MdePkg: Refine the cod logic of FileHandleLib.

When the file is empty, make FileHandleReadLine in FileHandleLib return EFI_SUCCESS instead of EFI_BUFFER_TOO_SMALL.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17668 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
index e1f3e89b8c80d89786456c7cadac78c45a9d4d6e..96f16cad53aac1ec4e53a1a6060b8b773e1b75bd 100644 (file)
--- a/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
+++ b/MdePkg/Library/UefiFileHandleLib/UefiFileHandleLib.c
@@ -909,25 +909,29 @@ FileHandleReturnLine(
 }\r
 \r
 /**\r
-  Function to read a single line (up to but not including the \n) from a EFI_FILE_HANDLE.\r
+  Function to read a single line (up to but not including the \n) from a file.\r
 \r
   If the position upon start is 0, then the Ascii Boolean will be set.  This should be\r
   maintained and not changed for all operations with the same file.\r
 \r
-  @param[in]       Handle        FileHandle to read from\r
-  @param[in, out]  Buffer        pointer to buffer to read into\r
-  @param[in, out]  Size          pointer to number of bytes in buffer\r
-  @param[in]       Truncate      if TRUE then allows for truncation of the line to fit.\r
-                                 if FALSE will reset the position to the begining of the\r
-                                 line if the buffer is not large enough.\r
-  @param[in, out]  Ascii         Boolean value for indicating whether the file is Ascii (TRUE) or UCS2 (FALSE);\r
-\r
-  @retval EFI_SUCCESS           the operation was sucessful.  the line is stored in\r
+  @param[in]       Handle        FileHandle to read from.\r
+  @param[in, out]  Buffer        The pointer to buffer to read into.\r
+  @param[in, out]  Size          The pointer to number of bytes in Buffer.\r
+  @param[in]       Truncate      If the buffer is large enough, this has no effect.\r
+                                 If the buffer is is too small and Truncate is TRUE,\r
+                                 the line will be truncated.\r
+                                 If the buffer is is too small and Truncate is FALSE,\r
+                                 then no read will occur.\r
+\r
+  @param[in, out]  Ascii         Boolean value for indicating whether the file is\r
+                                 Ascii (TRUE) or UCS2 (FALSE).\r
+\r
+  @retval EFI_SUCCESS           The operation was successful.  The line is stored in\r
                                 Buffer.\r
   @retval EFI_INVALID_PARAMETER Handle was NULL.\r
   @retval EFI_INVALID_PARAMETER Size was NULL.\r
-  @retval EFI_BUFFER_TOO_SMALL  Size was not enough space to store the line.\r
-                                Size was updated to minimum space required.\r
+  @retval EFI_BUFFER_TOO_SMALL  Size was not large enough to store the line.\r
+                                Size was updated to the minimum space required.\r
   @sa FileHandleRead\r
 **/\r
 EFI_STATUS\r
@@ -942,20 +946,29 @@ FileHandleReadLine(
 {\r
   EFI_STATUS  Status;\r
   CHAR16      CharBuffer;\r
+  UINT64      FileSize;\r
   UINTN       CharSize;\r
   UINTN       CountSoFar;\r
   UINT64      OriginalFilePosition;\r
 \r
-\r
   if (Handle == NULL\r
     ||Size   == NULL\r
     ||(Buffer==NULL&&*Size!=0)\r
    ){\r
     return (EFI_INVALID_PARAMETER);\r
-  }\r
+  } \r
+  \r
   if (Buffer != NULL) {\r
     *Buffer = CHAR_NULL;\r
   }\r
+  \r
+  Status = FileHandleGetSize (Handle, &FileSize);\r
+  if (EFI_ERROR (Status)) {\r
+    return Status;\r
+  } else if (FileSize == 0) {\r
+    return EFI_SUCCESS;\r
+  }  \r
+  \r
   FileHandleGetPosition(Handle, &OriginalFilePosition);\r
   if (OriginalFilePosition == 0) {\r
     CharSize = sizeof(CHAR16);\r