Re: [PATCH 1/7] OvmfPkg: introduce QemuFwCfgSimpleParserLib

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 4/24/20 9:53 AM, Laszlo Ersek wrote:
> We already parse some boolean and integer values from named fw_cfg files
> (usually into PCDs), and we're going to cover more. Add a dedicated
> library for centralizing the parsing logic.
> 
> Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Per Sundstrom <per_sundstrom@yahoo.com>
> Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2681
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
>   OvmfPkg/OvmfPkg.dec                                                   |   4 +
>   OvmfPkg/OvmfPkgIa32.dsc                                               |   1 +
>   OvmfPkg/OvmfPkgIa32X64.dsc                                            |   1 +
>   OvmfPkg/OvmfPkgX64.dsc                                                |   1 +
>   OvmfPkg/Include/Library/QemuFwCfgSimpleParserLib.h                    | 128 +++++++
>   OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf |  27 ++
>   OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParser.c      | 398 ++++++++++++++++++++
>   7 files changed, 560 insertions(+)
> 
> diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
> index 28030391cff2..8a46fe73344e 100644
> --- a/OvmfPkg/OvmfPkg.dec
> +++ b/OvmfPkg/OvmfPkg.dec
> @@ -60,6 +60,10 @@ [LibraryClasses]
>     #
>     QemuFwCfgS3Lib|Include/Library/QemuFwCfgS3Lib.h
>   
> +  ##  @libraryclass  Parse the contents of named fw_cfg files as simple
> +  #                  (scalar) data types.
> +  QemuFwCfgSimpleParserLib|Include/Library/QemuFwCfgSimpleParserLib.h
> +
>     ##  @libraryclass  Rewrite the BootOrder NvVar based on QEMU's "bootorder"
>     #                  fw_cfg file.
>     #
> diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
> index d5e90c001370..5e2972063110 100644
> --- a/OvmfPkg/OvmfPkgIa32.dsc
> +++ b/OvmfPkg/OvmfPkgIa32.dsc
> @@ -160,6 +160,7 @@ [LibraryClasses]
>     UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
>     SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
>     QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
> +  QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>     MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
> diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
> index 066f49aeaee0..18e6909a33fa 100644
> --- a/OvmfPkg/OvmfPkgIa32X64.dsc
> +++ b/OvmfPkg/OvmfPkgIa32X64.dsc
> @@ -164,6 +164,7 @@ [LibraryClasses]
>     UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
>     SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
>     QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
> +  QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>     MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
> index ac510522a9ff..3d24cc4c1cfb 100644
> --- a/OvmfPkg/OvmfPkgX64.dsc
> +++ b/OvmfPkg/OvmfPkgX64.dsc
> @@ -164,6 +164,7 @@ [LibraryClasses]
>     UefiUsbLib|MdePkg/Library/UefiUsbLib/UefiUsbLib.inf
>     SerializeVariablesLib|OvmfPkg/Library/SerializeVariablesLib/SerializeVariablesLib.inf
>     QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgDxeLib.inf
> +  QemuFwCfgSimpleParserLib|OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
>     VirtioLib|OvmfPkg/Library/VirtioLib/VirtioLib.inf
>     LoadLinuxLib|OvmfPkg/Library/LoadLinuxLib/LoadLinuxLib.inf
>     MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/BaseMemEncryptSevLib.inf
> diff --git a/OvmfPkg/Include/Library/QemuFwCfgSimpleParserLib.h b/OvmfPkg/Include/Library/QemuFwCfgSimpleParserLib.h
> new file mode 100644
> index 000000000000..c6062bae8770
> --- /dev/null
> +++ b/OvmfPkg/Include/Library/QemuFwCfgSimpleParserLib.h
> @@ -0,0 +1,128 @@
> +/** @file
> +  Parse the contents of named fw_cfg files as simple (scalar) data types.
> +
> +  Copyright (C) 2020, Red Hat, Inc.
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +**/
> +
> +#ifndef QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_
> +#define QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_
> +
> +#include <Base.h>
> +
> +/**
> +  Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
> +  file into a small array with automatic storage duration. Parse the array as
> +  the textual representation of a BOOLEAN.
> +
> +  @param[in] FileName  The name of the fw_cfg file to look up and parse.
> +
> +  @param[out] Value    On success, Value is TRUE if the contents of the fw_cfg
> +                       file case-insensitively match "true", "yes", "y",
> +                       "enable", "enabled", "1".
> +
> +                       On success, Value is FALSE if the contents of the fw_cfg
> +                       file case-insensitively match "false", "no", "n",
> +                       "disable", "disabled", "0".
> +
> +                       On failure, Value is not changed.
> +
> +  @retval RETURN_SUCCESS         Parsing successful. Value has been set.
> +
> +  @retval RETURN_UNSUPPORTED     Firmware configuration is unavailable.
> +
> +  @retval RETURN_PROTOCOL_ERROR  Parsing failed. Value has not been changed.
> +
> +  @return                        Error codes propagated from
> +                                 QemuFwCfgFindFile(). Value has not been
> +                                 changed.
> +**/
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseBool (
> +  IN  CONST CHAR8 *FileName,
> +  OUT BOOLEAN     *Value
> +  );
> +
> +/**
> +  Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
> +  file into a small array with automatic storage duration. Parse the array as
> +  the textual representation of a UINT8.
> +
> +  @param[in] FileName    The name of the fw_cfg file to look up and parse.
> +
> +  @param[in] ParseAsHex  If TRUE, call BaseLib's AsciiStrHexToUint64S() for
> +                         parsing the fw_cfg file.
> +
> +                         If FALSE, call BaseLib's AsciiStrDecimalToUint64S()
> +                         for parsing the fw_cfg file.
> +
> +  @param[out] Value      On success, Value has been parsed with the BaseLib
> +                         function determined by ParseAsHex, and also
> +                         range-checked for [0, MAX_UINT8].
> +
> +                         On failure, Value is not changed.
> +
> +  @retval RETURN_SUCCESS         Parsing successful. Value has been set.
> +
> +  @retval RETURN_UNSUPPORTED     Firmware configuration is unavailable.
> +
> +  @retval RETURN_PROTOCOL_ERROR  Parsing failed. Value has not been changed.
> +
> +  @retval RETURN_PROTOCOL_ERROR  Parsing succeeded, but the result does not fit
> +                                 in the [0, MAX_UINT8] range. Value has not
> +                                 been changed.

I wondered about RETURN_BAD_BUFFER_SIZE / RETURN_BUFFER_TOO_SMALL for 
this case, but RETURN_PROTOCOL_ERROR is less confusing.

> +
> +  @return                        Error codes propagated from
> +                                 QemuFwCfgFindFile() and from the BaseLib
> +                                 function selected by ParseAsHex. Value has not
> +                                 been changed.
> +**/
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint8 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT8       *Value
> +  );
> +
> +//
> +// The following functions behave identically to QemuFwCfgParseUint8(),
> +// only their range checks use MAX_UINT16, MAX_UINT32, MAX_UINT64, MAX_UINTN,
> +// respectively.
> +//
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint16 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT16      *Value
> +  );
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint32 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT32      *Value
> +  );
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint64 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT64      *Value
> +  );
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUintn (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINTN       *Value
> +  );
> +
> +#endif // QEMU_FW_CFG_SIMPLE_PARSER_LIB_H_
> diff --git a/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf b/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
> new file mode 100644
> index 000000000000..c0e6ab3a1303
> --- /dev/null
> +++ b/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf
> @@ -0,0 +1,27 @@
> +## @file
> +# Parse the contents of named fw_cfg files as simple (scalar) data types.
> +#
> +# Copyright (C) 2020, Red Hat, Inc.
> +#
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 1.29
> +  BASE_NAME                      = QemuFwCfgSimpleParserLib
> +  FILE_GUID                      = a9a1211d-061e-4b64-af30-5dd0cac9dc99
> +  MODULE_TYPE                    = BASE
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = QemuFwCfgSimpleParserLib
> +  CONSTRUCTOR                    = QemuFwCfgSimpleParserInit
> +
> +[Sources]
> +  QemuFwCfgSimpleParser.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  OvmfPkg/OvmfPkg.dec
> +
> +[LibraryClasses]
> +  BaseLib
> +  QemuFwCfgLib
> diff --git a/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParser.c b/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParser.c
> new file mode 100644
> index 000000000000..5ca22fcf0dee
> --- /dev/null
> +++ b/OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParser.c
> @@ -0,0 +1,398 @@
> +/** @file
> +  Parse the contents of named fw_cfg files as simple (scalar) data types.
> +
> +  Copyright (C) 2020, Red Hat, Inc.
> +
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +**/
> +
> +#include <Library/BaseLib.h>
> +#include <Library/QemuFwCfgLib.h>
> +#include <Library/QemuFwCfgSimpleParserLib.h>
> +
> +//
> +// Size of the longest valid UINT64 string, including the terminating NUL.
> +//
> +#define UINT64_STRING_MAX_SIZE \
> +  MAX (sizeof "18446744073709551615", sizeof "0xFFFFFFFFFFFFFFFF")
> +
> +//
> +// Size of the longest valid BOOL string (see the "mTrueString" and
> +// "mFalseString" arrays below), including the terminating NUL.
> +//
> +#define BOOL_STRING_MAX_SIZE (sizeof "disabled")
> +
> +//
> +// Length of "\r\n", not including the terminating NUL.
> +//
> +#define CRLF_LENGTH (sizeof "\r\n" - 1)
> +
> +//
> +// Words recognized as representing TRUE or FALSE.
> +//
> +STATIC CONST CHAR8 * CONST mTrueString[] = {
> +  "true", "yes", "y", "enable", "enabled", "1"
> +};
> +STATIC CONST CHAR8 * CONST mFalseString[] = {
> +  "false", "no", "n", "disable", "disabled", "0"
> +};
> +
> +//
> +// Helper functions.
> +//
> +
> +/**
> +  Look up FileName with QemuFwCfgFindFile() from QemuFwCfgLib. Read the fw_cfg
> +  file into the caller-provided CHAR8 array. NUL-terminate the array.
> +
> +  @param[in] FileName        The name of the fw_cfg file to look up and read.
> +
> +  @param[in,out] BufferSize  On input, number of bytes available in Buffer.
> +
> +                             On output, the number of bytes that have been
> +                             stored to Buffer.
> +
> +                             On error, BufferSize is indeterminate.
> +
> +  @param[out] Buffer         The buffer to read the fw_cfg file into. If the
> +                             fw_cfg file contents are not NUL-terminated, then
> +                             a NUL character is placed into Buffer after the
> +                             fw_cfg file contents.
> +
> +                             On error, Buffer is indeterminate.
> +
> +  @retval RETURN_SUCCESS         Buffer has been populated with the fw_cfg file
> +                                 contents. Buffer is NUL-terminated regardless
> +                                 of whether the fw_cfg file itself was
> +                                 NUL-terminated.
> +
> +  @retval RETURN_UNSUPPORTED     Firmware configuration is unavailable.
> +
> +  @retval RETURN_PROTOCOL_ERROR  The fw_cfg file does not fit into Buffer.
> +                                 (This is considered a QEMU configuration
> +                                 error; BufferSize is considered authoritative
> +                                 for the contents of the fw_cfg file identified
> +                                 by FileName.)
> +
> +  @retval RETURN_PROTOCOL_ERROR  The fw_cfg file contents are not themselves
> +                                 NUL-terminated, and an extra NUL byte does not
> +                                 fit into Buffer. (Again a QEMU configuration
> +                                 error.)
> +
> +  @return                        Error codes propagated from
> +                                 QemuFwCfgFindFile().
> +**/
> +STATIC
> +RETURN_STATUS
> +QemuFwCfgGetAsString (
> +  IN     CONST CHAR8 *FileName,
> +  IN OUT UINTN       *BufferSize,
> +  OUT    CHAR8       *Buffer
> +  )
> +{
> +  RETURN_STATUS        Status;
> +  FIRMWARE_CONFIG_ITEM FwCfgItem;
> +  UINTN                FwCfgSize;
> +
> +  if (!QemuFwCfgIsAvailable ()) {
> +    return RETURN_UNSUPPORTED;
> +  }
> +
> +  Status = QemuFwCfgFindFile (FileName, &FwCfgItem, &FwCfgSize);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  if (FwCfgSize > *BufferSize) {
> +    return RETURN_PROTOCOL_ERROR;
> +  }
> +
> +  QemuFwCfgSelectItem (FwCfgItem);
> +  QemuFwCfgReadBytes (FwCfgSize, Buffer);
> +
> +  //
> +  // If Buffer is already NUL-terminated due to fw_cfg contents, we're done.
> +  //
> +  if (FwCfgSize > 0 && Buffer[FwCfgSize - 1] == '\0') {
> +    *BufferSize = FwCfgSize;
> +    return RETURN_SUCCESS;
> +  }
> +  //
> +  // Otherwise, append a NUL byte to Buffer (if we have room for it).
> +  //
> +  if (FwCfgSize == *BufferSize) {
> +    return RETURN_PROTOCOL_ERROR;
> +  }
> +  Buffer[FwCfgSize] = '\0';
> +  *BufferSize = FwCfgSize + 1;
> +  return RETURN_SUCCESS;
> +}
> +
> +/**
> +  Remove a trailing \r\n or \n sequence from a string.
> +
> +  @param[in,out] BufferSize  On input, the number of bytes in Buffer, including
> +                             the terminating NUL.
> +
> +                             On output, the adjusted string size (including the
> +                             terminating NUL), after stripping the \r\n or \n
> +                             suffix.
> +
> +  @param[in,out] Buffer      The NUL-terminated string to trim.
> +**/
> +STATIC
> +VOID
> +StripNewline (
> +  IN OUT UINTN *BufferSize,
> +  IN OUT CHAR8 *Buffer
> +  )
> +{
> +  UINTN InSize, OutSize;
> +
> +  InSize = *BufferSize;
> +  OutSize = InSize;
> +
> +  if (InSize >= 3 &&
> +      Buffer[InSize - 3] == '\r' && Buffer[InSize - 2] == '\n') {
> +    OutSize = InSize - 2;
> +  } else if (InSize >= 2 && Buffer[InSize - 2] == '\n') {
> +    OutSize = InSize - 1;
> +  }
> +
> +  if (OutSize < InSize) {
> +    Buffer[OutSize - 1] = '\0';
> +    *BufferSize = OutSize;
> +  }
> +}
> +
> +/**
> +  Read the fw_cfg file identified by FileName as a string into a small array
> +  with automatic storage duration, using QemuFwCfgGetAsString(). Parse the
> +  string as a UINT64. Perform a range-check on the parsed value.
> +
> +  @param[in] FileName    The name of the fw_cfg file to look up and parse.
> +
> +  @param[in] ParseAsHex  If TRUE, call BaseLib's AsciiStrHexToUint64S() for
> +                         parsing the fw_cfg file.
> +
> +                         If FALSE, call BaseLib's AsciiStrDecimalToUint64S()
> +                         for parsing the fw_cfg file.
> +
> +  @param[in] Limit       The inclusive upper bound on the parsed UINT64 value.
> +
> +  @param[out] Value      On success, Value has been parsed with the BaseLib
> +                         function determined by ParseAsHex, and has been
> +                         range-checked against [0, Limit].
> +
> +                         On failure, Value is not changed.
> +
> +  @retval RETURN_SUCCESS         Parsing successful. Value has been set.
> +
> +  @retval RETURN_UNSUPPORTED     Firmware configuration is unavailable.
> +
> +  @retval RETURN_PROTOCOL_ERROR  Parsing failed. Value has not been changed.
> +
> +  @retval RETURN_PROTOCOL_ERROR  Parsing succeeded, but the result does not fit
> +                                 in the [0, Limit] range. Value has not been
> +                                 changed.
> +
> +  @return                        Error codes propagated from
> +                                 QemuFwCfgFindFile() and from the BaseLib
> +                                 function selected by ParseAsHex. Value has not
> +                                 been changed.
> +**/
> +STATIC
> +RETURN_STATUS
> +QemuFwCfgParseUint64WithLimit (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  IN  UINT64      Limit,
> +  OUT UINT64      *Value
> +  )
> +{
> +  UINTN         Uint64StringSize;
> +  CHAR8         Uint64String[UINT64_STRING_MAX_SIZE + CRLF_LENGTH];
> +  RETURN_STATUS Status;
> +  CHAR8         *EndPointer;
> +  UINT64        Uint64;
> +
> +  Uint64StringSize = sizeof Uint64String;
> +  Status = QemuFwCfgGetAsString (FileName, &Uint64StringSize, Uint64String);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  StripNewline (&Uint64StringSize, Uint64String);
> +
> +  if (ParseAsHex) {
> +    Status = AsciiStrHexToUint64S (Uint64String, &EndPointer, &Uint64);
> +  } else {
> +    Status = AsciiStrDecimalToUint64S (Uint64String, &EndPointer, &Uint64);
> +  }
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  //
> +  // Report a wire protocol error if the subject sequence is empty, or trailing
> +  // garbage is present, or Limit is not honored.
> +  //
> +  if (EndPointer == Uint64String || *EndPointer != '\0' || Uint64 > Limit) {
> +    return RETURN_PROTOCOL_ERROR;
> +  }
> +
> +  *Value = Uint64;
> +  return RETURN_SUCCESS;
> +}
> +
> +//
> +// Public functions.
> +//
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgSimpleParserInit (
> +  VOID
> +  )
> +{
> +  //
> +  // Do nothing, just participate in constructor dependency ordering.
> +  //
> +  return RETURN_SUCCESS;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseBool (
> +  IN  CONST CHAR8 *FileName,
> +  OUT BOOLEAN     *Value
> +  )
> +{
> +  UINTN         BoolStringSize;
> +  CHAR8         BoolString[BOOL_STRING_MAX_SIZE + CRLF_LENGTH];
> +  RETURN_STATUS Status;
> +  UINTN         Idx;
> +
> +  BoolStringSize = sizeof BoolString;
> +  Status = QemuFwCfgGetAsString (FileName, &BoolStringSize, BoolString);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +
> +  StripNewline (&BoolStringSize, BoolString);
> +
> +  for (Idx = 0; Idx < ARRAY_SIZE (mTrueString); ++Idx) {
> +    if (AsciiStriCmp (BoolString, mTrueString[Idx]) == 0) {
> +      *Value = TRUE;
> +      return RETURN_SUCCESS;
> +    }
> +  }
> +
> +  for (Idx = 0; Idx < ARRAY_SIZE (mFalseString); ++Idx) {
> +    if (AsciiStriCmp (BoolString, mFalseString[Idx]) == 0) {
> +      *Value = FALSE;
> +      return RETURN_SUCCESS;
> +    }
> +  }
> +
> +  return RETURN_PROTOCOL_ERROR;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint8 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT8       *Value
> +  )
> +{
> +  RETURN_STATUS Status;
> +  UINT64        Uint64;
> +
> +  Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT8,
> +             &Uint64);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  *Value = (UINT8)Uint64;
> +  return RETURN_SUCCESS;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint16 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT16      *Value
> +  )
> +{
> +  RETURN_STATUS Status;
> +  UINT64        Uint64;
> +
> +  Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT16,
> +             &Uint64);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  *Value = (UINT16)Uint64;
> +  return RETURN_SUCCESS;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint32 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT32      *Value
> +  )
> +{
> +  RETURN_STATUS Status;
> +  UINT64        Uint64;
> +
> +  Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT32,
> +             &Uint64);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  *Value = (UINT32)Uint64;
> +  return RETURN_SUCCESS;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUint64 (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINT64      *Value
> +  )
> +{
> +  RETURN_STATUS Status;
> +  UINT64        Uint64;
> +
> +  Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINT64,
> +             &Uint64);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  *Value = Uint64;
> +  return RETURN_SUCCESS;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgParseUintn (
> +  IN  CONST CHAR8 *FileName,
> +  IN  BOOLEAN     ParseAsHex,
> +  OUT UINTN       *Value
> +  )
> +{
> +  RETURN_STATUS Status;
> +  UINT64        Uint64;
> +
> +  Status = QemuFwCfgParseUint64WithLimit (FileName, ParseAsHex, MAX_UINTN,
> +             &Uint64);
> +  if (RETURN_ERROR (Status)) {
> +    return Status;
> +  }
> +  *Value = (UINTN)Uint64;
> +  return RETURN_SUCCESS;
> +}
> 

Neat.
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>