longjmp

#include <setjmp.h>

void longjmp (
  jmp_buf env,      /* environment to restore */
  int retval);      /* return value */

The longjmp function restores the state which was previously stored in env by the setjmp function. The retval argument specifies the value to return from the setjmp function.

The longjmp and setjmp functions may be used to execute a non-local goto. They are usually utilized to pass control to an error recovery routine.

Local variables and function arguments are restored only if declared with the volatile attribute.

None.

setjmp

#include <setjmp.h>
#include <stdio.h> /* for printf */

jmp_buf env; /* jump environment (must be global) */
bit error_flag;

void trigger (void) {
  .
  .
  .
  /* processing code here */
  .
  .
  .
  if (error_flag != 0) {
    longjmp (env, 1);   /* return 1 to setjmp */
  }
  .
  .
  .
}


void recover (void) {
  /* recovery code here */
}


void tst_longjmp (void) {
  .
  .
  .
  if (setjmp (env) != 0) {     /* setjmp returns a 0 */
    printf ("LONGJMP called\n");
    recover ();
  }

  else {
    printf ("SETJMP called\n");

    error_flag = 1;            /* force an error */

    trigger ();
  }
}