Hi Carlos,
I think David was working on some similar problems recently, so maybe
he has some comments on the overall approach?
Comment on the implementation: If you are going to add this tool to
the systemd codebase, it would be better to do it as a bulit-in
(calling out to binaries should only be done for third-party tools).
Cheers,
Tom
On Thu, Dec 18, 2014 at 3:58 PM, Carlos Garnacho <carl...@gnome.org> wrote:
> This rule is only run on tablet/touchscreen devices, and extracts their size
> in millimeters, as it can be found out through their struct input_absinfo.
>
> Conceivably, that information can be changed through EVIOCSABS anywhere
> else, but we're only interested in values prior to any calibration, this
> rule is thus only run on "add", and no tracking of changes is performed.
> This should only remain a problem if calibration were automatically applied
> by an earlier udev rule (read: don't).
> ---
> Makefile.am | 14 +++
> rules/60-input_abs_size.rules | 8 ++
> src/udev/input_abs_size/input_abs_size.c | 177
> +++++++++++++++++++++++++++++++
> 3 files changed, 199 insertions(+)
> create mode 100644 rules/60-input_abs_size.rules
> create mode 100644 src/udev/input_abs_size/input_abs_size.c
>
> diff --git a/Makefile.am b/Makefile.am
> index ab07d3b..a23705a 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -3741,6 +3741,20 @@ dist_udevrules_DATA += \
> rules/61-accelerometer.rules
>
> #
> ------------------------------------------------------------------------------
> +input_abs_size_SOURCES = \
> + src/udev/input_abs_size/input_abs_size.c
> +
> +input_abs_size_LDADD = \
> + libudev-internal.la -lm \
> + libsystemd-shared.la
> +
> +udevlibexec_PROGRAMS += \
> + input_abs_size_
> +
> +dist_udevrules_DATA += \
> + rules/60-input_abs_size.rules
> +
> +#
> ------------------------------------------------------------------------------
> if ENABLE_GUDEV
> if ENABLE_GTK_DOC
> SUBDIRS += \
> diff --git a/rules/60-input_abs_size.rules b/rules/60-input_abs_size.rules
> new file mode 100644
> index 0000000..5f613ac
> --- /dev/null
> +++ b/rules/60-input_abs_size.rules
> @@ -0,0 +1,8 @@
> +# do not edit this file, it will be overwritten on update
> +
> +ACTION!="add", GOTO="input_abs_size_end"
> +
> +ENV{ID_INPUT_TOUCHSCREEN}=="1", IMPORT{program}="input_abs_size %p"
> +ENV{ID_INPUT_TABLET}=="1", IMPORT{program}="input_abs_size %p"
> +
> +LABEL="input_abs_size_end"
> diff --git a/src/udev/input_abs_size/input_abs_size.c
> b/src/udev/input_abs_size/input_abs_size.c
> new file mode 100644
> index 0000000..34a6bf3
> --- /dev/null
> +++ b/src/udev/input_abs_size/input_abs_size.c
> @@ -0,0 +1,177 @@
> +/*
> + * input_abs_size - extracts abs X/Y size in millimeters from input devices
> + *
> + * Copyright (C) 2014 Red Hat
> + * Author:
> + * Carlos Garnacho <carl...@gnome.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 keymap; if not, write to the Free Software Foundation,
> + * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + */
> +
> +#include <stdio.h>
> +#include <string.h>
> +#include <math.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <getopt.h>
> +#include <limits.h>
> +#include <linux/limits.h>
> +#include <linux/input.h>
> +
> +#include "libudev.h"
> +#include "libudev-private.h"
> +
> +/* Resolution is defined to be in units/mm for ABS_X/Y */
> +#define ABS_SIZE_MM(absinfo) ((absinfo.maximum - absinfo.minimum) /
> absinfo.resolution)
> +
> +static void extract_info(struct udev *udev,
> + struct udev_device *dev,
> + const char *devpath)
> +{
> + struct input_absinfo xabsinfo = { 0 }, yabsinfo = { 0 };
> + _cleanup_close_ int fd = -1;
> + char text[1024];
> +
> + if ((fd = open(devpath, O_RDONLY)) < 0)
> + return;
> +
> + if (ioctl(fd, EVIOCGABS(ABS_X), &xabsinfo) < 0 ||
> + ioctl(fd, EVIOCGABS(ABS_Y), &yabsinfo) < 0)
> + return;
> +
> + if (xabsinfo.resolution <= 0 || yabsinfo.resolution <= 0)
> + return;
> +
> + snprintf (text, sizeof(text),
> + "ID_INPUT_WIDTH_MM=%d\n"
> + "ID_INPUT_HEIGHT_MM=%d",
> + ABS_SIZE_MM (xabsinfo),
> + ABS_SIZE_MM (yabsinfo));
> + puts (text);
> +}
> +
> +static void help(void)
> +{
> + printf("Usage: input_abs_size [options] <device path>\n"
> + " --debug debug to stderr\n"
> + " --help print this help text\n\n");
> +}
> +
> +int main(int argc, char** argv)
> +{
> + struct udev *udev;
> + struct udev_device *dev;
> +
> + static const struct option options[] = {
> + { "debug", no_argument, NULL, 'd' },
> + { "help", no_argument, NULL, 'h' },
> + {}
> + };
> +
> + char devpath[PATH_MAX];
> + char *devnode;
> + struct udev_enumerate *enumerate;
> + struct udev_list_entry *list_entry;
> +
> + udev = udev_new();
> + if (udev == NULL)
> + return 1;
> +
> + log_parse_environment();
> + log_open();
> +
> + /* CLI argument parsing */
> + while (1) {
> + int option;
> +
> + option = getopt_long(argc, argv, "dxh", options, NULL);
> + if (option == -1)
> + break;
> +
> + switch (option) {
> + case 'd':
> + log_set_target(LOG_TARGET_CONSOLE);
> + log_set_max_level(LOG_DEBUG);
> + log_open();
> + break;
> + case 'h':
> + help();
> + exit(0);
> + default:
> + exit(1);
> + }
> + }
> +
> + if (argv[optind] == NULL) {
> + help();
> + exit(1);
> + }
> +
> + /* get the device */
> + snprintf(devpath, sizeof(devpath), "/sys/%s", argv[optind]);
> + dev = udev_device_new_from_syspath(udev, devpath);
> + if (dev == NULL) {
> + fprintf(stderr, "unable to access '%s'\n", devpath);
> + return 1;
> + }
> +
> + /* Get the children devices and find the devnode */
> + devnode = NULL;
> + enumerate = udev_enumerate_new(udev);
> + udev_enumerate_add_match_parent(enumerate, dev);
> + udev_enumerate_scan_devices(enumerate);
> + udev_list_entry_foreach(list_entry,
> udev_enumerate_get_list_entry(enumerate)) {
> + struct udev_device *device;
> + const char *node;
> +
> + device =
> udev_device_new_from_syspath(udev_enumerate_get_udev(enumerate),
> +
> udev_list_entry_get_name(list_entry));
> + if (device == NULL)
> + continue;
> + /* Already found it */
> + if (devnode != NULL) {
> + udev_device_unref(device);
> + continue;
> + }
> +
> + node = udev_device_get_devnode(device);
> + if (node == NULL) {
> + udev_device_unref(device);
> + continue;
> + }
> + /* Use the event sub-device */
> + if (strstr(node, "/event") == NULL) {
> + udev_device_unref(device);
> + continue;
> + }
> +
> + devnode = strdup(node);
> + udev_device_unref(device);
> + }
> +
> + if (devnode == NULL) {
> + fprintf(stderr, "unable to get device node for '%s'\n",
> devpath);
> + return 0;
> + }
> +
> + log_debug("Opening input device %s\n", devnode);
> + extract_info(udev, dev, devnode);
> + free(devnode);
> +
> + return 0;
> +}
> --
> 2.1.0
>
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