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

IEEE Standards Interpretations for IEEE Std 1003.2™-1992 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)--Part 2: Shell and Utilities

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Interpretation Request #138
Topic: regex Relevant Sections: Annex B, Section B.5

Concerning the wording in 1003.2- 1992 Annex B section B.5 C Binding for RE matching, Table B-10 - regcomp(), regexec() Return Values (line 424) says: REG_BADRPT ?, *, or + not preceded by valid RE Was is it intentional to omit '{' from this error message? The Error Code, meaning "bad repeater" implies that it is to used as a Error Code and Description when a repeater is not preceded by a valid regular expression. "{m,n}" is a repeat construct that can be preceded by an invalid RE. While REG_BADPAT is an Error Code that will cover this situation it is vague and not as useful as the return of REG_BADRPT. Currently the description of REG_BADRPT is confusing to users who read it when the error to be indicated is applicable to an interval expression repeater (particularly if the RE does contain other types of repeaters). A proposed solution is that line 424 be changed to read: REG_BADRPT ?, *, +, or { not preceded by valid RE

Interpretation Response
The standard clearly states the requirements for return values for regcomp(), regexec() and conforming implementations must conform to this. However concerns have been raised about this which are being referred to the sponsor. We are concerned not only about { in EREs but \{ in BREs.

Rationale for Interpretation