usr/src/boot/sys/boot/efi/libefi/devpath.c

   1 /*-
   2  * Copyright (c) 2016 John Baldwin <jhb@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28
  29 #include <efi.h>
  30 #include <efilib.h>
  31
  32 static EFI_GUID ImageDevicePathGUID =
  33     EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID;
  34 static EFI_GUID DevicePathGUID = DEVICE_PATH_PROTOCOL;
  35 static EFI_GUID DevicePathToTextGUID = EFI_DEVICE_PATH_TO_TEXT_PROTOCOL_GUID;
  36 static EFI_DEVICE_PATH_TO_TEXT_PROTOCOL *textProtocol;
  37
  38 EFI_DEVICE_PATH *
  39 efi_lookup_image_devpath(EFI_HANDLE handle)
  40 {
  41         EFI_DEVICE_PATH *devpath;
  42         EFI_STATUS status;
  43
  44         status = BS->HandleProtocol(handle, &ImageDevicePathGUID,
  45             (VOID **)&devpath);
  46         if (EFI_ERROR(status))
  47                 devpath = NULL;
  48         return (devpath);
  49 }
  50
  51 EFI_DEVICE_PATH *
  52 efi_lookup_devpath(EFI_HANDLE handle)
  53 {
  54         EFI_DEVICE_PATH *devpath;
  55         EFI_STATUS status;
  56
  57         status = BS->HandleProtocol(handle, &DevicePathGUID, (VOID **)&devpath);
  58         if (EFI_ERROR(status))
  59                 devpath = NULL;
  60         return (devpath);
  61 }
  62
  63 CHAR16 *
  64 efi_devpath_name(EFI_DEVICE_PATH *devpath)
  65 {
  66         static int once = 1;
  67         EFI_STATUS status;
  68
  69         if (devpath == NULL)
  70                 return (NULL);
  71         if (once) {
  72                 status = BS->LocateProtocol(&DevicePathToTextGUID, NULL,
  73                     (VOID **)&textProtocol);
  74                 if (EFI_ERROR(status))
  75                         textProtocol = NULL;
  76                 once = 0;
  77         }
  78         if (textProtocol == NULL)
  79                 return (NULL);
  80
  81         return (textProtocol->ConvertDevicePathToText(devpath, TRUE, TRUE));
  82 }
  83
  84 void
  85 efi_free_devpath_name(CHAR16 *text)
  86 {
  87
  88         BS->FreePool(text);
  89 }
  90
  91 EFI_DEVICE_PATH *
  92 efi_devpath_last_node(EFI_DEVICE_PATH *devpath)
  93 {
  94
  95         if (IsDevicePathEnd(devpath))
  96                 return (NULL);
  97         while (!IsDevicePathEnd(NextDevicePathNode(devpath)))
  98                 devpath = NextDevicePathNode(devpath);
  99         return (devpath);
 100 }
 101
 102 EFI_DEVICE_PATH *
 103 efi_devpath_trim(EFI_DEVICE_PATH *devpath)
 104 {
 105         EFI_DEVICE_PATH *node, *copy;
 106         size_t prefix, len;
 107
 108         if ((node = efi_devpath_last_node(devpath)) == NULL)
 109                 return (NULL);
 110         prefix = (UINT8 *)node - (UINT8 *)devpath;
 111         if (prefix == 0)
 112                 return (NULL);
 113         len = prefix + DevicePathNodeLength(NextDevicePathNode(node));
 114         copy = malloc(len);
 115         if (copy != NULL) {
 116                 memcpy(copy, devpath, prefix);
 117                 node = (EFI_DEVICE_PATH *)((UINT8 *)copy + prefix);
 118                 SetDevicePathEndNode(node);
 119         }
 120         return (copy);
 121 }
 122
 123 EFI_HANDLE
 124 efi_devpath_handle(EFI_DEVICE_PATH *devpath)
 125 {
 126         EFI_STATUS status;
 127         EFI_HANDLE h;
 128
 129         /*
 130          * There isn't a standard way to locate a handle for a given
 131          * device path.  However, querying the EFI_DEVICE_PATH protocol
 132          * for a given device path should give us a handle for the
 133          * closest node in the path to the end that is valid.
 134          */
 135         status = BS->LocateDevicePath(&DevicePathGUID, &devpath, &h);
 136         if (EFI_ERROR(status))
 137                 return (NULL);
 138         return (h);
 139 }
 140
 141 bool
 142 efi_devpath_match(EFI_DEVICE_PATH *devpath1, EFI_DEVICE_PATH *devpath2)
 143 {
 144         size_t len;
 145
 146         if (devpath1 == NULL || devpath2 == NULL)
 147                 return (false);
 148
 149         while (true) {
 150                 if (DevicePathType(devpath1) != DevicePathType(devpath2) ||
 151                     DevicePathSubType(devpath1) != DevicePathSubType(devpath2))
 152                         return (false);
 153
 154                 len = DevicePathNodeLength(devpath1);
 155                 if (len != DevicePathNodeLength(devpath2))
 156                         return (false);
 157
 158                 if (memcmp(devpath1, devpath2, len) != 0)
 159                         return (false);
 160
 161                 if (IsDevicePathEnd(devpath1))
 162                         break;
 163                 devpath1 = NextDevicePathNode(devpath1);
 164                 devpath2 = NextDevicePathNode(devpath2);
 165         }
 166         return (true);
 167 }