minix/servers/pm/forkexit.c
David van Moolenbroek 4f6b382c41 Retire ptrace(T_DUMPCORE), dumpcore(1), gcore(1)
The T_DUMPCORE implementation was not only broken - it would currently
produce a coredump of the tracer process rather than the traced
process - but also deeply flawed, and fixing it would require serious
alteration of PM's internal state machine. It should be possible to
implement the same functionality in userland, and that is now the
suggested way forward. For now, also remove the (identical) utilities
using T_DUMPCORE: dumpcore(1) and gcore(1).

Change-Id: I1d51be19c739362b8a5833de949b76382a1edbcc
2014-02-18 11:25:03 +01:00

728 lines
24 KiB
C

/* This file deals with creating processes (via FORK) and deleting them (via
* EXIT/WAIT). When a process forks, a new slot in the 'mproc' table is
* allocated for it, and a copy of the parent's core image is made for the
* child. Then the kernel and file system are informed. A process is removed
* from the 'mproc' table when two events have occurred: (1) it has exited or
* been killed by a signal, and (2) the parent has done a WAIT. If the process
* exits first, it continues to occupy a slot until the parent does a WAIT.
*
* The entry points into this file are:
* do_fork: perform the FORK system call
* do_srv_fork: special FORK, used by RS to create sys services
* do_exit: perform the EXIT system call (by calling exit_proc())
* exit_proc: actually do the exiting, and tell VFS about it
* exit_restart: continue exiting a process after VFS has replied
* do_waitpid: perform the WAITPID or WAIT system call
* wait_test: check whether a parent is waiting for a child
*/
#include "pm.h"
#include <sys/wait.h>
#include <assert.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/sched.h>
#include <minix/vm.h>
#include <sys/ptrace.h>
#include <sys/resource.h>
#include <signal.h>
#include "mproc.h"
#include "param.h"
#define LAST_FEW 2 /* last few slots reserved for superuser */
static void zombify(struct mproc *rmp);
static void check_parent(struct mproc *child, int try_cleanup);
static void tell_parent(struct mproc *child);
static void tell_tracer(struct mproc *child);
static void tracer_died(struct mproc *child);
static void cleanup(register struct mproc *rmp);
/*===========================================================================*
* do_fork *
*===========================================================================*/
int do_fork()
{
/* The process pointed to by 'mp' has forked. Create a child process. */
register struct mproc *rmp; /* pointer to parent */
register struct mproc *rmc; /* pointer to child */
pid_t new_pid;
static unsigned int next_child = 0;
int i, n = 0, s;
endpoint_t child_ep;
message m;
/* If tables might fill up during FORK, don't even start since recovery half
* way through is such a nuisance.
*/
rmp = mp;
if ((procs_in_use == NR_PROCS) ||
(procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0))
{
printf("PM: warning, process table is full!\n");
return(EAGAIN);
}
/* Find a slot in 'mproc' for the child process. A slot must exist. */
do {
next_child = (next_child+1) % NR_PROCS;
n++;
} while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS);
if(n > NR_PROCS)
panic("do_fork can't find child slot");
if(next_child >= NR_PROCS || (mproc[next_child].mp_flags & IN_USE))
panic("do_fork finds wrong child slot: %d", next_child);
/* Memory part of the forking. */
if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) {
return s;
}
/* PM may not fail fork after call to vm_fork(), as VM calls sys_fork(). */
rmc = &mproc[next_child];
/* Set up the child and its memory map; copy its 'mproc' slot from parent. */
procs_in_use++;
*rmc = *rmp; /* copy parent's process slot to child's */
rmc->mp_parent = who_p; /* record child's parent */
if (!(rmc->mp_trace_flags & TO_TRACEFORK)) {
rmc->mp_tracer = NO_TRACER; /* no tracer attached */
rmc->mp_trace_flags = 0;
(void) sigemptyset(&rmc->mp_sigtrace);
}
/* Some system servers like to call regular fork, such as RS spawning
* recovery scripts; in this case PM will take care of their scheduling
* because RS cannot do so for non-system processes */
if (rmc->mp_flags & PRIV_PROC) {
assert(rmc->mp_scheduler == NONE);
rmc->mp_scheduler = SCHED_PROC_NR;
}
/* Inherit only these flags. In normal fork(), PRIV_PROC is not inherited. */
rmc->mp_flags &= (IN_USE|DELAY_CALL|TAINTED);
rmc->mp_child_utime = 0; /* reset administration */
rmc->mp_child_stime = 0; /* reset administration */
rmc->mp_exitstatus = 0;
rmc->mp_sigstatus = 0;
rmc->mp_endpoint = child_ep; /* passed back by VM */
for (i = 0; i < NR_ITIMERS; i++)
rmc->mp_interval[i] = 0; /* reset timer intervals */
/* Find a free pid for the child and put it in the table. */
new_pid = get_free_pid();
rmc->mp_pid = new_pid; /* assign pid to child */
m.m_type = PM_FORK;
m.PM_PROC = rmc->mp_endpoint;
m.PM_PPROC = rmp->mp_endpoint;
m.PM_CPID = rmc->mp_pid;
m.PM_REUID = -1; /* Not used by PM_FORK */
m.PM_REGID = -1; /* Not used by PM_FORK */
tell_vfs(rmc, &m);
#if USE_TRACE
/* Tell the tracer, if any, about the new child */
if (rmc->mp_tracer != NO_TRACER)
sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */);
#endif /* USE_TRACE */
/* Do not reply until VFS is ready to process the fork
* request
*/
return SUSPEND;
}
/*===========================================================================*
* do_srv_fork *
*===========================================================================*/
int do_srv_fork()
{
/* The process pointed to by 'mp' has forked. Create a child process. */
register struct mproc *rmp; /* pointer to parent */
register struct mproc *rmc; /* pointer to child */
int s;
pid_t new_pid;
static unsigned int next_child = 0;
int i, n = 0;
endpoint_t child_ep;
message m;
/* Only RS is allowed to use srv_fork. */
if (mp->mp_endpoint != RS_PROC_NR)
return EPERM;
/* If tables might fill up during FORK, don't even start since recovery half
* way through is such a nuisance.
*/
rmp = mp;
if ((procs_in_use == NR_PROCS) ||
(procs_in_use >= NR_PROCS-LAST_FEW && rmp->mp_effuid != 0))
{
printf("PM: warning, process table is full!\n");
return(EAGAIN);
}
/* Find a slot in 'mproc' for the child process. A slot must exist. */
do {
next_child = (next_child+1) % NR_PROCS;
n++;
} while((mproc[next_child].mp_flags & IN_USE) && n <= NR_PROCS);
if(n > NR_PROCS)
panic("do_fork can't find child slot");
if(next_child >= NR_PROCS || (mproc[next_child].mp_flags & IN_USE))
panic("do_fork finds wrong child slot: %d", next_child);
if((s=vm_fork(rmp->mp_endpoint, next_child, &child_ep)) != OK) {
return s;
}
rmc = &mproc[next_child];
/* Set up the child and its memory map; copy its 'mproc' slot from parent. */
procs_in_use++;
*rmc = *rmp; /* copy parent's process slot to child's */
rmc->mp_parent = who_p; /* record child's parent */
if (!(rmc->mp_trace_flags & TO_TRACEFORK)) {
rmc->mp_tracer = NO_TRACER; /* no tracer attached */
rmc->mp_trace_flags = 0;
(void) sigemptyset(&rmc->mp_sigtrace);
}
/* inherit only these flags */
rmc->mp_flags &= (IN_USE|PRIV_PROC|DELAY_CALL);
rmc->mp_child_utime = 0; /* reset administration */
rmc->mp_child_stime = 0; /* reset administration */
rmc->mp_exitstatus = 0;
rmc->mp_sigstatus = 0;
rmc->mp_endpoint = child_ep; /* passed back by VM */
rmc->mp_realuid = (uid_t) m_in.m1_i1;
rmc->mp_effuid = (uid_t) m_in.m1_i1;
rmc->mp_realgid = (uid_t) m_in.m1_i2;
rmc->mp_effgid = (uid_t) m_in.m1_i2;
for (i = 0; i < NR_ITIMERS; i++)
rmc->mp_interval[i] = 0; /* reset timer intervals */
/* Find a free pid for the child and put it in the table. */
new_pid = get_free_pid();
rmc->mp_pid = new_pid; /* assign pid to child */
m.m_type = PM_SRV_FORK;
m.PM_PROC = rmc->mp_endpoint;
m.PM_PPROC = rmp->mp_endpoint;
m.PM_CPID = rmc->mp_pid;
m.PM_REUID = m_in.m1_i1;
m.PM_REGID = m_in.m1_i2;
tell_vfs(rmc, &m);
#if USE_TRACE
/* Tell the tracer, if any, about the new child */
if (rmc->mp_tracer != NO_TRACER)
sig_proc(rmc, SIGSTOP, TRUE /*trace*/, FALSE /* ksig */);
#endif /* USE_TRACE */
/* Wakeup the newly created process */
setreply(rmc-mproc, OK);
return rmc->mp_pid;
}
/*===========================================================================*
* do_exit *
*===========================================================================*/
int do_exit()
{
/* Perform the exit(status) system call. The real work is done by exit_proc(),
* which is also called when a process is killed by a signal. System processes
* do not use PM's exit() to terminate. If they try to, we warn the user
* and send a SIGKILL signal to the system process.
*/
if(mp->mp_flags & PRIV_PROC) {
printf("PM: system process %d (%s) tries to exit(), sending SIGKILL\n",
mp->mp_endpoint, mp->mp_name);
sys_kill(mp->mp_endpoint, SIGKILL);
}
else {
exit_proc(mp, m_in.status, FALSE /*dump_core*/);
}
return(SUSPEND); /* can't communicate from beyond the grave */
}
/*===========================================================================*
* exit_proc *
*===========================================================================*/
void exit_proc(rmp, exit_status, dump_core)
register struct mproc *rmp; /* pointer to the process to be terminated */
int exit_status; /* the process' exit status (for parent) */
int dump_core; /* flag indicating whether to dump core */
{
/* A process is done. Release most of the process' possessions. If its
* parent is waiting, release the rest, else keep the process slot and
* become a zombie.
*/
register int proc_nr, proc_nr_e;
int r;
pid_t procgrp;
struct mproc *p_mp;
clock_t user_time, sys_time;
message m;
/* Do not create core files for set uid execution */
if (dump_core && rmp->mp_realuid != rmp->mp_effuid)
dump_core = FALSE;
/* System processes are destroyed before informing VFS, meaning that VFS can
* not get their CPU state, so we can't generate a coredump for them either.
*/
if (dump_core && (rmp->mp_flags & PRIV_PROC))
dump_core = FALSE;
proc_nr = (int) (rmp - mproc); /* get process slot number */
proc_nr_e = rmp->mp_endpoint;
/* Remember a session leader's process group. */
procgrp = (rmp->mp_pid == mp->mp_procgrp) ? mp->mp_procgrp : 0;
/* If the exited process has a timer pending, kill it. */
if (rmp->mp_flags & ALARM_ON) set_alarm(rmp, (clock_t) 0);
/* Do accounting: fetch usage times and accumulate at parent. */
if((r=sys_times(proc_nr_e, &user_time, &sys_time, NULL, NULL)) != OK)
panic("exit_proc: sys_times failed: %d", r);
p_mp = &mproc[rmp->mp_parent]; /* process' parent */
p_mp->mp_child_utime += user_time + rmp->mp_child_utime; /* add user time */
p_mp->mp_child_stime += sys_time + rmp->mp_child_stime; /* add system time */
/* Tell the kernel the process is no longer runnable to prevent it from
* being scheduled in between the following steps. Then tell VFS that it
* the process has exited and finally, clean up the process at the kernel.
* This order is important so that VFS can tell drivers to cancel requests
* such as copying to/ from the exiting process, before it is gone.
*/
if ((r = sys_stop(proc_nr_e)) != OK) /* stop the process */
panic("sys_stop failed: %d", r);
if((r=vm_willexit(proc_nr_e)) != OK) {
panic("exit_proc: vm_willexit failed: %d", r);
}
vm_notify_sig_wrapper(rmp->mp_endpoint);
if (proc_nr_e == INIT_PROC_NR)
{
printf("PM: INIT died\n");
return;
}
if (proc_nr_e == VFS_PROC_NR)
{
panic("exit_proc: VFS died: %d", r);
}
/* Tell VFS about the exiting process. */
m.m_type = dump_core ? PM_DUMPCORE : PM_EXIT;
m.PM_PROC = rmp->mp_endpoint;
if (dump_core) {
m.PM_TERM_SIG = rmp->mp_sigstatus;
m.PM_PATH = rmp->mp_name;
}
tell_vfs(rmp, &m);
if (rmp->mp_flags & PRIV_PROC)
{
/* Destroy system processes without waiting for VFS. This is
* needed because the system process might be a block device
* driver that VFS is blocked waiting on.
*/
if((r= sys_clear(rmp->mp_endpoint)) != OK)
panic("exit_proc: sys_clear failed: %d", r);
}
/* Clean up most of the flags describing the process's state before the exit,
* and mark it as exiting.
*/
rmp->mp_flags &= (IN_USE|VFS_CALL|PRIV_PROC|TRACE_EXIT);
rmp->mp_flags |= EXITING;
/* Keep the process around until VFS is finished with it. */
rmp->mp_exitstatus = (char) exit_status;
/* For normal exits, try to notify the parent as soon as possible.
* For core dumps, notify the parent only once the core dump has been made.
*/
if (!dump_core)
zombify(rmp);
/* If the process has children, disinherit them. INIT is the new parent. */
for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++) {
if (!(rmp->mp_flags & IN_USE)) continue;
#if USE_TRACE
if (rmp->mp_tracer == proc_nr) {
/* This child's tracer died. Do something sensible. */
tracer_died(rmp);
}
#endif /* USE_TRACE */
if (rmp->mp_parent == proc_nr) {
/* 'rmp' now points to a child to be disinherited. */
rmp->mp_parent = INIT_PROC_NR;
/* Notify new parent. */
if (rmp->mp_flags & ZOMBIE)
check_parent(rmp, TRUE /*try_cleanup*/);
}
}
/* Send a hangup to the process' process group if it was a session leader. */
if (procgrp != 0) check_sig(-procgrp, SIGHUP, FALSE /* ksig */);
}
/*===========================================================================*
* exit_restart *
*===========================================================================*/
void exit_restart(rmp, dump_core)
struct mproc *rmp; /* pointer to the process being terminated */
int dump_core; /* flag indicating whether to dump core */
{
/* VFS replied to our exit or coredump request. Perform the second half of the
* exit code.
*/
int r;
if((r = sched_stop(rmp->mp_scheduler, rmp->mp_endpoint)) != OK) {
/* If the scheduler refuses to give up scheduling, there is
* little we can do, except report it. This may cause problems
* later on, if this scheduler is asked to schedule another proc
* that has an endpoint->schedproc mapping identical to the proc
* we just tried to stop scheduling.
*/
printf("PM: The scheduler did not want to give up "
"scheduling %s, ret=%d.\n", rmp->mp_name, r);
}
/* sched_stop is either called when the process is exiting or it is
* being moved between schedulers. If it is being moved between
* schedulers, we need to set the mp_scheduler to NONE so that PM
* doesn't forward messages to the process' scheduler while being moved
* (such as sched_nice). */
rmp->mp_scheduler = NONE;
/* For core dumps, now is the right time to try to contact the parent. */
if (dump_core)
zombify(rmp);
if (!(rmp->mp_flags & PRIV_PROC))
{
/* destroy the (user) process */
if((r=sys_clear(rmp->mp_endpoint)) != OK)
panic("exit_restart: sys_clear failed: %d", r);
}
/* Release the memory occupied by the child. */
if((r=vm_exit(rmp->mp_endpoint)) != OK) {
panic("exit_restart: vm_exit failed: %d", r);
}
#if USE_TRACE
if (rmp->mp_flags & TRACE_EXIT)
{
/* Wake up the tracer, completing the ptrace(T_EXIT) call */
mproc[rmp->mp_tracer].mp_reply.reply_trace = 0;
setreply(rmp->mp_tracer, OK);
}
#endif /* USE_TRACE */
/* Clean up if the parent has collected the exit status */
if (rmp->mp_flags & TOLD_PARENT)
cleanup(rmp);
}
/*===========================================================================*
* do_waitpid *
*===========================================================================*/
int do_waitpid()
{
/* A process wants to wait for a child to terminate. If a child is already
* waiting, go clean it up and let this WAIT call terminate. Otherwise,
* really wait.
* A process calling WAIT never gets a reply in the usual way at the end
* of the main loop (unless WNOHANG is set or no qualifying child exists).
* If a child has already exited, the routine tell_parent() sends the reply
* to awaken the caller.
* Both WAIT and WAITPID are handled by this code.
*/
register struct mproc *rp;
int i, pidarg, options, children;
/* Set internal variables, depending on whether this is WAIT or WAITPID. */
pidarg = (call_nr == WAIT ? -1 : m_in.pid); /* 1st param of waitpid */
options = (call_nr == WAIT ? 0 : m_in.sig_nr); /* 3rd param of waitpid */
if (pidarg == 0) pidarg = -mp->mp_procgrp; /* pidarg < 0 ==> proc grp */
/* Is there a child waiting to be collected? At this point, pidarg != 0:
* pidarg > 0 means pidarg is pid of a specific process to wait for
* pidarg == -1 means wait for any child
* pidarg < -1 means wait for any child whose process group = -pidarg
*/
children = 0;
for (rp = &mproc[0]; rp < &mproc[NR_PROCS]; rp++) {
if ((rp->mp_flags & (IN_USE | TOLD_PARENT)) != IN_USE) continue;
if (rp->mp_parent != who_p && rp->mp_tracer != who_p) continue;
if (rp->mp_parent != who_p && (rp->mp_flags & ZOMBIE)) continue;
/* The value of pidarg determines which children qualify. */
if (pidarg > 0 && pidarg != rp->mp_pid) continue;
if (pidarg < -1 && -pidarg != rp->mp_procgrp) continue;
children++; /* this child is acceptable */
#if USE_TRACE
if (rp->mp_tracer == who_p) {
if (rp->mp_flags & TRACE_ZOMBIE) {
/* Traced child meets the pid test and has exited. */
tell_tracer(rp);
check_parent(rp, TRUE /*try_cleanup*/);
return(SUSPEND);
}
if (rp->mp_flags & STOPPED) {
/* This child meets the pid test and is being traced.
* Deliver a signal to the tracer, if any.
*/
for (i = 1; i < _NSIG; i++) {
if (sigismember(&rp->mp_sigtrace, i)) {
sigdelset(&rp->mp_sigtrace, i);
mp->mp_reply.reply_res2 =
0177 | (i << 8);
return(rp->mp_pid);
}
}
}
}
#endif /* USE_TRACE */
if (rp->mp_parent == who_p) {
if (rp->mp_flags & ZOMBIE) {
/* This child meets the pid test and has exited. */
tell_parent(rp); /* this child has already exited */
if (!(rp->mp_flags & VFS_CALL))
cleanup(rp);
return(SUSPEND);
}
}
}
/* No qualifying child has exited. Wait for one, unless none exists. */
if (children > 0) {
/* At least 1 child meets the pid test exists, but has not exited. */
if (options & WNOHANG) {
return(0); /* parent does not want to wait */
}
mp->mp_flags |= WAITING; /* parent wants to wait */
mp->mp_wpid = (pid_t) pidarg; /* save pid for later */
return(SUSPEND); /* do not reply, let it wait */
} else {
/* No child even meets the pid test. Return error immediately. */
return(ECHILD); /* no - parent has no children */
}
}
/*===========================================================================*
* wait_test *
*===========================================================================*/
int wait_test(rmp, child)
struct mproc *rmp; /* process that may be waiting */
struct mproc *child; /* process that may be waited for */
{
/* See if a parent or tracer process is waiting for a child process.
* A tracer is considered to be a pseudo-parent.
*/
int parent_waiting, right_child;
pid_t pidarg;
pidarg = rmp->mp_wpid; /* who's being waited for? */
parent_waiting = rmp->mp_flags & WAITING;
right_child = /* child meets one of the 3 tests? */
(pidarg == -1 || pidarg == child->mp_pid ||
-pidarg == child->mp_procgrp);
return (parent_waiting && right_child);
}
/*===========================================================================*
* zombify *
*===========================================================================*/
static void zombify(rmp)
struct mproc *rmp;
{
/* Zombify a process. First check if the exiting process is traced by a process
* other than its parent; if so, the tracer must be notified about the exit
* first. Once that is done, the real parent may be notified about the exit of
* its child.
*/
struct mproc *t_mp;
if (rmp->mp_flags & (TRACE_ZOMBIE | ZOMBIE))
panic("zombify: process was already a zombie");
/* See if we have to notify a tracer process first. */
if (rmp->mp_tracer != NO_TRACER && rmp->mp_tracer != rmp->mp_parent) {
#if USE_TRACE
rmp->mp_flags |= TRACE_ZOMBIE;
t_mp = &mproc[rmp->mp_tracer];
/* Do not bother sending SIGCHLD signals to tracers. */
if (!wait_test(t_mp, rmp))
return;
tell_tracer(rmp);
#endif /* USE_TRACE */
}
else {
rmp->mp_flags |= ZOMBIE;
}
/* No tracer, or tracer is parent, or tracer has now been notified. */
check_parent(rmp, FALSE /*try_cleanup*/);
}
/*===========================================================================*
* check_parent *
*===========================================================================*/
static void check_parent(child, try_cleanup)
struct mproc *child; /* tells which process is exiting */
int try_cleanup; /* clean up the child when done? */
{
/* We would like to inform the parent of an exiting child about the child's
* death. If the parent is waiting for the child, tell it immediately;
* otherwise, send it a SIGCHLD signal.
*
* Note that we may call this function twice on a single child; first with
* its original parent, later (if the parent died) with INIT as its parent.
*/
struct mproc *p_mp;
p_mp = &mproc[child->mp_parent];
if (p_mp->mp_flags & EXITING) {
/* This may trigger if the child of a dead parent dies. The child will
* be assigned to INIT and rechecked shortly after. Do nothing.
*/
}
else if (wait_test(p_mp, child)) {
tell_parent(child);
/* The 'try_cleanup' flag merely saves us from having to be really
* careful with statement ordering in exit_proc() and exit_restart().
*/
if (try_cleanup && !(child->mp_flags & VFS_CALL))
cleanup(child);
}
else {
/* Parent is not waiting. */
sig_proc(p_mp, SIGCHLD, TRUE /*trace*/, FALSE /* ksig */);
}
}
/*===========================================================================*
* tell_parent *
*===========================================================================*/
static void tell_parent(child)
register struct mproc *child; /* tells which process is exiting */
{
int exitstatus, mp_parent;
struct mproc *parent;
mp_parent= child->mp_parent;
if (mp_parent <= 0)
panic("tell_parent: bad value in mp_parent: %d", mp_parent);
if(!(child->mp_flags & ZOMBIE))
panic("tell_parent: child not a zombie");
if(child->mp_flags & TOLD_PARENT)
panic("tell_parent: telling parent again");
parent = &mproc[mp_parent];
/* Wake up the parent by sending the reply message. */
exitstatus = (child->mp_exitstatus << 8) | (child->mp_sigstatus & 0377);
parent->mp_reply.reply_res2 = exitstatus;
setreply(child->mp_parent, child->mp_pid);
parent->mp_flags &= ~WAITING; /* parent no longer waiting */
child->mp_flags &= ~ZOMBIE; /* child no longer a zombie */
child->mp_flags |= TOLD_PARENT; /* avoid informing parent twice */
}
#if USE_TRACE
/*===========================================================================*
* tell_tracer *
*===========================================================================*/
static void tell_tracer(child)
struct mproc *child; /* tells which process is exiting */
{
int exitstatus, mp_tracer;
struct mproc *tracer;
mp_tracer = child->mp_tracer;
if (mp_tracer <= 0)
panic("tell_tracer: bad value in mp_tracer: %d", mp_tracer);
if(!(child->mp_flags & TRACE_ZOMBIE))
panic("tell_tracer: child not a zombie");
tracer = &mproc[mp_tracer];
exitstatus = (child->mp_exitstatus << 8) | (child->mp_sigstatus & 0377);
tracer->mp_reply.reply_res2 = exitstatus;
setreply(child->mp_tracer, child->mp_pid);
tracer->mp_flags &= ~WAITING; /* tracer no longer waiting */
child->mp_flags &= ~TRACE_ZOMBIE; /* child no longer zombie to tracer */
child->mp_flags |= ZOMBIE; /* child is now zombie to parent */
}
/*===========================================================================*
* tracer_died *
*===========================================================================*/
static void tracer_died(child)
struct mproc *child; /* process being traced */
{
/* The process that was tracing the given child, has died for some reason.
* This is really the tracer's fault, but we can't let INIT deal with this.
*/
child->mp_tracer = NO_TRACER;
child->mp_flags &= ~TRACE_EXIT;
/* If the tracer died while the child was running or stopped, we have no
* idea what state the child is in. Avoid a trainwreck, by killing the child.
* Note that this may cause cascading exits.
*/
if (!(child->mp_flags & EXITING)) {
sig_proc(child, SIGKILL, TRUE /*trace*/, FALSE /* ksig */);
return;
}
/* If the tracer died while the child was telling it about its own death,
* forget about the tracer and notify the real parent instead.
*/
if (child->mp_flags & TRACE_ZOMBIE) {
child->mp_flags &= ~TRACE_ZOMBIE;
child->mp_flags |= ZOMBIE;
check_parent(child, TRUE /*try_cleanup*/);
}
}
#endif /* USE_TRACE */
/*===========================================================================*
* cleanup *
*===========================================================================*/
static void cleanup(rmp)
register struct mproc *rmp; /* tells which process is exiting */
{
/* Release the process table entry and reinitialize some field. */
rmp->mp_pid = 0;
rmp->mp_flags = 0;
rmp->mp_child_utime = 0;
rmp->mp_child_stime = 0;
procs_in_use--;
}