libudev: import hwdb and export lookup interface

1 files changed, 391 insertions, 0 deletions

diff --git a/src/libudev/libudev-hwdb.c b/src/libudev/libudev-hwdb.c
new file mode 100644
index 0000000000..92c58b61a2
--- /dev/null
+++ b/src/libudev/libudev-hwdb.c
@@ -0,0 +1,391 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2012 Kay Sievers <kay.sievers@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
+ *
+ * Libuded 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) {
+        /* TODO: add sub-matches (+) against DMI data */
+        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 (node->values_count && fnmatch(linebuf_get(buf), search, 0) == 0)
+                for (i = 0; i < 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 < 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:          %llu", (unsigned long long)le64toh(hwdb->head->tool_version));
+        log_debug("file size:        %8llu bytes\n", (unsigned long long)hwdb->st.st_size);
+        log_debug("header size       %8llu bytes\n", (unsigned long long)le64toh(hwdb->head->header_size));
+        log_debug("strings           %8llu bytes\n", (unsigned long long)le64toh(hwdb->head->strings_len));
+        log_debug("nodes             %8llu bytes\n", (unsigned long long)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->f)
+                fclose(hwdb->f);
+        if (hwdb->map)
+                munmap((void *)hwdb->map, hwdb->st.st_size);
+        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 (fstat(fileno(hwdb->f), &st) < 0)
+                return true;
+        if (ts_usec(&hwdb->st.st_mtim) != ts_usec(&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->f) {
+                errno = EINVAL;
+                return NULL;
+        }
+
+        err = trie_search_f(hwdb, modalias);
+        if (err < 0) {
+                errno = -err;
+                return NULL;
+        }
+        return udev_list_get_entry(&hwdb->properties_list);
+}