src/libudev/libudev-hwdb.c

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