radare2/libr/cons/utf8.c

/* radare - LGPL - Copyright 2014 - pancake */

// Copypasta from http://www.linuxquestions.org/questions/programming-9/get-cursor-position-in-c-947833/
#include <r_cons.h>
#if __UNIX__
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>

#define   RD_EOF   -1
#define   RD_EIO   -2

static inline int rd(const int fd) {
	unsigned char   buffer[4];
	ssize_t         n;

	for (;;) {
		n = read(fd, buffer, 1);
		if (n > (ssize_t)0) {
			return buffer[0];
		}
		if (n == (ssize_t)-1) {
			return RD_EOF;
		}
		if (n == (ssize_t)0) {
			return RD_EOF;
		}
		if (n != (ssize_t)-1) {
			return RD_EIO;
		}
		if (errno != EINTR && errno != EAGAIN && errno != EWOULDBLOCK) {
			return RD_EIO;
		}
	}
}

static inline int wr(const int fd, const char *const data, const size_t bytes) {
	write (fd, data, bytes);
	return 0;
	const char       *head = data;
	const char *const tail = data + bytes;
	ssize_t           n;
	while (head < tail) {
		n = write(fd, head, (size_t)(tail - head));
		if (n > (ssize_t)0) {
			head += n;
			continue;
		}
		if (n != (ssize_t)-1)
			return EIO;
		if (errno != EINTR && errno != EAGAIN && errno != EWOULDBLOCK)
			return errno;
	}

	return 0;
}

/* Return a new file descriptor to the current TTY.
 */
int current_tty(void) {
#if __WINDOWS__
	return 0;
#elif __ANDROID__
	return 1;
#else
	int fd;
	const char *dev = ttyname(STDERR_FILENO);
#if 0
	if (!dev)
		dev = ttyname(STDIN_FILENO);
	if (!dev)
		dev = ttyname(STDERR_FILENO);
#endif
	if (!dev) {
		errno = ENOTTY;
		return -1;
	}

	do {
		fd = open (dev, O_RDWR | O_NOCTTY);
	} while (fd == -1 && errno == EINTR);
	if (fd == -1)
		return -1;
	return fd;
#endif
}

/* As the tty for current cursor position.
 * This function returns 0 if success, errno code otherwise.
 * Actual errno will be unchanged.
 */
static int cursor_position(const int tty, int *const rowptr, int *const colptr) {
	struct termios  saved, temporary;
	int ret, res, rows, cols, saved_errno;

	/* Bad tty? */
	if (tty == -1)
		return ENOTTY;

	saved_errno = errno;

	/* Save current terminal settings. */
	res = tcgetattr (tty, &saved);
	if (res == -1) {
		ret = errno;
		errno = saved_errno;
		return ret;
	}

	/* Get current terminal settings for basis, too. */
	res = tcgetattr (tty, &temporary);
	if (res == -1) {
		ret = errno;
		errno = saved_errno;
		return ret;
	}

	/* Disable ICANON, ECHO, and CREAD. */
	temporary.c_lflag &= ~ICANON;
	temporary.c_lflag &= ~ECHO;
	temporary.c_cflag &= ~CREAD;

	/* This loop is only executed once. When broken out,
	 * the terminal settings will be restored, and the function
	 * will return ret to caller. It's better than goto.
	 */
	do {
		/* Set modified settings. */
		res = tcsetattr(tty, TCSANOW, &temporary);
		if (res == -1) {
			ret = errno;
			break;
		}

		/* Request cursor coordinates from the terminal. */
		ret = wr(tty, "\033[6n", 4);
		if (ret)
			break;

		/* Assume coordinate reponse parsing fails. */
		ret = EIO;

		// Read until ESC is found. previous chars, should be
		// refeeded to the terminal after finishing
		// that makes typing a command before the prompt
		// appears results in no data in it.

		/* Expect an ESC. */
		for (;;) {
			res = rd(tty);
			if (res == 27 || res < 1)
				break;
			// else store_skipped_data_from_stdin_here
		}

		/* Expect [ after the ESC. */
		res = rd(tty);
		if (res != '[')
			break;

		/* Parse rows. */
		rows = 0;
		res = rd(tty);
		while (res >= '0' && res <= '9') {
			rows = 10 * rows + res - '0';
			res = rd(tty);
		}

		if (res != ';')
			break;

		/* Parse cols. */
		cols = 0;
		res = rd(tty);
		if (res==-1)
			break;
		while (res >= '0' && res <= '9') {
			cols = 10 * cols + res - '0';
			res = rd(tty);
		}

		if (res != 'R')
			break;

		/* Success! */
		if (rowptr)
			*rowptr = rows;
		if (colptr)
			*colptr = cols;
		ret = 0;

	} while (0);

	/* Restore saved terminal settings. */
	res = tcsetattr (tty, TCSANOW, &saved);
	if (res == -1 && !ret)
		ret = errno;

	/* Done. */
	return ret;
}


R_API int r_cons_is_utf8() {
	int row = 0, col = 0;
	int row2 = 0, col2 = 0;
	int fd = current_tty();
	if (fd == -1)
		return 0;
	if (cursor_position(fd, &row, &col))
		return 0;
	write (1, "\xc3\x89\xc3\xa9", 4);
	if (cursor_position (fd, &row2, &col2))
		return 0;
	write (1, "\r    \r", 6);
	close(fd);
	return ((col2-col)==2);
}
#else
R_API int r_cons_is_utf8() {
	return 0;
}

#endif