[PATCH evtest 2/2] Add one-shot query functionality

Peter Hutterer peter.hutterer at who-t.net
Sun Jul 17 17:29:58 PDT 2011


On Sat, Jul 16, 2011 at 11:07:14PM +0100, Daniel Drake wrote:
> Add functionality to query evdev state of a specific key, switch, button,
> LED or sound event. This is useful in programs such as powerd
> (http://wiki.laptop.org/go/Powerd) which need to query things like the
> state of the laptop lid switch from shell code.
> 
> Original capture-mode functionality is left unchanged and is still
> activated by default. New usage modes are explained in the man page.
> 
> Signed-off-by: Daniel Drake <dsd at laptop.org>

Thanks, looking better and much easier to review. I've merged patch 1 again,
for this one see the comments below (and Walter's comments in the other
email).

> ---
>  evtest.c   |  203 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  evtest.txt |   33 ++++++++--
>  2 files changed, 226 insertions(+), 10 deletions(-)
> 
> diff --git a/evtest.c b/evtest.c
> index eb04a51..9a7ac7f 100644
> --- a/evtest.c
> +++ b/evtest.c
> @@ -49,6 +49,8 @@
>  #include <stdlib.h>
>  #include <dirent.h>
>  #include <errno.h>
> +#include <getopt.h>
> +#include <ctype.h>
>  
>  #define BITS_PER_LONG (sizeof(long) * 8)
>  #define NBITS(x) ((((x)-1)/BITS_PER_LONG)+1)
> @@ -69,6 +71,42 @@
>  
>  #define NAME_ELEMENT(element) [element] = #element
>  
> +enum evtest_mode {
> +	MODE_CAPTURE,
> +	MODE_QUERY,
> +};
> +
> +static const struct query_mode {
> +	const char *name;
> +	int event_type;
> +	int max;
> +	int rq;
> +} query_modes[] = {
> +	{ "key", EV_KEY, KEY_MAX, EVIOCGKEY(KEY_MAX) },
> +	{ "led", EV_LED, LED_MAX, EVIOCGLED(LED_MAX) },
> +	{ "snd", EV_SND, SND_MAX, EVIOCGSND(SND_MAX) },
> +	{ "sw",  EV_SW, SW_MAX, EVIOCGSW(SW_MAX) },
> +};

any particular reason you use "key", "led", etc. here instead of the
numerical value or the define name?
It seems to me that "evtest --query EV_KEY KEY_FOO" is a more consistent
UI than "evtest --query key KEY_FOO". And it may be useful to accept the
numerical values for EV_KEY etc. here as well.

> +
> +/**
> + * Look up an entry in the query_modes table by its textual name. The search
> + * is case-insensitive.
> + *
> + * @param mode The name of the entry to be found.
> + *
> + * @return The requested query_mode, or NULL if it could not be found.
> + */
> +static const struct query_mode *find_query_mode(const char *name)
> +{
> +	int i;
> +	for (i = 0; i < sizeof(query_modes) / sizeof(*query_modes); i++) {
> +		const struct query_mode *mode = &query_modes[i];
> +		if (strcasecmp(mode->name, name) == 0)
> +			return mode;
> +	}
> +	return NULL;
> +}
> +
>  static const char * const events[EV_MAX + 1] = {
>  	[0 ... EV_MAX] = NULL,
>  	NAME_ELEMENT(EV_SYN),			NAME_ELEMENT(EV_KEY),
> @@ -480,6 +518,41 @@ static const char * const * const names[EV_MAX + 1] = {
>  };
>  
>  /**
> + * Convert a string to a specific key/snd/led/sw code. The string can either
> + * be the name of the key in question (e.g. "SW_DOCK") or the numerical
> + * value, either as decimal (e.g. "5") or as hex (e.g. "0x5").
> + *
> + * @param mode The mode being queried (key, snd, led, sw)
> + * @param kstr The string to parse and convert
> + *
> + * @return The requested code's numerical value, or negative on error.
> + */
> +static int get_keycode(const struct query_mode *query_mode, const char *kstr)
> +{
> +	if (isdigit(kstr[0])) {
> +		unsigned long val;
> +		errno = 0;
> +		val = strtoul(kstr, NULL, 0);
> +		if (errno) {
> +			fprintf(stderr, "Could not interpret value %s\n", kstr);
> +			return -1;
> +		}
> +		return (int) val;
> +	} else {
> +		const char * const *keynames = names[query_mode->event_type];
> +		int i;
> +
> +		for (i = 0; i < query_mode->max; i++) {
> +			const char *name = keynames[i];
> +			if (name && strcasecmp(name, kstr) == 0)
> +				return i;
> +		}
> +
> +		return -1;
> +	}
> +}
> +
> +/**
>   * Filter for the AutoDevProbe scandir on /dev/input.
>   *
>   * @param dir The current directory entry provided by scandir.
> @@ -546,8 +619,18 @@ static char* scan_devices(void)
>   */
>  static void usage(void)
>  {
> -	printf("Usage: evtest /dev/input/eventX\n");
> -	printf("Where X = input device number\n");
> +	printf("USAGE:\n");
> +	printf(" Grab mode:\n");
> +	printf("   %s /dev/input/eventX\n", program_invocation_short_name);
> +	printf("\n");
> +	printf(" Query mode: (check exit code)\n");
> +	printf("   %s --query /dev/input/eventX <type> <value>\n",
> +		program_invocation_short_name);
> +
> +	printf("\n");
> +	printf("<type> is one of: key, sw, led, snd\n");
> +	printf("<value> can either be a numerical value, or the textual name of the\n");
> +	printf("key/switch/LED/sound being queried (e.g. SW_DOCK).\n");
>  }
>  
>  /**
> @@ -743,14 +826,124 @@ static int do_capture(const char *device)
>  	return print_events(fd);
>  }
>  
> +/**
> + * Perform a one-shot state query on a specific device. The query can be of
> + * any known mode, on any valid keycode.
> + *
> + * @param device Path to the evdev device node that should be queried.
> + * @param query_mode The event type that is being queried (e.g. key, switch)
> + * @param keycode The code of the key/switch/sound/LED to be queried
> + * @return 0 if the state bit is unset, 10 if the state bit is set, 1 on error.
> + */
> +static int query_device(const char *device, const struct query_mode *query_mode, int keycode)
> +{
> +	int fd;
> +	int r;
> +	unsigned char state[NBITS(query_mode->max)];
> +
> +	fd = open(device, O_RDONLY);
> +	if (fd < 0) {
> +		perror("open");
> +		return EXIT_FAILURE;
> +	}
> +
> +	memset(state, 0, sizeof(state));
> +	r = ioctl(fd, query_mode->rq, state);
> +	close(fd);
> +
> +	if (r == -1) {
> +		perror("ioctl");
> +		return EXIT_FAILURE;
> +	}
> +
> +	if (test_bit(keycode, state))
> +		return 10; /* different from EXIT_FAILURE */
> +	else
> +		return 0;
> +}
> +
> +/**
> + * Enter query mode. The requested event device will be queried for the state
> + * of a particular switch/key/sound/LED.
> + *
> + * @param device The device to query.
> + * @param mode The mode (event type) that is to be queried (snd, sw, key, led)
> + * @param keycode The key code to query the state of.
> + * @return 0 if the state bit is unset, 10 if the state bit is set.
> + */
> +static int do_query(const char *device, const char *event_type, const char *keyname)
> +{
> +	const struct query_mode *query_mode;
> +	int keycode;
> +
> +	if (!device) {
> +		fprintf(stderr, "Device argument is required for query.\n");
> +		usage();
> +		return EXIT_FAILURE;
> +	}
> +
> +	query_mode = find_query_mode(event_type);
> +	if (!query_mode) {
> +		fprintf(stderr, "Unrecognsied event type: %s\n", event_type);

                                        ^ typo


> +		usage();
> +		return EXIT_FAILURE;
> +	}
> +
> +	keycode = get_keycode(query_mode, keyname);
> +	if (keycode < 0) {
> +		fprintf(stderr, "Unrecognised key name: %s\n", keyname);
> +		usage();
> +		return EXIT_FAILURE;
> +	} else if (keycode > query_mode->max) {
> +		fprintf(stderr, "Key %d out of bounds.\n", keycode);

"key %d is out of bounds" maybe?

No other comments but please see Walter's comments in the other email.

Cheers,
  Peter

> +		return EXIT_FAILURE;
> +	}
> +
> +	return query_device(device, query_mode, keycode);
> +}
> +
> +static const struct option long_options[] = {
> +	{ "query", no_argument, NULL, MODE_QUERY },
> +	{ 0, },
> +};
> +
>  int main (int argc, char **argv)
>  {
>  	const char *device = NULL;
> +	const char *keyname;
> +	const char *event_type;
> +	enum evtest_mode mode = MODE_CAPTURE;
> +
> +	while (1) {
> +		int option_index = 0;
> +		int c = getopt_long(argc, argv, "", long_options, &option_index);
> +		if (c == -1)
> +			break;
> +		switch (c) {
> +		case MODE_QUERY:
> +			mode = c;
> +			break;
> +		default:
> +			usage();
> +			break;
> +		}
> +	}
>  
> -	if (argc >= 2)
> -		device = argv[1];
> +	if (optind < argc)
> +		device = argv[optind++];
> +
> +	if (mode == MODE_CAPTURE)
> +		return do_capture(device);
> +
> +	if ((argc - optind) < 2) {
> +		fprintf(stderr, "Query mode requires device, type and key parameters\n");
> +		usage();
> +		return EXIT_FAILURE;
> +	}
>  
> -	return do_capture(device);
> +	event_type = argv[optind++];
> +	keyname = argv[optind++];
> +	return do_query(device, event_type, keyname);
>  }
>  
>  /* vim: set noexpandtab tabstop=8 shiftwidth=8: */
> diff --git a/evtest.txt b/evtest.txt
> index 685a4de..4cb1a18 100644
> --- a/evtest.txt
> +++ b/evtest.txt
> @@ -4,17 +4,33 @@ EVTEST(1)
>  NAME
>  ----
>  
> -     evtest - Input device event monitor
> +     evtest - Input device event monitor and query tool
>  
>  SYNOPSIS
>  --------
> -     evtest "/dev/input/eventX"
> +     evtest /dev/input/eventX
> +
> +     evtest --query /dev/input/eventX <type> <value>
>  
>  DESCRIPTION
>  -----------
> -evtest displays information on the input device specified on the command
> -line, including all the events supported by the device. It then monitors the
> -device and displays all the events layer events generated.
> +The first invocation type displayed above ("capture mode") causes evtest to
> +display information about the specified input device, including all the events
> +supported by the device. It then monitors the device and displays all the
> +events layer events generated.
> +
> +In the second invocation type ("query mode"), evtest performs a one-shot query
> +of the state of a specific key *value* of an event *type*.
> +
> +*type* is one of: *key*, *sw*, *snd*, *led*
> +
> +*value* can be either a decimal representation (e.g. 44), hex
> +(e.g. 0x2c), or the constant name (e.g. KEY_Z) of the key/switch/sound/LED
> +being queried.
> +
> +If the state bit is set (key pressed, switch on, ...), evtest exits with
> +code 0. If the state bit is unset (key depressed, switch off, ...), evtest
> +exits with code 10. No other output is generated.
>  
>  evtest needs to be able to read from the device; in most cases this means it
>  must be run as root.
> @@ -32,6 +48,13 @@ when debugging a synaptics device from within X. VT switching to a TTY or
>  shutting down the X server terminates this grab and synaptics devices can be
>  debugged.
>  
> +EXIT CODE
> +---------
> +evtest returns 1 on error.
> +
> +When used to query state, evtest returns 0 if the state bit is unset and
> +10 if the state bit is set.
> +
>  SEE ALSO
>  --------
>  inputattach(1)
> -- 
> 1.7.6
> 


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