# Function Status Evaluate return values that most GSS-API functions use to indicate the outcome of an operation. ## Discussion The functions of the GSS-API return two status codes. The major status code, delivered as the function’s return value, provides a mechanism-independent status output. A value of [`GSS_S_COMPLETE`](/documentation/GSS/GSS_S_COMPLETE) typically indicates success, but the code is actually composed of several fields that enable communicating a more nuanced result. Always check the major status code to determine if an operation succeeds. The minor status code provides additional information, often mechanism-specific, when an operation fails. This result returns using the [`OM_uint32`](/documentation/GSS/OM_uint32) pointer given as the function’s first argument. Examine this value to further debug a problem. For example, many functions allocate memory as a side effect of their main task. If memory allocation fails, the entire operation fails. But while the major status indicates a generic problem, a minor status of `ENOMEM` indicates that failed memory allocation is the exact culprit. Three bitfields bundled together make up major status codes in a single [`OM_uint32`](/documentation/GSS/OM_uint32) value. These fields are: - The calling error: A generic GSS-API error in the most significant 8 bits. - The routine error: An error specific to the routine in the next 8 bits. - Supplementary Information: Additional information about the error in the lower 16 bits. When a function successfully runs to completion, it returns zero for all of these fields. As a convenience, you can compare the result directly with the status code [`GSS_S_COMPLETE`](/documentation/GSS/GSS_S_COMPLETE) to test for this condition.  For any other result, use one of the available extraction macros (such as [`GSS_CALLING_ERROR`](/documentation/GSS/GSS_CALLING_ERROR)) to obtain a value that you compare against one of the known error codes. For example, you can test for a failure to read one of the function inputs as follows: ```objc OM_uint32 major = <# Some GSS call #> if (GSS_CALLING_ERROR(major) == GSS_S_CALL_INACCESSIBLE_READ) { // Handle the error } ``` Use the [`gss_display_status(_:_:_:_:_:_:)`](/documentation/GSS/gss_display_status(_:_:_:_:_:_:)) function to retrieve a human readable string corresponding to a given status result. ## Topics ### Status and Error Creation [`OM_uint32`](/documentation/GSS/OM_uint32) A 32-bit unsigned integer. [`OM_uint64`](/documentation/GSS/OM_uint64) A 64-bit unsigned integer. [`gss_uint32`](/documentation/GSS/gss_uint32) A 32-bit unsigned integer. [`gss_status_id_t`](/documentation/GSS/gss_status_id_t) A pointer to a status result. [`GSS_C_MECH_CODE`](/documentation/GSS/GSS_C_MECH_CODE) A flag that indicates the status code comes from a call to an underlying mechanism, such as Kerberos. [`GSS_C_GSS_CODE`](/documentation/GSS/GSS_C_GSS_CODE) A flag that indicates the named status code comes from a GSS-API call. [`GSS_S_COMPLETE`](/documentation/GSS/GSS_S_COMPLETE) The operation completed without error. [`gss_display_status`](/documentation/GSS/gss_display_status(_:_:_:_:_:_:)) Returns a human readable string for a status code. [`GSSCreateError`](/documentation/GSS/GSSCreateError(_:_:_:)) Returns an error object based on GSS-API major and minor status codes. ### Calling Errors [`GSS_S_CALL_BAD_STRUCTURE`](/documentation/GSS/GSS_S_CALL_BAD_STRUCTURE) Improperly formatted parameter. [`GSS_S_CALL_INACCESSIBLE_READ`](/documentation/GSS/GSS_S_CALL_INACCESSIBLE_READ) A required input parameter could not be read. [`GSS_S_CALL_INACCESSIBLE_WRITE`](/documentation/GSS/GSS_S_CALL_INACCESSIBLE_WRITE) A required output parameter failed to write. ### Routine Errors [`GSS_S_BAD_MECH`](/documentation/GSS/GSS_S_BAD_MECH) Unsupported mechanism. [`GSS_S_BAD_NAME`](/documentation/GSS/GSS_S_BAD_NAME) Invalid name. [`GSS_S_BAD_NAMETYPE`](/documentation/GSS/GSS_S_BAD_NAMETYPE) Unsupported name type. [`GSS_S_BAD_MIC`](/documentation/GSS/GSS_S_BAD_MIC) Failed token integrity check. [`GSS_S_BAD_SIG`](/documentation/GSS/GSS_S_BAD_SIG) Failed token integrity check. [`GSS_S_BAD_STATUS`](/documentation/GSS/GSS_S_BAD_STATUS) Invalid status selector. [`GSS_S_BAD_BINDINGS`](/documentation/GSS/GSS_S_BAD_BINDINGS) Channel bindings mismatch. [`GSS_S_NO_CRED`](/documentation/GSS/GSS_S_NO_CRED) No valid credentials. [`GSS_S_NO_CONTEXT`](/documentation/GSS/GSS_S_NO_CONTEXT) No valid security context. [`GSS_S_DEFECTIVE_TOKEN`](/documentation/GSS/GSS_S_DEFECTIVE_TOKEN) Defective token. [`GSS_S_DEFECTIVE_CREDENTIAL`](/documentation/GSS/GSS_S_DEFECTIVE_CREDENTIAL) Defective credential. [`GSS_S_CREDENTIALS_EXPIRED`](/documentation/GSS/GSS_S_CREDENTIALS_EXPIRED) Expired credential. [`GSS_S_CONTEXT_EXPIRED`](/documentation/GSS/GSS_S_CONTEXT_EXPIRED) Expired context. [`GSS_S_FAILURE`](/documentation/GSS/GSS_S_FAILURE) An unspecified error. [`GSS_S_BAD_QOP`](/documentation/GSS/GSS_S_BAD_QOP) Unsupported QOP value. [`GSS_S_UNAUTHORIZED`](/documentation/GSS/GSS_S_UNAUTHORIZED) Unauthorized operation. [`GSS_S_UNAVAILABLE`](/documentation/GSS/GSS_S_UNAVAILABLE) Unavailable operation. [`GSS_S_DUPLICATE_ELEMENT`](/documentation/GSS/GSS_S_DUPLICATE_ELEMENT) A duplicate credential element requested. [`GSS_S_NAME_NOT_MN`](/documentation/GSS/GSS_S_NAME_NOT_MN) The name contains multimechanism elements. [`GSS_S_BAD_MECH_ATTR`](/documentation/GSS/GSS_S_BAD_MECH_ATTR) Unknown mechanism attribute. [`GSS_S_CRED_UNAVAIL`](/documentation/GSS/GSS_S_CRED_UNAVAIL) Unavailable credential. ### Token Macros [`GSS_S_CONTINUE_NEEDED`](/documentation/GSS/GSS_S_CONTINUE_NEEDED) A request for continuation during context establishment. [`GSS_S_DUPLICATE_TOKEN`](/documentation/GSS/GSS_S_DUPLICATE_TOKEN) The detection of a duplicate per-message token. [`GSS_S_OLD_TOKEN`](/documentation/GSS/GSS_S_OLD_TOKEN) The detection of a timed-out per-message token. [`GSS_S_UNSEQ_TOKEN`](/documentation/GSS/GSS_S_UNSEQ_TOKEN) The detection of a reordered (early) per-message token. [`GSS_S_GAP_TOKEN`](/documentation/GSS/GSS_S_GAP_TOKEN) The detection of a skipped predecessor token. ### Extraction Macros [`GSS_ERROR`](/documentation/GSS/GSS_ERROR) A macro that masks the supplementary info out of a major status code, leaving both calling and routine error fields. [`GSS_CALLING_ERROR`](/documentation/GSS/GSS_CALLING_ERROR) A macro that masks out all but the calling error field from a major status code. [`GSS_ROUTINE_ERROR`](/documentation/GSS/GSS_ROUTINE_ERROR) A macro that masks out all but the routine error field from a major status code. [`GSS_SUPPLEMENTARY_INFO`](/documentation/GSS/GSS_SUPPLEMENTARY_INFO) A macro that masks out all but the supplementary information field from a major status code. ### Masks and Offsets [`GSS_C_CALLING_ERROR_MASK`](/documentation/GSS/GSS_C_CALLING_ERROR_MASK) A mask with a width that matches the calling error field. [`GSS_C_CALLING_ERROR_OFFSET`](/documentation/GSS/GSS_C_CALLING_ERROR_OFFSET) The offset of the calling error field within the major status code. [`GSS_C_ROUTINE_ERROR_MASK`](/documentation/GSS/GSS_C_ROUTINE_ERROR_MASK) A mask with a width that matches the routine error field. [`GSS_C_ROUTINE_ERROR_OFFSET`](/documentation/GSS/GSS_C_ROUTINE_ERROR_OFFSET) The offset of the routine error field within the major status code. [`GSS_C_SUPPLEMENTARY_MASK`](/documentation/GSS/GSS_C_SUPPLEMENTARY_MASK) A mask with a width that matches the supplementary information field. [`GSS_C_SUPPLEMENTARY_OFFSET`](/documentation/GSS/GSS_C_SUPPLEMENTARY_OFFSET) The offset of the supplementary information field within the major status code. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)