[2/7] Add the attached-to thread in inf_ptrace_attach

[Pedro Alves <pedro at codesourcery dot com>]

This patch makes sure that the thread/task we attach to with ptrace
targets is added to GDB's thread table.  Targets that extend
inf-ptrace (inf_ptrace_target) should then use thread_change_ptid
as soon as then have more lwp or tid info, instead of just setting
inferior_ptid.  Targets that don't have a process_stratum target
overriding inf_ptrace_attach get it for free (BSD targets).

This was tested together with the rest of the series on
x86_64-unknown-linux-gnu, i386-unknown-openbsd4.3, i386-unknown-freebsd6.0
and i386-unknown-freebsd7.0.

OK?

-- 
Pedro Alves

2008-08-08  Pedro Alves  <pedro@codesourcery.com>

	* inf-ptrace.c: Include "gdbthread.h".
	(inf_ptrace_attach): Add the main thread here.
	* linux-nat.c (linux_nat_attach): Don't add the main thread here.
	Decorate the main thread id with the lwp id.

---
 gdb/inf-ptrace.c |    6 ++++++
 gdb/linux-nat.c  |   13 +++++++------
 2 files changed, 13 insertions(+), 6 deletions(-)

Index: src/gdb/inf-ptrace.c
===================================================================
--- src.orig/gdb/inf-ptrace.c	2008-08-07 20:58:54.000000000 +0100
+++ src/gdb/inf-ptrace.c	2008-08-07 22:52:19.000000000 +0100
@@ -33,6 +33,7 @@
 #include <signal.h>
 
 #include "inf-child.h"
+#include "gdbthread.h"
 
 /* HACK: Save the ptrace ops returned by inf_ptrace_target.  */
 static struct target_ops *ptrace_ops_hack;
@@ -218,6 +219,11 @@ inf_ptrace_attach (char *args, int from_
 #endif
 
   inferior_ptid = pid_to_ptid (pid);
+
+  /* Always add a main thread.  If some target extends the ptrace
+     target, it should decorate the ptid later with more info.  */
+  add_thread_silent (inferior_ptid);
+
   push_target (ptrace_ops_hack);
 }
 
Index: src/gdb/linux-nat.c
===================================================================
--- src.orig/gdb/linux-nat.c	2008-08-07 20:58:54.000000000 +0100
+++ src/gdb/linux-nat.c	2008-08-07 22:52:19.000000000 +0100
@@ -1348,6 +1348,7 @@ linux_nat_attach (char *args, int from_t
 {
   struct lwp_info *lp;
   int status;
+  ptid_t ptid;
 
   /* FIXME: We should probably accept a list of process id's, and
      attach all of them.  */
@@ -1362,18 +1363,18 @@ linux_nat_attach (char *args, int from_t
       sigdelset (&suspend_mask, SIGCHLD);
     }
 
+  /* The ptrace base target adds the main thread with (pid,0,0)
+     format.  Decorate it with lwp info.  */
+  ptid = BUILD_LWP (GET_PID (inferior_ptid), GET_PID (inferior_ptid));
+  thread_change_ptid (inferior_ptid, ptid);
+
   /* Add the initial process as the first LWP to the list.  */
-  inferior_ptid = BUILD_LWP (GET_PID (inferior_ptid), GET_PID (inferior_ptid));
-  lp = add_lwp (inferior_ptid);
+  lp = add_lwp (ptid);
 
   status = linux_nat_post_attach_wait (lp->ptid, 1, &lp->cloned,
 				       &lp->signalled);
   lp->stopped = 1;
 
-  /* If this process is not using thread_db, then we still don't
-     detect any other threads, but add at least this one.  */
-  add_thread_silent (lp->ptid);
-
   /* Save the wait status to report later.  */
   lp->resumed = 1;
   if (debug_linux_nat)