[PATCH libevdev v2 4/5] Add libevdev_event_type/code_from_name() resolvers
David Herrmann
dh.herrmann at gmail.com
Tue Oct 29 07:37:21 CET 2013
Hi Peter
On Tue, Oct 29, 2013 at 2:06 AM, Peter Hutterer
<peter.hutterer at who-t.net> wrote:
> On Mon, Oct 28, 2013 at 05:16:46PM +0100, David Herrmann wrote:
>> Three new helpers are added:
>> (1) libevdev_event_type_from_name() takes a string describing an EV_*
>> event type and returns the given event-type constant.
>> (2) libevdev_event_type_from_prefix() takes a string describing an event
>> code and returns the type given by the prefix of the event code.
>
> what's the use-case for this? Specifically returning a valid type for an
> invalid event code is what worries me a bit.
use-case is pretty simple. Say you have a config-option to map an ABS
value to another ABS value. You would do:
if (libevdev_event_type_from_prefix(name, -1) != EV_ABS)
return -EINVAL;
r = libevdev_event_code_from_name(name, -1);
if (r == -1)
return -EINVAL;
sth->code = r;
So you need it to verify your code is really an EV_ABS value. I
explicitly called it "from_prefix" to note that it does nothing more
than prefix-matching. This is the simplest API I could come up with
and I like it now. If you have ideas how to make it better, lemme
know.
The only other idea I had is adding an "unsigned int type" argument to
libevdev_event_code_from_name() to limit it explicitly to a given
group of names. I'm fine with both ideas.
>> (2) libevdev_event_code_from_name() takes a string describing an event
>> code and returns the given event-code constant.
>>
>> Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
>> ---
>> libevdev/Makefile.am | 3 +-
>> libevdev/libevdev-names.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++
>> libevdev/libevdev.h | 63 +++++++++++++++++++++++
>> test/Makefile.am | 1 +
>> 4 files changed, 194 insertions(+), 1 deletion(-)
>> create mode 100644 libevdev/libevdev-names.c
>>
>> diff --git a/libevdev/Makefile.am b/libevdev/Makefile.am
>> index 3833d61..38c8de0 100644
>> --- a/libevdev/Makefile.am
>> +++ b/libevdev/Makefile.am
>> @@ -10,7 +10,8 @@ libevdev_la_SOURCES = \
>> libevdev-uinput.h \
>> libevdev-uinput-int.h \
>> libevdev.c \
>> - ../include/linux/input.h
>> + ../include/linux/input.h \
>> + libevdev-names.c
>
> this is personal style, but I'd prefer to have the libevdev stuff grouped
> together, so that linux/input.h is always the last line (amplifies that it's
> a bit special). also, it'll mean the diff is only one line as opposed to
> two.
Will fix that once we agreed on the API above.
> The rest of the patch looks good, thanks.
Thanks!
David
> Cheers,
> Peter
>
>
>>
>> libevdev_la_LDFLAGS = \
>> -version-info $(LIBEVDEV_LT_VERSION) \
>> diff --git a/libevdev/libevdev-names.c b/libevdev/libevdev-names.c
>> new file mode 100644
>> index 0000000..ee6c7f3
>> --- /dev/null
>> +++ b/libevdev/libevdev-names.c
>> @@ -0,0 +1,128 @@
>> +/*
>> + * Copyright © 2013 David Herrmann <dh.herrmann at gmail.com>
>> + *
>> + * Permission to use, copy, modify, distribute, and sell this software and its
>> + * documentation for any purpose is hereby granted without fee, provided that
>> + * the above copyright notice appear in all copies and that both that copyright
>> + * notice and this permission notice appear in supporting documentation, and
>> + * that the name of the copyright holders not be used in advertising or
>> + * publicity pertaining to distribution of the software without specific,
>> + * written prior permission. The copyright holders make no representations
>> + * about the suitability of this software for any purpose. It is provided "as
>> + * is" without express or implied warranty.
>> + *
>> + * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
>> + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
>> + * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
>> + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
>> + * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
>> + * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
>> + * OF THIS SOFTWARE.
>> + */
>> +
>> +#include <config.h>
>> +#include <errno.h>
>> +#include <stdlib.h>
>> +#include <string.h>
>> +#include <strings.h>
>> +
>> +#include "libevdev.h"
>> +#include "libevdev-int.h"
>> +#include "libevdev-util.h"
>> +#include "event-names.h"
>> +
>> +struct name_lookup {
>> + const char *name;
>> + size_t len;
>> +};
>> +
>> +static int cmp_entry(const void *vlookup, const void *ventry)
>> +{
>> + const struct name_lookup *lookup = vlookup;
>> + const struct name_entry *entry = ventry;
>> + int r;
>> +
>> + r = strncmp(lookup->name, entry->name, lookup->len);
>> + if (!r) {
>> + if (entry->name[lookup->len])
>> + r = -1;
>> + else
>> + r = 0;
>> + }
>> +
>> + return r;
>> +}
>> +
>> +static const struct name_entry*
>> +lookup_name(const struct name_entry *array, size_t asize,
>> + struct name_lookup *lookup)
>> +{
>> + const struct name_entry *entry;
>> +
>> + entry = bsearch(lookup, array, asize, sizeof(*array), cmp_entry);
>> + if (!entry)
>> + return NULL;
>> +
>> + return entry;
>> +}
>> +
>> +LIBEVDEV_EXPORT int
>> +libevdev_event_type_from_name(const char *name, ssize_t len)
>> +{
>> + struct name_lookup lookup;
>> + const struct name_entry *entry;
>> +
>> + lookup.name = name;
>> + lookup.len = (len < 0) ? strlen(name) : (size_t)len;
>> +
>> + entry = lookup_name(ev_names, ARRAY_LENGTH(ev_names), &lookup);
>> +
>> + return entry ? (int)entry->value : -1;
>> +}
>> +
>> +LIBEVDEV_EXPORT int
>> +libevdev_event_type_from_prefix(const char *name, ssize_t len)
>> +{
>> + const char *e;
>> + size_t i;
>> + ssize_t l;
>> +
>> + if (len < 0)
>> + len = strlen(name);
>> +
>> + /* MAX_ is not allowed, even though EV_MAX exists */
>> + if (startswith(name, len, "MAX_", 4))
>> + return -1;
>> + /* BTN_ is special as there is no EV_BTN type */
>> + if (startswith(name, len, "BTN_", 4))
>> + return EV_KEY;
>> + /* FF_STATUS_ is special as FF_ is a prefix of it, so test it first */
>> + if (startswith(name, len, "FF_STATUS_", 10))
>> + return EV_FF_STATUS;
>> +
>> + for (i = 0; i < ARRAY_LENGTH(ev_names); ++i) {
>> + /* skip EV_ prefix */
>> + e = &ev_names[i].name[3];
>> + l = strlen(e);
>> +
>> + /* @e is suffix of [EV_]XYZ, test it and trailing _ */
>> + if (len > l && startswith(name, len, e, l) && name[l] == '_')
>> + return ev_names[i].value;
>> + }
>> +
>> + return -1;
>> +}
>> +
>> +LIBEVDEV_EXPORT int
>> +libevdev_event_code_from_name(const char *name, ssize_t len)
>> +{
>> + struct name_lookup lookup;
>> + const struct name_entry *entry;
>> +
>> + lookup.name = name;
>> + lookup.len = (len < 0) ? strlen(name) : (size_t)len;
>> +
>> + entry = lookup_name(code_names, ARRAY_LENGTH(code_names), &lookup);
>> +
>> + return entry ? (int)entry->value : -1;
>> +}
>> diff --git a/libevdev/libevdev.h b/libevdev/libevdev.h
>> index 426e9c8..b8d85e1 100644
>> --- a/libevdev/libevdev.h
>> +++ b/libevdev/libevdev.h
>> @@ -1416,6 +1416,7 @@ int libevdev_event_is_code(const struct input_event *ev, unsigned int type, unsi
>> * defines for new properties libevdev will not automatically pick these up.
>> */
>> const char * libevdev_event_type_get_name(unsigned int type);
>> +
>> /**
>> * @ingroup misc
>> *
>> @@ -1460,6 +1461,68 @@ const char* libevdev_property_get_name(unsigned int prop);
>> int libevdev_event_type_get_max(unsigned int type);
>>
>> /**
>> + * @ingroup misc
>> + *
>> + * Look up an event-type by its name. Event-types start with "EV_" followed by
>> + * the name (eg., "EV_ABS"). The "EV_" prefix must be included in the name. It
>> + * returns the constant assigned to the event-type or -1 if not found.
>> + *
>> + * @param name A non-NULL string describing an input-event type ("EV_KEY",
>> + * "EV_ABS", ...).
>> + * @param len The length of the passed string excluding any terminating 0
>> + * character. If less than zero the string is assumed to be zero-terminated.
>> + *
>> + * @return The given type constant for the passed name or -1 if not found.
>> + *
>> + * @note EV_MAX is also recognized.
>> + */
>> +int libevdev_event_type_from_name(const char *name, ssize_t len);
>> +
>> +/**
>> + * @ingroup misc
>> + *
>> + * Look up an event-type by an event-code name. Event-codes start with a fixed
>> + * prefix followed by their name (eg., "ABS_X"). It performs a prefix-match on
>> + * the name and returns the constant assigned to the event-type of the
>> + * event-code or -1 if the prefix is unknown.
>> + *
>> + * For instance this returns the constant EV_ABS for the string "ABS_X". Note
>> + * that the event-code must not necessarily exist. A lookup for "ABS_XYZ" will
>> + * also return EV_ABS, even though ABS_XYZ is not a valid event-code. This only
>> + * tests the prefix (for performance reasons).
>> + *
>> + * All EV_* codes are supported by this call and are returned if their prefix
>> + * is used. For BTN_* codes, EV_KEY is returned.
>> + *
>> + * @param name A non-NULL string describing an input-event code (KEY_A,
>> + * ABS_X, BTN_Y, ...).
>> + * @param len The length of the passed string excluding any terminating 0
>> + * character. If less than zero the string is assumed to be zero-terminated.
>> + *
>> + * @return The given type constant for the passed name or -1 if not found.
>> + */
>> +int libevdev_event_type_from_prefix(const char *name, ssize_t len);
>> +
>> +/**
>> + * @ingroup misc
>> + *
>> + * Look up an event-code by its name. Event-codes start with a fixed prefix
>> + * followed by their name (eg., "ABS_X"). The prefix must be included in the
>> + * name. It returns the constant assigned to the event-code or -1 if not found.
>> + *
>> + * Supported event-codes are codes starting with SYN_, KEY_, BTN_, REL_, ABS_,
>> + * MSC_, SND_, SW_, LED_, REP_, FF_.
>> + *
>> + * @param name A non-NULL string describing an input-event code (KEY_A,
>> + * ABS_X, BTN_Y, ...).
>> + * @param len The length of the passed string excluding any terminating 0
>> + * character. If less than zero the string is assumed to be zero-terminated.
>> + *
>> + * @return The given code constant for the passed name or -1 if not found.
>> + */
>> +int libevdev_event_code_from_name(const char *name, ssize_t len);
>> +
>> +/**
>> * @ingroup bits
>> *
>> * Get the repeat delay and repeat period values for this device.
>> diff --git a/test/Makefile.am b/test/Makefile.am
>> index 2baafb0..c18b277 100644
>> --- a/test/Makefile.am
>> +++ b/test/Makefile.am
>> @@ -5,6 +5,7 @@ TESTS = $(noinst_PROGRAMS)
>>
>> libevdev_sources = $(top_srcdir)/libevdev/libevdev.c \
>> $(top_srcdir)/libevdev/libevdev.h \
>> + $(top_srcdir)/libevdev/libevdev-names.c \
>> $(top_srcdir)/libevdev/libevdev-uinput.h \
>> $(top_srcdir)/libevdev/libevdev-uinput.c \
>> $(top_srcdir)/libevdev/libevdev-uinput-int.h \
>> --
>> 1.8.4.1
>>
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