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_(udev_list_freep) struct udev_list *list = NULL;
  39         _cleanup_(sd_hwdb_unrefp) sd_hwdb *hwdb_internal = NULL;
  40         struct udev_hwdb *hwdb;
  41         int r;
  42
  43         r = sd_hwdb_new(&hwdb_internal);
  44         if (r < 0)
  45                 return_with_errno(NULL, r);
  46
  47         list = udev_list_new(true);
  48         if (!list)
  49                 return_with_errno(NULL, ENOMEM);
  50
  51         hwdb = new(struct udev_hwdb, 1);
  52         if (!hwdb)
  53                 return_with_errno(NULL, ENOMEM);
  54
  55         *hwdb = (struct udev_hwdb) {
  56                 .n_ref = 1,
  57                 .hwdb = TAKE_PTR(hwdb_internal),
  58                 .properties_list = TAKE_PTR(list),
  59         };
  60
  61         return hwdb;
  62 }
  63
  64 static struct udev_hwdb *udev_hwdb_free(struct udev_hwdb *hwdb) {
  65         assert(hwdb);
  66
  67         sd_hwdb_unref(hwdb->hwdb);
  68         udev_list_free(hwdb->properties_list);
  69         return mfree(hwdb);
  70 }
  71
  72 /**
  73  * udev_hwdb_ref:
  74  * @hwdb: context
  75  *
  76  * Take a reference of a hwdb context.
  77  *
  78  * Returns: the passed enumeration context
  79  **/
  80
  81 /**
  82  * udev_hwdb_unref:
  83  * @hwdb: context
  84  *
  85  * Drop a reference of a hwdb context. If the refcount reaches zero,
  86  * all resources of the hwdb context will be released.
  87  *
  88  * Returns: #NULL
  89  **/
  90 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_hwdb, udev_hwdb, udev_hwdb_free);
  91
  92 /**
  93  * udev_hwdb_get_properties_list_entry:
  94  * @hwdb: context
  95  * @modalias: modalias string
  96  * @flags: (unused)
  97  *
  98  * Lookup a matching device in the hardware database. The lookup key is a
  99  * modalias string, whose formats are defined for the Linux kernel modules.
 100  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
 101  * of a list of retrieved properties is returned.
 102  *
 103  * Returns: a udev_list_entry.
 104  */
 105 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned flags) {
 106         const char *key, *value;
 107         struct udev_list_entry *e;
 108
 109         assert_return_errno(hwdb, NULL, EINVAL);
 110         assert_return_errno(modalias, NULL, EINVAL);
 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))
 116                         return_with_errno(NULL, ENOMEM);
 117
 118         e = udev_list_get_entry(hwdb->properties_list);
 119         if (!e)
 120                 return_with_errno(NULL, ENODATA);
 121
 122         return e;
 123 }