From e169dbe7c20ed4b4b1acf80c8e03e9aa58a60836 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Fri, 6 Nov 2020 18:42:26 +0100
Subject: add cpr function, basic setup

---
 Makefile |   4 ++
 l.c      | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+)
 create mode 100644 Makefile
 create mode 100644 l.c

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..62f142f
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,4 @@
+all: l
+
+%: %c
+	gcc -o $@ $<
diff --git a/l.c b/l.c
new file mode 100644
index 0000000..2248da6
--- /dev/null
+++ b/l.c
@@ -0,0 +1,137 @@
+#include <ctype.h>
+#include <err.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/ttydefaults.h>
+#include <termios.h>
+#include <unistd.h>
+
+#define ESC "\033"
+#define CSI ESC "["
+
+int ttyfd;
+
+/* enable/disable "raw" mode */
+void raw(bool enable) {
+	int r;
+	static struct termios orig;
+	struct termios raw;
+
+	if (enable) {
+		r = tcgetattr(0, &orig);
+		if (r == -1) err(1, "tcgetattr");
+
+		raw = orig;
+		raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
+		raw.c_oflag &= ~OPOST;
+		raw.c_cflag |= CS8;
+		raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
+
+		r = tcsetattr(0, TCSAFLUSH, &raw);
+		if (r == -1) err(1, "tcsetattr");
+
+	} else
+		tcsetattr(0, TCSAFLUSH, &orig);
+}
+
+/* cursor position report */
+int cpr(int *x, int *y) {
+	char c, xbuf[4], ybuf[4];
+	int i;
+
+	write (1, CSI "6n", 2+2);
+
+	/* get CSI */
+	read(1, &c, 1);
+	if (c != '\033') return -1;
+	read(1, &c, 1);
+	if (c != '[') return -1;
+
+	/* get x */
+	i = 0;
+	while (read(1, &c, 1) && c != ';') {
+		if (i > 3 || !isdigit(c)) return -1;
+		ybuf[i++] = c;
+	}
+	if (i == 0) return -1;
+	ybuf[i] = '\0';
+
+	/* get y */
+	i = 0;
+	while (read(1, &c, 1) && c != 'R') {
+		if (i > 3 || !isdigit(c)) return -1;
+		xbuf[i++] = c;
+	}
+	if (i == 0) return -1;
+	xbuf[i] = '\0';
+
+	*x = atoi(xbuf);
+	*y = atoi(ybuf);
+
+	return 0;
+}
+
+void up() {}
+void down() {}
+void right() {}
+void left() {}
+
+int main() {
+	char c, *p;
+	char *ex = "file1 file2 file3\r\nfile4 file5 file6\r\nfile7";
+	int i, r, x, x2, y, y2;
+	struct winsize w;
+
+	ttyfd = open("/dev/tty", O_RDWR);
+	if (ttyfd == -1) err(1, "open");
+
+	raw(true);
+
+	/* save original cursor position */
+	r = cpr(&x, &y);
+	if (r == -1) goto quit;
+
+	/* print output */
+	dprintf(ttyfd, "%s", ex);
+
+	/* get height of output */
+	p = ex - 1;
+	i = 0;
+	while (*(++p) != '\0')
+		if (*p == '\n') i++;
+
+	/* get height of terminal */
+	r = ioctl(ttyfd, TIOCGWINSZ, &w);
+	if (r == -1) err(1, "ioctl");
+
+	/* correct cursor position if original cursor was near bottom */
+	r = y + i - w.ws_row;
+	if (r > 0)
+		y = y - r;
+
+	/* restore original cursor position */
+	dprintf(ttyfd, "%s%d;%dH", CSI, y, x); /* restore cursor position (CUP) */
+
+	while (read(0, &c, 1) != 0) {
+		switch (c) {
+		case 'q':
+			goto quit;
+			break;
+		case '\033':
+			read(0, &c, 1);
+			if (c != '[') break;
+			read(0, &c, 1);
+			if (c == 'A') up();
+			if (c == 'B') down();
+			if (c == 'C') right();
+			if (c == 'D') left();
+			break;
+		}
+	}
+	
+quit:
+	raw(false);
+}
-- 
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