IEEE Standards Interpretations for IEEE Std 1003.1™-2001 IEEE Standard for Information Technology - Portable Operating System Interface (POSIX®)
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Interpretation Request #33
Topic: key_t arithemetic type Relevant Sections: XBD <sys/types.h> key_t
In XBD <sys/types.h> we find the following the statment that key_t need not be an arithmetic type: 13068 All of the types shall be defined as arithmetic types of an appropriate length, with the following 13069 exceptions: 13070 XSI key_t But in the description of "Data Types" in XSH (Section 2.12), we find the following contradictory statement: 3363 key_t Arithmetic type used for XSI interprocess communication. Since ftok() returns (key_t)-1 on error, if it is not an arithmetic type then the only other thing it could be is a pointer. Remove line 13070 "XSI key_t" from <sys/types.h>
The standard is inconsistent on this issue, and no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor.
Rationale for Interpretation
The standard developers agreed that key_t should be an arithmetic type.