rdchk(2xnx) (XENIX System Compatibility)

rdchk -- (XENIX) check to see if there is data to be read

Synopsis

   cc [flag . . . ] flag . . . -lx 
   int rdchk(int fdes);

Description

rdchk checks to see if a process will block if it attempts to read the file designated by fdes. rdchk returns 1 if there is data to be read or if it is the end of the file (EOF). In this context, the proper sequence of calls using rdchk is:

   if(rdchk(fildes) > 0) 
       read(fildes, buffer, nbytes);

Return values

rdchk returns -1 if an error occurs (for example, EBADF), 0 if the process will block if it issues a read and 1 if it is okay to read. EBADF is returned if a rdchk is done on a semaphore file or if the file specified doesn't exist.

References

read(2)