unfettered-keyboard/keymap.c

// SPDX-License-Identifier: GPL-3.0-only
/*
 * XKB keymap manager.
 *
 * Copyright (c) 2024, Richard Acayan. All rights reserved.
 */

#include <ctype.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <xkbcommon/xkbcommon.h>
#include <xkbcommon/xkbcommon-keysyms.h>

#include "keymap.h"
#include "layout.h"
#include "ufkbd.h"

static int write_keysym(int fd, xkb_keysym_t sym)
{
	char *name;
	int len, ret;

	len = xkb_keysym_get_name(sym, NULL, 0);
	if (len == -1)
		return len;

	name = malloc((size_t) len + 1);
	if (name == NULL)
		return -1;

	xkb_keysym_get_name(sym, name, (size_t) len + 1);

	ret = dprintf(fd, "%s", name);

	free(name);
	return ret;
}

static int maybe_write_modmap(int fd, int keyid, xkb_keysym_t sym)
{
	if (sym == XKB_KEY_Shift_L || sym == XKB_KEY_Shift_R)
		return dprintf(fd, "    modifier_map Shift { <I%03d> };\n",
			       keyid);
	else if (sym == XKB_KEY_Control_L || sym == XKB_KEY_Control_R)
		return dprintf(fd, "    modifier_map Control { <I%03d> };\n",
			       keyid);
	else if (sym == XKB_KEY_Alt_L || sym == XKB_KEY_Alt_R)
		return dprintf(fd, "    modifier_map Mod1 { <I%03d> };\n",
			       keyid);

	return 0;
}

int ufkbd_keymap_add_key(struct ufkbd_keymap *keymap, xkb_keysym_t keysym)
{
	xkb_keysym_t upper;
	int len;
	int keyid;

	keyid = keymap->count;
	if (keyid >= 256)
		return -1;

	upper = xkb_keysym_to_upper(keysym);

	len = dprintf(keymap->fd, "    key <I%03d> { [ ", keyid);
	if (len == -1)
		return len;
	keymap->size += len;

	len = write_keysym(keymap->fd, keysym);
	if (len == -1)
		return len;
	keymap->size += len;

	len = dprintf(keymap->fd, ", ");
	if (len == -1)
		return len;
	keymap->size += len;

	len = write_keysym(keymap->fd, upper);
	if (len == -1)
		return len;
	keymap->size += len;

	len = dprintf(keymap->fd, " ] };\n");
	if (len == -1)
		return len;
	keymap->size += len;

	len = maybe_write_modmap(keymap->fd, keyid, keysym);
	if (len == -1)
		return len;
	keymap->size += len;

	keymap->count++;

	return keyid;
}

void ufkbd_keymap_end(struct ufkbd_keymap *keymap)
{
	int i;
	int fd = keymap->fd;
	size_t written;

	written = dprintf(fd, "  };\n"
			      "\n"
			      "  xkb_keycodes \"ufkbd\" {\n"
			      "    minimum = 8;\n"
			      "    maximum = 255;\n");

	for (i = 8; i < keymap->count; i++)
		written += dprintf(fd, "    <I%03d> = %d;\n", i, i);

	written += dprintf(fd, "    indicator 1 = \"Caps Lock\";\n"
			       "  };\n"
			       "\n"
			       "  xkb_types \"ufkbd\" {\n"
			       "    type \"TWO_LEVEL\" {\n"
			       "        modifiers = Shift;\n"
			       "        map[Shift] = Level2;\n"
			       "        level_name[Level1] = \"Base\";\n"
			       "        level_name[Level2] = \"Shift\";\n"
			       "    };\n"
			       "  };\n"
			       "\n"
			       "  xkb_compatibility \"ufkbd\" {\n"
			       "  };\n"
			       "};\n");

	keymap->size += written;
}

struct ufkbd_keymap *ufkbd_keymap_init(void)
{
	struct ufkbd_keymap *keymap;
	intmax_t pid;

	keymap = malloc(sizeof(*keymap));
	if (keymap == NULL)
		return NULL;

	pid = getpid();
	snprintf(keymap->path, 256, "/tmp/ufkbd-keymap-pid%ju", pid);

	keymap->fd = open(keymap->path, O_RDWR | O_CREAT | O_TRUNC, 0644);
	if (keymap->fd == -1)
		goto err;

	keymap->count = 8;
	keymap->size = dprintf(keymap->fd, "xkb_keymap {\n"
					   "  xkb_symbols \"ufkbd\" {\n");

	return keymap;

err:
	free(keymap);
	return NULL;
}

void ufkbd_keymap_uninit(struct ufkbd_keymap *keymap)
{
	close(keymap->fd);
	unlink(keymap->path);
	free(keymap);
}