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[PATCH] vcsa attribute bits -> ioctl(VT_GETHIFONTMASK) 

When reading /dev/vcsa while a font with more than 256 characters is
loaded, one of the attribute bits records the 9th bit of the character.
But depending on the console driver (vgacon or fbcon for instance), that's
bit 3 or bit 0.  And there is no way for userland to know that, thus no way
for userland to safely grab the screen content.  So here is a (tested)
patch:

Add a VT_GETHIFONTMASK ioctl for knowing which bit is the 9th bit for VC
text (vc_hi_font_mask field of the vc_data structure).

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Samuel Thibault 2006-08-27 01:23:39 -07:00 committed by Linus Torvalds
parent b8cf368944
commit 533475d3d4
3 changed files with 4 additions and 0 deletions
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2
drivers/char/vt_ioctl.c
View File

@ -1011,6 +1011,8 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
return -EPERM; return -EPERM;
vt_dont_switch = 0; vt_dont_switch = 0;
return 0; return 0;
case VT_GETHIFONTMASK:
return put_user(vc->vc_hi_font_mask, (unsigned short __user *)arg);
default: default:
return -ENOIOCTLCMD; return -ENOIOCTLCMD;
} }

1
include/linux/compat_ioctl.h
View File

@ -216,6 +216,7 @@ COMPATIBLE_IOCTL(VT_RESIZE)
COMPATIBLE_IOCTL(VT_RESIZEX) COMPATIBLE_IOCTL(VT_RESIZEX)
COMPATIBLE_IOCTL(VT_LOCKSWITCH) COMPATIBLE_IOCTL(VT_LOCKSWITCH)
COMPATIBLE_IOCTL(VT_UNLOCKSWITCH) COMPATIBLE_IOCTL(VT_UNLOCKSWITCH)
COMPATIBLE_IOCTL(VT_GETHIFONTMASK)
/* Little p (/dev/rtc, /dev/envctrl, etc.) */ /* Little p (/dev/rtc, /dev/envctrl, etc.) */
COMPATIBLE_IOCTL(RTC_AIE_ON) COMPATIBLE_IOCTL(RTC_AIE_ON)
COMPATIBLE_IOCTL(RTC_AIE_OFF) COMPATIBLE_IOCTL(RTC_AIE_OFF)

1
include/linux/vt.h
View File

@ -60,5 +60,6 @@ struct vt_consize {
#define VT_RESIZEX 0x560A /* set kernel's idea of screensize + more */ #define VT_RESIZEX 0x560A /* set kernel's idea of screensize + more */
#define VT_LOCKSWITCH 0x560B /* disallow vt switching */ #define VT_LOCKSWITCH 0x560B /* disallow vt switching */
#define VT_UNLOCKSWITCH 0x560C /* allow vt switching */ #define VT_UNLOCKSWITCH 0x560C /* allow vt switching */
#define VT_GETHIFONTMASK 0x560D /* return hi font mask */
#endif /* _LINUX_VT_H */ #endif /* _LINUX_VT_H */