src/libudev/libudev-hwdb.c

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