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 "hwdb-util.h"
  23 #include "libudev-private.h"
  24
  25 /**
  26  * SECTION:libudev-hwdb
  27  * @short_description: retrieve properties from the hardware database
  28  *
  29  * Libudev hardware database interface.
  30  */
  31
  32 /**
  33  * udev_hwdb:
  34  *
  35  * Opaque object representing the hardware database.
  36  */
  37 struct udev_hwdb {
  38         struct udev *udev;
  39         int refcount;
  40
  41         sd_hwdb *hwdb;
  42
  43         struct udev_list properties_list;
  44 };
  45
  46 /**
  47  * udev_hwdb_new:
  48  * @udev: udev library context
  49  *
  50  * Create a hardware database context to query properties for devices.
  51  *
  52  * Returns: a hwdb context.
  53  **/
  54 _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
  55         _cleanup_hwdb_unref_ sd_hwdb *hwdb_internal = NULL;
  56         struct udev_hwdb *hwdb;
  57         int r;
  58
  59         assert_return(udev, NULL);
  60
  61         r = sd_hwdb_new(&hwdb_internal);
  62         if (r < 0)
  63                 return NULL;
  64
  65         hwdb = new0(struct udev_hwdb, 1);
  66         if (!hwdb)
  67                 return NULL;
  68
  69         hwdb->refcount = 1;
  70         hwdb->hwdb = hwdb_internal;
  71         hwdb_internal = NULL;
  72
  73         udev_list_init(udev, &hwdb->properties_list, true);
  74
  75         return hwdb;
  76 }
  77
  78 /**
  79  * udev_hwdb_ref:
  80  * @hwdb: context
  81  *
  82  * Take a reference of a hwdb context.
  83  *
  84  * Returns: the passed enumeration context
  85  **/
  86 _public_ struct udev_hwdb *udev_hwdb_ref(struct udev_hwdb *hwdb) {
  87         if (!hwdb)
  88                 return NULL;
  89         hwdb->refcount++;
  90         return hwdb;
  91 }
  92
  93 /**
  94  * udev_hwdb_unref:
  95  * @hwdb: context
  96  *
  97  * Drop a reference of a hwdb context. If the refcount reaches zero,
  98  * all resources of the hwdb context will be released.
  99  *
 100  * Returns: #NULL
 101  **/
 102 _public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
 103         if (!hwdb)
 104                 return NULL;
 105         hwdb->refcount--;
 106         if (hwdb->refcount > 0)
 107                 return NULL;
 108         sd_hwdb_unref(hwdb->hwdb);
 109         udev_list_cleanup(&hwdb->properties_list);
 110         free(hwdb);
 111         return NULL;
 112 }
 113
 114 /**
 115  * udev_hwdb_get_properties_list_entry:
 116  * @hwdb: context
 117  * @modalias: modalias string
 118  * @flags: (unused)
 119  *
 120  * Lookup a matching device in the hardware database. The lookup key is a
 121  * modalias string, whose formats are defined for the Linux kernel modules.
 122  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
 123  * of a list of retrieved properties is returned.
 124  *
 125  * Returns: a udev_list_entry.
 126  */
 127 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned int flags) {
 128         const char *key, *value;
 129
 130         if (!hwdb || !modalias) {
 131                 errno = EINVAL;
 132                 return NULL;
 133         }
 134
 135         udev_list_cleanup(&hwdb->properties_list);
 136
 137         SD_HWDB_FOREACH_PROPERTY(hwdb->hwdb, modalias, key, value) {
 138                 if (udev_list_entry_add(&hwdb->properties_list, key, value) == NULL) {
 139                         errno = ENOMEM;
 140                         return NULL;
 141                 }
 142         }
 143
 144         return udev_list_get_entry(&hwdb->properties_list);
 145 }