getdtablesize - get descriptor table size
getdtablesize(2) returns the maximum number of files a process can have open.
getdtablesize(2) is implemented as a library function in DLL 4.4.1. This function returns OPEN_MAX (set to 256 in Linux 2.0.23) if OPEN_MAX was defined when the library was compiled. Otherwise, -1 is returned, and errno is set to ENOSYS.
SVr4, 4.4BSD (the getdtablesize(2) function first appeared in BSD 4.2).