TNS/E Native Application Conversion Guide

C and C++ Conversion Tasks

TNS/E Native Application Conversion Guide—529659-003

3-12

Using the setjmp() and longjmp() Functions

Calling the setjmp() function in a function marked as inline and then doing a

subsequent longjmp() to the location of the calling function is a practice that should

be avoided. Programs that use setjmp() and longjmp() in this way generally

expect that functions marked as inline are actually inlined, and that the longjmp()

call will restore the execution context of the function that called setjmp(). In TNS

programs compiled at optimization level 0, this is sometimes the case and the

longmp() call might work as expected. But in a TNS/E native program compiled at

optimization level 0, functions marked as inline are never actually inlined, and the

longjmp() call will not work as expected. A preferred practice is to use a macro

instead of an inline function.

Using the semctl() Function

The semctl() function has an optional fourth parameter that is required in certain

cases. As described in the

Open System Services System Calls Reference Manual

the value passed in that parameter must be defined in the calling program as a semun

union, as in this example:

union semun {

int

val

;

struct semid_ds *

buf

;

unsigned short int *

array

;

}

arg

union semun semopts;

semopts.val = 1;

if (semctl(semid, 0, SETVAL, semopts) ==-1)

On TNS/R systems, you can also pass a value directly, without the use of the semun

union (for example, as a simple scalar), as in this example:

if (semctl(semid, 0, SETVAL, 1) ==1)

A value passed in this way gives the expected results.

However, on TNS/E systems, you must define the parameter value as a semun union.

Code that does not do so will not function as expected.