Toon Knapen wrote:
Markus Schöpflin wrote:
What does sysconf(_SC_THREAD_SAFE_FUNCTIONS) return?
It returns '1' wethere '-mt' is used or not.
But this is a runtime-if. We need a compile-time if to avoid calling readdir_r when '-mt' is not used on the command-line.
In your specific case, yes. But generally, you can't rely on that. The standard says: <quote> If a symbolic constant is defined with the value -1, the option is not supported. Headers, data types, and function interfaces required only for the option need not be supplied. An application that attempts to use anything associated only with the option is considered to be requiring an extension. If a symbolic constant is defined with a value greater than zero, the option shall always be supported when the application is executed. All headers, data types, and functions shall be present and shall operate as specified. If a symbolic constant is defined with the value zero, all headers, data types, and functions shall be present. The application can check at runtime to see whether the option is supported by calling fpathconf(), pathconf(), or sysconf() with the indicated name parameter. </quote> So in general you have to check with sysconf(_SC_THREAD_SAFE_FUNCTIONS) during runtime whenever _POSIX_THREAD_SAFE_FUNCTIONS == 0. But unfortunately this won't help you much. :-( Markus