From b293d758470e971253eec42b817bc9ef1213b228 Mon Sep 17 00:00:00 2001 From: Samuel Thibault Date: Thu, 18 Oct 2007 23:39:17 -0700 Subject: [PATCH] Console events and accessibility Some external modules like Speakup need to monitor console output. This adds a VT notifier that such modules can use to get console output events: allocation, deallocation, writes, other updates (cursor position, switch, etc.) [akpm@linux-foundation.org: fix headers_check] Signed-off-by: Samuel Thibault Cc: Dmitry Torokhov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/vt.c | 45 +++++++++++++++++++++++++++++++++++++++- include/linux/notifier.h | 6 ++++++ include/linux/vt.h | 12 +++++++++++ 3 files changed, 62 insertions(+), 1 deletion(-) diff --git a/drivers/char/vt.c b/drivers/char/vt.c index 1764c67b585f..7a5badfb7d84 100644 --- a/drivers/char/vt.c +++ b/drivers/char/vt.c @@ -99,6 +99,7 @@ #include #include #include +#include #include #include @@ -222,6 +223,35 @@ enum { blank_vesa_wait, }; +/* + * Notifier list for console events. + */ +static ATOMIC_NOTIFIER_HEAD(vt_notifier_list); + +int register_vt_notifier(struct notifier_block *nb) +{ + return atomic_notifier_chain_register(&vt_notifier_list, nb); +} +EXPORT_SYMBOL_GPL(register_vt_notifier); + +int unregister_vt_notifier(struct notifier_block *nb) +{ + return atomic_notifier_chain_unregister(&vt_notifier_list, nb); +} +EXPORT_SYMBOL_GPL(unregister_vt_notifier); + +static void notify_write(struct vc_data *vc, unsigned int unicode) +{ + struct vt_notifier_param param = { .vc = vc, unicode = unicode }; + atomic_notifier_call_chain(&vt_notifier_list, VT_WRITE, ¶m); +} + +static void notify_update(struct vc_data *vc) +{ + struct vt_notifier_param param = { .vc = vc }; + atomic_notifier_call_chain(&vt_notifier_list, VT_UPDATE, ¶m); +} + /* * Low-Level Functions */ @@ -718,6 +748,7 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */ return -ENXIO; if (!vc_cons[currcons].d) { struct vc_data *vc; + struct vt_notifier_param param; /* prevent users from taking too much memory */ if (currcons >= MAX_NR_USER_CONSOLES && !capable(CAP_SYS_RESOURCE)) @@ -729,7 +760,7 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */ /* although the numbers above are not valid since long ago, the point is still up-to-date and the comment still has its value even if only as a historical artifact. --mj, July 1998 */ - vc = kzalloc(sizeof(struct vc_data), GFP_KERNEL); + param.vc = vc = kzalloc(sizeof(struct vc_data), GFP_KERNEL); if (!vc) return -ENOMEM; vc_cons[currcons].d = vc; @@ -746,6 +777,7 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */ } vc->vc_kmalloced = 1; vc_init(vc, vc->vc_rows, vc->vc_cols, 1); + atomic_notifier_call_chain(&vt_notifier_list, VT_ALLOCATE, ¶m); } return 0; } @@ -907,6 +939,8 @@ void vc_deallocate(unsigned int currcons) if (vc_cons_allocated(currcons)) { struct vc_data *vc = vc_cons[currcons].d; + struct vt_notifier_param param = { .vc = vc }; + atomic_notifier_call_chain(&vt_notifier_list, VT_DEALLOCATE, ¶m); vc->vc_sw->con_deinit(vc); put_pid(vc->vt_pid); module_put(vc->vc_sw->owner); @@ -1019,6 +1053,7 @@ static void lf(struct vc_data *vc) vc->vc_pos += vc->vc_size_row; } vc->vc_need_wrap = 0; + notify_write(vc, '\n'); } static void ri(struct vc_data *vc) @@ -1039,6 +1074,7 @@ static inline void cr(struct vc_data *vc) { vc->vc_pos -= vc->vc_x << 1; vc->vc_need_wrap = vc->vc_x = 0; + notify_write(vc, '\r'); } static inline void bs(struct vc_data *vc) @@ -1047,6 +1083,7 @@ static inline void bs(struct vc_data *vc) vc->vc_pos -= 2; vc->vc_x--; vc->vc_need_wrap = 0; + notify_write(vc, '\b'); } } @@ -1593,6 +1630,7 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c) break; } vc->vc_pos += (vc->vc_x << 1); + notify_write(vc, '\t'); return; case 10: case 11: case 12: lf(vc); @@ -2252,6 +2290,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co tc = conv_uni_to_pc(vc, ' '); /* A space is printed in the second column */ if (tc < 0) tc = ' '; } + notify_write(vc, c); if (inverse) { FLUSH @@ -2274,6 +2313,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co release_console_sem(); out: + notify_update(vc); return n; #undef FLUSH } @@ -2317,6 +2357,7 @@ static void console_callback(struct work_struct *ignored) do_blank_screen(0); blank_timer_expired = 0; } + notify_update(vc_cons[fg_console].d); release_console_sem(); } @@ -2418,6 +2459,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) continue; } scr_writew((vc->vc_attr << 8) + c, (unsigned short *)vc->vc_pos); + notify_write(vc, c); cnt++; if (myx == vc->vc_cols - 1) { vc->vc_need_wrap = 1; @@ -2436,6 +2478,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) } } set_cursor(vc); + notify_update(vc); quit: clear_bit(0, &printing); diff --git a/include/linux/notifier.h b/include/linux/notifier.h index 6ec7e21a3699..0c40cc0b4a36 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -242,5 +242,11 @@ static inline int notifier_to_errno(int ret) extern struct blocking_notifier_head reboot_notifier_list; +/* Virtual Terminal events. */ +#define VT_ALLOCATE 0x0001 /* Console got allocated */ +#define VT_DEALLOCATE 0x0002 /* Console will be deallocated */ +#define VT_WRITE 0x0003 /* A char got output */ +#define VT_UPDATE 0x0004 /* A bigger update occurred */ + #endif /* __KERNEL__ */ #endif /* _LINUX_NOTIFIER_H */ diff --git a/include/linux/vt.h b/include/linux/vt.h index ba806e8711be..02c1c0288770 100644 --- a/include/linux/vt.h +++ b/include/linux/vt.h @@ -1,6 +1,18 @@ #ifndef _LINUX_VT_H #define _LINUX_VT_H +#ifdef __KERNEL__ +struct notifier_block; + +struct vt_notifier_param { + struct vc_data *vc; /* VC on which the update happened */ + unsigned int c; /* Printed char */ +}; + +extern int register_vt_notifier(struct notifier_block *nb); +extern int unregister_vt_notifier(struct notifier_block *nb); +#endif + /* * These constants are also useful for user-level apps (e.g., VC * resizing).