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 /**
  13   Helper function called as part of the code needed to allocate the proper
  14   sized buffer for various EFI interfaces.
  15
  16   @param[in, out] Status     Current status.
  17   @param[in, out] Buffer     Current allocated buffer, or NULL.
  18   @param[in]      BufferSize Current buffer size needed.
  19
  20   @retval  TRUE         If the buffer was reallocated and the caller should
  21                         try the API again.
  22   @retval  FALSE        The caller should not call this function again.
  23
  24 **/
  25 BOOLEAN
  26 GrowBuffer (
  27   IN OUT EFI_STATUS   *Status,
  28   IN OUT VOID         **Buffer,
  29   IN UINTN            BufferSize
  30   )
  31 {
  32   BOOLEAN TryAgain;
  33
  34   //
  35   // If this is an initial request, buffer will be null with a new buffer size
  36   //
  37   if ((*Buffer == NULL) && (BufferSize != 0)) {
  38     *Status = EFI_BUFFER_TOO_SMALL;
  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
  46     if (*Buffer != NULL) {
  47       FreePool (*Buffer);
  48     }
  49
  50     *Buffer = AllocateZeroPool (BufferSize);
  51
  52     if (*Buffer != NULL) {
  53       TryAgain = TRUE;
  54     } else {
  55       *Status = EFI_OUT_OF_RESOURCES;
  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 /**
  71   This function gets the file information from an open file descriptor,
  72   and stores it in a buffer allocated from pool.
  73
  74   @param[in] FHand           File Handle.
  75
  76   @return    A pointer to a buffer with file information or NULL is returned.
  77
  78 **/
  79 EFI_FILE_INFO *
  80 FileInfo (
  81   IN EFI_FILE_HANDLE                        FHand
  82   )
  83 {
  84   EFI_STATUS                           Status;
  85   EFI_FILE_INFO                        *Buffer;
  86   UINTN                                BufferSize;
  87
  88   //
  89   // Initialize for GrowBuffer loop
  90   //
  91   Buffer      = NULL;
  92   BufferSize  = SIZE_OF_EFI_FILE_INFO + 200;
  93
  94   //
  95   // Call the real function
  96   //
  97   while (GrowBuffer (&Status, (VOID **) &Buffer, BufferSize)) {
  98     Status = FHand->GetInfo (
  99                       FHand,
 100                       &gEfiFileInfoGuid,
 101                       &BufferSize,
 102                       Buffer
 103                       );
 104   }
 105
 106   return Buffer;
 107 }