Advanced Programming in the UNIX® Environment

ptg10805159

Section 2.6 Options 55

• _POSIX_READER_WRITER_LOCKS

• _POSIX_REALTIME_SIGNALS

• _POSIX_SEMAPHORES

• _POSIX_SPIN_LOCKS

• _POSIX_THREAD_SAFE_FUNCTIONS

• _POSIX_THREADS

• _POSIX_TIMEOUTS

• _POSIX_TIMERS

These constants aredefined to have the value 200809L. Their corresponding

_SCsymbols arealso retained for backwardcompatibility.

5. _PC_CHOWN_RESTRICTEDand_PC_NO_TRUNCreturn−1without changing
   errnoif the feature is not supported for the specifiedpathnameorfd.Onall
   POSIX-conforming systems, the return value will be greater than zero
   (indicating that the feature is supported).


6. Thereferenced file for_PC_CHOWN_RESTRICTEDmust be either a file or a
   directory.If it is a directory,the return value indicates whether this option
   applies to files within that directory.


7. Thereferenced file for _PC_NO_TRUNC and_PC_2_SYMLINKS must be a
   directory.


8. For_PC_NO_TRUNC,the return value applies to filenames within the directory.


9. Thereferenced file for_PC_VDISABLEmust be a terminal file.


10. For_PC_ASYNC_IO,_PC_PRIO_IO,and_PC_SYNC_IO,the referenced file
    must not be a directory.

Name of option Indicates ... nameargument

_POSIX_CHOWN_RESTRICTED whether use ofchownis restricted _PC_CHOWN_RESTRICTED

_POSIX_NO_TRUNC whether filenames longer thanNAME_MAX _PC_NO_TRUNC

generate an error

_POSIX_VDISABLE if defined, terminal special characters can be _PC_VDISABLE

disabled with this value

_POSIX_ASYNC_IO whether asynchronous I/O can be used with_PC_ASYNC_IO

the associated file

_POSIX_PRIO_IO whether prioritized I/O can be used with _PC_PRIO_IO

the associated file

_POSIX_SYNC_IO whether synchronized I/O can be used with _PC_SYNC_IO

the associated file

_POSIX2_SYMLINKS whether symbolic links aresupported in the _PC_2_SYMLINKS

directory

Figure 2.18 Options andnamearguments topathconfandfpathconf