git/compat/terminal.c

#ifndef NO_INTTYPES_H
#include <inttypes.h>
#endif
#include "git-compat-util.h"
#include "run-command.h"
#include "compat/terminal.h"
#include "sigchain.h"
#include "strbuf.h"
#include "cache.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_echo(void)
{
	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 &= ~ECHO;
	if (!tcsetattr(term_fd, TCSAFLUSH, &t))
		return 0;

error:
	close(term_fd);
	term_fd = -1;
	return -1;
}

#elif defined(GIT_WINDOWS_NATIVE)

#define INPUT_PATH "CONIN$"
#define OUTPUT_PATH "CONOUT$"
#define FORCE_TEXT "t"

static HANDLE hconin = INVALID_HANDLE_VALUE;
static DWORD cmode;

static void restore_term(void)
{
	if (hconin == INVALID_HANDLE_VALUE)
		return;

	SetConsoleMode(hconin, cmode);
	CloseHandle(hconin);
	hconin = INVALID_HANDLE_VALUE;
}

static int set_echo(int echo)
{
	DWORD new_cmode;

	if (hconin == INVALID_HANDLE_VALUE)
		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);
	new_cmode = cmode | ENABLE_LINE_INPUT;
	if (echo)
		new_cmode |= ENABLE_ECHO_INPUT;
	else
		new_cmode &= ~ENABLE_ECHO_INPUT;

	sigchain_push_common(restore_term_on_signal);
	if (!SetConsoleMode(hconin, new_cmode)) {
		CloseHandle(hconin);
		hconin = INVALID_HANDLE_VALUE;
		return -1;
	}

	return 0;
}

static int disable_echo(void)
{
	return set_echo(0);
}

static char *shell_prompt(const char *prompt, int echo)
{
	const char *read_input[] = {
		/* Note: call 'bash' explicitly, as 'read -s' is bash-specific */
		"bash", "-c", echo ?
		"test \"a$SHELL\" != \"a${SHELL%.exe}\" || exit 127; cat >/dev/tty &&"
		" read -r line </dev/tty && echo \"$line\"" :
		"test \"a$SHELL\" != \"a${SHELL%.exe}\" || exit 127; cat >/dev/tty &&"
		" read -r -s line </dev/tty && echo \"$line\" && echo >/dev/tty",
		NULL
	};
	struct child_process child = CHILD_PROCESS_INIT;
	static struct strbuf buffer = STRBUF_INIT;
	int prompt_len = strlen(prompt), len = -1, code;

	child.argv = read_input;
	child.in = -1;
	child.out = -1;
	child.silent_exec_failure = 1;

	if (start_command(&child))
		return NULL;

	if (write_in_full(child.in, prompt, prompt_len) != prompt_len) {
		error("could not write to prompt script");
		close(child.in);
		goto ret;
	}
	close(child.in);

	strbuf_reset(&buffer);
	len = strbuf_read(&buffer, child.out, 1024);
	if (len < 0) {
		error("could not read from prompt script");
		goto ret;
	}

	strbuf_strip_suffix(&buffer, "\n");
	strbuf_strip_suffix(&buffer, "\r");

ret:
	close(child.out);
	code = finish_command(&child);
	if (code) {
		if (code != 127)
			error("failed to execute prompt script (exit code %d)",
			      code);

		return NULL;
	}

	return len < 0 ? NULL : buffer.buf;
}

#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;

#ifdef GIT_WINDOWS_NATIVE

	/* try shell_prompt first, fall back to CONIN/OUT if bash is missing */
	char *result = shell_prompt(prompt, echo);
	if (result)
		return result;

	if (echo && set_echo(1))
		return NULL;
#endif

	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;
}

#else

char *git_terminal_prompt(const char *prompt, int echo)
{
	return getpass(prompt);
}

#endif