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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 <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"

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

    set_progname(argv[0]);

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

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

    if (argc > 2) {
      fprintf(stderr, _("usage: screendump [n]\n"));
      exit(1);
    }

    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) != rows*cols*2) {
        fprintf(stderr, _("Error reading %s\n"), infile);
        exit(1);
    }
    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)) {
          perror("TIOCGWINSZ");
          exit(1);
      }

      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 */
          fprintf(stderr,_("couldn't read %s\n"), infile);
#endif
          exit(1);
      }

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

      outbuf = xmalloc(rows*(cols+1));
      p = 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) {
        fprintf(stderr, _("Error writing screendump\n"));
        exit(1);
    }
    exit(0);
}

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