION, PROMPT_HUNK,
@@ -360,6 +361,7 @@ static int is_octal(const char *p, size_t len)
 static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 {
 	struct argv_array args = ARGV_ARRAY_INIT;
+	const char *diff_algorithm = s->s.interactive_diff_algorithm;
 	struct strbuf *plain = &s->plain, *colored = NULL;
 	struct child_process cp = CHILD_PROCESS_INIT;
 	char *p, *pend, *colored_p = NULL, *colored_pend = NULL, marker = '\0';
@@ -369,6 +371,8 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 	int res;
 
 	argv_array_pushv(&args, s->mode->diff_cmd);
+	if (diff_algorithm)
+		argv_array_pushf(&args, "--diff-algorithm=%s", diff_algorithm);
 	if (s->revision) {
 		struct object_id oid;
 		argv_array_push(&args,
@@ -398,6 +402,7 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 
 	if (want_color_fd(1, -1)) {
 		struct child_process colored_cp = CHILD_PROCESS_INIT;
+		const char *diff_filter = s->s.interactive_diff_filter;
 
 		setup_child_process(s, &colored_cp, NULL);
 		xsnprintf((char *)args.argv[color_arg_index], 8, "--color");
@@ -407,6 +412,24 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		argv_array_clear(&args);
 		if (res)
 			return error(_("could not parse colored diff"));
+
+		if (diff_filter) {
+			struct child_process filter_cp = CHILD_PROCESS_INIT;
+
+			setup_child_process(s, &filter_cp,
+					    diff_filter, NULL);
+			filter_cp.git_cmd = 0;
+			filter_cp.use_shell = 1;
+			strbuf_reset(&s->buf);
+			if (pipe_command(&filter_cp,
+					 colored->buf, colored->len,
+					 &s->buf, colored->len,
+					 NULL, 0) < 0)
+				return error(_("failed to run '%s'"),
+					     diff_filter);
+			strbuf_swap(colored, &s->buf);
+		}
+
 		strbuf_complete_line(colored);
 		colored_p = colored->buf;
 		colored_pend = colored_p + colored->len;
@@ -531,6 +554,9 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 						   colored_pend - colored_p);
 			if (colored_eol)
 				colored_p = colored_eol + 1;
+			else if (p != pend)
+				/* colored shorter than non-colored? */
+				goto mismatched_output;
 			else
 				colored_p = colored_pend;
 
@@ -555,6 +581,15 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 		 */
 		hunk->splittable_into++;
 
+	/* non-colored shorter than colored? */
+	if (colored_p != colored_pend) {
+mismatched_output:
+		error(_("mismatched output from interactive.diffFilter"));
+		advise(_("Your filter must maintain a one-to-one correspondence\n"
+			 "between its input and output lines."));
+		return -1;
+	}
+
 	return 0;
 }
 
@@ -1115,14 +1150,27 @@ static int run_apply_check(struct add_p_state *s,
 	return 0;
 }
 
+static int read_single_character(struct add_p_state *s)
+{
+	if (s->s.use_single_key) {
+		int res = read_key_without_echo(&s->answer);
+		printf("%s\n", res == EOF ? "" : s->answer.buf);
+		return res;
+	}
+
+	if (strbuf_getline(&s->answer, stdin) == EOF)
+		return EOF;
+	strbuf_trim_trailing_newline(&s->answer);
+	return 0;
+}
+
 static int prompt_yesno(struct add_p_state *s, const char *prompt)
 {
 	for (;;) {
 		color_fprintf(stdout, s->s.prompt_color, "%s", _(prompt));
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			return -1;
-		strbuf_trim_trailing_newline(&s->answer);
 		switch (tolower(s->answer.buf[0])) {
 		case 'n': return 0;
 		case 'y': return 1;
@@ -1362,9 +1410,8 @@ static int patch_update_file(struct add_p_state *s,
 			      _(s->mode->prompt_mode[prompt_mode_type]),
 			      s->buf.buf);
 		fflush(stdout);
-		if (strbuf_getline(&s->answer, stdin) == EOF)
+		if (read_single_character(s) == EOF)
 			break;
-		strbuf_trim_trailing_newline(&s->answer);
 
 		if (!s->answer.len)
 			continue;
@@ -1612,6 +1659,7 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
 		strbuf_release(&s.colored);
+		clear_add_i_state(&s.s);
 		return -1;
 	}
 
@@ -1630,5 +1678,6 @@ int run_add_p(struct repository *r, enum add_p_mode mode,
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
 	strbuf_release(&s.colored);
+	clear_add_i_state(&s.s);
 	return 0;
 }
diff --git a/ci/run-build-and-tests.sh b/ci/run-build-and-tests.sh
index ff0ef7f08e..4df54c4efe 100755
--- a/ci/run-build-and-tests.sh
+++ b/ci/run-build-and-tests.sh
@@ -20,6 +20,7 @@ linux-gcc)
 	export GIT_TEST_OE_DELTA_SIZE=5
 	export GIT_TEST_COMMIT_GRAPH=1
 	export GIT_TEST_MULTI_PACK_INDEX=1
+	export GIT_TEST_ADD_I_USE_BUILTIN=1
 	make test
 	;;
 linux-gcc-4.8)
diff --git a/compat/terminal.c b/compat/terminal.c
index fa13ee672d..35bca03d14 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -2,6 +2,9 @@
 #include "compat/terminal.h"
 #include "sigchain.h"
 #include "strbuf.h"
+#include "run-command.h"
+#include "string-list.h"
+#include "hashmap.h"
 
 #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
 
@@ -32,7 +35,7 @@ static void restore_term(void)
 	term_fd = -1;
 }
 
-static int disable_echo(void)
+static int disable_bits(tcflag_t bits)
 {
 	struct termios t;
 
@@ -43,7 +46,7 @@ static int disable_echo(void)
 	old_term = t;
 	sigchain_push_common(restore_term_on_signal);
 
-	t.c_lflag &= ~ECHO;
+	t.c_lflag &= ~bits;
 	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
 		return 0;
 
@@ -53,17 +56,44 @@ error:
 	return -1;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ECHO);
+}
+
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"
 #define OUTPUT_PATH "CONOUT$"
 #define FORCE_TEXT "t"
 
+static int use_stty = 1;
+static struct string_list stty_restore = STRING_LIST_INIT_DUP;
 static HANDLE hconin = INVALID_HANDLE_VALUE;
 static DWORD cmode;
 
 static void restore_term(void)
 {
+	if (use_stty) {
+		int i;
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		if (stty_restore.nr == 0)
+			return;
+
+		argv_array_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			argv_array_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
 	if (hconin == INVALID_HANDLE_VALUE)
 		return;
 
@@ -72,8 +102,39 @@ static void restore_term(void)
 	hconin = INVALID_HANDLE_VALUE;
 }
 
-static int disable_echo(void)
+static int disable_bits(DWORD bits)
 {
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		argv_array_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			argv_array_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			argv_array_push(&cp.args, "-echo");
+		}
+
+		if (bits & ENABLE_PROCESSED_INPUT) {
+			string_list_append(&stty_restore, "-ignbrk");
+			string_list_append(&stty_restore, "intr");
+			string_list_append(&stty_restore, "^c");
+			argv_array_push(&cp.args, "ignbrk");
+			argv_array_push(&cp.args, "intr");
+			argv_array_push(&cp.args, "");
+		}
+
+		if (run_command(&cp) == 0)
+			return 0;
+
+		/* `stty` could not be executed; access the Console directly */
+		use_stty = 0;
+	}
+
 	hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
 	    FILE_SHARE_READ, NULL, OPEN_EXISTING,
 	    FILE_ATTRIBUTE_NORMAL, NULL);
@@ -82,7 +143,7 @@ static int disable_echo(void)
 
 	GetConsoleMode(hconin, &cmode);
 	sigchain_push_common(restore_term_on_signal);
-	if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) {
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
 		CloseHandle(hconin);
 		hconin = INVALID_HANDLE_VALUE;
 		return -1;
@@ -91,6 +152,47 @@ static int disable_echo(void)
 	return 0;
 }
 
+static int disable_echo(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT);
+}
+
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
+
+/*
+ * Override `getchar()`, as the default implementation does not use
+ * `ReadFile()`.
+ *
+ * This poses a problem when we want to see whether the standard
+ * input has more characters, as the default of Git for Windows is to start the
+ * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
+ * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
+ * `ReadFile()` to be called first to work properly (it only reports 0
+ * available bytes, otherwise).
+ *
+ * So let's just override `getchar()` with a version backed by `ReadFile()` and
+ * go our merry ways from here.
+ */
+static int mingw_getchar(void)
+{
+	DWORD read = 0;
+	unsigned char ch;
+
+	if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
+		return EOF;
+
+	if (!read) {
+		error("Unexpected 0 read");
+		return EOF;
+	}
+
+	return ch;
+}
+#define getchar mingw_getchar
+
 #endif
 
 #ifndef FORCE_TEXT
@@ -137,6 +239,126 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+/*
+ * The `is_known_escape_sequence()` function returns 1 if the passed string
+ * corresponds to an Escape sequence that the terminal capabilities contains.
+ *
+ * To avoid depending on ncurses or other platform-specific libraries, we rely
+ * on the presence of the `infocmp` executable to do the job for us (failing
+ * silently if the program is not available or refused to run).
+ */
+struct escape_sequence_entry {
+	struct hashmap_entry entry;
+	char sequence[FLEX_ARRAY];
+};
+
+static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
+			      const struct escape_sequence_entry *e1,
+			      const struct escape_sequence_entry *e2,
+			      const void *keydata)
+{
+	return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
+}
+
+static int is_known_escape_sequence(const char *sequence)
+{
+	static struct hashmap sequences;
+	static int initialized;
+
+	if (!initialized) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		char *p, *eol;
+
+		hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
+			     NULL, 0);
+
+		argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
+		if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
+			strbuf_setlen(&buf, 0);
+
+		for (eol = p = buf.buf; *p; p = eol + 1) {
+			p = strchr(p, '=');
+			if (!p)
+				break;
+			p++;
+			eol = strchrnul(p, '\n');
+
+			if (starts_with(p, "\\E")) {
+				char *comma = memchr(p, ',', eol - p);
+				struct escape_sequence_entry *e;
+
+				p[0] = '^';
+				p[1] = '[';
+				FLEX_ALLOC_MEM(e, sequence, p, comma - p);
+				hashmap_entry_init(&e->entry,
+						   strhash(e->sequence));
+				hashmap_add(&sequences, &e->entry);
+			}
+			if (!*eol)
+				break;
+		}
+		initialized = 1;
+	}
+
+	return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
+}
+
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+	strbuf_addch(buf, ch);
+
+	if (ch == '\033' /* ESC */) {
+		/*
+		 * We are most likely looking at an Escape sequence. Let's try
+		 * to read more bytes, waiting at most half a second, assuming
+		 * that the sequence is complete if we did not receive any byte
+		 * within that time.
+		 *
+		 * Start by replacing the Escape byte with ^[ */
+		strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
+
+		/*
+		 * Query the terminal capabilities once about all the Escape
+		 * sequences it knows about, so that we can avoid waiting for
+		 * half a second when we know that the sequence is complete.
+		 */
+		while (!is_known_escape_sequence(buf->buf)) {
+			struct pollfd pfd = { .fd = 0, .events = POLLIN };
+
+			if (poll(&pfd, 1, 500) < 1)
+				break;
+
+			ch = getchar();
+			if (ch == EOF)
+				return 0;
+			strbuf_addch(buf, ch);
+		}
+	}
+
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)
@@ -144,4 +366,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif
diff --git a/compat/terminal.h b/compat/terminal.h
index 97db7cd69d..a9d52b8464 100644
--- a/compat/terminal.h
+++ b/compat/terminal.h
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */
diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index 2182b1c030..e36fd0a5d3 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -570,7 +570,7 @@ test_expect_success 'detect bogus diffFilter output' '
 	git reset --hard &&
 
 	echo content >test &&
-	test_config interactive.diffFilter "echo too-short" &&
+	test_config interactive.diffFilter "sed 1d" &&
 	printf y >y &&
 	test_must_fail force_color git add -p <y
 '