systemd/src/udev/udev-builtin-input_id.c

/*
 * compose persistent device path
 *
 * Copyright (C) 2009 Martin Pitt <martin.pitt@ubuntu.com>
 * Portions Copyright (C) 2004 David Zeuthen, <david@fubar.dk>
 * Copyright (C) 2011 Kay Sievers <kay@vrfy.org>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <linux/limits.h>
#include <linux/input.h>

#include "udev.h"

/* we must use this kernel-compatible implementation */
#define BITS_PER_LONG (sizeof(unsigned long) * 8)
#define NBITS(x) ((((x)-1)/BITS_PER_LONG)+1)
#define OFF(x)  ((x)%BITS_PER_LONG)
#define BIT(x)  (1UL<<OFF(x))
#define LONG(x) ((x)/BITS_PER_LONG)
#define test_bit(bit, array)    ((array[LONG(bit)] >> OFF(bit)) & 1)

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
/*
 * Read a capability attribute and return bitmask.
 * @param dev udev_device
 * @param attr sysfs attribute name (e. g. "capabilities/key")
 * @param bitmask: Output array which has a sizeof of bitmask_size
 */
static void get_cap_mask(struct udev_device *dev,
                         struct udev_device *pdev, const char* attr,
                         unsigned long *bitmask, size_t bitmask_size,
                         bool test)
{
        char text[4096];
        unsigned i;
        char* word;
        unsigned long val;

        snprintf(text, sizeof(text), "%s", udev_device_get_sysattr_value(pdev, attr));
        log_debug("%s raw kernel attribute: %s\n", attr, text);

        memset (bitmask, 0, bitmask_size);
        i = 0;
        while ((word = strrchr(text, ' ')) != NULL) {
                val = strtoul (word+1, NULL, 16);
                if (i < bitmask_size/sizeof(unsigned long))
                        bitmask[i] = val;
                else
                        log_debug("ignoring %s block %lX which is larger than maximum size\n", attr, val);
                *word = '\0';
                ++i;
        }
        val = strtoul (text, NULL, 16);
        if (i < bitmask_size / sizeof(unsigned long))
                bitmask[i] = val;
        else
                log_debug("ignoring %s block %lX which is larger than maximum size\n", attr, val);

        if (test) {
                /* printf pattern with the right unsigned long number of hex chars */
                snprintf(text, sizeof(text), "  bit %%4u: %%0%zilX\n", 2 * sizeof(unsigned long));
                log_debug("%s decoded bit map:\n", attr);
                val = bitmask_size / sizeof (unsigned long);
                /* skip over leading zeros */
                while (bitmask[val-1] == 0 && val > 0)
                        --val;
                for (i = 0; i < val; ++i)
                        log_debug(text, i * BITS_PER_LONG, bitmask[i]);
        }
}
#pragma GCC diagnostic pop

/* pointer devices */
static void test_pointers (struct udev_device *dev,
                           const unsigned long* bitmask_ev,
                           const unsigned long* bitmask_abs,
                           const unsigned long* bitmask_key,
                           const unsigned long* bitmask_rel,
                           bool test)
{
        int is_mouse = 0;
        int is_touchpad = 0;

        if (!test_bit (EV_KEY, bitmask_ev)) {
                if (test_bit (EV_ABS, bitmask_ev) &&
                    test_bit (ABS_X, bitmask_abs) &&
                    test_bit (ABS_Y, bitmask_abs) &&
                    test_bit (ABS_Z, bitmask_abs))
                        udev_builtin_add_property(dev, test, "ID_INPUT_ACCELEROMETER", "1");
                return;
        }

        if (test_bit (EV_ABS, bitmask_ev) &&
            test_bit (ABS_X, bitmask_abs) && test_bit (ABS_Y, bitmask_abs)) {
                if (test_bit (BTN_STYLUS, bitmask_key) || test_bit (BTN_TOOL_PEN, bitmask_key))
                        udev_builtin_add_property(dev, test, "ID_INPUT_TABLET", "1");
                else if (test_bit (BTN_TOOL_FINGER, bitmask_key) && !test_bit (BTN_TOOL_PEN, bitmask_key))
                        is_touchpad = 1;
                else if (test_bit (BTN_TRIGGER, bitmask_key) ||
                         test_bit (BTN_A, bitmask_key) ||
                         test_bit (BTN_1, bitmask_key))
                        udev_builtin_add_property(dev, test, "ID_INPUT_JOYSTICK", "1");
                else if (test_bit (BTN_MOUSE, bitmask_key))
                        /* This path is taken by VMware's USB mouse, which has
                         * absolute axes, but no touch/pressure button. */
                        is_mouse = 1;
                else if (test_bit (BTN_TOUCH, bitmask_key))
                        udev_builtin_add_property(dev, test, "ID_INPUT_TOUCHSCREEN", "1");
        }

        if (test_bit (EV_REL, bitmask_ev) &&
            test_bit (REL_X, bitmask_rel) && test_bit (REL_Y, bitmask_rel) &&
            test_bit (BTN_MOUSE, bitmask_key))
                is_mouse = 1;

        if (is_mouse)
                udev_builtin_add_property(dev, test, "ID_INPUT_MOUSE", "1");
        if (is_touchpad)
                udev_builtin_add_property(dev, test, "ID_INPUT_TOUCHPAD", "1");
}

/* key like devices */
static void test_key (struct udev_device *dev,
                      const unsigned long* bitmask_ev,
                      const unsigned long* bitmask_key,
                      bool test)
{
        unsigned i;
        unsigned long found;
        unsigned long mask;

        /* do we have any KEY_* capability? */
        if (!test_bit (EV_KEY, bitmask_ev)) {
                log_debug("test_key: no EV_KEY capability\n");
                return;
        }

        /* only consider KEY_* here, not BTN_* */
        found = 0;
        for (i = 0; i < BTN_MISC/BITS_PER_LONG; ++i) {
                found |= bitmask_key[i];
                log_debug("test_key: checking bit block %lu for any keys; found=%i\n", (unsigned long)i*BITS_PER_LONG, found > 0);
        }
        /* If there are no keys in the lower block, check the higher block */
        if (!found) {
                for (i = KEY_OK; i < BTN_TRIGGER_HAPPY; ++i) {
                        if (test_bit (i, bitmask_key)) {
                                log_debug("test_key: Found key %x in high block\n", i);
                                found = 1;
                                break;
                        }
                }
        }

        if (found > 0)
                udev_builtin_add_property(dev, test, "ID_INPUT_KEY", "1");

        /* the first 32 bits are ESC, numbers, and Q to D; if we have all of
         * those, consider it a full keyboard; do not test KEY_RESERVED, though */
        mask = 0xFFFFFFFE;
        if ((bitmask_key[0] & mask) == mask)
                udev_builtin_add_property(dev, test, "ID_INPUT_KEYBOARD", "1");
}

static int builtin_input_id(struct udev_device *dev, int argc, char *argv[], bool test)
{
        struct udev_device *pdev;
        unsigned long bitmask_ev[NBITS(EV_MAX)];
        unsigned long bitmask_abs[NBITS(ABS_MAX)];
        unsigned long bitmask_key[NBITS(KEY_MAX)];
        unsigned long bitmask_rel[NBITS(REL_MAX)];

        /* walk up the parental chain until we find the real input device; the
         * argument is very likely a subdevice of this, like eventN */
        pdev = dev;
        while (pdev != NULL && udev_device_get_sysattr_value(pdev, "capabilities/ev") == NULL)
                pdev = udev_device_get_parent_with_subsystem_devtype(pdev, "input", NULL);

        /* not an "input" class device */
        if (pdev == NULL)
                return EXIT_SUCCESS;

        /* Use this as a flag that input devices were detected, so that this
         * program doesn't need to be called more than once per device */
        udev_builtin_add_property(dev, test, "ID_INPUT", "1");
        get_cap_mask(dev, pdev, "capabilities/ev", bitmask_ev, sizeof(bitmask_ev), test);
        get_cap_mask(dev, pdev, "capabilities/abs", bitmask_abs, sizeof(bitmask_abs), test);
        get_cap_mask(dev, pdev, "capabilities/rel", bitmask_rel, sizeof(bitmask_rel), test);
        get_cap_mask(dev, pdev, "capabilities/key", bitmask_key, sizeof(bitmask_key), test);
        test_pointers(dev, bitmask_ev, bitmask_abs, bitmask_key, bitmask_rel, test);
        test_key(dev, bitmask_ev, bitmask_key, test);
        return EXIT_SUCCESS;
}

const struct udev_builtin udev_builtin_input_id = {
        .name = "input_id",
        .cmd = builtin_input_id,
        .help = "input device properties",
};