Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretation for IEEE Std 1003.1™-1990 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)

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Interpretation Request #75
Topic: off_t error messages and 1003.1/INT #37 Relevant Sections: Classification

IEEE Std 1003.1/2003.1/Int, October 1994 edition states that EINVAL is the errno that applies when you exceed the upper limit for off_t. Is it conforming for an implementation defined error such as EOVERFLOW to be given as the errno in the case where the file is larger in size than can be represented in an off_t? In this case seeking beyond an off_t is not an invalid position in this file and thus EINVAL would not be the appropriate errno.

Interpretation Response
Yes it is conforming. Interpretation #37 does not apply EINVAL to this case. The standard clearly states that implementations may support additional errors not listed in this clause, but shall not generate a different error number from one required by this part of ISO/IEC 9945 for an error condition described in this part of ISO/IEC 9945.

Rationale for Interpretation
None. Forwarded to Interpretation group: Aug 30 1995 Finalized: Nov 21 1995