bsd/kern/kern_fork.c

152 #define	DOVFORK	0x2	/* vfork() system call */
157  * Description:	start a vfork on a process
159  * Parameters:	parent_proc		process (re)entering vfork state
166  *		_exit() following a vfork(), including calling vfork()
181  * Description:	stop a vfork on a process
183  * Parameters:	parent_proc		process leaving vfork state
187  * Notes:	Decrements the count; currently, reentrancy of vfork()
196 		panic("vfork cnt is -ve");
204  * vfork
206  * Description:	vfork system call
215  *		EINVAL			vfork() called during vfork()
276 vfork(proc_t parent_proc, __unused struct vfork_args *uap, int32_t *retval)
285 		 * kludge: rely on uu_proc being set in the vfork case,
348  *		the block diagram above the implementation of vfork()), this
407 		 * Prevent a vfork while we are in vfork(); we should
412 		 * that case.  We do not support vfork() in vfork()
422 			printf("fork1 called within vfork by %s\n", parent_proc->p_comm);
428 		 * Flag us in progress; if we chose to support vfork() in
429 		 * vfork(), we would chain our parent at this point (in
458 		 * NOTE: This has no effect in the vfork case, since
478 		 * it for nested vfork() support (see proc_vfork_end() for
505 		 * Preserve synchronization semantics of vfork.  If
561 		 * NOTE: This has no effect in the vfork case, since
680  * Description:	"Return" to parent vfork thread() following execve/_exit;
684  *		Refer to the ASCII art above vfork() to figure out the
706 	/* clear vfork state in parent proc structure */
749  *		graph, if implementing an execve() following a vfork(), from
751  *		vfork() equivalent call, and in the system bootstrap case.
1328 	 *	routine is called in the non-duplication case of vfork()
1352 		 * vfork() or posix_spawn() cases.