MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskFileExplorer.c

   1 /** @file
   2   Internal file explorer helper functions for RamDiskDxe driver.
   3
   4   Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
   5   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include "RamDiskImpl.h"
  16
  17
  18 /**
  19   Helper function called as part of the code needed to allocate the proper
  20   sized buffer for various EFI interfaces.
  21
  22   @param[in, out] Status     Current status.
  23   @param[in, out] Buffer     Current allocated buffer, or NULL.
  24   @param[in]      BufferSize Current buffer size needed.
  25
  26   @retval  TRUE         If the buffer was reallocated and the caller should
  27                         try the API again.
  28   @retval  FALSE        The caller should not call this function again.
  29
  30 **/
  31 BOOLEAN
  32 GrowBuffer (
  33   IN OUT EFI_STATUS   *Status,
  34   IN OUT VOID         **Buffer,
  35   IN UINTN            BufferSize
  36   )
  37 {
  38   BOOLEAN TryAgain;
  39
  40   //
  41   // If this is an initial request, buffer will be null with a new buffer size
  42   //
  43   if ((*Buffer == NULL) && (BufferSize != 0)) {
  44     *Status = EFI_BUFFER_TOO_SMALL;
  45   }
  46   //
  47   // If the status code is "buffer too small", resize the buffer
  48   //
  49   TryAgain = FALSE;
  50   if (*Status == EFI_BUFFER_TOO_SMALL) {
  51
  52     if (*Buffer != NULL) {
  53       FreePool (*Buffer);
  54     }
  55
  56     *Buffer = AllocateZeroPool (BufferSize);
  57
  58     if (*Buffer != NULL) {
  59       TryAgain = TRUE;
  60     } else {
  61       *Status = EFI_OUT_OF_RESOURCES;
  62     }
  63   }
  64   //
  65   // If there's an error, free the buffer
  66   //
  67   if (!TryAgain && EFI_ERROR (*Status) && (*Buffer != NULL)) {
  68     FreePool (*Buffer);
  69     *Buffer = NULL;
  70   }
  71
  72   return TryAgain;
  73 }
  74
  75
  76 /**
  77   This function gets the file information from an open file descriptor,
  78   and stores it in a buffer allocated from pool.
  79
  80   @param[in] FHand           File Handle.
  81
  82   @return    A pointer to a buffer with file information or NULL is returned.
  83
  84 **/
  85 EFI_FILE_INFO *
  86 FileInfo (
  87   IN EFI_FILE_HANDLE                        FHand
  88   )
  89 {
  90   EFI_STATUS                           Status;
  91   EFI_FILE_INFO                        *Buffer;
  92   UINTN                                BufferSize;
  93
  94   //
  95   // Initialize for GrowBuffer loop
  96   //
  97   Buffer      = NULL;
  98   BufferSize  = SIZE_OF_EFI_FILE_INFO + 200;
  99
 100   //
 101   // Call the real function
 102   //
 103   while (GrowBuffer (&Status, (VOID **) &Buffer, BufferSize)) {
 104     Status = FHand->GetInfo (
 105                       FHand,
 106                       &gEfiFileInfoGuid,
 107                       &BufferSize,
 108                       Buffer
 109                       );
 110   }
 111
 112   return Buffer;
 113 }