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   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "RamDiskImpl.h"
  10
  11 /**
  12   Helper function called as part of the code needed to allocate the proper
  13   sized buffer for various EFI interfaces.
  14
  15   @param[in, out] Status     Current status.
  16   @param[in, out] Buffer     Current allocated buffer, or NULL.
  17   @param[in]      BufferSize Current buffer size needed.
  18
  19   @retval  TRUE         If the buffer was reallocated and the caller should
  20                         try the API again.
  21   @retval  FALSE        The caller should not call this function again.
  22
  23 **/
  24 BOOLEAN
  25 GrowBuffer (
  26   IN OUT EFI_STATUS  *Status,
  27   IN OUT VOID        **Buffer,
  28   IN UINTN           BufferSize
  29   )
  30 {
  31   BOOLEAN  TryAgain;
  32
  33   //
  34   // If this is an initial request, buffer will be null with a new buffer size
  35   //
  36   if ((*Buffer == NULL) && (BufferSize != 0)) {
  37     *Status = EFI_BUFFER_TOO_SMALL;
  38   }
  39
  40   //
  41   // If the status code is "buffer too small", resize the buffer
  42   //
  43   TryAgain = FALSE;
  44   if (*Status == EFI_BUFFER_TOO_SMALL) {
  45     if (*Buffer != NULL) {
  46       FreePool (*Buffer);
  47     }
  48
  49     *Buffer = AllocateZeroPool (BufferSize);
  50
  51     if (*Buffer != NULL) {
  52       TryAgain = TRUE;
  53     } else {
  54       *Status = EFI_OUT_OF_RESOURCES;
  55     }
  56   }
  57
  58   //
  59   // If there's an error, free the buffer
  60   //
  61   if (!TryAgain && EFI_ERROR (*Status) && (*Buffer != NULL)) {
  62     FreePool (*Buffer);
  63     *Buffer = NULL;
  64   }
  65
  66   return TryAgain;
  67 }
  68
  69 /**
  70   This function gets the file information from an open file descriptor,
  71   and stores it in a buffer allocated from pool.
  72
  73   @param[in] FHand           File Handle.
  74
  75   @return    A pointer to a buffer with file information or NULL is returned.
  76
  77 **/
  78 EFI_FILE_INFO *
  79 FileInfo (
  80   IN EFI_FILE_HANDLE  FHand
  81   )
  82 {
  83   EFI_STATUS     Status;
  84   EFI_FILE_INFO  *Buffer;
  85   UINTN          BufferSize;
  86
  87   //
  88   // Initialize for GrowBuffer loop
  89   //
  90   Buffer     = NULL;
  91   BufferSize = SIZE_OF_EFI_FILE_INFO + 200;
  92
  93   //
  94   // Call the real function
  95   //
  96   while (GrowBuffer (&Status, (VOID **)&Buffer, BufferSize)) {
  97     Status = FHand->GetInfo (
  98                       FHand,
  99                       &gEfiFileInfoGuid,
 100                       &BufferSize,
 101                       Buffer
 102                       );
 103   }
 104
 105   return Buffer;
 106 }