/*
 * refind/gpt.c
 * Functions related to GPT data structures
 *
 * Copyright (c) 2014-2015 Roderick W. Smith
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "gpt.h"
#include "lib.h"
#include "screen.h"
#include "crc32.h"
#include "../include/refit_call_wrapper.h"

#ifdef __MAKEWITH_TIANO
#define BlockIoProtocol gEfiBlockIoProtocolGuid
#endif

extern GPT_DATA *gPartitions;

// Allocate data for the main GPT_DATA structure, as well as the ProtectiveMBR
// and Header structures it contains. This function does *NOT*, however,
// allocate memory for the Entries data structure, since its size is variable
// and is determined by the contents of Header.
GPT_DATA * AllocateGptData(VOID) {
   GPT_DATA *GptData;

   GptData = AllocateZeroPool(sizeof(GPT_DATA));
   if (GptData != NULL) {
      GptData->ProtectiveMBR = AllocateZeroPool(sizeof(MBR_RECORD));
      GptData->Header = AllocateZeroPool(sizeof(GPT_HEADER));
      if ((GptData->ProtectiveMBR == NULL) || (GptData->Header == NULL)) {
         MyFreePool(GptData->ProtectiveMBR);
         MyFreePool(GptData->Header);
         MyFreePool(GptData);
         GptData = NULL;
      } // if
   } // if
   return GptData;
} // GPT_DATA * AllocateGptData()

// Unallocate a single GPT_DATA structure. This does NOT follow the
// linked list, though.
VOID ClearGptData(GPT_DATA *Data) {
   if (Data) {
      if (Data->ProtectiveMBR)
         MyFreePool(Data->ProtectiveMBR);
      if (Data->Header)
         MyFreePool(Data->Header);
      if (Data->Entries)
         MyFreePool(Data->Entries);
      MyFreePool(Data);
   } // if
} // VOID ClearGptData()

// TODO: Make this work on big-endian systems; at the moment, it contains
// little-endian assumptions!
// Returns TRUE if the GPT protective MBR and header data appear valid,
// FALSE otherwise.
static BOOLEAN GptHeaderValid(GPT_DATA *GptData) {
   BOOLEAN IsValid;
   UINT32 CrcValue, StoredCrcValue;
   UINTN HeaderSize = sizeof(GPT_HEADER);

   if ((GptData == NULL) || (GptData->ProtectiveMBR == NULL) || (GptData->Header == NULL))
      return FALSE;

   IsValid = (GptData->ProtectiveMBR->MBRSignature == 0xAA55);
   IsValid = IsValid && ((GptData->ProtectiveMBR->partitions[0].type == 0xEE) ||
                         (GptData->ProtectiveMBR->partitions[1].type == 0xEE) ||
                         (GptData->ProtectiveMBR->partitions[2].type == 0xEE) ||
                         (GptData->ProtectiveMBR->partitions[3].type == 0xEE));

   IsValid = IsValid && ((GptData->Header->signature == 0x5452415020494645ULL) &&
                         (GptData->Header->spec_revision == 0x00010000) &&
                         (GptData->Header->entry_size == 128));

   // Looks good so far; check CRC value....
   if (IsValid) {
      if (GptData->Header->header_size < HeaderSize)
         HeaderSize = GptData->Header->header_size;
      StoredCrcValue = GptData->Header->header_crc32;
      GptData->Header->header_crc32 = 0;
      CrcValue = crc32(0x0, GptData->Header, HeaderSize);
      if (CrcValue != StoredCrcValue)
         IsValid = FALSE;
      GptData->Header->header_crc32 = StoredCrcValue;
   } // if

   return IsValid;
} // BOOLEAN GptHeaderValid()

// Read GPT data from Volume and store it in *Data. Note that this function
// may be called on a Volume that is not in fact a GPT disk (an MBR disk,
// a partition, etc.), in which case it will return EFI_LOAD_ERROR or some
// other error condition. In this case, *Data will be left alone.
// Note also that this function checks CRCs and does other sanity checks
// on the input data, but does NOT resort to using the backup data if the
// primary data structures are damaged. The intent is that the function
// be very conservative about reading GPT data. Currently (version 0.7.10),
// rEFInd uses the data only to provide access to partition names. This is
// non-critical data, so it's OK to return nothing, but having the program
// hang on reading garbage or return nonsense could be very bad.
EFI_STATUS ReadGptData(REFIT_VOLUME *Volume, GPT_DATA **Data) {
   EFI_STATUS Status = EFI_SUCCESS;
   UINT64     BufferSize;
   UINTN      i;
   GPT_DATA   *GptData = NULL; // Temporary holding storage; transferred to *Data later

   if ((Volume == NULL) || (Data == NULL))
      return EFI_INVALID_PARAMETER;

   // get block i/o
   if ((Status == EFI_SUCCESS) && (Volume->BlockIO == NULL)) {
      Status = refit_call3_wrapper(BS->HandleProtocol, Volume->DeviceHandle, &BlockIoProtocol, (VOID **) &(Volume->BlockIO));
      if (EFI_ERROR(Status)) {
         Volume->BlockIO = NULL;
         Print(L"Warning: Can't get BlockIO protocol in ReadGptData().\n");
         Status = EFI_NOT_READY;
      }
   } // if

   if ((Status == EFI_SUCCESS) && ((!Volume->BlockIO->Media->MediaPresent) || (Volume->BlockIO->Media->LogicalPartition)))
      Status = EFI_NO_MEDIA;

   if (Status == EFI_SUCCESS) {
      GptData = AllocateGptData(); // Note: All but GptData->Entries
      if (GptData == NULL) {
         Status = EFI_OUT_OF_RESOURCES;
      } // if
   } // if

   // Read the MBR and store it in GptData->ProtectiveMBR.
   if (Status == EFI_SUCCESS) {
      Status = refit_call5_wrapper(Volume->BlockIO->ReadBlocks, Volume->BlockIO, Volume->BlockIO->Media->MediaId,
                                   0, sizeof(MBR_RECORD), (VOID*) GptData->ProtectiveMBR);
   }

   // Read the GPT header and store it in GptData->Header.
   if (Status == EFI_SUCCESS) {
      Status = refit_call5_wrapper(Volume->BlockIO->ReadBlocks, Volume->BlockIO, Volume->BlockIO->Media->MediaId,
                                   1, sizeof(GPT_HEADER), GptData->Header);
   }

   // If it looks like a valid protective MBR & GPT header, try to do more with it....
   if (Status == EFI_SUCCESS) {
      if (GptHeaderValid(GptData)) {
         // Load actual GPT table....
         BufferSize = GptData->Header->entry_count * 128;
         GptData->Entries = AllocatePool(BufferSize);
         if (GptData->Entries == NULL)
            Status = EFI_OUT_OF_RESOURCES;

         if (Status == EFI_SUCCESS)
            Status = refit_call5_wrapper(Volume->BlockIO->ReadBlocks, Volume->BlockIO, Volume->BlockIO->Media->MediaId,
                                         GptData->Header->entry_lba, BufferSize, GptData->Entries);

         // Check CRC status of table
         if ((Status == EFI_SUCCESS) && (crc32(0x0, GptData->Entries, BufferSize) != GptData->Header->entry_crc32))
            Status = EFI_CRC_ERROR;

         // Now, ensure that every name is null-terminated....
         if (Status == EFI_SUCCESS) {
            for (i = 0; i < GptData->Header->entry_count; i++)
               GptData->Entries[i].name[35] = '\0';
         } // if
      } else {
         Status = EFI_UNSUPPORTED;
      } // if/else valid header
   } // if header read OK

   if (Status == EFI_SUCCESS) {
      // Everything looks OK, so copy it over
      ClearGptData(*Data);
      *Data = GptData;
   } else {
      ClearGptData(GptData);
   } // if/else

   return Status;
} // EFI_STATUS ReadGptData()

// Look in gPartitions for a partition with the specified Guid. If found, return
// a pointer to that partition's data. If not found, return a NULL pointer.
// The calling function is responsible for freeing the returned memory.
GPT_ENTRY * FindPartWithGuid(EFI_GUID *Guid) {
   UINTN     i;
   GPT_ENTRY *Found = NULL;
   GPT_DATA  *GptData;

   if ((Guid == NULL) || (gPartitions == NULL))
      return NULL;

   GptData = gPartitions;
   while ((GptData != NULL) && (!Found)) {
      i = 0;
      while ((i < GptData->Header->entry_count) && (!Found)) {
         if (GuidsAreEqual((EFI_GUID*) &(GptData->Entries[i].partition_guid), Guid)) {
            Found = AllocateZeroPool(sizeof(GPT_ENTRY));
            CopyMem(Found, &GptData->Entries[i], sizeof(GPT_ENTRY));
         } else {
            i++;
         } // if/else
      } // while(scanning entries)
      GptData = GptData->NextEntry;
   } // while(scanning GPTs)
   return Found;
} // GPT_ENTRY * FindPartWithGuid()

// Erase the gPartitions linked-list data structure
VOID ForgetPartitionTables(VOID) {
   GPT_DATA  *Next;

   while (gPartitions != NULL) {
      Next = gPartitions->NextEntry;
      ClearGptData(gPartitions);
      gPartitions = Next;
   } // while
} // VOID ForgetPartitionTables()

// If Volume points to a whole disk with a GPT, add it to the gPartitions
// linked list of GPTs.
VOID AddPartitionTable(REFIT_VOLUME *Volume) {
   GPT_DATA    *GptData = NULL, *GptList;
   EFI_STATUS  Status;
   UINTN       NumTables = 1;

   Status = ReadGptData(Volume, &GptData);
   if (Status == EFI_SUCCESS) {
      if (gPartitions == NULL) {
         gPartitions = GptData;
      } else {
         GptList = gPartitions;
         while (GptList->NextEntry != NULL) {
            GptList = GptList->NextEntry;
            NumTables++;
         } // while
         GptList->NextEntry = GptData;
         NumTables++;
      } // if/else
   } else if (GptData != NULL) {
      ClearGptData(GptData);
      NumTables = 0;
   } // if/else
} // VOID AddPartitionTable()

