src/libudev/libudev-hwdb.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright Tom Gundersen <teg@jklm.no>
   6 ***/
   7
   8 #include "sd-hwdb.h"
   9
  10 #include "alloc-util.h"
  11 #include "hwdb-util.h"
  12 #include "libudev-private.h"
  13
  14 /**
  15  * SECTION:libudev-hwdb
  16  * @short_description: retrieve properties from the hardware database
  17  *
  18  * Libudev hardware database interface.
  19  */
  20
  21 /**
  22  * udev_hwdb:
  23  *
  24  * Opaque object representing the hardware database.
  25  */
  26 struct udev_hwdb {
  27         struct udev *udev;
  28         int refcount;
  29
  30         sd_hwdb *hwdb;
  31
  32         struct udev_list properties_list;
  33 };
  34
  35 /**
  36  * udev_hwdb_new:
  37  * @udev: udev library context
  38  *
  39  * Create a hardware database context to query properties for devices.
  40  *
  41  * Returns: a hwdb context.
  42  **/
  43 _public_ struct udev_hwdb *udev_hwdb_new(struct udev *udev) {
  44         _cleanup_(sd_hwdb_unrefp) sd_hwdb *hwdb_internal = NULL;
  45         struct udev_hwdb *hwdb;
  46         int r;
  47
  48         assert_return_errno(udev, NULL, EINVAL);
  49
  50         r = sd_hwdb_new(&hwdb_internal);
  51         if (r < 0) {
  52                 errno = -r;
  53                 return NULL;
  54         }
  55
  56         hwdb = new0(struct udev_hwdb, 1);
  57         if (!hwdb) {
  58                 errno = ENOMEM;
  59                 return NULL;
  60         }
  61
  62         hwdb->refcount = 1;
  63         hwdb->hwdb = TAKE_PTR(hwdb_internal);
  64
  65         udev_list_init(udev, &hwdb->properties_list, true);
  66
  67         return 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 _public_ struct udev_hwdb *udev_hwdb_ref(struct udev_hwdb *hwdb) {
  79         if (!hwdb)
  80                 return NULL;
  81         hwdb->refcount++;
  82         return hwdb;
  83 }
  84
  85 /**
  86  * udev_hwdb_unref:
  87  * @hwdb: context
  88  *
  89  * Drop a reference of a hwdb context. If the refcount reaches zero,
  90  * all resources of the hwdb context will be released.
  91  *
  92  * Returns: #NULL
  93  **/
  94 _public_ struct udev_hwdb *udev_hwdb_unref(struct udev_hwdb *hwdb) {
  95         if (!hwdb)
  96                 return NULL;
  97         hwdb->refcount--;
  98         if (hwdb->refcount > 0)
  99                 return NULL;
 100         sd_hwdb_unref(hwdb->hwdb);
 101         udev_list_cleanup(&hwdb->properties_list);
 102         return mfree(hwdb);
 103 }
 104
 105 /**
 106  * udev_hwdb_get_properties_list_entry:
 107  * @hwdb: context
 108  * @modalias: modalias string
 109  * @flags: (unused)
 110  *
 111  * Lookup a matching device in the hardware database. The lookup key is a
 112  * modalias string, whose formats are defined for the Linux kernel modules.
 113  * Examples are: pci:v00008086d00001C2D*, usb:v04F2pB221*. The first entry
 114  * of a list of retrieved properties is returned.
 115  *
 116  * Returns: a udev_list_entry.
 117  */
 118 _public_ struct udev_list_entry *udev_hwdb_get_properties_list_entry(struct udev_hwdb *hwdb, const char *modalias, unsigned int flags) {
 119         const char *key, *value;
 120         struct udev_list_entry *e;
 121
 122         if (!hwdb || !modalias) {
 123                 errno = EINVAL;
 124                 return NULL;
 125         }
 126
 127         udev_list_cleanup(&hwdb->properties_list);
 128
 129         SD_HWDB_FOREACH_PROPERTY(hwdb->hwdb, modalias, key, value) {
 130                 if (udev_list_entry_add(&hwdb->properties_list, key, value) == NULL) {
 131                         errno = ENOMEM;
 132                         return NULL;
 133                 }
 134         }
 135
 136         e = udev_list_get_entry(&hwdb->properties_list);
 137         if (!e)
 138                 errno = ENODATA;
 139
 140         return e;
 141 }