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grub/grub-core/commands/i386/pc/sendkey.c
Michael Chang acffb81485 build: Fix -Werror=array-bounds array subscript 0 is outside array bounds 
The GRUB is failing to build with GCC-12 in many places like this:

  In function 'init_cbfsdisk',
      inlined from 'grub_mod_init' at ../../grub-core/fs/cbfs.c:391:3:
  ../../grub-core/fs/cbfs.c:345:7: error: array subscript 0 is outside array bounds of 'grub_uint32_t[0]' {aka 'unsigned int[]'} [-Werror=array-bounds]
    345 |   ptr = *(grub_uint32_t *) 0xfffffffc;
        |   ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is caused by GCC regression in 11/12 [1]. In a nut shell, the
warning is about detected invalid accesses at non-zero offsets to NULL
pointers. Since hardwired constant address is treated as NULL plus an
offset in the same underlying code, the warning is therefore triggered.

Instead of inserting #pragma all over the places where literal pointers
are accessed to avoid diagnosing array-bounds, we can try to borrow the
idea from Linux kernel that the absolute_pointer() macro [2][3] is used
to disconnect a pointer using literal address from it's original object,
hence GCC won't be able to make assumptions on the boundary while doing
pointer arithmetic. With that we can greatly reduce the code we have to
cover up by making initial literal pointer assignment to use the new
wrapper but not having to track everywhere literal pointers are
accessed. This also makes code looks cleaner.

Please note the grub_absolute_pointer() macro requires to be invoked in
a function as long as it is compound expression. Some global variables
with literal pointers has been changed to local ones in order to use
grub_absolute_pointer() to initialize it. The shuffling is basically done
in a selective and careful way that the variable's scope doesn't matter
being local or global, for example, the global variable must not get
modified at run time throughout. For the record, here's the list of
global variables got shuffled in this patch:

  grub-core/commands/i386/pc/drivemap.c:int13slot
  grub-core/term/i386/pc/console.c:bios_data_area
  grub-core/term/ns8250.c:serial_hw_io_addr

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
[2] https://elixir.bootlin.com/linux/v5.16.14/source/include/linux/compiler.h#L180
[3] https://elixir.bootlin.com/linux/v5.16.14/source/include/linux/compiler-gcc.h#L31

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2022-04-20 18:27:52 +02:00

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/* sendkey.c - fake keystroke. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2009 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <grub/types.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/err.h>
#include <grub/dl.h>
#include <grub/extcmd.h>
#include <grub/cpu/io.h>
#include <grub/loader.h>
#include <grub/i18n.h>
GRUB_MOD_LICENSE ("GPLv2+");
static char sendkey[0x20];
/* Length of sendkey. */
static int keylen = 0;
static int noled = 0;
static const struct grub_arg_option options[] =
{
{"num", 'n', 0, N_("set numlock mode"), "[on|off]", ARG_TYPE_STRING},
{"caps", 'c', 0, N_("set capslock mode"), "[on|off]", ARG_TYPE_STRING},
{"scroll", 's', 0, N_("set scrolllock mode"), "[on|off]", ARG_TYPE_STRING},
{"insert", 0, 0, N_("set insert mode"), "[on|off]", ARG_TYPE_STRING},
{"pause", 0, 0, N_("set pause mode"), "[on|off]", ARG_TYPE_STRING},
{"left-shift", 0, 0, N_("press left shift"), "[on|off]", ARG_TYPE_STRING},
{"right-shift", 0, 0, N_("press right shift"), "[on|off]", ARG_TYPE_STRING},
{"sysrq", 0, 0, N_("press SysRq"), "[on|off]", ARG_TYPE_STRING},
{"numkey", 0, 0, N_("press NumLock key"), "[on|off]", ARG_TYPE_STRING},
{"capskey", 0, 0, N_("press CapsLock key"), "[on|off]", ARG_TYPE_STRING},
{"scrollkey", 0, 0, N_("press ScrollLock key"), "[on|off]", ARG_TYPE_STRING},
{"insertkey", 0, 0, N_("press Insert key"), "[on|off]", ARG_TYPE_STRING},
{"left-alt", 0, 0, N_("press left alt"), "[on|off]", ARG_TYPE_STRING},
{"right-alt", 0, 0, N_("press right alt"), "[on|off]", ARG_TYPE_STRING},
{"left-ctrl", 0, 0, N_("press left ctrl"), "[on|off]", ARG_TYPE_STRING},
{"right-ctrl", 0, 0, N_("press right ctrl"), "[on|off]", ARG_TYPE_STRING},
{"no-led", 0, 0, N_("don't update LED state"), 0, 0},
{0, 0, 0, 0, 0, 0}
};
static int simple_flag_offsets[]
= {5, 6, 4, 7, 11, 1, 0, 10, 13, 14, 12, 15, 9, 3, 8, 2};
static grub_uint32_t andmask = 0xffffffff, ormask = 0;
struct
keysym
{
const char *unshifted_name; /* the name in unshifted state */
const char *shifted_name; /* the name in shifted state */
unsigned char unshifted_ascii; /* the ascii code in unshifted state */
unsigned char shifted_ascii; /* the ascii code in shifted state */
unsigned char keycode; /* keyboard scancode */
};
/* The table for key symbols. If the "shifted" member of an entry is
NULL, the entry does not have shifted state. Copied from GRUB Legacy setkey fuction */
static struct keysym keysym_table[] =
{
{"escape", 0, 0x1b, 0, 0x01},
{"1", "exclam", '1', '!', 0x02},
{"2", "at", '2', '@', 0x03},
{"3", "numbersign", '3', '#', 0x04},
{"4", "dollar", '4', '$', 0x05},
{"5", "percent", '5', '%', 0x06},
{"6", "caret", '6', '^', 0x07},
{"7", "ampersand", '7', '&', 0x08},
{"8", "asterisk", '8', '*', 0x09},
{"9", "parenleft", '9', '(', 0x0a},
{"0", "parenright", '0', ')', 0x0b},
{"minus", "underscore", '-', '_', 0x0c},
{"equal", "plus", '=', '+', 0x0d},
{"backspace", 0, '\b', 0, 0x0e},
{"tab", 0, '\t', 0, 0x0f},
{"q", "Q", 'q', 'Q', 0x10},
{"w", "W", 'w', 'W', 0x11},
{"e", "E", 'e', 'E', 0x12},
{"r", "R", 'r', 'R', 0x13},
{"t", "T", 't', 'T', 0x14},
{"y", "Y", 'y', 'Y', 0x15},
{"u", "U", 'u', 'U', 0x16},
{"i", "I", 'i', 'I', 0x17},
{"o", "O", 'o', 'O', 0x18},
{"p", "P", 'p', 'P', 0x19},
{"bracketleft", "braceleft", '[', '{', 0x1a},
{"bracketright", "braceright", ']', '}', 0x1b},
{"enter", 0, '\r', 0, 0x1c},
{"control", 0, 0, 0, 0x1d},
{"a", "A", 'a', 'A', 0x1e},
{"s", "S", 's', 'S', 0x1f},
{"d", "D", 'd', 'D', 0x20},
{"f", "F", 'f', 'F', 0x21},
{"g", "G", 'g', 'G', 0x22},
{"h", "H", 'h', 'H', 0x23},
{"j", "J", 'j', 'J', 0x24},
{"k", "K", 'k', 'K', 0x25},
{"l", "L", 'l', 'L', 0x26},
{"semicolon", "colon", ';', ':', 0x27},
{"quote", "doublequote", '\'', '"', 0x28},
{"backquote", "tilde", '`', '~', 0x29},
{"shift", 0, 0, 0, 0x2a},
{"backslash", "bar", '\\', '|', 0x2b},
{"z", "Z", 'z', 'Z', 0x2c},
{"x", "X", 'x', 'X', 0x2d},
{"c", "C", 'c', 'C', 0x2e},
{"v", "V", 'v', 'V', 0x2f},
{"b", "B", 'b', 'B', 0x30},
{"n", "N", 'n', 'N', 0x31},
{"m", "M", 'm', 'M', 0x32},
{"comma", "less", ',', '<', 0x33},
{"period", "greater", '.', '>', 0x34},
{"slash", "question", '/', '?', 0x35},
{"rshift", 0, 0, 0, 0x36},
{"numasterisk", 0, '*', 0, 0x37},
{"alt", 0, 0, 0, 0x38},
{"space", 0, ' ', 0, 0x39},
{"capslock", 0, 0, 0, 0x3a},
{"F1", 0, 0, 0, 0x3b},
{"F2", 0, 0, 0, 0x3c},
{"F3", 0, 0, 0, 0x3d},
{"F4", 0, 0, 0, 0x3e},
{"F5", 0, 0, 0, 0x3f},
{"F6", 0, 0, 0, 0x40},
{"F7", 0, 0, 0, 0x41},
{"F8", 0, 0, 0, 0x42},
{"F9", 0, 0, 0, 0x43},
{"F10", 0, 0, 0, 0x44},
{"num7", "numhome", '7', 0, 0x47},
{"num8", "numup", '8', 0, 0x48},
{"num9", "numpgup", '9', 0, 0x49},
{"numminus", 0, '-', 0, 0x4a},
{"num4", "numleft", '4', 0, 0x4b},
{"num5", "numcenter", '5', 0, 0x4c},
{"num6", "numright", '6', 0, 0x4d},
{"numplus", 0, '-', 0, 0x4e},
{"num1", "numend", '1', 0, 0x4f},
{"num2", "numdown", '2', 0, 0x50},
{"num3", "numpgdown", '3', 0, 0x51},
{"num0", "numinsert", '0', 0, 0x52},
{"numperiod", "numdelete", 0, 0x7f, 0x53},
{"F11", 0, 0, 0, 0x57},
{"F12", 0, 0, 0, 0x58},
{"numenter", 0, '\r', 0, 0xe0},
{"numslash", 0, '/', 0, 0xe0},
{"delete", 0, 0x7f, 0, 0xe0},
{"insert", 0, 0xe0, 0, 0x52},
{"home", 0, 0xe0, 0, 0x47},
{"end", 0, 0xe0, 0, 0x4f},
{"pgdown", 0, 0xe0, 0, 0x51},
{"pgup", 0, 0xe0, 0, 0x49},
{"down", 0, 0xe0, 0, 0x50},
{"up", 0, 0xe0, 0, 0x48},
{"left", 0, 0xe0, 0, 0x4b},
{"right", 0, 0xe0, 0, 0x4d}
};
/* Set a simple flag in flags variable
OUTOFFSET - offset of flag in FLAGS,
OP - action id
*/
static void
grub_sendkey_set_simple_flag (int outoffset, int op)
{
if (op == 2)
{
andmask |= (1 << outoffset);
ormask &= ~(1 << outoffset);
}
else
{
andmask &= (~(1 << outoffset));
if (op == 1)
ormask |= (1 << outoffset);
else
ormask &= ~(1 << outoffset);
}
}
static int
grub_sendkey_parse_op (struct grub_arg_list state)
{
if (! state.set)
return 2;
if (grub_strcmp (state.arg, "off") == 0 || grub_strcmp (state.arg, "0") == 0
|| grub_strcmp (state.arg, "unpress") == 0)
return 0;
if (grub_strcmp (state.arg, "on") == 0 || grub_strcmp (state.arg, "1") == 0
|| grub_strcmp (state.arg, "press") == 0)
return 1;
return 2;
}
static grub_uint32_t oldflags;
static grub_err_t
grub_sendkey_postboot (void)
{
/* For convention: pointer to flags. */
grub_uint32_t *flags = grub_absolute_pointer (0x417);
*flags = oldflags;
*((volatile char *) grub_absolute_pointer (0x41a)) = 0x1e;
*((volatile char *) grub_absolute_pointer (0x41c)) = 0x1e;
return GRUB_ERR_NONE;
}
/* Set keyboard buffer to our sendkey */
static grub_err_t
grub_sendkey_preboot (int noret __attribute__ ((unused)))
{
/* For convention: pointer to flags. */
grub_uint32_t *flags = grub_absolute_pointer (0x417);
oldflags = *flags;
/* Set the sendkey. */
*((volatile char *) grub_absolute_pointer (0x41a)) = 0x1e;
*((volatile char *) grub_absolute_pointer (0x41c)) = keylen + 0x1e;
grub_memcpy ((char *) 0x41e, sendkey, 0x20);
/* Transform "any ctrl" to "right ctrl" flag. */
if (*flags & (1 << 8))
*flags &= ~(1 << 2);
/* Transform "any alt" to "right alt" flag. */
if (*flags & (1 << 9))
*flags &= ~(1 << 3);
*flags = (*flags & andmask) | ormask;
/* Transform "right ctrl" to "any ctrl" flag. */
if (*flags & (1 << 8))
*flags |= (1 << 2);
/* Transform "right alt" to "any alt" flag. */
if (*flags & (1 << 9))
*flags |= (1 << 3);
/* Write new LED state */
if (!noled)
{
int value = 0;
int failed;
/* Try 5 times */
for (failed = 0; failed < 5; failed++)
{
value = 0;
/* Send command change LEDs */
grub_outb (0xed, 0x60);
/* Wait */
do
value = grub_inb (0x60);
while ((value != 0xfa) && (value != 0xfe));
if (value == 0xfa)
{
/* Set new LEDs*/
grub_outb ((*flags >> 4) & 7, 0x60);
break;
}
}
}
return GRUB_ERR_NONE;
}
/* Helper for grub_cmd_sendkey. */
static int
find_key_code (char *key)
{
unsigned i;
for (i = 0; i < ARRAY_SIZE(keysym_table); i++)
{
if (keysym_table[i].unshifted_name
&& grub_strcmp (key, keysym_table[i].unshifted_name) == 0)
return keysym_table[i].keycode;
else if (keysym_table[i].shifted_name
&& grub_strcmp (key, keysym_table[i].shifted_name) == 0)
return keysym_table[i].keycode;
}
return 0;
}
/* Helper for grub_cmd_sendkey. */
static int
find_ascii_code (char *key)
{
unsigned i;
for (i = 0; i < ARRAY_SIZE(keysym_table); i++)
{
if (keysym_table[i].unshifted_name
&& grub_strcmp (key, keysym_table[i].unshifted_name) == 0)
return keysym_table[i].unshifted_ascii;
else if (keysym_table[i].shifted_name
&& grub_strcmp (key, keysym_table[i].shifted_name) == 0)
return keysym_table[i].shifted_ascii;
}
return 0;
}
static grub_err_t
grub_cmd_sendkey (grub_extcmd_context_t ctxt, int argc, char **args)
{
struct grub_arg_list *state = ctxt->state;
andmask = 0xffffffff;
ormask = 0;
{
int i;
keylen = 0;
for (i = 0; i < argc && keylen < 0x20; i++)
{
int key_code;
key_code = find_key_code (args[i]);
if (key_code)
{
sendkey[keylen++] = find_ascii_code (args[i]);
sendkey[keylen++] = key_code;
}
}
}
{
unsigned i;
for (i = 0; i < ARRAY_SIZE(simple_flag_offsets); i++)
grub_sendkey_set_simple_flag (simple_flag_offsets[i],
grub_sendkey_parse_op(state[i]));
}
/* Set noled. */
noled = (state[ARRAY_SIZE(simple_flag_offsets)].set);
return GRUB_ERR_NONE;
}
static grub_extcmd_t cmd;
static struct grub_preboot *preboot_hook;
GRUB_MOD_INIT (sendkey)
{
cmd = grub_register_extcmd ("sendkey", grub_cmd_sendkey, 0,
N_("[KEYSTROKE1] [KEYSTROKE2] ..."),
/* TRANSLATORS: It can emulate multiple
keypresses. */
N_("Emulate a keystroke sequence"), options);
preboot_hook
= grub_loader_register_preboot_hook (grub_sendkey_preboot,
grub_sendkey_postboot,
GRUB_LOADER_PREBOOT_HOOK_PRIO_CONSOLE);
}
GRUB_MOD_FINI (sendkey)
{
grub_unregister_extcmd (cmd);
grub_loader_unregister_preboot_hook (preboot_hook);
}
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