kernel-ark/drivers/char/selection.c
Alan Cox c65c9bc3ef tty: rewrite the ldisc locking
There are several pretty much unfixable races in the old ldisc code, especially
with respect to pty behaviour and also to hangup. It's easier to rewrite the
code than simply try and patch it up.

This patch
- splits the ldisc from the tty (so we will be able to refcount it more cleanly
  later)
- introduces a mutex lock for ldisc changing on an active device
- fixes the complete mess that hangup caused
- implements hopefully correct setldisc/close/hangup locking

There are still some problems around pty pairs that have always been there but
at least it is now possible to understand the code and fix further problems.

This fixes the following known bugs
- hang up can leak ldisc references
- hang up may not call open/close on ldisc in a matched way
- pty/tty pairs can deadlock during an ldisc change
- reading the ldisc proc files can cause every ldisc to be loaded

and probably a few other of the mysterious ldisc race reports.

I'm sure it also adds the odd new one.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-11 08:51:01 -07:00

340 lines
8.5 KiB
C

/*
* linux/drivers/char/selection.c
*
* This module exports the functions:
*
* 'int set_selection(struct tiocl_selection __user *, struct tty_struct *)'
* 'void clear_selection(void)'
* 'int paste_selection(struct tty_struct *)'
* 'int sel_loadlut(char __user *)'
*
* Now that /dev/vcs exists, most of this can disappear again.
*/
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <asm/uaccess.h>
#include <linux/kbd_kern.h>
#include <linux/vt_kern.h>
#include <linux/consolemap.h>
#include <linux/selection.h>
#include <linux/tiocl.h>
#include <linux/console.h>
/* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
#define isspace(c) ((c) == ' ')
extern void poke_blanked_console(void);
/* Variables for selection control. */
/* Use a dynamic buffer, instead of static (Dec 1994) */
struct vc_data *sel_cons; /* must not be deallocated */
static int use_unicode;
static volatile int sel_start = -1; /* cleared by clear_selection */
static int sel_end;
static int sel_buffer_lth;
static char *sel_buffer;
/* clear_selection, highlight and highlight_pointer can be called
from interrupt (via scrollback/front) */
/* set reverse video on characters s-e of console with selection. */
static inline void highlight(const int s, const int e)
{
invert_screen(sel_cons, s, e-s+2, 1);
}
/* use complementary color to show the pointer */
static inline void highlight_pointer(const int where)
{
complement_pos(sel_cons, where);
}
static u16
sel_pos(int n)
{
return inverse_translate(sel_cons, screen_glyph(sel_cons, n),
use_unicode);
}
/* remove the current selection highlight, if any,
from the console holding the selection. */
void
clear_selection(void) {
highlight_pointer(-1); /* hide the pointer */
if (sel_start != -1) {
highlight(sel_start, sel_end);
sel_start = -1;
}
}
/*
* User settable table: what characters are to be considered alphabetic?
* 256 bits
*/
static u32 inwordLut[8]={
0x00000000, /* control chars */
0x03FF0000, /* digits */
0x87FFFFFE, /* uppercase and '_' */
0x07FFFFFE, /* lowercase */
0x00000000,
0x00000000,
0xFF7FFFFF, /* latin-1 accented letters, not multiplication sign */
0xFF7FFFFF /* latin-1 accented letters, not division sign */
};
static inline int inword(const u16 c) {
return c > 0xff || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
}
/* set inwordLut contents. Invoked by ioctl(). */
int sel_loadlut(char __user *p)
{
return copy_from_user(inwordLut, (u32 __user *)(p+4), 32) ? -EFAULT : 0;
}
/* does screen address p correspond to character at LH/RH edge of screen? */
static inline int atedge(const int p, int size_row)
{
return (!(p % size_row) || !((p + 2) % size_row));
}
/* constrain v such that v <= u */
static inline unsigned short limit(const unsigned short v, const unsigned short u)
{
return (v > u) ? u : v;
}
/* stores the char in UTF8 and returns the number of bytes used (1-3) */
static int store_utf8(u16 c, char *p)
{
if (c < 0x80) {
/* 0******* */
p[0] = c;
return 1;
} else if (c < 0x800) {
/* 110***** 10****** */
p[0] = 0xc0 | (c >> 6);
p[1] = 0x80 | (c & 0x3f);
return 2;
} else {
/* 1110**** 10****** 10****** */
p[0] = 0xe0 | (c >> 12);
p[1] = 0x80 | ((c >> 6) & 0x3f);
p[2] = 0x80 | (c & 0x3f);
return 3;
}
}
/* set the current selection. Invoked by ioctl() or by kernel code. */
int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
{
struct vc_data *vc = vc_cons[fg_console].d;
int sel_mode, new_sel_start, new_sel_end, spc;
char *bp, *obp;
int i, ps, pe, multiplier;
u16 c;
struct kbd_struct *kbd = kbd_table + fg_console;
poke_blanked_console();
{ unsigned short xs, ys, xe, ye;
if (!access_ok(VERIFY_READ, sel, sizeof(*sel)))
return -EFAULT;
__get_user(xs, &sel->xs);
__get_user(ys, &sel->ys);
__get_user(xe, &sel->xe);
__get_user(ye, &sel->ye);
__get_user(sel_mode, &sel->sel_mode);
xs--; ys--; xe--; ye--;
xs = limit(xs, vc->vc_cols - 1);
ys = limit(ys, vc->vc_rows - 1);
xe = limit(xe, vc->vc_cols - 1);
ye = limit(ye, vc->vc_rows - 1);
ps = ys * vc->vc_size_row + (xs << 1);
pe = ye * vc->vc_size_row + (xe << 1);
if (sel_mode == TIOCL_SELCLEAR) {
/* useful for screendump without selection highlights */
clear_selection();
return 0;
}
if (mouse_reporting() && (sel_mode & TIOCL_SELMOUSEREPORT)) {
mouse_report(tty, sel_mode & TIOCL_SELBUTTONMASK, xs, ys);
return 0;
}
}
if (ps > pe) /* make sel_start <= sel_end */
{
int tmp = ps;
ps = pe;
pe = tmp;
}
if (sel_cons != vc_cons[fg_console].d) {
clear_selection();
sel_cons = vc_cons[fg_console].d;
}
use_unicode = kbd && kbd->kbdmode == VC_UNICODE;
switch (sel_mode)
{
case TIOCL_SELCHAR: /* character-by-character selection */
new_sel_start = ps;
new_sel_end = pe;
break;
case TIOCL_SELWORD: /* word-by-word selection */
spc = isspace(sel_pos(ps));
for (new_sel_start = ps; ; ps -= 2)
{
if ((spc && !isspace(sel_pos(ps))) ||
(!spc && !inword(sel_pos(ps))))
break;
new_sel_start = ps;
if (!(ps % vc->vc_size_row))
break;
}
spc = isspace(sel_pos(pe));
for (new_sel_end = pe; ; pe += 2)
{
if ((spc && !isspace(sel_pos(pe))) ||
(!spc && !inword(sel_pos(pe))))
break;
new_sel_end = pe;
if (!((pe + 2) % vc->vc_size_row))
break;
}
break;
case TIOCL_SELLINE: /* line-by-line selection */
new_sel_start = ps - ps % vc->vc_size_row;
new_sel_end = pe + vc->vc_size_row
- pe % vc->vc_size_row - 2;
break;
case TIOCL_SELPOINTER:
highlight_pointer(pe);
return 0;
default:
return -EINVAL;
}
/* remove the pointer */
highlight_pointer(-1);
/* select to end of line if on trailing space */
if (new_sel_end > new_sel_start &&
!atedge(new_sel_end, vc->vc_size_row) &&
isspace(sel_pos(new_sel_end))) {
for (pe = new_sel_end + 2; ; pe += 2)
if (!isspace(sel_pos(pe)) ||
atedge(pe, vc->vc_size_row))
break;
if (isspace(sel_pos(pe)))
new_sel_end = pe;
}
if (sel_start == -1) /* no current selection */
highlight(new_sel_start, new_sel_end);
else if (new_sel_start == sel_start)
{
if (new_sel_end == sel_end) /* no action required */
return 0;
else if (new_sel_end > sel_end) /* extend to right */
highlight(sel_end + 2, new_sel_end);
else /* contract from right */
highlight(new_sel_end + 2, sel_end);
}
else if (new_sel_end == sel_end)
{
if (new_sel_start < sel_start) /* extend to left */
highlight(new_sel_start, sel_start - 2);
else /* contract from left */
highlight(sel_start, new_sel_start - 2);
}
else /* some other case; start selection from scratch */
{
clear_selection();
highlight(new_sel_start, new_sel_end);
}
sel_start = new_sel_start;
sel_end = new_sel_end;
/* Allocate a new buffer before freeing the old one ... */
multiplier = use_unicode ? 3 : 1; /* chars can take up to 3 bytes */
bp = kmalloc(((sel_end-sel_start)/2+1)*multiplier, GFP_KERNEL);
if (!bp) {
printk(KERN_WARNING "selection: kmalloc() failed\n");
clear_selection();
return -ENOMEM;
}
kfree(sel_buffer);
sel_buffer = bp;
obp = bp;
for (i = sel_start; i <= sel_end; i += 2) {
c = sel_pos(i);
if (use_unicode)
bp += store_utf8(c, bp);
else
*bp++ = c;
if (!isspace(c))
obp = bp;
if (! ((i + 2) % vc->vc_size_row)) {
/* strip trailing blanks from line and add newline,
unless non-space at end of line. */
if (obp != bp) {
bp = obp;
*bp++ = '\r';
}
obp = bp;
}
}
sel_buffer_lth = bp - sel_buffer;
return 0;
}
/* Insert the contents of the selection buffer into the
* queue of the tty associated with the current console.
* Invoked by ioctl().
*/
int paste_selection(struct tty_struct *tty)
{
struct vc_data *vc = tty->driver_data;
int pasted = 0;
unsigned int count;
struct tty_ldisc *ld;
DECLARE_WAITQUEUE(wait, current);
acquire_console_sem();
poke_blanked_console();
release_console_sem();
ld = tty_ldisc_ref_wait(tty);
add_wait_queue(&vc->paste_wait, &wait);
while (sel_buffer && sel_buffer_lth > pasted) {
set_current_state(TASK_INTERRUPTIBLE);
if (test_bit(TTY_THROTTLED, &tty->flags)) {
schedule();
continue;
}
count = sel_buffer_lth - pasted;
count = min(count, tty->receive_room);
tty->ldisc->ops->receive_buf(tty, sel_buffer + pasted,
NULL, count);
pasted += count;
}
remove_wait_queue(&vc->paste_wait, &wait);
__set_current_state(TASK_RUNNING);
tty_ldisc_deref(ld);
return 0;
}