src/libudev/libudev-hwdb.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright Tom Gundersen <teg@jklm.no>
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include "sd-hwdb.h"
  21
  22 #include "alloc-util.h"
  23 #include "hwdb-util.h"
  24 #include "libudev-private.h"
  25
  26 /**
  27  * SECTION:libudev-hwdb
  28  * @short_description: retrieve properties from the hardware database
  29  *
  30  * Libudev hardware database interface.
  31  */
  32
  33 /**
  34  * udev_hwdb:
  35  *
  36  * Opaque object representing the hardware database.
  37  */
  38 struct udev_hwdb {
  39         struct udev *udev;
  40         int refcount;
  41
  42         sd_hwdb *hwdb;
  43
  44         struct udev_list properties_list;
  45 };
  46
  47 /**
  48  * udev_hwdb_new:
  49  * @udev: udev library context
  50  *
  51  * Create a hardware database context to query properties for devices.
  52  *
  53  * Returns: a hwdb context.
  54  **/
  55 _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
  56         _cleanup_(sd_hwdb_unrefp) sd_hwdb *hwdb_internal = NULL;
  57         struct udev_hwdb *hwdb;
  58         int r;
  59
  60         assert_return(udev, NULL);
  61
  62         r = sd_hwdb_new(&hwdb_internal);
  63         if (r < 0)
  64                 return NULL;
  65
  66         hwdb = new0(struct udev_hwdb, 1);
  67         if (!hwdb)
  68                 return NULL;
  69
  70         hwdb->refcount = 1;
  71         hwdb->hwdb = hwdb_internal;
  72         hwdb_internal = NULL;
  73
  74         udev_list_init(udev, &hwdb->properties_list, true);
  75
  76         return hwdb;
  77 }
  78
  79 /**
  80  * udev_hwdb_ref:
  81  * @hwdb: context
  82  *
  83  * Take a reference of a hwdb context.
  84  *
  85  * Returns: the passed enumeration context
  86  **/
  87 _public_ struct udev_hwdb *udev_hwdb_ref(struct udev_hwdb *hwdb) {
  88         if (!hwdb)
  89                 return NULL;
  90         hwdb->refcount++;
  91         return hwdb;
  92 }
  93
  94 /**
  95  * udev_hwdb_unref:
  96  * @hwdb: context
  97  *
  98  * Drop a reference of a hwdb context. If the refcount reaches zero,
  99  * all resources of the hwdb context will be released.
 100  *
 101  * Returns: #NULL
 102  **/
 103 _public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
 104         if (!hwdb)
 105                 return NULL;
 106         hwdb->refcount--;
 107         if (hwdb->refcount > 0)
 108                 return NULL;
 109         sd_hwdb_unref(hwdb->hwdb);
 110         udev_list_cleanup(&hwdb->properties_list);
 111         free(hwdb);
 112         return NULL;
 113 }
 114
 115 /**
 116  * udev_hwdb_get_properties_list_entry:
 117  * @hwdb: context
 118  * @modalias: modalias string
 119  * @flags: (unused)
 120  *
 121  * Lookup a matching device in the hardware database. The lookup key is a
 122  * modalias string, whose formats are defined for the Linux kernel modules.
 123  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
 124  * of a list of retrieved properties is returned.
 125  *
 126  * Returns: a udev_list_entry.
 127  */
 128 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned int flags) {
 129         const char *key, *value;
 130
 131         if (!hwdb || !modalias) {
 132                 errno = EINVAL;
 133                 return NULL;
 134         }
 135
 136         udev_list_cleanup(&hwdb->properties_list);
 137
 138         SD_HWDB_FOREACH_PROPERTY(hwdb->hwdb, modalias, key, value) {
 139                 if (udev_list_entry_add(&hwdb->properties_list, key, value) == NULL) {
 140                         errno = ENOMEM;
 141                         return NULL;
 142                 }
 143         }
 144
 145         return udev_list_get_entry(&hwdb->properties_list);
 146 }