# 10. EFI\_STATUS 타입 과 EFI\_ERROR 매크로

UEFI 코드에서는 아래와 같은 구성의 코드를 일반적으로 사용한다.

```
if (!EFI_ERROR(Status) {
  ...
} else {
  ...
}
```

EFI\_STATUS 기능의 내부 구현에 대해서 아래의 경로의 파일을 확인하면 된다.\
(MdePkg/Include/Uefi/UefiBaseType.h MdePkg/Include/Base.h)

```
#define EFI_ERROR(A)              RETURN_ERROR(A)

...

/**
  Returns TRUE if a specified RETURN_STATUS code is an error code.

  This function returns TRUE if StatusCode has the high bit set.  Otherwise, FALSE is returned.

  @param  StatusCode    The status code value to evaluate.

  @retval TRUE          The high bit of StatusCode is set.
  @retval FALSE         The high bit of StatusCode is clear.

**/
#define RETURN_ERROR(StatusCode)     (((INTN)(RETURN_STATUS)(StatusCode)) < 0)

...

//
// Status codes common to all execution phases
//
typedef UINTN RETURN_STATUS;
```

따라서 `EFI_ERROR` 매크로는 단순히 전달된 값이 음수인지 테스트를 하며 이는 `signed integer`에 대해서도 마찬가지이다.\
가능한 `EFI_STATUS`의 값은 MdePkg/Include/Uefi/UefiBaseType.h에 명시되어 있다.

```
///
/// Enumeration of EFI_STATUS.
///@{
#define EFI_SUCCESS               RETURN_SUCCESS
#define EFI_LOAD_ERROR            RETURN_LOAD_ERROR
#define EFI_INVALID_PARAMETER     RETURN_INVALID_PARAMETER
#define EFI_UNSUPPORTED           RETURN_UNSUPPORTED
#define EFI_BAD_BUFFER_SIZE       RETURN_BAD_BUFFER_SIZE
#define EFI_BUFFER_TOO_SMALL      RETURN_BUFFER_TOO_SMALL
#define EFI_NOT_READY             RETURN_NOT_READY
#define EFI_DEVICE_ERROR          RETURN_DEVICE_ERROR
#define EFI_WRITE_PROTECTED       RETURN_WRITE_PROTECTED
#define EFI_OUT_OF_RESOURCES      RETURN_OUT_OF_RESOURCES
#define EFI_VOLUME_CORRUPTED      RETURN_VOLUME_CORRUPTED
#define EFI_VOLUME_FULL           RETURN_VOLUME_FULL
#define EFI_NO_MEDIA              RETURN_NO_MEDIA
#define EFI_MEDIA_CHANGED         RETURN_MEDIA_CHANGED
#define EFI_NOT_FOUND             RETURN_NOT_FOUND
#define EFI_ACCESS_DENIED         RETURN_ACCESS_DENIED
#define EFI_NO_RESPONSE           RETURN_NO_RESPONSE
#define EFI_NO_MAPPING            RETURN_NO_MAPPING
#define EFI_TIMEOUT               RETURN_TIMEOUT
#define EFI_NOT_STARTED           RETURN_NOT_STARTED
#define EFI_ALREADY_STARTED       RETURN_ALREADY_STARTED
#define EFI_ABORTED               RETURN_ABORTED
#define EFI_ICMP_ERROR            RETURN_ICMP_ERROR
#define EFI_TFTP_ERROR            RETURN_TFTP_ERROR
#define EFI_PROTOCOL_ERROR        RETURN_PROTOCOL_ERROR
#define EFI_INCOMPATIBLE_VERSION  RETURN_INCOMPATIBLE_VERSION
#define EFI_SECURITY_VIOLATION    RETURN_SECURITY_VIOLATION
#define EFI_CRC_ERROR             RETURN_CRC_ERROR
#define EFI_END_OF_MEDIA          RETURN_END_OF_MEDIA
#define EFI_END_OF_FILE           RETURN_END_OF_FILE
#define EFI_INVALID_LANGUAGE      RETURN_INVALID_LANGUAGE
#define EFI_COMPROMISED_DATA      RETURN_COMPROMISED_DATA
#define EFI_HTTP_ERROR            RETURN_HTTP_ERROR

#define EFI_WARN_UNKNOWN_GLYPH    RETURN_WARN_UNKNOWN_GLYPH
#define EFI_WARN_DELETE_FAILURE   RETURN_WARN_DELETE_FAILURE
#define EFI_WARN_WRITE_FAILURE    RETURN_WARN_WRITE_FAILURE
#define EFI_WARN_BUFFER_TOO_SMALL RETURN_WARN_BUFFER_TOO_SMALL
#define EFI_WARN_STALE_DATA       RETURN_WARN_STALE_DATA
#define EFI_WARN_FILE_SYSTEM      RETURN_WARN_FILE_SYSTEM
```

만약 해당 값을 인코딩 하는 방법을 보려면 MdePkg\Include\Base.h를 확인하면 된다.

```
///
/// The operation completed successfully.
///
#define RETURN_SUCCESS               0

///
/// The image failed to load.
///
#define RETURN_LOAD_ERROR            ENCODE_ERROR (1)

///
/// The parameter was incorrect.
///
#define RETURN_INVALID_PARAMETER     ENCODE_ERROR (2)

<...>

/**
  Produces a RETURN_STATUS code with the highest bit set.

  @param  StatusCode    The status code value to convert into a warning code.
                        StatusCode must be in the range 0x00000000..0x7FFFFFFF.

  @return The value specified by StatusCode with the highest bit set.

**/
#define ENCODE_ERROR(StatusCode)     ((RETURN_STATUS)(MAX_BIT | (StatusCode)))

/**
  Produces a RETURN_STATUS code with the highest bit clear.

  @param  StatusCode    The status code value to convert into a warning code.
                        StatusCode must be in the range 0x00000000..0x7FFFFFFF.

  @return The value specified by StatusCode with the highest bit clear.

**/
#define ENCODE_WARNING(StatusCode)   ((RETURN_STATUS)(StatusCode))
```

이제 코드에서 `EFI_ERROR` 매크로를 사용하고 `Print`의 `%r` 출력 옵션을 사용하여 에러가 출력되는지 확인 해보겠다.

`ImageHandle` 대신 `NULL` 포인터를 인자로 전달하여 오류 표시 테스트할 수 있다.

```
Print(L"________\n");
EFI_GUID **ProtocolGuidArray;
UINTN ArrayCount;
EFI_STATUS Status = gBS->ProtocolsPerHandle(NULL,
                                            &ProtocolGuidArray,
                                            &ArrayCount);

if (!EFI_ERROR(Status)) {
  for (int i=0; i<ArrayCount; i++) {
    Print(L"%g\n", ProtocolGuidArray[i]);
  }
  FreePool(ProtocolGuidArray);
} else {
  Print(L"ProtocolsPerHandle error: %r\n", Status);
}
```

빌드 후 실행하면 아래와 같은 에러 문구를 볼 수 있다.

```
ProtocolsPerHandle error: Invalid Parameter
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://bob-mcd-team.gitbook.io/uefi/uefi-development/handle-protocol/10.efi_status.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.