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 #45
Topic: creat() - implementation restrictions Relevant Sections: 8.2.3
Chapter 8 of POSIX.1 lists the functions required from the C Standard, required as part of POSIX.1 with the C Language Binding. Section 8.1 lines 25-29 specify the particular input/output functions required. Section 8.2 lines 193-198 state that functions from the C standard which "creat[e] a file shall do so as if they called the creat() function" with specified flags. Section 8.2.3 lines 341-345 describe that each function operating on a stream has "underlying functions" which "share certain traits with the underlying functions, but [do] not require that there be any relation between the implementations of the stream function and its underlying functions."
Although section 8.2.3 clearly allows for independent implementation of the function from its underlying functions, are restrictions placed on the underlying function implicitly applied to the function listed here? For example, if an additional standard (such as POSIX.6) imposes additional restrictions on write(), are they automatically imposed on functions which use write() as an underlying function (such as fprintf() or fputs()) by virtue of the requirement to "share certain traits"? Or must the additional standard explicitly spell out equivalent restrictions for the functions from the C standard? (Jeremy Epstein)