libudev-hwdb.c revision cabaa37a602ea787d3b3d1f6ec402de7918a4823
/***
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;
}
/**
* 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 sig[] = HWDB_SIG;
hwdb = new0(struct udev_hwdb, 1);
if (!hwdb)
return NULL;
hwdb->refcount = 1;
udev_list_init(udev, &hwdb->properties_list, true);
hwdb->f = fopen("/etc/udev/hwdb.bin", "re");
if (!hwdb->f) {
log_debug("error reading /etc/udev/hwdb.bin: %m");
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) {
log_debug("error reading /etc/udev/hwdb.bin: %m");
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) {
log_debug("error mapping /etc/udev/hwdb.bin: %m");
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)) {
log_debug("error recognizing the format of /etc/udev/hwdb.bin");
udev_hwdb_unref(hwdb);
return NULL;
}
log_debug("=== trie on-disk ===\n");
log_debug("tool version: %"PRIu64, le64toh(hwdb->head->tool_version));
log_debug("file size: %8llu bytes\n", (unsigned long long) hwdb->st.st_size);
log_debug("header size %8"PRIu64" bytes\n", le64toh(hwdb->head->header_size));
log_debug("strings %8"PRIu64" bytes\n", le64toh(hwdb->head->strings_len));
log_debug("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: the passed hwdb context if it has still an active reference, or #NULL otherwise.
**/
_public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
if (!hwdb)
return NULL;
hwdb->refcount--;
if (hwdb->refcount > 0)
return hwdb;
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) {
struct stat st;
if (!hwdb)
return false;
if (!hwdb->f)
return false;
if (stat("/etc/udev/hwdb.bin", &st) < 0)
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);
}