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 #83
sysconf Relevant Sections:

I would like to request an official binding interpretation of IEEE Std 1003.1-1996 (POSIX.1). This request deals with the return value of the sysconf(int name) function when the value of the system variable selected by "name" is not limited by the implementation. Currently the standard says (, p. 112, l. 491 ff.): If name is an invalid value, sysconf() shall return -1.

Otherwise, the sysconf() function returns the current variable value on the system. The value returned shall not be more restrictive than the corresponding value described to the application when it was compiled with the implementation's <limits.h> or <unistd.h>

The standard as published does not address the case where the current variable is not limited by <limits.h> or <unistd.h>, as is the case for one or more variables in our implementation. The POSIX.1 committee has, however, added the following sentence to section in the latest (D13.2) version of the POSIX.1a draft: If the value corresponding to name has no limit, the sysconf() function shall return a value of -1 without changing errno. This is how our implementation behaves, and we ask the committee to verify that such an implementation is compliant with the standard.

Permit behaviour as specified in D13.2 of POSIX.1a draft

Interpretation Response
The standard does not speak to this issue, and as such no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor.

Rationale for Interpretation

Editor's Response
See interpretation response above. Forwarded to Interpretations group: 4 Jan 1998 Circulated for review: Feb 1 1998 Finalized: March 4 1998