Date: Thu, 17 May 2001 12:19:02 +0100 From: Nik Clayton <nik@freebsd.org> To: arch@freebsd.org Subject: [PATCH] syscons ioctl() to grab text mode buffer Message-ID: <20010517121902.A3047@catkin.nothing-going-on.org>
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Two things for review.
The first set of patches add a new ioctl, CONS_SCRSHOT, to syscons.
This allows user mode programs to request a dump of the current contents
of the text mode video buffer, typically consisting of tuples of the
form (character code x video attribute).
This isn't a security problem, because it will only work on vtys that
you already have read access to.
The second, scrshot.c uses the ioctl to dump the contents of the video
memory to stdout. Usage is
scrshot /dev/ttyv0 > shot.scr
Both of these were (IIRC) originally written by jmallet back in the
2.2.x days, I've just forward-ported them to -current.
I'd like to commit both of these, with scrshot becoming
src/usr.bin/scrshot (I'll write a man page before I commit it).
There's a third utility, shot2gif which reads the screen dumps and kicks
out GIF files -- I'll bring that in as a port.
In case you're wondering, this should make it a bit easier for the doc.
project to generate accurate screenshots.
1. You don't need to be in X to do screenshots.
2. The size of the .scr files is smaller than the equivalent .gif or
.png files.
3. An accompanying shot2txt utility is trivial to write, making the
production of text only alternatives for the images much less
effort.
4. Should a screen dump need to be changed (perhaps to fix a typo),
it's easier to fix a .scr file than it is to recapture the screen.
5. shot2gif parses the same font files as syscons, giving a much
closer rendition of the output from a text screen than doing the=20
capture in X.
N
--=20
FreeBSD: The Power to Serve http://www.freebsd.org/
FreeBSD Documentation Project http://www.freebsd.org/docproj/
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Index: dev/syscons/syscons.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
RCS file: /home/ncvs/src/sys/dev/syscons/syscons.c,v
retrieving revision 1.357
diff -u -r1.357 syscons.c
--- dev/syscons/syscons.c 2001/05/01 08:12:05 1.357
+++ dev/syscons/syscons.c 2001/05/17 09:42:15
@@ -838,6 +838,24 @@
splx(s);
return 0;
=20
+ case CONS_SCRSHOT: /* get a screen shot */
+ {
+ scrshot_t *ptr =3D (scrshot_t*)data;
+ s =3D spltty();
+ if (ISGRAPHSC(scp)) {
+ splx(s);
+ return EOPNOTSUPP;
+ }
+ if (scp->xsize !=3D ptr->xsize || scp->ysize !=3D ptr->ysize) {
+ splx(s);
+ return EINVAL;
+ }
+ copyout ((void*)scp->vtb.vtb_buffer, ptr->buf,
+ ptr->xsize * ptr->ysize * sizeof(u_int16_t));
+ splx(s);
+ return 0;
+ }
+
case VT_SETMODE: /* set screen switcher mode */
{
struct vt_mode *mode;
Index: sys/consio.h
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
RCS file: /home/ncvs/src/sys/sys/consio.h,v
retrieving revision 1.6
diff -u -r1.6 consio.h
--- sys/consio.h 2000/04/27 13:34:31 1.6
+++ sys/consio.h 2001/05/16 22:54:44
@@ -239,6 +239,16 @@
/* release the current keyboard */
#define CONS_RELKBD _IO('c', 111)
=20
+/* Snapshot the current video buffer */
+#define CONS_SCRSHOT _IOWR('c', 105, scrshot_t)
+
+struct scrshot {
+ int xsize;
+ int ysize;
+ u_int16_t* buf;
+};
+typedef struct scrshot scrshot_t;
+
/* get/set the current terminal emulator info. */
#define TI_NAME_LEN 32
#define TI_DESC_LEN 64
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/*-
* Copyright (c) 2001 Nik Clayton
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer,
* without modification, immediately at the beginning of the file.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/consio.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
/*
* Given the path to a syscons terminal (e.g., "/dev/ttyv0"), tries to
* snapshot the video memory of that terminal, using the CONS_SCRSHOT
* ioctl, and writes the results to stdout.
*/
int
main(int argc, char *argv[])
{
int fd;
int result;
scrshot_t shot;
vid_info_t info;
if (argc !=3D 2)
errx(1, "improper # of args");
fd =3D open(argv[1], O_RDWR);
if (fd < 0) {
perror(argv[1]);
exit(1);
}
=09
info.size =3D sizeof(info);
result =3D ioctl(fd, CONS_GETINFO, &info);
if (result !=3D 0) {
perror("getinfo failed");
exit(1);
}
=09
shot.buf =3D malloc(info.mv_csz * info.mv_rsz * sizeof(u_int16_t));
if (!shot.buf) {
perror("couldn't allocate shot space");
exit(1);
}
=09
shot.xsize =3D info.mv_csz;
shot.ysize =3D info.mv_rsz;
result =3D ioctl (fd, CONS_SCRSHOT, &shot);
if (result !=3D 0) {
perror("CONS_SCRSHOT failed");
exit(1);
}
=09
write(1, shot.buf, shot.xsize * shot.ysize * sizeof(u_int16_t));
return 0;
}
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