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#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 "["
#define prn(...) dprintf(ttyfd, __VA_ARGS__)
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;
prn(CSI "6n");
/* 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;
int i, r;
struct winsize w;
int height; /* height of output in rows */
int x, y; /* original cursor position in cols, rows */
char *ex = "file1 file2 file3\r\nfile4 file5 file6\r\nfile7";
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 */
prn("%s", ex);
/* get height of output */
p = ex - 1;
height = 0;
while (*(++p) != '\0')
if (*p == '\n') height++;
/* 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 + height - w.ws_row;
if (r > 0)
y = y - r;
/* restore original cursor position (CUP) */
prn("%s%d;%dH", CSI, y, x);
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:
prn(CSI "J"); /* delete from cursor to end of display (ED) */
raw(false);
}
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