minix/commands/screendump/screendump.c
2010-07-06 12:10:23 +00:00

136 lines
3 KiB
C

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