Interpretations

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 #29
Topic: SSIZE_MAX minimum values Relevant Sections: 2.8.6 Classification: Editorial defect

Table 2-7 in section 2.8.6 (Invariant Values) lists {_POSIX_SSIZE_MAX} as the value for the symbol {SSIZE_MAX}. It is not made clear in this section that an implementation is per- mitted to support a value for {SSIZE_MAX} that exceeds {_POSIX_SSIZE_MAX}.

Without clarification, it might be possible to interpret the standard as requiring all implementations to set {SSIZE_MAX} to 32767. The text of sections 2.8.2 through 2.8.5 explicitly per- mit the symbols in tables 2-5 and 2-6 to take on values larger than the minimum values in table 2-3. The third columns of tables 2-4 and 2-5 are even titled "Minimum Value".

In contrast to this possible interpretation, BSD currently de- clares the read() and write() functions with return values and nbyte parameters to be 32-bit signed ints, for which SSIZE_MAX would be defined to be MAX_INT, 21474783647 not 32767.

Interpretation Response
The third column header in table 2-7 had the word "Minimum" inadvertantly omitted.

Rationale for Interpretation
This is an editorial defect with no impact on test assertions.