src/screendump.c

/*
 * screendump.c - aeb 950214
 *
 * [Note: similar functionality can be found in setterm]
 *
 * Call: "screendump N" when the screen of /dev/ttyN has to be dumped
 *
 * On Linux up to 1.1.91 there is an ioctl that will do the dumping.
 * Because of problems with security this has been scrapped.
 * From 1.1.92 on, make devices "virtual console screen" and
 * "virtual console screen with attributes" by (fill in the ellipses):
 *	cd /dev
 *	for i in 0 1 2 3 ...; do
 *		mknod vcs$i c 7 $i
 *		mknod vcsa$i c 7 `expr 128 + $i`
 *	done
 * and give them your favourite owners and permissions.
 */
#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include "xmalloc.h"
#include "nls.h"
#include "version.h"
#include "kbd_error.h"

int main(int argc, char **argv)
{
	int cons = 0;
	char infile[20];
	unsigned char header[4];
	unsigned int rows, cols;
	int fd;
	unsigned int i, j;
	char *inbuf, *outbuf, *p, *q;

	set_progname(argv[0]);

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE_NAME, LOCALEDIR);
	textdomain(PACKAGE_NAME);

	if (argc == 2 && !strcmp(argv[1], "-V"))
		print_version_and_exit();

	if (argc > 2) {
		fprintf(stderr, _("usage: screendump [n]\n"));
		exit(EXIT_FAILURE);
	}

	cons = (argc == 2) ? atoi(argv[1]) : 0;

	sprintf(infile, "/dev/vcsa%d", cons);
	fd = open(infile, O_RDONLY);
	if (fd < 0 && cons == 0 && errno == ENOENT) {
		sprintf(infile, "/dev/vcsa");
		fd = open(infile, O_RDONLY);
	}
	if (fd < 0 && errno == ENOENT) {
		sprintf(infile, "/dev/vcs/a%d", cons);
		fd = open(infile, O_RDONLY);
	}
	if (fd < 0 && cons == 0 && errno == ENOENT) {
		sprintf(infile, "/dev/vcs/a");
		fd = open(infile, O_RDONLY);
	}
	if (fd < 0 || read(fd, header, 4) != 4)
		goto try_ioctl;
	rows = header[0];
	cols = header[1];
	if (rows * cols == 0)
		goto try_ioctl;
	inbuf  = xmalloc(rows * cols * 2);
	outbuf = xmalloc(rows * (cols + 1));

	if (read(fd, inbuf, rows * cols * 2) != (ssize_t)(rows * cols * 2)) {
		kbd_error(EXIT_FAILURE, errno, _("Error reading %s"), infile);
	}
	p = inbuf;
	q = outbuf;
	for (i = 0; i < rows; i++) {
		for (j = 0; j < cols; j++) {
			*q++ = *p;
			p += 2;
		}
		while (j-- > 0 && q[-1] == ' ')
			q--;
		*q++ = '\n';
	}
	goto done;

try_ioctl : {
	struct winsize win;
	char consnam[20], devfsconsnam[20];
	unsigned char *screenbuf;

	sprintf(consnam, "/dev/tty%d", cons);
	fd = open(consnam, O_RDONLY);
	if (fd < 0 && errno == ENOENT) {
		sprintf(devfsconsnam, "/dev/vc/%d", cons);
		fd = open(devfsconsnam, O_RDONLY);
		if (fd < 0)
			errno = ENOENT;
	}
	if (fd < 0) {
		perror(consnam);
		fd = 0;
	}

	if (ioctl(fd, TIOCGWINSZ, &win)) {
		kbd_error(EXIT_FAILURE, errno, "ioctl TIOCGWINSZ");
	}

	screenbuf    = xmalloc(2 + win.ws_row * win.ws_col);
	screenbuf[0] = 0;
	screenbuf[1] = (unsigned char)cons;

	if (ioctl(fd, TIOCLINUX, screenbuf) &&
	    (!fd || ioctl(0, TIOCLINUX, screenbuf))) {
#if 0
	    perror("TIOCLINUX");
	    fprintf(stderr,_("couldn't read %s, and cannot ioctl dump\n"),
		    infile);
#else
		/* we tried this just to be sure, but TIOCLINUX
	       function 0 has been disabled since 1.1.92
	       Do not mention `ioctl dump' in error msg */
		kbd_warning(0, _("couldn't read %s\n"), infile);
#endif
		return EXIT_FAILURE;
	}

	rows = screenbuf[0];
	cols = screenbuf[1];
	if (rows != win.ws_row || cols != win.ws_col) {
		kbd_error(EXIT_FAILURE, 0,
		          _("Strange ... screen is both %dx%d and %dx%d ??\n"),
		          win.ws_col, win.ws_row, cols, rows);
	}

	outbuf = xmalloc(rows * (cols + 1));
	p      = ((char *)screenbuf) + 2;
	q      = outbuf;
	for (i = 0; i < rows; i++) {
		for (j = 0; j < cols; j++)
			*q++ = *p++;
		while (j-- > 0 && (q[-1] == ' '))
			q--;
		*q++ = '\n';
	}
}
done:
	if (write(1, outbuf, q - outbuf) != q - outbuf) {
		kbd_error(EXIT_FAILURE, 0, _("Error writing screendump\n"));
	}

	return EXIT_SUCCESS;
}