src/libudev/libudev-hwdb.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "sd-hwdb.h"
   4
   5 #include "alloc-util.h"
   6 #include "hwdb-util.h"
   7 #include "libudev-private.h"
   8
   9 /**
  10  * SECTION:libudev-hwdb
  11  * @short_description: retrieve properties from the hardware database
  12  *
  13  * Libudev hardware database interface.
  14  */
  15
  16 /**
  17  * udev_hwdb:
  18  *
  19  * Opaque object representing the hardware database.
  20  */
  21 struct udev_hwdb {
  22         unsigned n_ref;
  23         sd_hwdb *hwdb;
  24         struct udev_list properties_list;
  25 };
  26
  27 /**
  28  * udev_hwdb_new:
  29  * @udev: udev library context (unused)
  30  *
  31  * Create a hardware database context to query properties for devices.
  32  *
  33  * Returns: a hwdb context.
  34  **/
  35 _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
  36         _cleanup_(sd_hwdb_unrefp) sd_hwdb *hwdb_internal = NULL;
  37         struct udev_hwdb *hwdb;
  38         int r;
  39
  40         r = sd_hwdb_new(&hwdb_internal);
  41         if (r < 0) {
  42                 errno = -r;
  43                 return NULL;
  44         }
  45
  46         hwdb = new(struct udev_hwdb, 1);
  47         if (!hwdb) {
  48                 errno = ENOMEM;
  49                 return NULL;
  50         }
  51
  52         *hwdb = (struct udev_hwdb) {
  53                 .n_ref = 1,
  54                 .hwdb = TAKE_PTR(hwdb_internal),
  55         };
  56
  57         udev_list_init(udev, &hwdb->properties_list, true);
  58
  59         return hwdb;
  60 }
  61
  62 static struct udev_hwdb *udev_hwdb_free(struct udev_hwdb *hwdb) {
  63         assert(hwdb);
  64
  65         sd_hwdb_unref(hwdb->hwdb);
  66         udev_list_cleanup(&hwdb->properties_list);
  67         return mfree(hwdb);
  68 }
  69
  70 /**
  71  * udev_hwdb_ref:
  72  * @hwdb: context
  73  *
  74  * Take a reference of a hwdb context.
  75  *
  76  * Returns: the passed enumeration context
  77  **/
  78
  79 /**
  80  * udev_hwdb_unref:
  81  * @hwdb: context
  82  *
  83  * Drop a reference of a hwdb context. If the refcount reaches zero,
  84  * all resources of the hwdb context will be released.
  85  *
  86  * Returns: #NULL
  87  **/
  88 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_hwdb, udev_hwdb, udev_hwdb_free);
  89
  90 /**
  91  * udev_hwdb_get_properties_list_entry:
  92  * @hwdb: context
  93  * @modalias: modalias string
  94  * @flags: (unused)
  95  *
  96  * Lookup a matching device in the hardware database. The lookup key is a
  97  * modalias string, whose formats are defined for the Linux kernel modules.
  98  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
  99  * of a list of retrieved properties is returned.
 100  *
 101  * Returns: a udev_list_entry.
 102  */
 103 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned int flags) {
 104         const char *key, *value;
 105         struct udev_list_entry *e;
 106
 107         if (!hwdb || !modalias) {
 108                 errno = EINVAL;
 109                 return NULL;
 110         }
 111
 112         udev_list_cleanup(&hwdb->properties_list);
 113
 114         SD_HWDB_FOREACH_PROPERTY(hwdb->hwdb, modalias, key, value) {
 115                 if (udev_list_entry_add(&hwdb->properties_list, key, value) == NULL) {
 116                         errno = ENOMEM;
 117                         return NULL;
 118                 }
 119         }
 120
 121         e = udev_list_get_entry(&hwdb->properties_list);
 122         if (!e)
 123                 errno = ENODATA;
 124
 125         return e;
 126 }