Add libevdev_event_type/code_from_name() resolvers

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_code_from_name() takes a string describing an event
code and returns the given event-code constant.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

libevdev/Makefile.am

@@ -10,6 +10,7 @@ libevdev_la_SOURCES = \
                    libevdev-uinput.h \
                    libevdev-uinput-int.h \
                    libevdev.c \
+                   libevdev-names.c \
 		   ../include/linux/input.h
 
 libevdev_la_LDFLAGS = \

libevdev/libevdev-names.c

@@ -0,0 +1,134 @@
+/*
+ * Copyright © 2013 David Herrmann <dh.herrmann@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;
+}
+
+static int 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 so @e is suffix of [EV_]XYZ */
+		e = &ev_names[i].name[3];
+		l = strlen(e);
+
+		/* compare prefix and test for 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(unsigned int type, const char *name, ssize_t len)
+{
+	struct name_lookup lookup;
+	const struct name_entry *entry;
+	int real_type;
+
+	/* verify that @name is really of type @type */
+	real_type = type_from_prefix(name, len);
+	if (real_type < 0 || (unsigned int)real_type != type)
+		return -1;
+
+	/* now look up the name @name and return the constant */
+	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;
+}

libevdev/libevdev.h

@@ -1459,6 +1459,48 @@ 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-code by its type and 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.
+ *
+ * You have to pass the event-type where to look for the name. For instance, to
+ * resolve "ABS_X" you need to pass EV_ABS as type and "ABS_X" as string.
+ * Supported event-codes are codes starting with SYN_, KEY_, BTN_, REL_, ABS_,
+ * MSC_, SND_, SW_, LED_, REP_, FF_.
+ *
+ * @param type The event type (EV_* constant) where to look for the name.
+ * @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(unsigned int type, const char *name,
+				  ssize_t len);
+
 /**
  * @ingroup bits
  *

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 \