From 12451e6b06f4a552acdfaac96637aedd69448920 Mon Sep 17 00:00:00 2001
From: David van Moolenbroek <david@minix3.org>
Date: Sun, 5 Jul 2009 22:48:18 +0000
Subject: [PATCH] Miscellaneous PM fixes: o Don't call vm_willexit() more than
 once upon normal process exit o Correct two cases of indenting of the
 no-discussion-possible kind o Perform slightly stricter ptrace(2) checks:   -
 process calling ptrace must be target process's parent   - process must call
 wait/waitpid before using ptrace on stopped child   - no ptrace on zombies o
 Allow user processes to use ptrace(T_STOP) to stop an active child

---
 servers/pm/forkexit.c |  4 ++--
 servers/pm/signal.c   | 12 ++++--------
 servers/pm/trace.c    | 30 +++++++++++++++++++++++++-----
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/servers/pm/forkexit.c b/servers/pm/forkexit.c
index 4bfe4ad30..eae82993d 100644
--- a/servers/pm/forkexit.c
+++ b/servers/pm/forkexit.c
@@ -226,8 +226,8 @@ int for_trace;
    * such as copying to/ from the exiting process, before it is gone.
    */
   sys_nice(proc_nr_e, PRIO_STOP);	/* stop the process */
-  if(vm_willexit(proc_nr_e) != OK) {
-	panic(__FILE__, "pm_exit: vm_willexit failed", proc_nr_e);
+  if((r=vm_willexit(proc_nr_e)) != OK) {
+	panic(__FILE__, "pm_exit: vm_willexit failed", r);
   }
 
   if (proc_nr_e == INIT_PROC_NR)
diff --git a/servers/pm/signal.c b/servers/pm/signal.c
index 23c2cb4d1..f80dc0ba4 100644
--- a/servers/pm/signal.c
+++ b/servers/pm/signal.c
@@ -260,7 +260,7 @@ sigset_t sig_map;
   if ((rmp->mp_flags & (IN_USE | ZOMBIE)) != IN_USE) {
 	printf("PM: handle_ksig: %d?? zombie / not in use\n", proc_nr_e);
 	return;
-}
+  }
   proc_id = rmp->mp_pid;
   mp = &mproc[0];			/* pretend signals are from PM */
   mp->mp_procgrp = rmp->mp_procgrp;	/* get process group right */
@@ -517,13 +517,6 @@ doterminate:
   /* Signal should not or cannot be caught.  Take default action. */
   if (sigismember(&ign_sset, signo)) {
 	return;
-}
-
-  /* This process will exit, with or without dumping core. 
-   * Announce this fact to VM.
-   */
-  if((s=vm_willexit(rmp->mp_endpoint)) != OK) {
-	panic(__FILE__,"sig_proc: vm_willexit failed", s);
   }
 
   rmp->mp_sigstatus = (char) signo;
@@ -745,6 +738,9 @@ register struct mproc *rmp;	/* whose core is to be dumped */
    * such as copying to/ from the exiting process, before it is gone.
    */
   sys_nice(proc_nr_e, PRIO_STOP);	/* stop the process */
+  if((r=vm_willexit(proc_nr_e)) != OK) {
+	panic(__FILE__,"dump_core: vm_willexit failed", r);
+  }
 
   if(proc_nr_e != FS_PROC_NR)		/* if it is not FS that is exiting.. */
   {
diff --git a/servers/pm/trace.c b/servers/pm/trace.c
index 943169602..ec7b35a9a 100644
--- a/servers/pm/trace.c
+++ b/servers/pm/trace.c
@@ -87,12 +87,29 @@ PUBLIC int do_trace()
 	return(OK);
   }
 
-  if ((child=find_proc(m_in.pid))==NIL_MPROC || !(child->mp_flags & STOPPED)) {
-	return(ESRCH);
-  }
   /* all the other calls are made by the parent fork of the debugger to 
    * control execution of the child
    */
+  if ((child=find_proc(m_in.pid))==NIL_MPROC || child->mp_parent != who_p)
+	return(ESRCH);
+
+  if (m_in.request == T_STOP) {
+	if ((r = sys_trace(T_STOP, child->mp_endpoint, 0L, (long *) 0)) != OK)
+		return(r);
+
+	child->mp_flags |= STOPPED;
+	child->mp_sigstatus = 0;
+
+	mp->mp_reply.reply_trace = 0;
+	return(OK);
+  }
+
+  /* for calls other than T_STOP, the child must be stopped and the parent
+   * must have waited for it
+   */
+  if (!(child->mp_flags & STOPPED) || child->mp_sigstatus > 0)
+	return(ESRCH);
+
   switch (m_in.request) {
   case T_EXIT:		/* exit */
 	pm_exit(child, (int) m_in.data, TRUE /*for_trace*/);
@@ -127,7 +144,10 @@ pid_t lpid;
   register struct mproc *rmp;
 
   for (rmp = &mproc[0]; rmp < &mproc[NR_PROCS]; rmp++)
-	if (rmp->mp_flags & IN_USE && rmp->mp_pid == lpid) return(rmp);
+	if ((rmp->mp_flags & (IN_USE | ZOMBIE)) == IN_USE &&
+		rmp->mp_pid == lpid) {
+		return(rmp);
+	}
   return(NIL_MPROC);
 }
 
@@ -143,7 +163,7 @@ int signo;
   register struct mproc *rpmp = mproc + rmp->mp_parent;
   int r;
 
-  r= sys_trace(-1, rmp->mp_endpoint, 0L, (long *) 0);
+  r= sys_trace(T_STOP, rmp->mp_endpoint, 0L, (long *) 0);
   if (r != OK) panic("pm", "sys_trace failed", r);
  
   rmp->mp_flags |= STOPPED;