1 files changed, 388 insertions, 0 deletions
diff --git a/compat/terminal.c b/compat/terminal.c
new file mode 100644
index 0000000000..43b73ddc75
--- /dev/null
+++ b/compat/terminal.c
@@ -0,0 +1,388 @@
+#include "git-compat-util.h"
+#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)
+
+static void restore_term(void);
+
+static void restore_term_on_signal(int sig)
+{
+	restore_term();
+	sigchain_pop(sig);
+	raise(sig);
+}
+
+#ifdef HAVE_DEV_TTY
+
+#define INPUT_PATH "/dev/tty"
+#define OUTPUT_PATH "/dev/tty"
+
+static int term_fd = -1;
+static struct termios old_term;
+
+static void restore_term(void)
+{
+	if (term_fd < 0)
+		return;
+
+	tcsetattr(term_fd, TCSAFLUSH, &old_term);
+	close(term_fd);
+	term_fd = -1;
+}
+
+static int disable_bits(tcflag_t bits)
+{
+	struct termios t;
+
+	term_fd = open("/dev/tty", O_RDWR);
+	if (tcgetattr(term_fd, &t) < 0)
+		goto error;
+
+	old_term = t;
+	sigchain_push_common(restore_term_on_signal);
+
+	t.c_lflag &= ~bits;
+	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
+		return 0;
+
+error:
+	close(term_fd);
+	term_fd = -1;
+	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;
+
+		strvec_push(&cp.args, "stty");
+		for (i = 0; i < stty_restore.nr; i++)
+			strvec_push(&cp.args, stty_restore.items[i].string);
+		run_command(&cp);
+		string_list_clear(&stty_restore, 0);
+		return;
+	}
+
+	if (hconin == INVALID_HANDLE_VALUE)
+		return;
+
+	SetConsoleMode(hconin, cmode);
+	CloseHandle(hconin);
+	hconin = INVALID_HANDLE_VALUE;
+}
+
+static int disable_bits(DWORD bits)
+{
+	if (use_stty) {
+		struct child_process cp = CHILD_PROCESS_INIT;
+
+		strvec_push(&cp.args, "stty");
+
+		if (bits & ENABLE_LINE_INPUT) {
+			string_list_append(&stty_restore, "icanon");
+			strvec_push(&cp.args, "-icanon");
+		}
+
+		if (bits & ENABLE_ECHO_INPUT) {
+			string_list_append(&stty_restore, "echo");
+			strvec_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");
+			strvec_push(&cp.args, "ignbrk");
+			strvec_push(&cp.args, "intr");
+			strvec_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);
+	if (hconin == INVALID_HANDLE_VALUE)
+		return -1;
+
+	GetConsoleMode(hconin, &cmode);
+	sigchain_push_common(restore_term_on_signal);
+	if (!SetConsoleMode(hconin, cmode & ~bits)) {
+		CloseHandle(hconin);
+		hconin = INVALID_HANDLE_VALUE;
+		return -1;
+	}
+
+	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
+#define FORCE_TEXT
+#endif
+
+char *git_terminal_prompt(const char *prompt, int echo)
+{
+	static struct strbuf buf = STRBUF_INIT;
+	int r;
+	FILE *input_fh, *output_fh;
+
+	input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
+	if (!input_fh)
+		return NULL;
+
+	output_fh = fopen(OUTPUT_PATH, "w" FORCE_TEXT);
+	if (!output_fh) {
+		fclose(input_fh);
+		return NULL;
+	}
+
+	if (!echo && disable_echo()) {
+		fclose(input_fh);
+		fclose(output_fh);
+		return NULL;
+	}
+
+	fputs(prompt, output_fh);
+	fflush(output_fh);
+
+	r = strbuf_getline_lf(&buf, input_fh);
+	if (!echo) {
+		putc('\n', output_fh);
+		fflush(output_fh);
+	}
+
+	restore_term();
+	fclose(input_fh);
+	fclose(output_fh);
+
+	if (r == EOF)
+		return NULL;
+	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);
+
+		strvec_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)
+{
+	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