/*
* Implement fork's actions on an address space.
* Here we arrange for the address space to be copied or referenced,
* allocate a user struct (pcb and kernel stack), then call the
* machine-dependent layer to fill those in and make the new process
* ready to run. The new process is set up so that it returns directly
* to user mode to avoid stack copying and relocation problems.
*
* No requirements.
*/
void
vm_fork(struct proc *p1, struct proc *p2, int flags)
{
if ((flags & RFPROC) == 0) {
/*
* Divorce the memory, if it is shared, essentially
* this changes shared memory amongst threads, into
* COW locally.
*/
if ((flags & RFMEM) == 0) {
if (p1->p_vmspace->vm_sysref.refcnt > 1) {
vmspace_unshare(p1);
}
}
cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags);
return;
}
if (flags & RFMEM) {
vmspace_ref(p1->p_vmspace);
p2->p_vmspace = p1->p_vmspace;
}
while (vm_page_count_severe()) {
vm_wait(0);
}
if ((flags & RFMEM) == 0) {
p2->p_vmspace = vmspace_fork(p1->p_vmspace);
pmap_pinit2(vmspace_pmap(p2->p_vmspace));
if (p1->p_vmspace->vm_shm)
shmfork(p1, p2);
}
pmap_init_proc(p2);
}
/*
* forkproc
*
* Description: Create a new process structure, given a parent process
* structure.
*
* Parameters: parent_proc The parent process
*
* Returns: !NULL The new process structure
* NULL Error (insufficient free memory)
*
* Note: When successful, the newly created process structure is
* partially initialized; if a caller needs to deconstruct the
* returned structure, they must call forkproc_free() to do so.
*/
proc_t
forkproc(proc_t parent_proc)
{
proc_t child_proc; /* Our new process */
static int nextpid = 0, pidwrap = 0, nextpidversion = 0;
int error = 0;
struct session *sessp;
uthread_t parent_uthread = (uthread_t)get_bsdthread_info(current_thread());
MALLOC_ZONE(child_proc, proc_t , sizeof *child_proc, M_PROC, M_WAITOK);
if (child_proc == NULL) {
printf("forkproc: M_PROC zone exhausted\n");
goto bad;
}
/* zero it out as we need to insert in hash */
bzero(child_proc, sizeof *child_proc);
MALLOC_ZONE(child_proc->p_stats, struct pstats *,
sizeof *child_proc->p_stats, M_PSTATS, M_WAITOK);
if (child_proc->p_stats == NULL) {
printf("forkproc: M_SUBPROC zone exhausted (p_stats)\n");
FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
child_proc = NULL;
goto bad;
}
MALLOC_ZONE(child_proc->p_sigacts, struct sigacts *,
sizeof *child_proc->p_sigacts, M_SIGACTS, M_WAITOK);
if (child_proc->p_sigacts == NULL) {
printf("forkproc: M_SUBPROC zone exhausted (p_sigacts)\n");
FREE_ZONE(child_proc->p_stats, sizeof *child_proc->p_stats, M_PSTATS);
FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
child_proc = NULL;
goto bad;
}
/* allocate a callout for use by interval timers */
child_proc->p_rcall = thread_call_allocate((thread_call_func_t)realitexpire, child_proc);
if (child_proc->p_rcall == NULL) {
FREE_ZONE(child_proc->p_sigacts, sizeof *child_proc->p_sigacts, M_SIGACTS);
FREE_ZONE(child_proc->p_stats, sizeof *child_proc->p_stats, M_PSTATS);
FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
child_proc = NULL;
goto bad;
}
/*
* Find an unused PID.
*/
proc_list_lock();
nextpid++;
retry:
/*
* If the process ID prototype has wrapped around,
* restart somewhat above 0, as the low-numbered procs
* tend to include daemons that don't exit.
*/
if (nextpid >= PID_MAX) {
nextpid = 100;
pidwrap = 1;
}
if (pidwrap != 0) {
/* if the pid stays in hash both for zombie and runniing state */
if (pfind_locked(nextpid) != PROC_NULL) {
nextpid++;
goto retry;
}
if (pgfind_internal(nextpid) != PGRP_NULL) {
nextpid++;
goto retry;
}
if (session_find_internal(nextpid) != SESSION_NULL) {
nextpid++;
goto retry;
}
}
nprocs++;
child_proc->p_pid = nextpid;
child_proc->p_idversion = nextpidversion++;
#if 1
if (child_proc->p_pid != 0) {
if (pfind_locked(child_proc->p_pid) != PROC_NULL)
panic("proc in the list already\n");
}
#endif
/* Insert in the hash */
child_proc->p_listflag |= (P_LIST_INHASH | P_LIST_INCREATE);
LIST_INSERT_HEAD(PIDHASH(child_proc->p_pid), child_proc, p_hash);
proc_list_unlock();
/*
* We've identified the PID we are going to use; initialize the new
* process structure.
*/
child_proc->p_stat = SIDL;
child_proc->p_pgrpid = PGRPID_DEAD;
/*
* The zero'ing of the proc was at the allocation time due to need
* for insertion to hash. Copy the section that is to be copied
* directly from the parent.
*/
bcopy(&parent_proc->p_startcopy, &child_proc->p_startcopy,
(unsigned) ((caddr_t)&child_proc->p_endcopy - (caddr_t)&child_proc->p_startcopy));
/*
* Some flags are inherited from the parent.
* Duplicate sub-structures as needed.
* Increase reference counts on shared objects.
* The p_stats and p_sigacts substructs are set in vm_fork.
*/
child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_AFFINITY));
if (parent_proc->p_flag & P_PROFIL)
startprofclock(child_proc);
/*
* Note that if the current thread has an assumed identity, this
* credential will be granted to the new process.
*/
child_proc->p_ucred = kauth_cred_get_with_ref();
#ifdef CONFIG_EMBEDDED
lck_mtx_init(&child_proc->p_mlock, proc_lck_grp, proc_lck_attr);
lck_mtx_init(&child_proc->p_fdmlock, proc_lck_grp, proc_lck_attr);
#if CONFIG_DTRACE
lck_mtx_init(&child_proc->p_dtrace_sprlock, proc_lck_grp, proc_lck_attr);
#endif
lck_spin_init(&child_proc->p_slock, proc_lck_grp, proc_lck_attr);
#else /* !CONFIG_EMBEDDED */
lck_mtx_init(&child_proc->p_mlock, proc_mlock_grp, proc_lck_attr);
lck_mtx_init(&child_proc->p_fdmlock, proc_fdmlock_grp, proc_lck_attr);
#if CONFIG_DTRACE
lck_mtx_init(&child_proc->p_dtrace_sprlock, proc_lck_grp, proc_lck_attr);
#endif
lck_spin_init(&child_proc->p_slock, proc_slock_grp, proc_lck_attr);
#endif /* !CONFIG_EMBEDDED */
klist_init(&child_proc->p_klist);
if (child_proc->p_textvp != NULLVP) {
/* bump references to the text vnode */
/* Need to hold iocount across the ref call */
if (vnode_getwithref(child_proc->p_textvp) == 0) {
error = vnode_ref(child_proc->p_textvp);
vnode_put(child_proc->p_textvp);
if (error != 0)
child_proc->p_textvp = NULLVP;
}
}
/*
* Copy the parents per process open file table to the child; if
* there is a per-thread current working directory, set the childs
* per-process current working directory to that instead of the
* parents.
*
* XXX may fail to copy descriptors to child
*/
child_proc->p_fd = fdcopy(parent_proc, parent_uthread->uu_cdir);
#if SYSV_SHM
if (parent_proc->vm_shm) {
/* XXX may fail to attach shm to child */
(void)shmfork(parent_proc, child_proc);
}
#endif
/*
* inherit the limit structure to child
*/
proc_limitfork(parent_proc, child_proc);
if (child_proc->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
uint64_t rlim_cur = child_proc->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur;
child_proc->p_rlim_cpu.tv_sec = (rlim_cur > __INT_MAX__) ? __INT_MAX__ : rlim_cur;
}
/* Intialize new process stats, including start time */
/* <rdar://6640543> non-zeroed portion contains garbage AFAICT */
bzero(&child_proc->p_stats->pstat_startzero,
(unsigned) ((caddr_t)&child_proc->p_stats->pstat_endzero -
(caddr_t)&child_proc->p_stats->pstat_startzero));
bzero(&child_proc->p_stats->user_p_prof, sizeof(struct user_uprof));
microtime(&child_proc->p_start);
child_proc->p_stats->p_start = child_proc->p_start; /* for compat */
if (parent_proc->p_sigacts != NULL)
(void)memcpy(child_proc->p_sigacts,
parent_proc->p_sigacts, sizeof *child_proc->p_sigacts);
else
(void)memset(child_proc->p_sigacts, 0, sizeof *child_proc->p_sigacts);
sessp = proc_session(parent_proc);
if (sessp->s_ttyvp != NULL && parent_proc->p_flag & P_CONTROLT)
OSBitOrAtomic(P_CONTROLT, &child_proc->p_flag);
session_rele(sessp);
/*
* block all signals to reach the process.
* no transition race should be occuring with the child yet,
* but indicate that the process is in (the creation) transition.
*/
proc_signalstart(child_proc, 0);
proc_transstart(child_proc, 0);
child_proc->p_pcaction = (parent_proc->p_pcaction) & P_PCMAX;
TAILQ_INIT(&child_proc->p_uthlist);
TAILQ_INIT(&child_proc->p_aio_activeq);
TAILQ_INIT(&child_proc->p_aio_doneq);
/* Inherit the parent flags for code sign */
child_proc->p_csflags = parent_proc->p_csflags;
/*
* All processes have work queue locks; cleaned up by
* reap_child_locked()
*/
workqueue_init_lock(child_proc);
/*
* Copy work queue information
*
* Note: This should probably only happen in the case where we are
* creating a child that is a copy of the parent; since this
* routine is called in the non-duplication case of vfork()
* or posix_spawn(), then this information should likely not
* be duplicated.
*
* <rdar://6640553> Work queue pointers that no longer point to code
*/
child_proc->p_wqthread = parent_proc->p_wqthread;
child_proc->p_threadstart = parent_proc->p_threadstart;
child_proc->p_pthsize = parent_proc->p_pthsize;
child_proc->p_targconc = parent_proc->p_targconc;
if ((parent_proc->p_lflag & P_LREGISTER) != 0) {
child_proc->p_lflag |= P_LREGISTER;
}
child_proc->p_dispatchqueue_offset = parent_proc->p_dispatchqueue_offset;
#if PSYNCH
pth_proc_hashinit(child_proc);
#endif /* PSYNCH */
#if CONFIG_LCTX
child_proc->p_lctx = NULL;
/* Add new process to login context (if any). */
if (parent_proc->p_lctx != NULL) {
/*
* <rdar://6640564> This should probably be delayed in the
* vfork() or posix_spawn() cases.
*/
LCTX_LOCK(parent_proc->p_lctx);
enterlctx(child_proc, parent_proc->p_lctx, 0);
}
#endif
bad:
return(child_proc);
}