In order to better understand what is meant by POSIX compliance, I would like to pose the following question/scenario. I am using a version of UNIX that is stated to be POSIX 1003.1 compliant and I would like to compile and run a C program in POSIX mode that utilizes the lstat() function. The POSIX 1003.1 standard does not include Berkeley-style symbolic file links. Symbolic links were not included in the standard until POSIX 1003.1b. Therefore, the lstat() function is not part of the POSIX standard that my system conforms to. What should happen or be expected to happen when I try to compile this program specifying POSIX compliance.
a) A fatal error should occur during compile/link time.
b) The program should compile/link with warnings.
c) The program should compile/link without warnings.
If the program does compile, what should happen when the lstat() function is performed during execution of the program.
a) The program should generate a run-time error.
b) The lstat() function should work properly as defined by the ANSI C or K&R standard.
c) Since the lstat() function is not part of this POSIX standard, it can behave any way it chooses which includes giving totally erroneous results.
Since POSIX is an evolving standard, does it attempt to define expected results from functions that are not yet part of the standard but part of the systems C programming environment?. I would be interested in any responses or comments to this question. As a note, my system returns erroneous results when the lstat() function is performed, improperly mapped stat structure elements, which I have been informed is totally acceptable performance.