From 533475d3d48eb839be2b57f6b020150abae91063 Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Sun, 27 Aug 2006 01:23:39 -0700 Subject: [PATCH] [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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/vt_ioctl.c | 2 ++ include/linux/compat_ioctl.h | 1 + include/linux/vt.h | 1 + 3 files changed, 4 insertions(+) diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c index eccffaf26f..a5628a8b66 100644 --- a/drivers/char/vt_ioctl.c +++ b/drivers/char/vt_ioctl.c @@ -1011,6 +1011,8 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, return -EPERM; vt_dont_switch = 0; return 0; + case VT_GETHIFONTMASK: + return put_user(vc->vc_hi_font_mask, (unsigned short __user *)arg); default: return -ENOIOCTLCMD; } diff --git a/include/linux/compat_ioctl.h b/include/linux/compat_ioctl.h index 269d000bb2..bea0255196 100644 --- a/include/linux/compat_ioctl.h +++ b/include/linux/compat_ioctl.h @@ -216,6 +216,7 @@ COMPATIBLE_IOCTL(VT_RESIZE) COMPATIBLE_IOCTL(VT_RESIZEX) COMPATIBLE_IOCTL(VT_LOCKSWITCH) COMPATIBLE_IOCTL(VT_UNLOCKSWITCH) +COMPATIBLE_IOCTL(VT_GETHIFONTMASK) /* Little p (/dev/rtc, /dev/envctrl, etc.) */ COMPATIBLE_IOCTL(RTC_AIE_ON) COMPATIBLE_IOCTL(RTC_AIE_OFF) diff --git a/include/linux/vt.h b/include/linux/vt.h index 8ab334a482..ba806e8711 100644 --- a/include/linux/vt.h +++ b/include/linux/vt.h @@ -60,5 +60,6 @@ struct vt_consize { #define VT_RESIZEX 0x560A /* set kernel's idea of screensize + more */ #define VT_LOCKSWITCH 0x560B /* disallow vt switching */ #define VT_UNLOCKSWITCH 0x560C /* allow vt switching */ +#define VT_GETHIFONTMASK 0x560D /* return hi font mask */ #endif /* _LINUX_VT_H */ -- 2.39.5