]> git.saurik.com Git - apple/xnu.git/blobdiff - bsd/kern/kern_proc.c
xnu-2422.90.20.tar.gz
[apple/xnu.git] / bsd / kern / kern_proc.c
index 3a44414347f5d9a58020ad21e7e49e7b7901a5a5..5125e49b68e0657345a78a1f7fc5b54d5eb3586a 100644 (file)
@@ -83,7 +83,6 @@
 #include <sys/acct.h>
 #include <sys/wait.h>
 #include <sys/file_internal.h>
-#include <ufs/ufs/quota.h>
 #include <sys/uio.h>
 #include <sys/malloc.h>
 #include <sys/lock.h>
 #include <sys/kauth.h>
 #include <sys/codesign.h>
 #include <sys/kernel_types.h>
+#include <sys/ubc.h>
 #include <kern/kalloc.h>
 #include <kern/task.h>
 #include <kern/assert.h>
 #include <vm/vm_protos.h>
+#include <vm/vm_map.h>         /* vm_map_switch_protect() */
+#include <mach/task.h>
+#include <mach/message.h>
+
+#if CONFIG_MEMORYSTATUS
+#include <sys/kern_memorystatus.h>
+#endif
 
 #if CONFIG_MACF
 #include <security/mac_framework.h>
@@ -155,22 +162,25 @@ lck_attr_t * lctx_lck_attr;
 static void    lctxinit(void);
 #endif
 
+extern int cs_debug;
+
+#if DEBUG
 #define __PROC_INTERNAL_DEBUG 1
+#endif
 /* Name to give to core files */
-__private_extern__ char corefilename[MAXPATHLEN+1] = {"/cores/core.%P"};
+__XNU_PRIVATE_EXTERN char corefilename[MAXPATHLEN+1] = {"/cores/core.%P"};
 
 static void orphanpg(struct pgrp *pg);
 void   proc_name_kdp(task_t t, char * buf, int size);
 char   *proc_name_address(void *p);
 
-static proc_t proc_refinternal_locked(proc_t p);
 static void  pgrp_add(struct pgrp * pgrp, proc_t parent, proc_t child);
 static void pgrp_remove(proc_t p);
 static void pgrp_replace(proc_t p, struct pgrp *pgrp);
 static void pgdelete_dropref(struct pgrp *pgrp);
-static proc_t proc_find_zombref(int pid);
-static void proc_drop_zombref(proc_t p);
 extern void pg_rele_dropref(struct pgrp * pgrp);
+static int csops_internal(pid_t pid, int ops, user_addr_t uaddr, user_size_t usersize, user_addr_t uaddittoken);
+static boolean_t proc_parent_is_currentproc(proc_t p);
 
 struct fixjob_iterargs {
        struct pgrp * pg;
@@ -284,16 +294,22 @@ out:
 int
 isinferior(proc_t p, proc_t t)
 {
-int retval = 0;
+       int retval = 0;
+       int nchecked = 0;
+       proc_t start = p;
 
        /* if p==t they are not inferior */
        if (p == t)
                return(0);
 
        proc_list_lock();
-       for (; p != t; p = p->p_pptr)
-               if (p->p_pid == 0)
+       for (; p != t; p = p->p_pptr) {
+               nchecked++;
+
+               /* Detect here if we're in a cycle */
+               if ((p->p_pid == 0) || (p->p_pptr == start) || (nchecked >= nprocs))
                        goto out;
+       }
        retval = 1;
 out:
        proc_list_unlock();
@@ -334,7 +350,7 @@ proc_findinternal(int pid, int locked)
        }
 
        p = pfind_locked(pid);
-       if ((p == PROC_NULL) || (p != proc_refinternal_locked(p)))
+       if ((p == PROC_NULL) || (p != proc_ref_locked(p)))
                p = PROC_NULL;
 
        if (locked == 0) {
@@ -344,6 +360,23 @@ proc_findinternal(int pid, int locked)
        return(p);
 }
 
+proc_t
+proc_findthread(thread_t thread)
+{
+       proc_t p = PROC_NULL;
+       struct uthread *uth;
+
+       proc_list_lock();
+       uth = get_bsdthread_info(thread);
+       if (uth && (uth->uu_flag & UT_VFORK))
+               p = uth->uu_proc;
+       else
+               p = (proc_t)(get_bsdthreadtask_info(thread));
+       p = proc_ref_locked(p);
+       proc_list_unlock();
+       return(p);
+}
+
 int 
 proc_rele(proc_t p)
 {
@@ -362,15 +395,15 @@ proc_self(void)
        p = current_proc();
 
        proc_list_lock();
-       if (p != proc_refinternal_locked(p))
+       if (p != proc_ref_locked(p))
                p = PROC_NULL;
        proc_list_unlock();
        return(p);
 }
 
 
-static proc_t
-proc_refinternal_locked(proc_t p)
+proc_t
+proc_ref_locked(proc_t p)
 {
        proc_t p1 = p;
        
@@ -401,35 +434,38 @@ proc_rele_locked(proc_t p)
 
 }
 
-static proc_t
+proc_t
 proc_find_zombref(int pid)
 {
-       proc_t p1 = PROC_NULL;
-       proc_t p = PROC_NULL;
+       proc_t p;
 
        proc_list_lock();
 
+ again:
        p = pfind_locked(pid);
 
-       /* if process still in creation return NULL */
-       if ((p == PROC_NULL) || ((p->p_listflag & P_LIST_INCREATE) != 0)) {
+       /* should we bail? */
+       if ((p == PROC_NULL)                                    /* not found */
+           || ((p->p_listflag & P_LIST_INCREATE) != 0)         /* not created yet */
+           || ((p->p_listflag & P_LIST_EXITED) == 0)) {        /* not started exit */
+
                proc_list_unlock();
-               return (p1);
+               return (PROC_NULL);
        }
 
-       /* if process has not started exit or  is being reaped, return NULL */
-       if (((p->p_listflag & P_LIST_EXITED) != 0) && ((p->p_listflag & P_LIST_WAITING) == 0)) {
-               p->p_listflag |=  P_LIST_WAITING;
-               p1 = p;
-       } else 
-               p1 = PROC_NULL;
+       /* If someone else is controlling the (unreaped) zombie - wait */
+       if ((p->p_listflag & P_LIST_WAITING) != 0) {
+               (void)msleep(&p->p_stat, proc_list_mlock, PWAIT, "waitcoll", 0);
+               goto again;
+       }
+       p->p_listflag |=  P_LIST_WAITING;
 
        proc_list_unlock();
 
-       return(p1);
+       return(p);
 }
 
-static void
+void
 proc_drop_zombref(proc_t p)
 {
        proc_list_lock();
@@ -548,46 +584,82 @@ proc_childdrainend(proc_t p)
 }
 
 void
-proc_checkdeadrefs(proc_t p)
+proc_checkdeadrefs(__unused proc_t p)
 {
-//#if __PROC_INTERNAL_DEBUG
+#if __PROC_INTERNAL_DEBUG
        if ((p->p_listflag  & P_LIST_INHASH) != 0)
-               panic("proc being freed and still in hash %x: %x\n", (unsigned int)p, (unsigned int)p->p_listflag);
+               panic("proc being freed and still in hash %p: %u\n", p, p->p_listflag);
        if (p->p_childrencnt != 0)
-               panic("proc being freed and pending children cnt %x:%x\n", (unsigned int)p, (unsigned int)p->p_childrencnt);
+               panic("proc being freed and pending children cnt %p:%d\n", p, p->p_childrencnt);
        if (p->p_refcount != 0)
-               panic("proc being freed and pending refcount %x:%x\n", (unsigned int)p, (unsigned int)p->p_refcount);
+               panic("proc being freed and pending refcount %p:%d\n", p, p->p_refcount);
        if (p->p_parentref != 0)
-               panic("proc being freed and pending parentrefs %x:%x\n", (unsigned int)p, (unsigned int)p->p_parentref);
-//#endif
+               panic("proc being freed and pending parentrefs %p:%d\n", p, p->p_parentref);
+#endif
 }
 
 int
 proc_pid(proc_t p)
 {
-       return(p->p_pid);
+       return (p->p_pid);
 }
 
 int 
 proc_ppid(proc_t p)
 {
-               return(p->p_ppid);
+       return (p->p_ppid);
 }
 
-int 
+int
 proc_selfpid(void)
 {
-       proc_t p = current_proc();
-       return(p->p_pid);
+       return (current_proc()->p_pid);
 }
 
-int 
+int
 proc_selfppid(void)
 {
-       proc_t p = current_proc();
-       return(p->p_ppid);
+       return (current_proc()->p_ppid);
+}
+
+#if CONFIG_DTRACE
+static proc_t
+dtrace_current_proc_vforking(void)
+{
+       thread_t th = current_thread();
+       struct uthread *ut = get_bsdthread_info(th);
+
+       if (ut &&
+           ((ut->uu_flag & (UT_VFORK|UT_VFORKING)) == (UT_VFORK|UT_VFORKING))) {
+               /*
+                * Handle the narrow window where we're in the vfork syscall,
+                * but we're not quite ready to claim (in particular, to DTrace)
+                * that we're running as the child.
+                */
+               return (get_bsdtask_info(get_threadtask(th)));
+       }
+       return (current_proc());
+}
+
+int
+dtrace_proc_selfpid(void)
+{
+       return (dtrace_current_proc_vforking()->p_pid);
 }
 
+int 
+dtrace_proc_selfppid(void)
+{
+       return (dtrace_current_proc_vforking()->p_ppid);
+}
+
+uid_t
+dtrace_proc_selfruid(void)
+{
+       return (dtrace_current_proc_vforking()->p_ruid);
+}
+#endif /* CONFIG_DTRACE */
+
 proc_t 
 proc_parent(proc_t p)
 {
@@ -597,7 +669,7 @@ proc_parent(proc_t p)
        proc_list_lock();
 loop:
        pp = p->p_pptr;
-       parent =  proc_refinternal_locked(pp);
+       parent =  proc_ref_locked(pp);
        if ((parent == PROC_NULL) && (pp != PROC_NULL) && (pp->p_stat != SZOMB) && ((pp->p_listflag & P_LIST_EXITED) != 0) && ((pp->p_listflag & P_LIST_CHILDDRAINED)== 0)){
                pp->p_listflag |= P_LIST_CHILDLKWAIT;
                msleep(&pp->p_childrencnt, proc_list_mlock, 0, "proc_parent", 0);
@@ -607,6 +679,18 @@ loop:
        return(parent);
 }
 
+static boolean_t
+proc_parent_is_currentproc(proc_t p)
+{
+       boolean_t ret = FALSE;
+       
+       proc_list_lock();
+       if (p->p_pptr == current_proc())
+               ret = TRUE;
+
+       proc_list_unlock();
+       return ret;
+}
 
 void
 proc_name(int pid, char * buf, int size)
@@ -724,6 +808,12 @@ proc_suser(proc_t p)
        return(error);
 }
 
+task_t
+proc_task(proc_t proc)
+{
+       return (task_t)proc->task;
+}
+
 /*      
  * Obtain the first thread in a process
  *
@@ -749,24 +839,77 @@ proc_ucred(proc_t p)
        return(p->p_ucred);
 }
 
+struct uthread *
+current_uthread()
+{
+       thread_t th = current_thread();
+
+       return((struct uthread *)get_bsdthread_info(th));
+}
+
+
 int
 proc_is64bit(proc_t p)
 {
        return(IS_64BIT_PROCESS(p));
 }
 
+int
+proc_pidversion(proc_t p)
+{
+       return(p->p_idversion);
+}
+
+uint64_t
+proc_uniqueid(proc_t p)
+{
+       return(p->p_uniqueid);
+}
+
+uint64_t
+proc_puniqueid(proc_t p)
+{
+       return(p->p_puniqueid);
+}
+
+uint64_t
+proc_was_throttled(proc_t p)
+{
+       return (p->was_throttled);
+}
+
+uint64_t
+proc_did_throttle(proc_t p)
+{
+       return (p->did_throttle);
+}
+
+int
+proc_getcdhash(proc_t p, unsigned char *cdhash)
+{
+       return vn_getcdhash(p->p_textvp, p->p_textoff, cdhash);
+}
+
+void
+proc_getexecutableuuid(proc_t p, unsigned char *uuidbuf, unsigned long size)
+{
+       if (size >= sizeof(p->p_uuid)) {
+               memcpy(uuidbuf, p->p_uuid, sizeof(p->p_uuid));
+       }
+}
+
+
 void
 bsd_set_dependency_capable(task_t task)
 {
     proc_t p = get_bsdtask_info(task);
 
     if (p) {
-       OSBitOrAtomic(P_DEPENDENCY_CAPABLE, (UInt32 *)&p->p_flag);
+       OSBitOrAtomic(P_DEPENDENCY_CAPABLE, &p->p_flag);
     }
 }
 
 
-/* LP64todo - figure out how to identify 64-bit processes if NULL procp */
 int
 IS_64BIT_PROCESS(proc_t p)
 {
@@ -783,7 +926,7 @@ proc_t
 pfind_locked(pid_t pid)
 {
        proc_t p;
-#ifdef DEBUG
+#if DEBUG
        proc_t q;
 #endif
 
@@ -792,10 +935,10 @@ pfind_locked(pid_t pid)
 
        for (p = PIDHASH(pid)->lh_first; p != 0; p = p->p_hash.le_next) {
                if (p->p_pid == pid) {
-#ifdef DEBUG
+#if DEBUG
                        for (q = p->p_hash.le_next; q != 0; q = q->p_hash.le_next) {
                                if ((p !=q) && (q->p_pid == pid))       
-                                       panic("two procs with same pid %x:%x:%d:%d\n", (unsigned int)p, (unsigned int)q, p->p_pid, q->p_pid);
+                                       panic("two procs with same pid %p:%p:%d:%d\n", p, q, p->p_pid, q->p_pid);
                        }
 #endif
                        return (p);
@@ -915,12 +1058,18 @@ pinsertchild(proc_t parent, proc_t child)
        TAILQ_INIT(&child->p_evlist);
        child->p_pptr = parent;
        child->p_ppid = parent->p_pid;
+       child->p_puniqueid = parent->p_uniqueid;
 
        pg = proc_pgrp(parent);
        pgrp_add(pg, parent, child);
        pg_rele(pg);
 
        proc_list_lock();
+       
+#if CONFIG_MEMORYSTATUS
+       memorystatus_add(child, TRUE);
+#endif
+       
        parent->p_childrencnt++;
        LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
 
@@ -929,7 +1078,6 @@ pinsertchild(proc_t parent, proc_t child)
        child->p_listflag &= ~P_LIST_INCREATE;
 
        proc_list_unlock();
-
 }
 
 /*
@@ -994,14 +1142,18 @@ enterpgrp(proc_t p, pid_t pgid, int mksess)
                        sess->s_sid = p->p_pid;
                        sess->s_count = 1;
                        sess->s_ttyvp = NULL;
-                       sess->s_ttyp = NULL;
+                       sess->s_ttyp = TTY_NULL;
                        sess->s_flags = 0;
                        sess->s_listflags = 0;
                        sess->s_ttypgrpid = NO_PID;
+#if CONFIG_FINE_LOCK_GROUPS
+                       lck_mtx_init(&sess->s_mlock, proc_mlock_grp, proc_lck_attr);
+#else
                        lck_mtx_init(&sess->s_mlock, proc_lck_grp, proc_lck_attr);
+#endif
                        bcopy(procsp->s_login, sess->s_login,
                            sizeof(sess->s_login));
-                       OSBitAndAtomic(~((uint32_t)P_CONTROLT), (UInt32 *)&p->p_flag);
+                       OSBitAndAtomic(~((uint32_t)P_CONTROLT), &p->p_flag);
                        proc_list_lock();
                        LIST_INSERT_HEAD(SESSHASH(sess->s_sid), sess, s_hash);
                        proc_list_unlock();
@@ -1020,7 +1172,11 @@ enterpgrp(proc_t p, pid_t pgid, int mksess)
                        proc_list_unlock();
                }
                pgrp->pg_id = pgid;
+#if CONFIG_FINE_LOCK_GROUPS
+               lck_mtx_init(&pgrp->pg_mlock, proc_mlock_grp, proc_lck_attr);
+#else
                lck_mtx_init(&pgrp->pg_mlock, proc_lck_grp, proc_lck_attr);
+#endif
                LIST_INIT(&pgrp->pg_members);
                pgrp->pg_membercnt = 0;
                pgrp->pg_jobc = 0;
@@ -1073,8 +1229,7 @@ leavepgrp(proc_t p)
 static void
 pgdelete_dropref(struct pgrp *pgrp)
 {
-       struct tty * ttyp;
-       boolean_t fstate;
+       struct tty *ttyp;
        int emptypgrp  = 1;
        struct session *sessp;
 
@@ -1104,14 +1259,18 @@ pgdelete_dropref(struct pgrp *pgrp)
 
        proc_list_unlock();
        
-       fstate = thread_funnel_set(kernel_flock, TRUE);
-       
-       ttyp = pgrp->pg_session->s_ttyp;
-       if ((ttyp != NULL) && (pgrp->pg_session->s_ttyp->t_pgrp == pgrp)) {
-               pgrp->pg_session->s_ttyp->t_pgrp = NULL;
-               pgrp->pg_session->s_ttypgrpid = NO_PID;
+       ttyp = SESSION_TP(pgrp->pg_session);
+       if (ttyp != TTY_NULL) {
+               if (ttyp->t_pgrp == pgrp) {
+                       tty_lock(ttyp);
+                       /* Re-check after acquiring the lock */
+                       if (ttyp->t_pgrp == pgrp) {
+                               ttyp->t_pgrp = NULL;
+                               pgrp->pg_session->s_ttypgrpid = NO_PID;
+                       }
+                       tty_unlock(ttyp);
+               }
        }
-       (void) thread_funnel_set(kernel_flock, fstate);
 
        proc_list_lock();
 
@@ -1122,23 +1281,33 @@ pgdelete_dropref(struct pgrp *pgrp)
                if ((sessp->s_listflags & (S_LIST_TERM | S_LIST_DEAD)) != 0)
                        panic("pg_deleteref: terminating already terminated session");
                sessp->s_listflags |= S_LIST_TERM;
-               ttyp = sessp->s_ttyp;
+               ttyp = SESSION_TP(sessp);
                LIST_REMOVE(sessp, s_hash);
                proc_list_unlock();
-               fstate = thread_funnel_set(kernel_flock, TRUE);
-               if (ttyp != NULL && ttyp->t_session == sessp)
-                       ttyp->t_session = NULL;
-               (void) thread_funnel_set(kernel_flock, fstate);
+               if (ttyp != TTY_NULL) {
+                       tty_lock(ttyp);
+                       if (ttyp->t_session == sessp)
+                               ttyp->t_session = NULL;
+                       tty_unlock(ttyp);
+               }
                proc_list_lock();
                sessp->s_listflags |= S_LIST_DEAD;
                if (sessp->s_count != 0)
                        panic("pg_deleteref: freeing session in use");  
                proc_list_unlock();
+#if CONFIG_FINE_LOCK_GROUPS
+               lck_mtx_destroy(&sessp->s_mlock, proc_mlock_grp);
+#else
                lck_mtx_destroy(&sessp->s_mlock, proc_lck_grp);
+#endif
                FREE_ZONE(sessp, sizeof(struct session), M_SESSION);
        } else
                proc_list_unlock();
+#if CONFIG_FINE_LOCK_GROUPS
+       lck_mtx_destroy(&pgrp->pg_mlock, proc_mlock_grp);
+#else
        lck_mtx_destroy(&pgrp->pg_mlock, proc_lck_grp);
+#endif
        FREE_ZONE(pgrp, sizeof(*pgrp), M_PGRP);
 }
 
@@ -1197,12 +1366,24 @@ fixjobc(proc_t p, struct pgrp *pgrp, int entering)
        struct session *mysession = pgrp->pg_session;
        proc_t parent;
        struct fixjob_iterargs fjarg;
+       boolean_t proc_parent_self;
+
+       /*
+        * Check if p's parent is current proc, if yes then no need to take 
+        * a ref; calling proc_parent with current proc as parent may 
+        * deadlock if current proc is exiting.
+        */
+       proc_parent_self = proc_parent_is_currentproc(p);
+       if (proc_parent_self)
+               parent = current_proc();
+       else 
+               parent = proc_parent(p);
 
-       parent = proc_parent(p);
        if (parent != PROC_NULL) {
                hispgrp = proc_pgrp(parent);    
                hissess = proc_session(parent);
-               proc_rele(parent);
+               if (!proc_parent_self)
+                       proc_rele(parent);
        }
 
 
@@ -1327,6 +1508,12 @@ current_proc_EXTERNAL(void)
        return (current_proc());
 }
 
+int
+proc_is_forcing_hfs_case_sensitivity(proc_t p)
+{
+       return (p->p_vfs_iopolicy & P_VFS_IOPOLICY_FORCE_HFS_CASE_SENSITIVITY) ? 1 : 0;
+}
+
 /*
  * proc_core_name(name, uid, pid)
  * Expand the name described in corefilename, using name, uid, and pid.
@@ -1389,8 +1576,8 @@ proc_core_name(const char *name, uid_t uid, pid_t pid, char *cf_name,
                goto toolong;
        return (0);
 toolong:
-       log(LOG_ERR, "pid %ld (%s), uid (%lu): corename is too long\n",
-           (long)pid, name, (u_long)uid);
+       log(LOG_ERR, "pid %ld (%s), uid (%u): corename is too long\n",
+           (long)pid, name, (uint32_t)uid);
        return (1);
 }
 
@@ -1598,34 +1785,73 @@ out:
 
 SYSCTL_NODE(_kern, KERN_LCTX, lctx, CTLFLAG_RW|CTLFLAG_LOCKED, 0, "Login Context");
 
-SYSCTL_PROC(_kern_lctx, KERN_LCTX_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT,
+SYSCTL_PROC(_kern_lctx, KERN_LCTX_ALL, all, CTLFLAG_RD|CTLTYPE_STRUCT | CTLFLAG_LOCKED,
            0, 0, sysctl_kern_lctx, "S,lctx",
            "Return entire login context table");
-SYSCTL_NODE(_kern_lctx, KERN_LCTX_LCID, lcid, CTLFLAG_RD,
+SYSCTL_NODE(_kern_lctx, KERN_LCTX_LCID, lcid, CTLFLAG_RD | CTLFLAG_LOCKED,
            sysctl_kern_lctx, "Login Context Table");
-SYSCTL_INT(_kern_lctx, OID_AUTO, last,  CTLFLAG_RD, &lastlcid, 0, ""); 
-SYSCTL_INT(_kern_lctx, OID_AUTO, count, CTLFLAG_RD, &alllctx_cnt, 0, "");
-SYSCTL_INT(_kern_lctx, OID_AUTO, max, CTLFLAG_RW, &maxlcid, 0, "");
+SYSCTL_INT(_kern_lctx, OID_AUTO, last,  CTLFLAG_RD | CTLFLAG_LOCKED, &lastlcid, 0, ""); 
+SYSCTL_INT(_kern_lctx, OID_AUTO, count, CTLFLAG_RD | CTLFLAG_LOCKED, &alllctx_cnt, 0, "");
+SYSCTL_INT(_kern_lctx, OID_AUTO, max, CTLFLAG_RW | CTLFLAG_LOCKED, &maxlcid, 0, "");
 
 #endif /* LCTX */
 
 /* Code Signing related routines */
 
 int 
-csops(__unused proc_t p, struct csops_args *uap, __unused register_t *retval)
+csops(__unused proc_t p, struct csops_args *uap, __unused int32_t *retval)
 {
-       int ops = uap->ops;
-       pid_t pid = uap->pid;
-       user_addr_t uaddr = uap->useraddr;
-       size_t usize = (size_t)CAST_DOWN(size_t, uap->usersize);
+       return(csops_internal(uap->pid, uap->ops, uap->useraddr, 
+               uap->usersize, USER_ADDR_NULL));
+}
+
+int 
+csops_audittoken(__unused proc_t p, struct csops_audittoken_args *uap, __unused int32_t *retval)
+{
+       if (uap->uaudittoken == USER_ADDR_NULL)
+               return(EINVAL);
+       return(csops_internal(uap->pid, uap->ops, uap->useraddr, 
+               uap->usersize, uap->uaudittoken));
+}
+
+static int
+csops_copy_token(void *start, size_t length, user_size_t usize, user_addr_t uaddr)
+{
+       char fakeheader[8] = { 0 };
+       int error;
+
+       if (usize < sizeof(fakeheader))
+               return ERANGE;
+
+       /* if no blob, fill in zero header */
+       if (NULL == start) {
+               start = fakeheader;
+               length = sizeof(fakeheader);
+       } else if (usize < length) {
+               /* ... if input too short, copy out length of entitlement */
+               uint32_t length32 = htonl((uint32_t)length);
+               memcpy(&fakeheader[4], &length32, sizeof(length32));
+               
+               error = copyout(fakeheader, uaddr, sizeof(fakeheader));
+               if (error == 0)
+                       return ERANGE; /* input buffer to short, ERANGE signals that */
+               return error;
+       }
+       return copyout(start, uaddr, length);
+}
+
+static int
+csops_internal(pid_t pid, int ops, user_addr_t uaddr, user_size_t usersize, user_addr_t uaudittoken)
+{
+       size_t usize = (size_t)CAST_DOWN(size_t, usersize);
        proc_t pt;
-       uint32_t retflags;
-       int vid, forself;
+       int forself;
        int error;
        vnode_t tvp;
        off_t toff;
-       char * buf;
        unsigned char cdhash[SHA1_RESULTLEN];
+       audit_token_t token;
+       unsigned int upid=0, uidversion = 0;
        
        forself = error = 0;
 
@@ -1635,37 +1861,64 @@ csops(__unused proc_t p, struct csops_args *uap, __unused register_t *retval)
                forself = 1;
 
 
-       /* Pre flight checks for CS_OPS_PIDPATH */
-       if (ops == CS_OPS_PIDPATH) {
-               /* usize is unsigned.. */
-               if (usize > 4 * PATH_MAX)
-                       return(EOVERFLOW);
-               if (kauth_cred_issuser(kauth_cred_get()) != TRUE) 
-                       return(EPERM);
-       } else if ((forself == 0) && ((ops != CS_OPS_STATUS) && (ops != CS_OPS_CDHASH) && (kauth_cred_issuser(kauth_cred_get()) != TRUE))) {
-               return(EPERM);
+       switch (ops) {
+               case CS_OPS_STATUS:
+               case CS_OPS_CDHASH:
+               case CS_OPS_PIDOFFSET:
+               case CS_OPS_ENTITLEMENTS_BLOB:
+               case CS_OPS_BLOB:
+                       break;  /* unrestricted */
+               default:
+                       if (forself == 0 && kauth_cred_issuser(kauth_cred_get()) != TRUE)
+                               return(EPERM);
+                       break;
        }
 
        pt = proc_find(pid);
        if (pt == PROC_NULL)
                return(ESRCH);
 
-
+       upid = pt->p_pid;
+       uidversion = pt->p_idversion;
+       if (uaudittoken != USER_ADDR_NULL) {
+               
+               error = copyin(uaudittoken, &token, sizeof(audit_token_t));
+               if (error != 0)
+                       goto out;
+               /* verify the audit token pid/idversion matches with proc */
+               if ((token.val[5] != upid) || (token.val[7] != uidversion)) {
+                       error = ESRCH;
+                       goto out;
+               }
+       }
 
        switch (ops) {
 
-               case CS_OPS_STATUS:
+               case CS_OPS_STATUS: {
+                       uint32_t retflags;
+
+                       proc_lock(pt);
                        retflags = pt->p_csflags;
+                       if (cs_enforcement(pt))
+                               retflags |= CS_ENFORCEMENT;
+                       proc_unlock(pt);
+
                        if (uaddr != USER_ADDR_NULL)
                                error = copyout(&retflags, uaddr, sizeof(uint32_t));
                        break;
-               
+               }
                case CS_OPS_MARKINVALID:
                        proc_lock(pt);
                        if ((pt->p_csflags & CS_VALID) == CS_VALID) {   /* is currently valid */
                                pt->p_csflags &= ~CS_VALID;     /* set invalid */
                                if ((pt->p_csflags & CS_KILL) == CS_KILL) {
+                                       pt->p_csflags |= CS_KILLED;
                                        proc_unlock(pt);
+                                       if (cs_debug) {
+                                               printf("CODE SIGNING: marked invalid by pid %d: "
+                                               "p=%d[%s] honoring CS_KILL, final status 0x%x\n",
+                                               proc_selfpid(), pt->p_pid, pt->p_comm, pt->p_csflags);
+                                       }
                                        psignal(pt, SIGKILL);
                                } else
                                        proc_unlock(pt);
@@ -1696,40 +1949,23 @@ csops(__unused proc_t p, struct csops_args *uap, __unused register_t *retval)
                                proc_unlock(pt);
                        break;
 
-               case CS_OPS_PIDPATH:
-                       tvp = pt->p_textvp;
-                       vid = vnode_vid(tvp);
-
+               case CS_OPS_PIDOFFSET:
+                       toff = pt->p_textoff;
                        proc_rele(pt);
-
-                       buf = (char *)kalloc(usize);
-                       if (buf == NULL) 
-                               return(ENOMEM);
-
-
-                       error = vnode_getwithvid(tvp, vid);
-                       if (error == 0) {
-                               int len; 
-                               len = usize;
-                               error = vn_getpath(tvp, buf, &len);
-                               vnode_put(tvp);
-                               if (error == 0) {
-                                       error = copyout(buf, uaddr, usize);
-                               }
-                               kfree(buf, usize);
-                       }
+                       error = copyout(&toff, uaddr, sizeof(toff));
                        return(error);
 
                case CS_OPS_CDHASH:
-                       if (usize != SHA1_RESULTLEN) {
-                               proc_rele(pt);
-                               return EINVAL;
-                       }
 
                        /* pt already holds a reference on its p_textvp */
                        tvp = pt->p_textvp;
                        toff = pt->p_textoff;
 
+                       if (tvp == NULLVP || usize != SHA1_RESULTLEN) {
+                               proc_rele(pt);
+                               return EINVAL;
+                       }
+
                        error = vn_getcdhash(tvp, toff, cdhash);
                        proc_rele(pt);
 
@@ -1738,7 +1974,135 @@ csops(__unused proc_t p, struct csops_args *uap, __unused register_t *retval)
                        }
 
                        return error;
-               
+
+               case CS_OPS_ENTITLEMENTS_BLOB: {
+                       void *start;
+                       size_t length;
+
+                       proc_lock(pt);
+
+                       if ((pt->p_csflags & CS_VALID) == 0) {
+                               proc_unlock(pt);
+                               error = EINVAL;
+                               break;
+                       }
+
+                       error = cs_entitlements_blob_get(pt, &start, &length);
+                       proc_unlock(pt);
+                       if (error)
+                               break;
+
+                       error = csops_copy_token(start, length, usize, uaddr);
+                       break;
+               }
+               case CS_OPS_MARKRESTRICT:
+                       proc_lock(pt);
+                       pt->p_csflags |= CS_RESTRICT;
+                       proc_unlock(pt);
+                       break;
+
+               case CS_OPS_SET_STATUS: {
+                       uint32_t flags;
+
+                       if (usize < sizeof(flags)) {
+                               error = ERANGE;
+                               break;
+                       }
+
+                       error = copyin(uaddr, &flags, sizeof(flags));
+                       if (error)
+                               break;
+
+                       /* only allow setting a subset of all code sign flags */
+                       flags &=
+                           CS_HARD | CS_EXEC_SET_HARD |
+                           CS_KILL | CS_EXEC_SET_KILL |
+                           CS_RESTRICT |
+                           CS_ENFORCEMENT | CS_EXEC_SET_ENFORCEMENT;
+
+                       proc_lock(pt);
+                       if (pt->p_csflags & CS_VALID)
+                               pt->p_csflags |= flags;
+                       else
+                               error = EINVAL;
+                       proc_unlock(pt);
+
+                       break;
+               }
+               case CS_OPS_BLOB: {
+                       void *start;
+                       size_t length;
+
+                       proc_lock(pt);
+                       if ((pt->p_csflags & CS_VALID) == 0) {
+                               proc_unlock(pt);
+                               error = EINVAL;
+                               break;
+                       }
+
+                       error = cs_blob_get(pt, &start, &length);
+                       proc_unlock(pt);
+                       if (error)
+                               break;
+
+                       error = csops_copy_token(start, length, usize, uaddr);
+                       break;
+               }
+               case CS_OPS_IDENTITY: {
+                       const char *identity;
+                       uint8_t fakeheader[8];
+                       uint32_t idlen;
+                       size_t length;
+
+                       /*
+                        * Make identity have a blob header to make it
+                        * easier on userland to guess the identity
+                        * length.
+                        */
+                       if (usize < sizeof(fakeheader)) {
+                           error = ERANGE;
+                           break;
+                       }
+                       memset(fakeheader, 0, sizeof(fakeheader));
+
+                       proc_lock(pt);
+                       if ((pt->p_csflags & CS_VALID) == 0) {
+                               proc_unlock(pt);
+                               error = EINVAL;
+                               break;
+                       }
+
+                       identity = cs_identity_get(pt);
+                       proc_unlock(pt);
+                       if (identity == NULL) {
+                               error = ENOENT;
+                               break;
+                       }
+                       
+                       length = strlen(identity) + 1; /* include NUL */
+                       idlen = htonl(length + sizeof(fakeheader));
+                       memcpy(&fakeheader[4], &idlen, sizeof(idlen));
+
+                       error = copyout(fakeheader, uaddr, sizeof(fakeheader));
+                       if (error)
+                               break;
+
+                       if (usize < sizeof(fakeheader) + length)
+                               error = ERANGE;
+                       else if (usize > sizeof(fakeheader))
+                               error = copyout(identity, uaddr + sizeof(fakeheader), length);
+
+                       break;
+               }
+
+               case CS_OPS_SIGPUP_INSTALL:
+                       error = sigpup_install(uaddr);
+                       break;
+
+               case CS_OPS_SIGPUP_DROP:
+                       error = sigpup_drop();
+                       break;
+
                default:
                        error = EINVAL;
                        break;
@@ -1748,7 +2112,6 @@ out:
        return(error);
 }
 
-
 int
 proc_iterate(flags, callout, arg, filterfn, filterarg)
        int flags;
@@ -1901,14 +2264,17 @@ proc_rebootscan(callout, arg, filterfn, filterarg)
        proc_t p;
        int lockheld = 0, retval;
 
+       proc_shutdown_exitcount = 0;
+
 ps_allprocscan:
 
        proc_list_lock();
+
        lockheld = 1;
 
        for (p = allproc.lh_first; (p != 0); p = p->p_list.le_next) {
                if ( (filterfn == 0 ) || (filterfn(p, filterarg) != 0)) {
-                       p = proc_refinternal_locked(p);
+                       p = proc_ref_locked(p);
 
                        proc_list_unlock();
                        lockheld = 0;
@@ -2169,7 +2535,7 @@ pgrp_remove(struct proc * p)
        pg->pg_membercnt--;
 
        if (pg->pg_membercnt < 0)
-               panic("pgprp: -ve membercnt pgprp:%x p:%x\n",(unsigned int)pg, (unsigned int)p);
+               panic("pgprp: -ve membercnt pgprp:%p p:%p\n",pg, p);
 
        LIST_REMOVE(p, p_pglist);
        if (pg->pg_members.lh_first == 0) {
@@ -2216,7 +2582,7 @@ pgrp_replace(struct proc * p, struct pgrp * newpg)
        pgrp_lock(oldpg);
        oldpg->pg_membercnt--;
        if (oldpg->pg_membercnt < 0)
-                panic("pgprp: -ve membercnt pgprp:%x p:%x\n",(unsigned int)oldpg, (unsigned int)p);
+                panic("pgprp: -ve membercnt pgprp:%p p:%p\n",oldpg, p);
        LIST_REMOVE(p, p_pglist);
         if (oldpg->pg_members.lh_first == 0) {
                 pgrp_unlock(oldpg);
@@ -2306,11 +2672,12 @@ proc_pgrp(proc_t p)
 
        assert(pgrp != NULL);
 
-       if ((pgrp->pg_listflags & (PGRP_FLAG_TERMINATE | PGRP_FLAG_DEAD)) != 0)
-               panic("proc_pgrp: ref being povided for dead pgrp");
-               
-       if (pgrp != PGRP_NULL) 
+       if (pgrp != PGRP_NULL) {
                pgrp->pg_refcount++;
+               if ((pgrp->pg_listflags & (PGRP_FLAG_TERMINATE | PGRP_FLAG_DEAD)) != 0)
+                       panic("proc_pgrp: ref being povided for dead pgrp");
+       }
+               
        proc_list_unlock();
        
        return(pgrp);
@@ -2372,18 +2739,27 @@ session_rele(struct session *sess)
                if (sess->s_count != 0)
                        panic("session_rele: freeing session in use");  
                proc_list_unlock();
+#if CONFIG_FINE_LOCK_GROUPS
+               lck_mtx_destroy(&sess->s_mlock, proc_mlock_grp);
+#else
                lck_mtx_destroy(&sess->s_mlock, proc_lck_grp);
+#endif
                FREE_ZONE(sess, sizeof(struct session), M_SESSION);
        } else
                proc_list_unlock();
 }
 
-void
+int
 proc_transstart(proc_t p, int locked)
 {
        if (locked == 0)
                proc_lock(p);
        while ((p->p_lflag & P_LINTRANSIT) == P_LINTRANSIT) {
+               if ((p->p_lflag & P_LTRANSCOMMIT) == P_LTRANSCOMMIT) {
+                       if (locked == 0)
+                               proc_unlock(p);
+                       return EDEADLK;
+               }
                p->p_lflag |= P_LTRANSWAIT;
                msleep(&p->p_lflag, &p->p_mlock, 0, "proc_signstart", NULL);
        }
@@ -2391,37 +2767,61 @@ proc_transstart(proc_t p, int locked)
        p->p_transholder = current_thread();
        if (locked == 0)
                proc_unlock(p);
-
+       return 0;
 }
 
+void
+proc_transcommit(proc_t p, int locked)
+{
+       if (locked == 0)
+               proc_lock(p);
+
+       assert ((p->p_lflag & P_LINTRANSIT) == P_LINTRANSIT);
+       assert (p->p_transholder == current_thread());
+       p->p_lflag |= P_LTRANSCOMMIT;
+
+       if ((p->p_lflag & P_LTRANSWAIT) == P_LTRANSWAIT) {
+               p->p_lflag &= ~P_LTRANSWAIT;
+               wakeup(&p->p_lflag);
+       }
+       if (locked == 0)
+               proc_unlock(p);
+}
 
 void
 proc_transend(proc_t p, int locked)
 {
        if (locked == 0)
                proc_lock(p);
-       p->p_lflag &= ~P_LINTRANSIT;
+
+       p->p_lflag &= ~( P_LINTRANSIT | P_LTRANSCOMMIT);
+       p->p_transholder = NULL;
 
        if ((p->p_lflag & P_LTRANSWAIT) == P_LTRANSWAIT) {
                p->p_lflag &= ~P_LTRANSWAIT;
                wakeup(&p->p_lflag);
        }
-       p->p_transholder = NULL;
        if (locked == 0)
                proc_unlock(p);
 }
 
-void
+int
 proc_transwait(proc_t p, int locked)
 {
        if (locked == 0)
                proc_lock(p);
        while ((p->p_lflag & P_LINTRANSIT) == P_LINTRANSIT) {
+               if ((p->p_lflag & P_LTRANSCOMMIT) == P_LTRANSCOMMIT && current_proc() == p) {
+                       if (locked == 0)
+                               proc_unlock(p);
+                       return EDEADLK;
+               }
                p->p_lflag |= P_LTRANSWAIT;
                msleep(&p->p_lflag, &p->p_mlock, 0, "proc_signstart", NULL);
        }
        if (locked == 0)
                proc_unlock(p);
+       return 0;
 }
 
 void
@@ -2444,81 +2844,263 @@ proc_knote(struct proc * p, long hint)
        proc_klist_unlock();
 }
 
+void
+proc_knote_drain(struct proc *p)
+{
+       struct knote *kn = NULL;
+
+       /*
+        * Clear the proc's klist to avoid references after the proc is reaped.
+        */
+       proc_klist_lock();
+       while ((kn = SLIST_FIRST(&p->p_klist))) {
+               kn->kn_ptr.p_proc = PROC_NULL;
+               KNOTE_DETACH(&p->p_klist, kn);
+       }
+       proc_klist_unlock();
+}
+
+void 
+proc_setregister(proc_t p)
+{
+       proc_lock(p);
+       p->p_lflag |= P_LREGISTER;
+       proc_unlock(p);
+}
 
-unsigned long cs_procs_killed = 0;
-unsigned long cs_procs_invalidated = 0;
-int cs_force_kill = 0;
-int cs_force_hard = 0;
-int cs_debug = 0;
-SYSCTL_INT(_vm, OID_AUTO, cs_force_kill, CTLFLAG_RW, &cs_force_kill, 0, "");
-SYSCTL_INT(_vm, OID_AUTO, cs_force_hard, CTLFLAG_RW, &cs_force_hard, 0, "");
-SYSCTL_INT(_vm, OID_AUTO, cs_debug, CTLFLAG_RW, &cs_debug, 0, "");
+void 
+proc_resetregister(proc_t p)
+{
+       proc_lock(p);
+       p->p_lflag &= ~P_LREGISTER;
+       proc_unlock(p);
+}
+
+pid_t
+proc_pgrpid(proc_t p)
+{
+       return p->p_pgrpid;
+}
 
+pid_t
+proc_selfpgrpid()
+{
+       return current_proc()->p_pgrpid;
+}
+
+
+/* return control and action states */
 int
-cs_invalid_page(void)
+proc_getpcontrol(int pid, int * pcontrolp)
 {
-       struct proc     *p;
-       int             retval;
+       proc_t p;
 
-       p = current_proc();
+       p = proc_find(pid);
+       if (p == PROC_NULL)
+               return(ESRCH);
+       if (pcontrolp != NULL)
+               *pcontrolp = p->p_pcaction;
 
-       /*
-        * XXX revisit locking when proc is no longer protected
-        * by the kernel funnel...
-        */
+       proc_rele(p);
+       return(0);
+}
+
+int
+proc_dopcontrol(proc_t p, void *num_found)
+{
+       int pcontrol;
 
-       /* XXX for testing */
        proc_lock(p);
-       if (cs_force_kill)
-               p->p_csflags |= CS_KILL;
-       if (cs_force_hard)
-               p->p_csflags |= CS_HARD;
 
-       if (p->p_csflags & CS_VALID) {
-               p->p_csflags &= ~CS_VALID;
+       pcontrol = PROC_CONTROL_STATE(p);
 
-               proc_unlock(p);
-               cs_procs_invalidated++;
-               printf("CODE SIGNING: cs_invalid_page: "
-                      "p=%d[%s] clearing CS_VALID\n",
-                      p->p_pid, p->p_comm);
-               proc_lock(p);
+       if (PROC_ACTION_STATE(p) ==0) {
+               switch(pcontrol) {
+                       case P_PCTHROTTLE:
+                               PROC_SETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: throttling pid %d (%s)\n", p->p_pid, p->p_comm);
+                               (*(int *)num_found)++;
+                               break;
 
+                       case P_PCSUSP:
+                               PROC_SETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: suspending pid %d (%s)\n", p->p_pid, p->p_comm);
+                               task_suspend(p->task);
+                               (*(int *)num_found)++;
+                               break;
 
-               if (p->p_csflags & CS_KILL) {
-                       proc_unlock(p);
-                       if (cs_debug) {
-                               printf("CODE SIGNING: cs_invalid_page: "
-                                      "p=%d[%s] honoring CS_KILL\n",
-                                      p->p_pid, p->p_comm);
-                       }
-                       cs_procs_killed++;
-                       psignal(p, SIGKILL);
-                       proc_lock(p);
-               }
-               
-               if (p->p_csflags & CS_HARD) {
-                       proc_unlock(p);
-                       if (cs_debug) {
-                               printf("CODE SIGNING: cs_invalid_page: "
-                                      "p=%d[%s] honoring CS_HARD\n",
-                                      p->p_pid, p->p_comm);
-                       }
-                       retval = 1;
-               } else {
-                       proc_unlock(p);
-                       retval = 0;
+                       case P_PCKILL:
+                               PROC_SETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: killing pid %d (%s)\n", p->p_pid, p->p_comm);
+                               psignal(p, SIGKILL);
+                               (*(int *)num_found)++;
+                               break;
+
+                       default:
+                               proc_unlock(p);
                }
-       } else {
+
+       } else 
                proc_unlock(p);
-               if (cs_debug) {
-                       printf("CODE SIGNING: cs_invalid_page: "
-                              "p=%d[%s] ignored...\n",
-                              p->p_pid, p->p_comm);
+
+       return(PROC_RETURNED);
+}
+
+
+/*
+ * Resume a throttled or suspended process.  This is an internal interface that's only
+ * used by the user level code that presents the GUI when we run out of swap space and 
+ * hence is restricted to processes with superuser privileges.
+ */
+
+int
+proc_resetpcontrol(int pid)
+{
+       proc_t p;
+       int pcontrol;
+       int error;
+       proc_t self = current_proc();
+
+       /* if the process has been validated to handle resource control or root is valid one */
+       if (((self->p_lflag & P_LVMRSRCOWNER) == 0) && (error = suser(kauth_cred_get(), 0)))
+               return error;
+
+       p = proc_find(pid);
+       if (p == PROC_NULL)
+               return(ESRCH);
+       
+       proc_lock(p);
+
+       pcontrol = PROC_CONTROL_STATE(p);
+
+       if(PROC_ACTION_STATE(p) !=0) {
+               switch(pcontrol) {
+                       case P_PCTHROTTLE:
+                               PROC_RESETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: unthrottling pid %d (%s)\n", p->p_pid, p->p_comm);
+                               break;
+
+                       case P_PCSUSP:
+                               PROC_RESETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: resuming pid %d (%s)\n", p->p_pid, p->p_comm);
+                               task_resume(p->task);
+                               break;
+
+                       case P_PCKILL:
+                               /* Huh? */
+                               PROC_SETACTION_STATE(p);
+                               proc_unlock(p);
+                               printf("low swap: attempt to unkill pid %d (%s) ignored\n", p->p_pid, p->p_comm);
+                               break;
+
+                       default:
+                               proc_unlock(p);
                }
-               retval = 0;
-       }
 
-       return retval;
+       } else 
+               proc_unlock(p);
+
+       proc_rele(p);
+       return(0);
 }
 
+
+/*
+ * Return true if the specified process has an action state specified for it and it isn't
+ * already in an action state and it's using more physical memory than the specified threshold.
+ * Note: the memory_threshold argument is specified in bytes and is of type uint64_t.
+ */
+
+static int
+proc_pcontrol_filter(proc_t p, void *memory_thresholdp)
+{
+       
+       return PROC_CONTROL_STATE(p) &&                                                 /* if there's an action state specified... */
+             (PROC_ACTION_STATE(p) == 0) &&                                            /* and we're not in the action state yet... */
+             (get_task_resident_size(p->task) > *((uint64_t *)memory_thresholdp));     /* and this proc is over the mem threshold, */
+                                                                                       /* then return true to take action on this proc */
+}
+
+
+
+/*
+ * Deal with the out of swap space condition.  This routine gets called when
+ * we want to swap something out but there's no more space left.  Since this
+ * creates a memory deadlock situtation, we need to take action to free up
+ * some memory resources in order to prevent the system from hanging completely.
+ * The action we take is based on what the system processes running at user level
+ * have specified.  Processes are marked in one of four categories: ones that
+ * can be killed immediately, ones that should be suspended, ones that should
+ * be throttled, and all the rest which are basically none of the above.  Which
+ * processes are marked as being in which category is a user level policy decision;
+ * we just take action based on those decisions here.
+ */
+
+#define STARTING_PERCENTAGE    50      /* memory threshold expressed as a percentage */
+                                       /* of physical memory                         */
+
+struct timeval last_no_space_action = {0, 0};
+
+void
+no_paging_space_action(void)
+{
+
+       uint64_t        memory_threshold;
+       int             num_found;
+       struct timeval  now;
+
+       /*
+        * Throttle how often we come through here.  Once every 20 seconds should be plenty.
+        */
+
+       microtime(&now);
+
+       if (now.tv_sec <= last_no_space_action.tv_sec + 20)
+               return;
+
+       last_no_space_action = now;
+
+       /*
+        * Examine all processes and find those that have been marked to have some action
+        * taken when swap space runs out.  Of those processes, select one or more and 
+        * apply the specified action to them.  The idea is to only take action against
+        * a few processes rather than hitting too many at once.  If the low swap condition
+        * persists, this routine will get called again and we'll take action against more
+        * processes.
+        *
+        * Of the processes that have been marked, we choose which ones to take action 
+        * against according to how much physical memory they're presently using.  We
+        * start with the STARTING_THRESHOLD and any processes using more physical memory
+        * than the percentage threshold will have action taken against it.  If there
+        * are no processes over the threshold, then the threshold is cut in half and we
+        * look again for processes using more than this threshold.  We continue in
+        * this fashion until we find at least one process to take action against.  This
+        * iterative approach is less than ideally efficient, however we only get here
+        * when the system is almost in a memory deadlock and is pretty much just
+        * thrashing if it's doing anything at all.  Therefore, the cpu overhead of
+        * potentially multiple passes here probably isn't revelant.
+        */
+
+       memory_threshold = (sane_size * STARTING_PERCENTAGE) / 100;     /* resident threshold in bytes */
+
+       for (num_found = 0; num_found == 0; memory_threshold = memory_threshold / 2) {
+               proc_iterate(PROC_ALLPROCLIST, proc_dopcontrol, (void *)&num_found, proc_pcontrol_filter, (void *)&memory_threshold);
+
+               /*
+                * If we just looked with memory_threshold == 0, then there's no need to iterate any further since
+                * we won't find any eligible processes at this point.
+                */
+
+               if (memory_threshold == 0) {
+                       if (num_found == 0)     /* log that we couldn't do anything in this case */
+                               printf("low swap: unable to find any eligible processes to take action on\n");
+
+                       break;
+               }
+       }
+}