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kbd: three layouts, and the arrow keys were sitting on top of UTF-8

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`∞`, `→`, `≤` and `'` could not be typed. `ą` and `ę` could. That pairing is
the whole diagnosis: KBD_UP was 0xE2 and its neighbours filled 0xE0..0xE9,
which are exactly the UTF-8 lead bytes for three-byte characters. Every
character in U+0800..U+FFFF -- most punctuation, every arrow, every maths
symbol, the whole of CJK -- arrived as a value the console read as an arrow key
and helpfully turned into `ESC [ A`. Two-byte sequences lead with 0xC4 and
nothing claimed 0xC4, so Polish came through and the rest did not.

The chord codes already knew this rule and said so in a comment. The navigation
keys predate them and were never brought in line. Stated once, in kbd.h: a key
produces either a Unicode codepoint or a value above 0x10FFFF, and nothing in
between means anything. KEY_* -> KBD_*, which also settles a silent collision
-- include/input.h defines its own KEY_HOME, KEY_UP and KEY_END as evdev
numbers, and kbd.c includes both headers, so three macros were being quietly
redefined in the one file that used them.

Then the layouts, which is what the codepoint-sized keycodes were for.

kernel/dev/keymap.c: us, pl, de. A layout is four tables -- plain, Shift,
AltGr, Shift+AltGr -- of uint32 codepoints. uint32 and not uchar is the reason
the file exists: `ó` fits in a byte and `ą` does not, and half a Polish
alphabet is not a Polish layout.

Two things deliberately are *not* tables:

  - **Ctrl is derived from the plain codepoint.** The table it replaces was
    indexed by scancode, which quietly assumed US -- on QWERTZ the Y and Z keys
    swap, so Ctrl+Z would have suspended a job only on some layouts.
  - **Caps Lock is a case toggle on the result**, so AltGr+a with Caps Lock is
    `Ą`. No second table could say that, because Caps Lock combines with AltGr
    rather than replacing it. Latin Extended-A alternates upper/lower by
    codepoint but not all the same way round -- Ł is U+0141 (odd) and Ą is
    U+0104 (even) -- so Polish lands in both halves and the parity matters.

kbdgetc() encodes to UTF-8 and returns the bytes one call at a time.
consoleintr()'s contract is bytes: the serial line hands it UTF-8 already and
it could not tell an encoded codepoint from a byte of the same value.

The layouts live in the kernel. Linux's loadkeys compiles a text keymap and
uploads it a key at a time through KDSKBENT, which puts the data in userspace
-- and a machine whose /usr has not mounted then has no layout at all. Here the
kernel always has a working keyboard and `loadkeys` only names which one.
KB_GETLAYOUT/KB_SETLAYOUT/KB_LISTLAYOUT; /etc/vconsole.conf and an
os.schos.keymap job for the boot-time choice. No dead keys, so French and
Spanish are absent rather than wrong.

/etc/locale.conf and LANG=C.UTF-8 in profile and zshenv. Only the charset half
of that is real -- musl decodes UTF-8 whatever the locale says and ships no
locale data -- but an unset LANG reads as "ASCII only" to everything that asks,
which is its own way of producing `?`.

And two symlink bugs found while chasing

    zsh: locking failed for /root/.zsh_history: operation not permitted

on every boot. symlink() is the classic atomic lock -- create the link, and if
it exists someone else holds it -- and zsh distinguishes EEXIST ("contended,
retry") from anything else ("this cannot work, give up"). sys_symlink returned
a bare -1, which is -EPERM, so every zsh on the machine took the second branch
on a filesystem that supports symlinks perfectly well. Same errno class as
commit 75ccf98.

The second one the first was hiding: **divesymlink() has been in fs.c since the
fork and nothing ever called it.** A symlink behaved as a small file containing
its own target, so `cat link` printed the target's *name*. open() and openat()
follow the final component now (O_NOFOLLOW gives ELOOP), and stat() and lstat()
stop being the same function, since which one follows is the only difference
between them. Mid-path symlinks are still not resolved -- that belongs in
namex(), which would re-enter lookup holding a directory lock.

Verified on the emulated keyboard, not just over serial: AltGr+a/e/s gives
ąęś, Shift+AltGr gives ĄĘŚ, Caps Lock+AltGr gives ĄĘŚ, de types zy for the
physical y/z keys and @€µ on AltGr. `∞ 'x' → ≤ • — …` typed over serial now
survives. Three fresh boots: 0 lock failures, 0 faults.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Nexoniarz 2026-09-20 01:09:32 +02:00
commit 4e3e345b41
15 changed files with 994 additions and 208 deletions
Download patch file Download diff file Expand all files Collapse all files

70
kernel/core/console.c
View file

@ -4,7 +4,7 @@
#include "klog.h"
#include "dbg.h"
#include "vt.h"
#include "kbd.h" /* KEY_VT_SWITCH -- the terminal-switch chords */
#include "kbd.h" /* KBD_VT_SWITCH -- the terminal-switch chords */
#include "gfx.h"
#include "theme.h"
#include "irq.h"
@ -434,14 +434,14 @@ erase_one(struct vt *v)
// ---------------------------------------------------------------------------
// Ctrl+Alt+Shift+F1..F6 switch terminals. kbd.c reports them as
// KEY_VT_SWITCH+n so that the
// KBD_VT_SWITCH+n so that the
// decision of what a chord *means* is made here, where the terminals are,
// rather than in a driver that should not know they exist.
int
console_vt_hotkey(int key)
{
if (key != KEY_VT_PREV && key != KEY_VT_NEXT &&
(key < KEY_VT_SWITCH || key >= KEY_VT_SWITCH + NVT))
if (key != KBD_VT_PREV && key != KBD_VT_NEXT &&
(key < KBD_VT_SWITCH || key >= KBD_VT_SWITCH + NVT))
return 0;
// A program that called VT_SETMODE(VT_PROCESS) owns switching on this
// terminal. Dropping the chord entirely would be worse than not binding it:
@ -449,9 +449,9 @@ console_vt_hotkey(int key)
// falls through to the line discipline as an ordinary key.
if (!vt_kernel_switches())
return 0;
if (key == KEY_VT_PREV) vt_cycle(-1);
else if (key == KEY_VT_NEXT) vt_cycle(+1);
else vt_switch(key - KEY_VT_SWITCH);
if (key == KBD_VT_PREV) vt_cycle(-1);
else if (key == KBD_VT_NEXT) vt_cycle(+1);
else vt_switch(key - KBD_VT_SWITCH);
return 1;
}
@ -467,8 +467,8 @@ consoleintr(int (*getc)(void))
// Terminal switching happens before the line discipline sees anything:
// the chord is not input for the terminal you are leaving.
if (c == KEY_VT_PREV || c == KEY_VT_NEXT ||
(c >= KEY_VT_SWITCH && c < KEY_VT_SWITCH + NVT)) {
if (c == KBD_VT_PREV || c == KBD_VT_NEXT ||
(c >= KBD_VT_SWITCH && c < KBD_VT_SWITCH + NVT)) {
release(&input_lock);
int taken = console_vt_hotkey(c);
acquire(&input_lock);
@ -481,8 +481,10 @@ consoleintr(int (*getc)(void))
// terminal a terminal: the keyboard follows the eyes.
struct vt *v = vt_current();
// Input mapping, before anything looks at the character.
if (v->tio.c_iflag & ISTRIP) c &= 0x7f;
// Input mapping, before anything looks at the character. ISTRIP is about
// seven-bit lines and applies to characters only -- masking a keycode
// would turn an arrow key into whatever letter its low seven bits spell.
if ((v->tio.c_iflag & ISTRIP) && c < KBD_SPECIAL) c &= 0x7f;
if (c == '\r') {
if (v->tio.c_iflag & IGNCR) continue;
if (v->tio.c_iflag & ICRNL) c = '\n';
@ -567,12 +569,13 @@ consoleintr(int (*getc)(void))
// Arrow keys and the rest of the navigation block, as escape sequences.
//
// These arrive as single keycodes -- KEY_UP is 0xE2 -- and used to be
// pushed into the input buffer exactly like that. A terminal has never
// worked that way, and 0xE2 in particular is the worst possible choice of
// byte: it is a UTF-8 lead byte for a three-byte character, so a reader
// decoding UTF-8 swallowed the next two keys waiting for continuations
// that never came. Every arrow key corrupted the two keystrokes after it.
// These arrive as single keycodes and used to be pushed into the input
// buffer exactly like that. A terminal has never worked that way, and the
// values chosen made it worse: KBD_UP was 0xE2, a UTF-8 lead byte for a
// three-byte character, so a reader decoding UTF-8 swallowed the next two
// keys waiting for continuations that never came -- every arrow key
// corrupted the two keystrokes after it. The keycodes now sit above
// U+10FFFF where nothing can collide with them; see include/kbd.h.
//
// What a terminal sends is `ESC [ A`, and what makes zsh's line editor
// work is receiving that. The sequences below are the DEC/xterm ones that
@ -580,16 +583,16 @@ consoleintr(int (*getc)(void))
{
const char *esc = 0;
switch (c) {
case KEY_UP: esc = "\033[A"; break;
case KEY_DN: esc = "\033[B"; break;
case KEY_RT: esc = "\033[C"; break;
case KEY_LF: esc = "\033[D"; break;
case KEY_HOME: esc = "\033[H"; break;
case KEY_END: esc = "\033[F"; break;
case KEY_PGUP: esc = "\033[5~"; break;
case KEY_PGDN: esc = "\033[6~"; break;
case KEY_INS: esc = "\033[2~"; break;
case KEY_DEL: esc = "\033[3~"; break;
case KBD_UP: esc = "\033[A"; break;
case KBD_DN: esc = "\033[B"; break;
case KBD_RT: esc = "\033[C"; break;
case KBD_LF: esc = "\033[D"; break;
case KBD_HOME: esc = "\033[H"; break;
case KBD_END: esc = "\033[F"; break;
case KBD_PGUP: esc = "\033[5~"; break;
case KBD_PGDN: esc = "\033[6~"; break;
case KBD_INS: esc = "\033[2~"; break;
case KBD_DEL: esc = "\033[3~"; break;
}
if (esc) {
// Not echoed. In raw mode -- which is where a line editor lives, and
@ -610,12 +613,19 @@ consoleintr(int (*getc)(void))
}
}
// Any keycode still here is a special nobody translated. Dropping it is
// the only safe thing: storing it would truncate to a byte and type a
// character the user did not press.
if (c >= KBD_SPECIAL)
continue;
if (v->in.e - v->in.r >= VT_INPUT_BUF)
continue; // buffer full: drop it
// Everything else goes in, including bytes above 127 -- those are UTF-8
// continuation bytes, and the old `c >= 32 && c <= 126` test silently
// refused every non-ASCII character anyone tried to type.
// Everything else goes in, including bytes above 127 -- those are UTF-8,
// arriving a byte at a time from the serial line or encoded by kbdgetc,
// and the old `c >= 32 && c <= 126` test silently refused every non-ASCII
// character anyone tried to type.
v->in.buf[v->in.e++ % VT_INPUT_BUF] = c;
echo(v, c);

95
kernel/dev/kbd.c
View file

@ -5,6 +5,7 @@
#include "posix.h"
#include "vt.h" /* NVT -- how many terminals the chords reach */
#include "input.h"
#include "keymap.h"
// The chord, settable at run time through VT_SETCHORD.
//
@ -21,14 +22,72 @@
uint vt_chord_mods = RALT;
uint vt_chord_base = SCAN_F1;
// Which scancodes are modifiers, and which are locks. Hardware facts rather
// than layout ones -- every layout agrees that 0x2A is a Shift key -- so they
// stay here while the character tables live in keymap.c.
static const uchar shiftcode[256] = {
[0x1D] = CTL,
[0x2A] = SHIFT,
[0x36] = SHIFT,
[0x38] = ALT,
[0x9D] = CTL,
[0xB8] = RALT // right Alt / AltGr -- see RALT in kbd.h
};
static const uchar togglecode[256] = {
[0x3A] = CAPSLOCK,
[0x45] = NUMLOCK,
[0x46] = SCROLLLOCK
};
// A key can produce more than one byte.
//
// consoleintr's contract with getc() is bytes: the serial line hands it raw
// UTF-8 already, and it would have no way to tell an encoded codepoint apart
// from a byte that happened to have the same value. So the keyboard encodes
// here and hands the bytes over one call at a time -- kbdintr loops until
// getc() returns negative, so a queue of at most four drains on its own
// before the next scancode is read.
static uchar pend[4];
static int pend_n, pend_i;
static int
queue_utf8(uint32 cp)
{
pend_i = 0;
if (cp < 0x80) {
pend_n = 0;
return (int)cp; // the common case: no queue at all
}
if (cp < 0x800) {
pend[0] = 0xC0 | (cp >> 6);
pend[1] = 0x80 | (cp & 0x3F);
pend_n = 2;
} else if (cp < 0x10000) {
pend[0] = 0xE0 | (cp >> 12);
pend[1] = 0x80 | ((cp >> 6) & 0x3F);
pend[2] = 0x80 | (cp & 0x3F);
pend_n = 3;
} else {
pend[0] = 0xF0 | (cp >> 18);
pend[1] = 0x80 | ((cp >> 12) & 0x3F);
pend[2] = 0x80 | ((cp >> 6) & 0x3F);
pend[3] = 0x80 | (cp & 0x3F);
pend_n = 4;
}
return pend[pend_i++];
}
int
kbdgetc(void)
{
static uint shift;
static uchar *charcode[4] = {
normalmap, shiftmap, ctlmap, ctlmap
};
uint st, data, c;
uint st, data;
uint32 cp;
if (pend_i < pend_n)
return pend[pend_i++]; // finish the last key first
pend_i = pend_n = 0;
st = inb(KBSTATP);
if((st & KBS_DIB) == 0)
@ -81,29 +140,25 @@ kbdgetc(void)
// terminal". What it means is decided in console.c, which is where the
// terminals are; this only has to name it. See console_vt_hotkey().
//
// The modifier test is an equality, not a mask. A mask fires on any superset,
// so a chord aimed at the host would switch terminals behind your back.
//
// The modifier test is an equality, not a mask. `shift & ALT` would fire on
// Ctrl+Alt+1 and on AltGr+1 as well, so a chord aimed at the host -- or a
// Polish keystroke -- would switch terminals behind your back. Exactly left
// Alt, and nothing else held.
// Polish keystroke -- would switch terminals behind your back. Exactly the
// modifiers named, and nothing else held.
if (vt_chord_mods != 0 &&
(shift & (CTL | SHIFT | ALT | RALT)) == vt_chord_mods) {
if (data >= vt_chord_base && data < vt_chord_base + NVT)
return KEY_VT_SWITCH + (data - vt_chord_base);
if (data == SCAN_MINUS) return KEY_VT_PREV;
if (data == SCAN_EQUALS) return KEY_VT_NEXT;
return KBD_VT_SWITCH + (data - vt_chord_base);
if (data == SCAN_MINUS) return KBD_VT_PREV;
if (data == SCAN_EQUALS) return KBD_VT_NEXT;
}
c = charcode[shift & (CTL | SHIFT)][data];
if(shift & CAPSLOCK){
if('a' <= c && c <= 'z')
c += 'A' - 'a';
else if('A' <= c && c <= 'Z')
c += 'a' - 'A';
}
return c;
cp = keymap_lookup(data, shift);
if (cp == 0)
return 0;
if (cp >= KBD_SPECIAL)
return (int)cp; // arrows and the rest, not characters
return queue_utf8(cp);
}
void

297
kernel/dev/keymap.c Normal file
View file

@ -0,0 +1,297 @@
// Keyboard layouts. See include/keymap.h for the interface and its limits.
//
// Every table is indexed by set-1 scancode, with the E0-prefixed keys folded
// into 0x80..0xFF by kbd.c before the lookup -- the same numbering the single
// hardcoded table used, so a layout is a diff against a shape that was already
// proven to work rather than a new mapping to get wrong.
//
// The tables are `uint32` and not `uchar`. That is the whole reason this file
// exists: `ą` is U+0105 and does not fit in a byte, and a Polish layout that
// cannot type `ą` is not one.
#include "types.h"
#include "defs.h"
#include "kbd.h"
#include "keymap.h"
// Shared by every layout that does not move the navigation block, which is
// all of them -- the arrow keys are not a national matter. Merged into each
// level table below rather than consulted separately, because a layout is
// allowed to disagree and none currently does.
#define NAV_KEYS \
[0xC8] = KBD_UP, [0xD0] = KBD_DN, \
[0xC9] = KBD_PGUP, [0xD1] = KBD_PGDN, \
[0xCB] = KBD_LF, [0xCD] = KBD_RT, \
[0x97] = KBD_HOME, [0xCF] = KBD_END, \
[0xD2] = KBD_INS, [0xD3] = KBD_DEL, \
[0x9C] = '\n', /* KP_Enter */ \
[0xB5] = '/' /* KP_Div */
// --- US ---------------------------------------------------------------------
static const uint32 us_plain[256] = {
NO, 0x1B, '1', '2', '3', '4', '5', '6', // 0x00
'7', '8', '9', '0', '-', '=', '\b', '\t',
'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', // 0x10
'o', 'p', '[', ']', '\n', NO, 'a', 's',
'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', // 0x20
'\'', '`', NO, '\\', 'z', 'x', 'c', 'v',
'b', 'n', 'm', ',', '.', '/', NO, '*', // 0x30
NO, ' ', NO, NO, NO, NO, NO, NO,
NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
'8', '9', '-', '4', '5', '6', '+', '1',
'2', '3', '0', '.', NO, NO, NO, NO, // 0x50
NAV_KEYS
};
static const uint32 us_shift[256] = {
NO, 0x1B, '!', '@', '#', '$', '%', '^', // 0x00
'&', '*', '(', ')', '_', '+', '\b', '\t',
'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', // 0x10
'O', 'P', '{', '}', '\n', NO, 'A', 'S',
'D', 'F', 'G', 'H', 'J', 'K', 'L', ':', // 0x20
'"', '~', NO, '|', 'Z', 'X', 'C', 'V',
'B', 'N', 'M', '<', '>', '?', NO, '*', // 0x30
NO, ' ', NO, NO, NO, NO, NO, NO,
NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
'8', '9', '-', '4', '5', '6', '+', '1',
'2', '3', '0', '.', NO, NO, NO, NO, // 0x50
NAV_KEYS
};
// --- Polish (programmers) ---------------------------------------------------
//
// US QWERTY with nine letters on AltGr. This is the layout essentially every
// Polish developer uses, and the reason is that the alternative -- "Polish
// (214)", a genuine national arrangement -- moves Y, Z and most of the
// punctuation, which makes every shell and every editor shortcut land
// somewhere else. The diacritics go on AltGr and nothing else moves.
//
// AltGr+x is ź and AltGr+z is ż, which looks arbitrary and is not: the letter
// x is unused in Polish, so its key is free, and ź and ż both need one.
static const uint32 pl_altgr[256] = {
[0x1E] = 0x0105, // a -> ą
[0x2E] = 0x0107, // c -> ć
[0x12] = 0x0119, // e -> ę
[0x26] = 0x0142, // l -> ł
[0x31] = 0x0144, // n -> ń
[0x18] = 0x00F3, // o -> ó
[0x1F] = 0x015B, // s -> ś
[0x2D] = 0x017A, // x -> ź
[0x2C] = 0x017C, // z -> ż
};
static const uint32 pl_shiftaltgr[256] = {
[0x1E] = 0x0104, // A -> Ą
[0x2E] = 0x0106, // C -> Ć
[0x12] = 0x0118, // E -> Ę
[0x26] = 0x0141, // L -> Ł
[0x31] = 0x0143, // N -> Ń
[0x18] = 0x00D3, // O -> Ó
[0x1F] = 0x015A, // S -> Ś
[0x2D] = 0x0179, // X -> Ź
[0x2C] = 0x017B, // Z -> Ż
};
// --- German (QWERTZ) --------------------------------------------------------
//
// Y and Z swap, the umlauts and ß take the punctuation keys on the home and
// top rows, and the key between left Shift and Z -- scancode 0x56, which a US
// keyboard does not have at all -- carries < > |.
//
// The acute (0x0D) and circumflex (0x29) keys are dead on a real German
// layout. Here they type the accent on its own. See include/keymap.h.
static const uint32 de_plain[256] = {
NO, 0x1B, '1', '2', '3', '4', '5', '6', // 0x00
'7', '8', '9', '0', 0x00DF, 0x00B4, '\b', '\t', // ß ´
'q', 'w', 'e', 'r', 't', 'z', 'u', 'i', // 0x10
'o', 'p', 0x00FC, '+', '\n', NO, 'a', 's', // ü
'd', 'f', 'g', 'h', 'j', 'k', 'l', 0x00F6, // ö
0x00E4, '^', NO, '#', 'y', 'x', 'c', 'v', // ä
'b', 'n', 'm', ',', '.', '-', NO, '*', // 0x30
NO, ' ', NO, NO, NO, NO, NO, NO,
NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
'8', '9', '-', '4', '5', '6', '+', '1',
'2', '3', '0', ',', NO, NO, '<', NO, // 0x50, 0x56 = <>|
NAV_KEYS
};
static const uint32 de_shift[256] = {
NO, 0x1B, '!', '"', 0x00A7, '$', '%', '&', // 0x00 §
'/', '(', ')', '=', '?', '`', '\b', '\t',
'Q', 'W', 'E', 'R', 'T', 'Z', 'U', 'I', // 0x10
'O', 'P', 0x00DC, '*', '\n', NO, 'A', 'S', // Ü
'D', 'F', 'G', 'H', 'J', 'K', 'L', 0x00D6, // Ö
0x00C4, 0x00B0, NO, '\'', 'Y', 'X', 'C', 'V', // Ä °
'B', 'N', 'M', ';', ':', '_', NO, '*', // 0x30
NO, ' ', NO, NO, NO, NO, NO, NO,
NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
'8', '9', '-', '4', '5', '6', '+', '1',
'2', '3', '0', ',', NO, NO, '>', NO, // 0x50
NAV_KEYS
};
static const uint32 de_altgr[256] = {
[0x03] = 0x00B2, // 2 -> ²
[0x04] = 0x00B3, // 3 -> ³
[0x08] = '{', // 7
[0x09] = '[', // 8
[0x0A] = ']', // 9
[0x0B] = '}', // 0
[0x0C] = '\\', // ß
[0x10] = '@', // q
[0x12] = 0x20AC, // e -> €
[0x1B] = '~', // +
[0x32] = 0x00B5, // m -> µ
[0x56] = '|',
};
// --- the catalogue ----------------------------------------------------------
//
// Order matters only in that the first entry is the default. US, because a
// machine whose keyboard layout has never been set should behave the way the
// scancodes are printed on the majority of keyboards, and because every
// installation instruction anyone follows is written in ASCII.
static const struct keylayout layouts[] = {
{ "us", "English (US), QWERTY",
{ us_plain, us_shift, 0, 0 } },
{ "pl", "Polish (programmers) -- US QWERTY, diacritics on AltGr",
{ us_plain, us_shift, pl_altgr, pl_shiftaltgr } },
{ "de", "German, QWERTZ -- no dead keys, so the accent keys type the accent",
{ de_plain, de_shift, de_altgr, 0 } },
};
#define NLAYOUTS ((int)(sizeof(layouts) / sizeof(layouts[0])))
static const struct keylayout *active = &layouts[0];
const struct keylayout *
keymap_active(void)
{
return active;
}
const struct keylayout *
keymap_by_index(int i)
{
if (i < 0 || i >= NLAYOUTS)
return 0;
return &layouts[i];
}
int
keymap_set(const char *name)
{
for (int i = 0; i < NLAYOUTS; i++) {
const char *a = layouts[i].name, *b = name;
while (*a && *a == *b) { a++; b++; }
if (*a == 0 && *b == 0) {
active = &layouts[i];
return 0;
}
}
return -1;
}
// A control character from the plain codepoint rather than from a table of
// its own.
//
// The table this replaces was indexed by scancode, which quietly assumed a US
// keyboard: on QWERTZ, Ctrl+Z and Ctrl+Y would have swapped with the letters,
// so suspending a job would have depended on the layout. Deriving from what
// the key actually types is both shorter and correct everywhere.
static uint32
control_of(uint32 cp)
{
if (cp >= 'a' && cp <= 'z') return cp - 'a' + 1;
if (cp >= 'A' && cp <= 'Z') return cp - 'A' + 1;
switch (cp) {
case '@': case ' ': case '2': return 0; // NUL
case '[': return 0x1B; // ESC
case '\\': return 0x1C;
case ']': return 0x1D;
case '^': case '6': return 0x1E;
case '_': case '-': case '/': return 0x1F;
case '?': return 0x7F;
case '\n': case '\r': return '\r';
}
return 0; // no control character on this key
}
// Upper <-> lower for the letters these layouts can produce.
//
// Caps Lock needs this and Shift does not: Shift has its own table, so the
// layout has already said what the shifted key gives. Caps Lock has no table
// -- it applies to whatever came out, including `ą` from the AltGr level --
// so the case pair has to be derived from the codepoint.
//
// Latin Extended-A is laid out in alternating pairs, but not all the same way
// round: U+0100..U+0137 and U+014A..U+0177 have the capital on the even
// codepoint, while U+0139..U+0148 and U+0179..U+017E have it on the odd one.
// L-stroke is U+0141/U+0142 and Z-dot is U+017B/U+017C, so Polish lands in
// both halves and getting the parity wrong would shift one of them to a
// neighbouring letter rather than to its own capital.
static uint32
case_toggle(uint32 cp)
{
if (cp >= 'a' && cp <= 'z') return cp - 'a' + 'A';
if (cp >= 'A' && cp <= 'Z') return cp - 'A' + 'a';
// Latin-1: the accented letters run C0..DE and E0..FE, with multiplication
// and division signs punched out of the middle of each. Eszett (DF) has no
// single-codepoint capital and stays as it is.
if (cp >= 0xC0 && cp <= 0xDE && cp != 0xD7) return cp + 0x20;
if (cp >= 0xE0 && cp <= 0xFE && cp != 0xF7) return cp - 0x20;
if ((cp >= 0x0100 && cp <= 0x0137) || (cp >= 0x014A && cp <= 0x0177))
return (cp & 1) ? cp - 1 : cp + 1; // even is the capital
if ((cp >= 0x0139 && cp <= 0x0148) || (cp >= 0x0179 && cp <= 0x017E))
return (cp & 1) ? cp + 1 : cp - 1; // odd is the capital
return cp;
}
uint32
keymap_lookup(uint scancode, uint mods)
{
const struct keylayout *l = active;
uint32 cp;
if (scancode > 0xFF)
return 0;
// AltGr first. It is the only modifier that selects a whole different table,
// and on a layout that has no AltGr level the lookup falls back rather than
// producing nothing -- otherwise holding AltGr on a US keyboard would make
// every key dead.
int level = KM_PLAIN;
if (mods & RALT) level = (mods & SHIFT) ? KM_SHIFTALTGR : KM_ALTGR;
else if (mods & SHIFT) level = KM_SHIFT;
cp = l->level[level] ? l->level[level][scancode] : 0;
if (cp == 0 && level >= KM_ALTGR) {
level = (mods & SHIFT) ? KM_SHIFT : KM_PLAIN;
cp = l->level[level] ? l->level[level][scancode] : 0;
}
if (cp == 0)
return 0;
// Caps Lock is a letter-case toggle, not a Shift: it applies to whatever
// the table produced, including a letter that only exists on AltGr. `ą`
// with Caps Lock on is `Ą`, and only the layout knows that -- so the case
// pair has to come from the codepoint, not from a second table lookup.
if ((mods & CAPSLOCK) && cp < KBD_SPECIAL)
cp = case_toggle(cp);
// Ctrl is last and overrides: Ctrl+Shift+C is still Ctrl+C.
if (mods & CTL) {
if (cp >= KBD_SPECIAL)
return cp; // Ctrl+arrow stays an arrow
return control_of(cp);
}
return cp;
}

187
kernel/sys/sys_fs.c
View file

@ -18,6 +18,7 @@
#include "gfx.h" /* gfx_cols/gfx_rows — TIOCGWINSZ reports them */
#include "vt.h" /* the terminals TIOC*/VT_* act on */
#include "pciuser.h"
#include "keymap.h" /* KB_*LAYOUT — the keyboard layout catalogue */
#include "netuser.h"
// -----------------------------------------------------------------------
@ -459,6 +460,35 @@ addr_t sys_pipe2(void)
// Filesystem ops
// -----------------------------------------------------------------------
// Resolve a symlink opened as the final path component.
//
// divesymlink() has been in kernel/fs/fs.c since the fork and nothing ever
// called it, so a symlink behaved as a small file containing its own target:
// `cat link` printed the target's *name* rather than its contents, and every
// program that follows a symlink to find something followed it nowhere.
//
// Only the last component. A symlink in the middle of a path -- /a/link/b --
// is still not resolved; that belongs in namex(), which would have to re-enter
// path lookup while holding a directory lock, and getting that wrong is a
// deadlock rather than a wrong answer. Final-component resolution is what
// open(), exec() and stat() need, which is nearly everything that matters.
//
// Takes a locked inode and returns a locked inode, or 0 with everything
// released -- the same contract divesymlink() already had.
static struct inode *
follow_final(struct inode *ip, int omode)
{
if (ip->type != T_SYMLINK)
return ip;
if (omode & O_NOFOLLOW) {
// POSIX: opening a symlink itself is an error unless O_PATH, which
// this kernel does not have. Saying so beats handing back the link.
iunlockput(ip);
return 0;
}
return divesymlink(ip);
}
addr_t sys_open(void)
{
char *path;
@ -486,6 +516,7 @@ addr_t sys_open(void)
} else {
if (!(ip = namei(path))) { end_op(); return -ENOENT; }
ilock(ip);
if (!(ip = follow_final(ip, omode))) { end_op(); return -ELOOP; }
// Directories may only be opened for reading, but callers (e.g.
// opendir()) legitimately OR in flags like O_DIRECTORY/O_CLOEXEC/
// O_NONBLOCK alongside O_RDONLY — only the access-mode bits matter.
@ -530,6 +561,7 @@ addr_t sys_openat(void)
} else {
if (!(ip = at_namei(dirfd, path))) { end_op(); return -ENOENT; }
ilock(ip);
if (!(ip = follow_final(ip, omode))) { end_op(); return -ELOOP; }
// Directories may only be opened for reading, but callers (e.g.
// opendir()) legitimately OR in flags like O_DIRECTORY/O_CLOEXEC/
// O_NONBLOCK alongside O_RDONLY — only the access-mode bits matter.
@ -572,16 +604,21 @@ addr_t sys_fstat(void)
return 0;
}
addr_t sys_stat(void)
// stat/lstat differ in exactly one thing: whether a final symlink is followed.
// They used to be the same function, which was invisible while nothing
// followed symlinks anywhere and becomes wrong the moment something does.
static addr_t
do_stat(int dirfd, char *path, char *st, int follow)
{
char *path;
char *st;
struct inode *ip;
int size = myproc()->syscall_map ? sizeof(struct linux_stat) : sizeof(struct stat);
if (argstr(0, &path) < 0 || argptr(1, &st, size) < 0) return -1;
begin_op();
if (!(ip = namei(path))) { end_op(); return -ENOENT; }
if (!(ip = at_namei(dirfd, path))) { end_op(); return -ENOENT; }
ilock(ip);
if (follow && ip->type == T_SYMLINK && !(ip = divesymlink(ip))) {
end_op();
return -ELOOP;
}
if (myproc()->syscall_map) stati_linux(ip, (struct linux_stat*)st);
else stati(ip, (struct stat*)st);
iunlockput(ip);
@ -589,7 +626,23 @@ addr_t sys_stat(void)
return 0;
}
addr_t sys_lstat(void) { return sys_stat(); }
addr_t sys_stat(void)
{
char *path, *st;
int size = myproc()->syscall_map ? sizeof(struct linux_stat) : sizeof(struct stat);
if (argstr(0, &path) < 0) return -EFAULT;
if (argptr(1, &st, size) < 0) return -EFAULT;
return do_stat(AT_FDCWD, path, st, 1);
}
addr_t sys_lstat(void)
{
char *path, *st;
int size = myproc()->syscall_map ? sizeof(struct linux_stat) : sizeof(struct stat);
if (argstr(0, &path) < 0) return -EFAULT;
if (argptr(1, &st, size) < 0) return -EFAULT;
return do_stat(AT_FDCWD, path, st, 0);
}
addr_t sys_access(void)
{
@ -865,31 +918,71 @@ bad_rename:
ilock(ip); ip->nlink--; iupdate(ip); iunlockput(ip); end_op(); return -err;
}
// symlink(2).
//
// The errno matters more here than anywhere else in this file, because the one
// widespread use of symlink() is as an atomic lock: create a link, and if it
// already exists someone else holds the lock. zsh's history locking is exactly
// that, and it distinguishes EEXIST ("contended, wait and retry") from
// anything else ("this cannot work, give up"). Returning a bare -1 -- which is
// -EPERM -- put every zsh on the machine in the second bucket, and printed
//
// zsh: locking failed for /root/.zsh_history: operation not permitted
//
// on every boot, on a filesystem that supports symlinks perfectly well.
static addr_t
do_symlink(int newdirfd, char *target, char *linkpath)
{
struct inode *ip;
int len;
if (*target == 0)
return -ENOENT; // an empty target resolves to nothing
begin_op();
// Distinguishing the two ways createat() returns 0 -- the name is taken,
// or the path to it does not exist -- has to be done before the create,
// because createat() does not say which.
if ((ip = at_namei(newdirfd, linkpath)) != 0) {
iput(ip);
end_op();
return -EEXIST;
}
if (!(ip = createat(newdirfd, linkpath, T_SYMLINK, 0, 0))) {
end_op();
return -ENOENT;
}
len = strlen(target);
if (writei(ip, 0, (uint64)target, 0, len) != len) {
iunlockput(ip);
end_op();
return -EIO;
}
iunlockput(ip);
end_op();
return 0;
}
addr_t sys_symlink(void)
{
char *target, *linkpath;
if (argstr(0, &target) < 0 || argstr(1, &linkpath) < 0) return -1;
begin_op();
struct inode *ip = create(linkpath, T_SYMLINK, 0, 0);
if (!ip) { end_op(); return -1; }
int len = strlen(target);
if (writei(ip, 0, (uint64)target, 0, len) != len) { iunlockput(ip); end_op(); return -1; }
iunlockput(ip); end_op();
return 0;
if (argstr(0, &target) < 0 || argstr(1, &linkpath) < 0) return -EFAULT;
return do_symlink(AT_FDCWD, target, linkpath);
}
addr_t sys_readlink(void)
{
char *path, *buf;
int bufsiz;
if (argstr(0, &path) < 0 || argint(2, &bufsiz) < 0 || bufsiz <= 0) return -1;
if (argptr(1, &buf, bufsiz) < 0) return -1;
if (argstr(0, &path) < 0) return -EFAULT;
if (argint(2, &bufsiz) < 0 || bufsiz <= 0) return -EINVAL;
if (argptr(1, &buf, bufsiz) < 0) return -EFAULT;
struct inode *ip;
if (!(ip = namei(path))) return -ENOENT;
ilock(ip);
if (ip->type != T_SYMLINK) { iunlockput(ip); return -EINVAL; }
int n = (int)ip->size < bufsiz ? (int)ip->size : bufsiz;
if (readi(ip, 0, (uint64)buf, 0, n) != n) { iunlockput(ip); return -1; }
if (readi(ip, 0, (uint64)buf, 0, n) != n) { iunlockput(ip); return -EIO; }
iunlockput(ip);
return n;
}
@ -1255,6 +1348,32 @@ addr_t sys_ioctl(void)
return 0;
}
// Which keyboard layout the console uses. One layout for the machine, not
// one per terminal: there is one keyboard, and a user who switches to
// tty3 has not changed which keys their fingers are on.
if (request == KB_SETLAYOUT) {
struct kb_layout *k = (struct kb_layout*)user_ptr(argp, sizeof(*k));
if (!k) return -EFAULT;
k->name[sizeof(k->name) - 1] = 0;
if (keymap_set(k->name) < 0)
return -EINVAL;
return 0;
}
if (request == KB_GETLAYOUT || request == KB_LISTLAYOUT) {
struct kb_layout *k = (struct kb_layout*)user_ptr(argp, sizeof(*k));
if (!k) return -EFAULT;
const struct keylayout *l;
if (request == KB_GETLAYOUT) {
l = keymap_active();
} else {
l = keymap_by_index(k->index);
if (!l) return -EINVAL; // the documented end of the list
}
safestrcpy(k->name, l->name, sizeof(k->name));
safestrcpy(k->desc, l->desc, sizeof(k->desc));
return 0;
}
if (request == VT_GETMODE) {
struct vt_mode *m = (struct vt_mode*)user_ptr(argp, sizeof(*m));
if (!m) return -EFAULT;
@ -1596,18 +1715,10 @@ addr_t sys_symlinkat(void)
{
char *target, *linkpath;
int newdirfd;
if (argstr(0, &target) < 0) return -1;
if (argstr(0, &target) < 0) return -EFAULT;
argint(1, &newdirfd);
if (argstr(2, &linkpath) < 0) return -1;
begin_op();
struct inode *ip = createat(newdirfd, linkpath, T_SYMLINK, 0, 0);
if (!ip) { end_op(); return -1; }
int len = strlen(target);
if (writei(ip, 0, (uint64)target, 0, len) != len) {
iunlockput(ip); end_op(); return -1;
}
iunlockput(ip); end_op();
return 0;
if (argstr(2, &linkpath) < 0) return -EFAULT;
return do_symlink(newdirfd, target, linkpath);
}
addr_t sys_readlinkat(void)
@ -1616,15 +1727,15 @@ addr_t sys_readlinkat(void)
char *path, *buf;
int bufsiz;
argint(0, &dirfd);
if (argstr(1, &path) < 0) return -1;
if (argint(3, &bufsiz) < 0 || bufsiz <= 0) return -1;
if (argptr(2, &buf, bufsiz) < 0) return -1;
if (argstr(1, &path) < 0) return -EFAULT;
if (argint(3, &bufsiz) < 0 || bufsiz <= 0) return -EINVAL;
if (argptr(2, &buf, bufsiz) < 0) return -EFAULT;
struct inode *ip;
if (!(ip = at_namei(dirfd, path))) return -ENOENT;
ilock(ip);
if (ip->type != T_SYMLINK) { iunlockput(ip); return -EINVAL; }
int n = (int)ip->size < bufsiz ? (int)ip->size : bufsiz;
if (readi(ip, 0, (uint64)buf, 0, n) != n) { iunlockput(ip); return -1; }
if (readi(ip, 0, (uint64)buf, 0, n) != n) { iunlockput(ip); return -EIO; }
iunlockput(ip);
return n;
}
@ -1670,15 +1781,7 @@ addr_t sys_fstatat(void)
return 0;
}
begin_op();
struct inode *ip = at_namei(dirfd, path);
if (!ip) { end_op(); return -ENOENT; }
ilock(ip);
if (myproc()->syscall_map) stati_linux(ip, (struct linux_stat*)st);
else stati(ip, (struct stat*)st);
iunlockput(ip);
end_op();
return 0;
return do_stat(dirfd, path, st, !(flags & AT_SYMLINK_NOFOLLOW));
}
// -----------------------------------------------------------------------