src/libudev/libudev-hwdb.c - systemd-stable - Rivoreo Source Code Repositories

 /***
   This file is part of systemd.

   Copyright 2012 Kay Sievers <kay@vrfy.org>
   Copyright 2008 Alan Jenkins <alan.christopher.jenkins@googlemail.com>

   systemd is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.

   systemd 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/

 #include <stdio.h>
 #include <errno.h>
 #include <string.h>
 #include <inttypes.h>
 #include <ctype.h>
 #include <stdlib.h>
 #include <fnmatch.h>
 #include <getopt.h>
 #include <sys/mman.h>

 #include "libudev-private.h"
 #include "libudev-hwdb-def.h"

 /**
  * SECTION:libudev-hwdb
  * @short_description: retrieve properties from the hardware database
  *
  * Libudev hardware database interface.
  */

 /**
  * udev_hwdb:
  *
  * Opaque object representing the hardware database.
  */
 struct udev_hwdb {
         struct udev *udev;
         int refcount;

         FILE *f;
         struct stat st;
         union {
                 struct trie_header_f *head;
                 const char *map;
         };

         struct udev_list properties_list;
 };

 struct linebuf {
         char bytes[LINE_MAX];
         size_t size;
         size_t len;
 };

 static void linebuf_init(struct linebuf *buf) {
         buf->size = 0;
         buf->len = 0;
 }

 static const char *linebuf_get(struct linebuf *buf) {
         if (buf->len + 1 >= sizeof(buf->bytes))
                 return NULL;
         buf->bytes[buf->len] = '\0';
         return buf->bytes;
 }

 static bool linebuf_add(struct linebuf *buf, const char *s, size_t len) {
         if (buf->len + len >= sizeof(buf->bytes))
                 return false;
         memcpy(buf->bytes + buf->len, s, len);
         buf->len += len;
         return true;
 }

 static bool linebuf_add_char(struct linebuf *buf, char c)
 {
         if (buf->len + 1 >= sizeof(buf->bytes))
                 return false;
         buf->bytes[buf->len++] = c;
         return true;
 }

 static void linebuf_rem(struct linebuf *buf, size_t count) {
         assert(buf->len >= count);
         buf->len -= count;
 }

 static void linebuf_rem_char(struct linebuf *buf) {
         linebuf_rem(buf, 1);
 }

 static const struct trie_child_entry_f *trie_node_children(struct udev_hwdb *hwdb, const struct trie_node_f *node) {
         return (const struct trie_child_entry_f *)((const char *)node + le64toh(hwdb->head->node_size));
 }

 static const struct trie_value_entry_f *trie_node_values(struct udev_hwdb *hwdb, const struct trie_node_f *node) {
         const char *base = (const char *)node;

         base += le64toh(hwdb->head->node_size);
         base += node->children_count * le64toh(hwdb->head->child_entry_size);
         return (const struct trie_value_entry_f *)base;
 }

 static const struct trie_node_f *trie_node_from_off(struct udev_hwdb *hwdb, le64_t off) {
         return (const struct trie_node_f *)(hwdb->map + le64toh(off));
 }

 static const char *trie_string(struct udev_hwdb *hwdb, le64_t off) {
         return hwdb->map + le64toh(off);
 }

 static int trie_children_cmp_f(const void *v1, const void *v2) {
         const struct trie_child_entry_f *n1 = v1;
         const struct trie_child_entry_f *n2 = v2;

         return n1->c - n2->c;
 }

 static const struct trie_node_f *node_lookup_f(struct udev_hwdb *hwdb, const struct trie_node_f *node, uint8_t c) {
         struct trie_child_entry_f *child;
         struct trie_child_entry_f search;

         search.c = c;
         child = bsearch(&search, trie_node_children(hwdb, node), node->children_count,
                         le64toh(hwdb->head->child_entry_size), trie_children_cmp_f);
         if (child)
                 return trie_node_from_off(hwdb, child->child_off);
         return NULL;
 }

 static int hwdb_add_property(struct udev_hwdb *hwdb, const char *key, const char *value) {
         /*
          * Silently ignore all properties which do not start with a
          * space; future extensions might use additional prefixes.
          */
         if (key[0] != ' ')
                 return 0;

         if (udev_list_entry_add(&hwdb->properties_list, key+1, value) == NULL)
                 return -ENOMEM;
         return 0;
 }

 static int trie_fnmatch_f(struct udev_hwdb *hwdb, const struct trie_node_f *node, size_t p,
                           struct linebuf *buf, const char *search) {
         size_t len;
         size_t i;
         const char *prefix;
         int err;

         prefix = trie_string(hwdb, node->prefix_off);
         len = strlen(prefix + p);
         linebuf_add(buf, prefix + p, len);

         for (i = 0; i < node->children_count; i++) {
                 const struct trie_child_entry_f *child = &trie_node_children(hwdb, node)[i];

                 linebuf_add_char(buf, child->c);
                 err = trie_fnmatch_f(hwdb, trie_node_from_off(hwdb, child->child_off), 0, buf, search);
                 if (err < 0)
                         return err;
                 linebuf_rem_char(buf);
         }

         if (le64toh(node->values_count) && fnmatch(linebuf_get(buf), search, 0) == 0)
                 for (i = 0; i < le64toh(node->values_count); i++) {
                         err = hwdb_add_property(hwdb, trie_string(hwdb, trie_node_values(hwdb, node)[i].key_off),
                                                 trie_string(hwdb, trie_node_values(hwdb, node)[i].value_off));
                         if (err < 0)
                                 return err;
                 }

         linebuf_rem(buf, len);
         return 0;
 }

 static int trie_search_f(struct udev_hwdb *hwdb, const char *search) {
         struct linebuf buf;
         const struct trie_node_f *node;
         size_t i = 0;
         int err;

         linebuf_init(&buf);

         node = trie_node_from_off(hwdb, hwdb->head->nodes_root_off);
         while (node) {
                 const struct trie_node_f *child;
                 size_t p = 0;

                 if (node->prefix_off) {
                         uint8_t c;

                         for (; (c = trie_string(hwdb, node->prefix_off)[p]); p++) {
                                 if (c == '*' || c == '?' || c == '[')
                                         return trie_fnmatch_f(hwdb, node, p, &buf, search + i + p);
                                 if (c != search[i + p])
                                         return 0;
                         }
                         i += p;
                 }

                 child = node_lookup_f(hwdb, node, '*');
                 if (child) {
                         linebuf_add_char(&buf, '*');
                         err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
                         if (err < 0)
                                 return err;
                         linebuf_rem_char(&buf);
                 }

                 child = node_lookup_f(hwdb, node, '?');
                 if (child) {
                         linebuf_add_char(&buf, '?');
                         err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
                         if (err < 0)
                                 return err;
                         linebuf_rem_char(&buf);
                 }

                 child = node_lookup_f(hwdb, node, '[');
                 if (child) {
                         linebuf_add_char(&buf, '[');
                         err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
                         if (err < 0)
                                 return err;
                         linebuf_rem_char(&buf);
                 }

                 if (search[i] == '\0') {
                         size_t n;

                         for (n = 0; n < le64toh(node->values_count); n++) {
                                 err = hwdb_add_property(hwdb, trie_string(hwdb, trie_node_values(hwdb, node)[n].key_off),
                                                         trie_string(hwdb, trie_node_values(hwdb, node)[n].value_off));
                                 if (err < 0)
                                         return err;
                         }
                         return 0;
                 }

                 child = node_lookup_f(hwdb, node, search[i]);
                 node = child;
                 i++;
         }
         return 0;
 }

 static const char hwdb_bin_paths[] =
     "/etc/udev/hwdb.bin\0"
     UDEVLIBEXECDIR "/hwdb.bin\0";


 /**
  * udev_hwdb_new:
  * @udev: udev library context
  *
  * Create a hardware database context to query properties for devices.
  *
  * Returns: a hwdb context.
  **/
 _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
         struct udev_hwdb *hwdb;
         const char *hwdb_bin_path;
         const char sig[] = HWDB_SIG;

         hwdb = new0(struct udev_hwdb, 1);
         if (!hwdb)
                 return NULL;

         hwdb->refcount = 1;
         udev_list_init(udev, &hwdb->properties_list, true);

         /* find hwdb.bin in hwdb_bin_paths */
         NULSTR_FOREACH(hwdb_bin_path, hwdb_bin_paths) {
                 hwdb->f = fopen(hwdb_bin_path, "re");
                 if (hwdb->f)
                         break;
                 else if (errno == ENOENT)
                         continue;
                 else {
                         udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
                         udev_hwdb_unref(hwdb);
                         return NULL;
                 }
         }

         if (!hwdb->f) {
                 udev_dbg(udev, "hwdb.bin does not exist, please run udevadm hwdb --update");
                 udev_hwdb_unref(hwdb);
                 return NULL;
         }

         if (fstat(fileno(hwdb->f), &hwdb->st) < 0 ||
             (size_t)hwdb->st.st_size < offsetof(struct trie_header_f, strings_len) + 8) {
                 udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
                 udev_hwdb_unref(hwdb);
                 return NULL;
         }

         hwdb->map = mmap(0, hwdb->st.st_size, PROT_READ, MAP_SHARED, fileno(hwdb->f), 0);
         if (hwdb->map == MAP_FAILED) {
                 udev_dbg(udev, "error mapping %s: %m", hwdb_bin_path);
                 udev_hwdb_unref(hwdb);
                 return NULL;
         }

         if (memcmp(hwdb->map, sig, sizeof(hwdb->head->signature)) != 0 ||
             (size_t)hwdb->st.st_size != le64toh(hwdb->head->file_size)) {
                 udev_dbg(udev, "error recognizing the format of %s", hwdb_bin_path);
                 udev_hwdb_unref(hwdb);
                 return NULL;
         }

         udev_dbg(udev, "=== trie on-disk ===\n");
         udev_dbg(udev, "tool version:          %"PRIu64, le64toh(hwdb->head->tool_version));
         udev_dbg(udev, "file size:        %8"PRIu64" bytes\n", hwdb->st.st_size);
         udev_dbg(udev, "header size       %8"PRIu64" bytes\n", le64toh(hwdb->head->header_size));
         udev_dbg(udev, "strings           %8"PRIu64" bytes\n", le64toh(hwdb->head->strings_len));
         udev_dbg(udev, "nodes             %8"PRIu64" bytes\n", le64toh(hwdb->head->nodes_len));
         return hwdb;
 }

 /**
  * udev_hwdb_ref:
  * @hwdb: context
  *
  * Take a reference of a hwdb context.
  *
  * Returns: the passed enumeration context
  **/
 _public_ struct udev_hwdb *udev_hwdb_ref(struct udev_hwdb *hwdb) {
         if (!hwdb)
                 return NULL;
         hwdb->refcount++;
         return hwdb;
 }

 /**
  * udev_hwdb_unref:
  * @hwdb: context
  *
  * Drop a reference of a hwdb context. If the refcount reaches zero,
  * all resources of the hwdb context will be released.
  *
  * Returns: #NULL
  **/
 _public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
         if (!hwdb)
                 return NULL;
         hwdb->refcount--;
         if (hwdb->refcount > 0)
                 return NULL;
         if (hwdb->map)
                 munmap((void *)hwdb->map, hwdb->st.st_size);
         if (hwdb->f)
                 fclose(hwdb->f);
         udev_list_cleanup(&hwdb->properties_list);
         free(hwdb);
         return NULL;
 }

 bool udev_hwdb_validate(struct udev_hwdb *hwdb) {
         bool found = false;
         const char* p;
         struct stat st;

         if (!hwdb)
                 return false;
         if (!hwdb->f)
                 return false;

         /* if hwdb.bin doesn't exist anywhere, we need to update */
         NULSTR_FOREACH(p, hwdb_bin_paths) {
                 if (stat(p, &st) >= 0) {
                         found = true;
                         break;
                 }
         }
         if (!found)
                 return true;

         if (timespec_load(&hwdb->st.st_mtim) != timespec_load(&st.st_mtim))
                 return true;
         return false;
 }

 /**
  * udev_hwdb_get_properties_list_entry:
  * @hwdb: context
  * @modalias: modalias string
  * @flags: (unused)
  *
  * Lookup a matching device in the hardware database. The lookup key is a
  * modalias string, whose formats are defined for the Linux kernel modules.
  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
  * of a list of retrieved properties is returned.
  *
  * Returns: a udev_list_entry.
  */
 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned int flags) {
         int err;

         if (!hwdb || !hwdb->f) {
                 errno = EINVAL;
                 return NULL;
         }

         udev_list_cleanup(&hwdb->properties_list);
         err = trie_search_f(hwdb, modalias);
         if (err < 0) {
                 errno = -err;
                 return NULL;
         }
         return udev_list_get_entry(&hwdb->properties_list);
 }
	/***
	This file is part of systemd.

	Copyright 2012 Kay Sievers <kay@vrfy.org>
	Copyright 2008 Alan Jenkins <alan.christopher.jenkins@googlemail.com>

	systemd is free software; you can redistribute it and/or modify it
	under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2.1 of the License, or
	(at your option) any later version.

	systemd 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
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	***/

	#include <stdio.h>
	#include <errno.h>
	#include <string.h>
	#include <inttypes.h>
	#include <ctype.h>
	#include <stdlib.h>
	#include <fnmatch.h>
	#include <getopt.h>
	#include <sys/mman.h>

	#include "libudev-private.h"
	#include "libudev-hwdb-def.h"

	/**
	* SECTION:libudev-hwdb
	* @short_description: retrieve properties from the hardware database
	*
	* Libudev hardware database interface.
	*/

	/**
	* udev_hwdb:
	*
	* Opaque object representing the hardware database.
	*/
	struct udev_hwdb {
	struct udev *udev;
	int refcount;

	FILE *f;
	struct stat st;
	union {
	struct trie_header_f *head;
	const char *map;
	};

	struct udev_list properties_list;
	};

	struct linebuf {
	char bytes[LINE_MAX];
	size_t size;
	size_t len;
	};

	static void linebuf_init(struct linebuf *buf) {
	buf->size = 0;
	buf->len = 0;
	}

	static const char linebuf_get(struct linebuf buf) {
	if (buf->len + 1 >= sizeof(buf->bytes))
	return NULL;
	buf->bytes[buf->len] = '\0';
	return buf->bytes;
	}

	static bool linebuf_add(struct linebuf buf, const char s, size_t len) {
	if (buf->len + len >= sizeof(buf->bytes))
	return false;
	memcpy(buf->bytes + buf->len, s, len);
	buf->len += len;
	return true;
	}

	static bool linebuf_add_char(struct linebuf *buf, char c)
	{
	if (buf->len + 1 >= sizeof(buf->bytes))
	return false;
	buf->bytes[buf->len++] = c;
	return true;
	}

	static void linebuf_rem(struct linebuf *buf, size_t count) {
	assert(buf->len >= count);
	buf->len -= count;
	}

	static void linebuf_rem_char(struct linebuf *buf) {
	linebuf_rem(buf, 1);
	}

	static const struct trie_child_entry_f trie_node_children(struct udev_hwdb hwdb, const struct trie_node_f *node) {
	return (const struct trie_child_entry_f )((const char )node + le64toh(hwdb->head->node_size));
	}

	static const struct trie_value_entry_f trie_node_values(struct udev_hwdb hwdb, const struct trie_node_f *node) {
	const char base = (const char )node;

	base += le64toh(hwdb->head->node_size);
	base += node->children_count * le64toh(hwdb->head->child_entry_size);
	return (const struct trie_value_entry_f *)base;
	}

	static const struct trie_node_f trie_node_from_off(struct udev_hwdb hwdb, le64_t off) {
	return (const struct trie_node_f *)(hwdb->map + le64toh(off));
	}

	static const char trie_string(struct udev_hwdb hwdb, le64_t off) {
	return hwdb->map + le64toh(off);
	}

	static int trie_children_cmp_f(const void v1, const void v2) {
	const struct trie_child_entry_f *n1 = v1;
	const struct trie_child_entry_f *n2 = v2;

	return n1->c - n2->c;
	}

	static const struct trie_node_f node_lookup_f(struct udev_hwdb hwdb, const struct trie_node_f *node, uint8_t c) {
	struct trie_child_entry_f *child;
	struct trie_child_entry_f search;

	search.c = c;
	child = bsearch(&search, trie_node_children(hwdb, node), node->children_count,
	le64toh(hwdb->head->child_entry_size), trie_children_cmp_f);
	if (child)
	return trie_node_from_off(hwdb, child->child_off);
	return NULL;
	}

	static int hwdb_add_property(struct udev_hwdb hwdb, const char key, const char *value) {
	/*
	* Silently ignore all properties which do not start with a
	* space; future extensions might use additional prefixes.
	*/
	if (key[0] != ' ')
	return 0;

	if (udev_list_entry_add(&hwdb->properties_list, key+1, value) == NULL)
	return -ENOMEM;
	return 0;
	}

	static int trie_fnmatch_f(struct udev_hwdb hwdb, const struct trie_node_f node, size_t p,
	struct linebuf buf, const char search) {
	size_t len;
	size_t i;
	const char *prefix;
	int err;

	prefix = trie_string(hwdb, node->prefix_off);
	len = strlen(prefix + p);
	linebuf_add(buf, prefix + p, len);

	for (i = 0; i < node->children_count; i++) {
	const struct trie_child_entry_f *child = &trie_node_children(hwdb, node)[i];

	linebuf_add_char(buf, child->c);
	err = trie_fnmatch_f(hwdb, trie_node_from_off(hwdb, child->child_off), 0, buf, search);
	if (err < 0)
	return err;
	linebuf_rem_char(buf);
	}

	if (le64toh(node->values_count) && fnmatch(linebuf_get(buf), search, 0) == 0)
	for (i = 0; i < le64toh(node->values_count); i++) {
	err = hwdb_add_property(hwdb, trie_string(hwdb, trie_node_values(hwdb, node)[i].key_off),
	trie_string(hwdb, trie_node_values(hwdb, node)[i].value_off));
	if (err < 0)
	return err;
	}

	linebuf_rem(buf, len);
	return 0;
	}

	static int trie_search_f(struct udev_hwdb hwdb, const char search) {
	struct linebuf buf;
	const struct trie_node_f *node;
	size_t i = 0;
	int err;

	linebuf_init(&buf);

	node = trie_node_from_off(hwdb, hwdb->head->nodes_root_off);
	while (node) {
	const struct trie_node_f *child;
	size_t p = 0;

	if (node->prefix_off) {
	uint8_t c;

	for (; (c = trie_string(hwdb, node->prefix_off)[p]); p++) {
	if (c == '*' \|\| c == '?' \|\| c == '[')
	return trie_fnmatch_f(hwdb, node, p, &buf, search + i + p);
	if (c != search[i + p])
	return 0;
	}
	i += p;
	}

	child = node_lookup_f(hwdb, node, '*');
	if (child) {
	linebuf_add_char(&buf, '*');
	err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
	if (err < 0)
	return err;
	linebuf_rem_char(&buf);
	}

	child = node_lookup_f(hwdb, node, '?');
	if (child) {
	linebuf_add_char(&buf, '?');
	err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
	if (err < 0)
	return err;
	linebuf_rem_char(&buf);
	}

	child = node_lookup_f(hwdb, node, '[');
	if (child) {
	linebuf_add_char(&buf, '[');
	err = trie_fnmatch_f(hwdb, child, 0, &buf, search + i);
	if (err < 0)
	return err;
	linebuf_rem_char(&buf);
	}

	if (search[i] == '\0') {
	size_t n;

	for (n = 0; n < le64toh(node->values_count); n++) {
	err = hwdb_add_property(hwdb, trie_string(hwdb, trie_node_values(hwdb, node)[n].key_off),
	trie_string(hwdb, trie_node_values(hwdb, node)[n].value_off));
	if (err < 0)
	return err;
	}
	return 0;
	}

	child = node_lookup_f(hwdb, node, search[i]);
	node = child;
	i++;
	}
	return 0;
	}

	static const char hwdb_bin_paths[] =
	"/etc/udev/hwdb.bin\0"
	UDEVLIBEXECDIR "/hwdb.bin\0";


	/**
	* udev_hwdb_new:
	* @udev: udev library context
	*
	* Create a hardware database context to query properties for devices.
	*
	* Returns: a hwdb context.
	**/
	_public_ struct udev_hwdb udev_hwdb_new(struct udev udev) {
	struct udev_hwdb *hwdb;
	const char *hwdb_bin_path;
	const char sig[] = HWDB_SIG;

	hwdb = new0(struct udev_hwdb, 1);
	if (!hwdb)
	return NULL;

	hwdb->refcount = 1;
	udev_list_init(udev, &hwdb->properties_list, true);

	/* find hwdb.bin in hwdb_bin_paths */
	NULSTR_FOREACH(hwdb_bin_path, hwdb_bin_paths) {
	hwdb->f = fopen(hwdb_bin_path, "re");
	if (hwdb->f)
	break;
	else if (errno == ENOENT)
	continue;
	else {
	udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
	udev_hwdb_unref(hwdb);
	return NULL;
	}
	}

	if (!hwdb->f) {
	udev_dbg(udev, "hwdb.bin does not exist, please run udevadm hwdb --update");
	udev_hwdb_unref(hwdb);
	return NULL;
	}

	if (fstat(fileno(hwdb->f), &hwdb->st) < 0 \|\|
	(size_t)hwdb->st.st_size < offsetof(struct trie_header_f, strings_len) + 8) {
	udev_dbg(udev, "error reading %s: %m", hwdb_bin_path);
	udev_hwdb_unref(hwdb);
	return NULL;
	}

	hwdb->map = mmap(0, hwdb->st.st_size, PROT_READ, MAP_SHARED, fileno(hwdb->f), 0);
	if (hwdb->map == MAP_FAILED) {
	udev_dbg(udev, "error mapping %s: %m", hwdb_bin_path);
	udev_hwdb_unref(hwdb);
	return NULL;
	}

	if (memcmp(hwdb->map, sig, sizeof(hwdb->head->signature)) != 0 \|\|
	(size_t)hwdb->st.st_size != le64toh(hwdb->head->file_size)) {
	udev_dbg(udev, "error recognizing the format of %s", hwdb_bin_path);
	udev_hwdb_unref(hwdb);
	return NULL;
	}

	udev_dbg(udev, "=== trie on-disk ===\n");
	udev_dbg(udev, "tool version: %"PRIu64, le64toh(hwdb->head->tool_version));
	udev_dbg(udev, "file size: %8"PRIu64" bytes\n", hwdb->st.st_size);
	udev_dbg(udev, "header size %8"PRIu64" bytes\n", le64toh(hwdb->head->header_size));
	udev_dbg(udev, "strings %8"PRIu64" bytes\n", le64toh(hwdb->head->strings_len));
	udev_dbg(udev, "nodes %8"PRIu64" bytes\n", le64toh(hwdb->head->nodes_len));
	return hwdb;
	}

	/**
	* udev_hwdb_ref:
	* @hwdb: context
	*
	* Take a reference of a hwdb context.
	*
	* Returns: the passed enumeration context
	**/
	_public_ struct udev_hwdb udev_hwdb_ref(struct udev_hwdb hwdb) {
	if (!hwdb)
	return NULL;
	hwdb->refcount++;
	return hwdb;
	}

	/**
	* udev_hwdb_unref:
	* @hwdb: context
	*
	* Drop a reference of a hwdb context. If the refcount reaches zero,
	* all resources of the hwdb context will be released.
	*
	* Returns: #NULL
	**/
	_public_ struct udev_hwdb udev_hwdb_unref(struct udev_hwdb hwdb) {
	if (!hwdb)
	return NULL;
	hwdb->refcount--;
	if (hwdb->refcount > 0)
	return NULL;
	if (hwdb->map)
	munmap((void *)hwdb->map, hwdb->st.st_size);
	if (hwdb->f)
	fclose(hwdb->f);
	udev_list_cleanup(&hwdb->properties_list);
	free(hwdb);
	return NULL;
	}

	bool udev_hwdb_validate(struct udev_hwdb *hwdb) {
	bool found = false;
	const char* p;
	struct stat st;

	if (!hwdb)
	return false;
	if (!hwdb->f)
	return false;

	/* if hwdb.bin doesn't exist anywhere, we need to update */
	NULSTR_FOREACH(p, hwdb_bin_paths) {
	if (stat(p, &st) >= 0) {
	found = true;
	break;
	}
	}
	if (!found)
	return true;

	if (timespec_load(&hwdb->st.st_mtim) != timespec_load(&st.st_mtim))
	return true;
	return false;
	}

	/**
	* udev_hwdb_get_properties_list_entry:
	* @hwdb: context
	* @modalias: modalias string
	* @flags: (unused)
	*
	* Lookup a matching device in the hardware database. The lookup key is a
	* modalias string, whose formats are defined for the Linux kernel modules.
	* Examples are: pci:v00008086d00001C2D, usb:v04F2pB221. The first entry
	* of a list of retrieved properties is returned.
	*
	* Returns: a udev_list_entry.
	*/
	_public_ struct udev_list_entry udev_hwdb_get_properties_list_entry(struct udev_hwdb hwdb, const char *modalias, unsigned int flags) {
	int err;

	if (!hwdb \|\| !hwdb->f) {
	errno = EINVAL;
	return NULL;
	}

	udev_list_cleanup(&hwdb->properties_list);
	err = trie_search_f(hwdb, modalias);
	if (err < 0) {
	errno = -err;
	return NULL;
	}
	return udev_list_get_entry(&hwdb->properties_list);
	}