137 lines
3.0 KiB
C
137 lines
3.0 KiB
C
/* screendump 1.2 - dump the contents of the console
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* Author: Kees J. Bot
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* 16 Dec 1994
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*/
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#define nil 0
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#include <sys/types.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <termios.h>
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#include <sys/ioctl.h>
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#define BIOS_CRTBASE 0x00463L /* BIOS parameters: CRT base. */
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#define CRTBASE_MONO 0x03B4 /* Value of CRT base for mono mode. */
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#define MONO_BASE 0xB0000L /* Screen memory in monochrome mode. */
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#define COLOR_BASE 0xB8000L /* ... colour mode. */
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#define DEF_COLS 80 /* Default screen geometry. */
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#define DEF_ROWS 25
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#define MAX_COLS 132 /* Maximum screen geometry. */
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#define MAX_ROWS 60
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char MEMORY[] = "/dev/mem"; /* Memory device to read screen. */
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int mfd; /* Open memory device. */
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void tell(const char *message)
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{
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write(2, message, strlen(message));
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}
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void fatal(const char *label)
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{
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const char *err= strerror(errno);
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tell("screendump: ");
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tell(label);
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tell(": ");
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tell(err);
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tell("\n");
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exit(1);
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}
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long video_base(void)
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/* Is it monochrome or colour? */
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{
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static unsigned short bios_crtbase;
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if (lseek(mfd, (off_t) BIOS_CRTBASE, SEEK_SET) == -1) fatal(MEMORY);
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switch (read(mfd, &bios_crtbase, sizeof(bios_crtbase))) {
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case -1:
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fatal(MEMORY);
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default:
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tell("screendump: can't obtain BIOS parameter: short read\n");
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exit(1);
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case sizeof(bios_crtbase):
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/* Fine */;
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}
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return bios_crtbase == CRTBASE_MONO ? MONO_BASE : COLOR_BASE;
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}
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void main(void)
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{
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static unsigned char screen[MAX_COLS * MAX_ROWS * 2];
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unsigned char *ps;
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long base;
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int lfd;
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int row;
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int nrows, ncols;
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struct winsize winsize;
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/* Open the memory device. */
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if ((mfd= open(MEMORY, O_RDONLY)) < 0) fatal(MEMORY);
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base= video_base();
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/* Read screen memory. */
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if (lseek(mfd, base, SEEK_SET) == -1) fatal(MEMORY);
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switch (read(mfd, screen, sizeof(screen))) {
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case -1:
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fatal(MEMORY);
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default:
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tell("screendump: can't obtain screen dump: short read\n");
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exit(1);
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case sizeof(screen):
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/* Fine */;
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}
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/* Try to obtain the screen geometry from /dev/log. */
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ncols= DEF_COLS;
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nrows= DEF_ROWS;
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if ((lfd= open("/dev/log", O_WRONLY)) != -1
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&& ioctl(lfd, TIOCGWINSZ, &winsize) == 0
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) {
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if (40 <= winsize.ws_col && winsize.ws_col <= MAX_COLS) {
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ncols= winsize.ws_col;
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}
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if (25 <= winsize.ws_row && winsize.ws_row <= MAX_COLS) {
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nrows= winsize.ws_row;
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}
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}
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if (lfd != -1) close(lfd);
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/* Print the contents of the screen line by line. Omit trailing
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* blanks. Note that screen memory consists of pairs of characters
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* and attribute bytes.
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*/
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ps= screen;
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for (row= 0; row < nrows; row++) {
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char line[MAX_COLS + 1];
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char *pl= line;
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int column;
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int blanks= 0;
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for (column= 0; column < ncols; column++) {
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if (*ps <= ' ') {
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/* Skip trailing junk. */
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blanks++;
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} else {
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/* Reinsert blanks and add a character. */
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while (blanks > 0) { *pl++= ' '; blanks--; }
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*pl++= *ps;
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}
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/* Skip character and attribute byte. */
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ps+= 2;
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}
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*pl++= '\n';
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if (write(1, line, pl - line) < 0) fatal("stdout");
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}
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exit(0);
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}
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