Link Old With New

Table 7-2 shows that multithreaded object modules should be linked with old object modules only with great caution.

Table 7-2 Compiling With and Without the _REENTRANT Flag


The File Type	Compiled	Reference	And Return
Old object files (non-threaded) and new object files	Without the `_REENTRANT` or `_POSIX_C_SOURCE` flag	Static storage	The traditional `errno`
New object files	With the `_REENTRANT` or `_POSIX_C_SOURCE` flag	`__errno`, the new binary entry point	The address of the thread's definition of `errno`
Programs using TLI in libnsl [Include `tiuser.h` to get the TLI global error variable. ]	With the `_REENTRANT` or `_POSIX_C_SOURCE` flag (required)	`__t_errno`, a new entry point	The address of the thread's definition of `t_errno`.