[multiprocess] Linux-nat multiprocess switch

[teawater <teawater@gmail.com>]

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Hi,

I got and test the multiprocess branch. And can't find a interface to
switch the process.
So I make this example patch make multiprocess be switched in
linux-nat. It still have a lot of bugs.

I will make it better if you guys like it.

Example:
(gdb) list
During symbol reading, DW_AT_name missing from DW_TAG_base_type.
5	#include <unistd.h>
6	#include <errno.h>
7	#include <sys/stat.h>
8	#include <fcntl.h>
9	#include <stdint.h>
10	
11	int
12	main(int argc,char *argv[],char *envp[])
13	{
14		pid_t	pid = fork ();
(gdb)
15	
16		if (pid == 0) {
17			while (1) {
18				printf ("%d: C\n", getpid ());
19				sleep (2);
20			}
21		}
22		else {
23			while (1) {
24				printf ("%d: F\n", getpid ());
(gdb)
25				sleep (2);
26			}
27		}
28	
29		return (0);
30	}
31	
(gdb) set detach-on-fork off
(gdb) set follow-fork-mode child
(gdb) r
Starting program: /home/teawater/multiprocess/a.out
9004: C
9001: F
9004: C
9001: F
9004: C
9001: F

Program received signal SIGINT, Interrupt.
0xb7fe3410 in __kernel_vsyscall ()
(gdb) info inferiors
  3 9004 a.out
* 2 9001 a.out
  1 0 #a.out# /home/teawater/multiprocess/a.out
(gdb) b 18
Breakpoint 1 at 0x8048433: file 1.c, line 18.
(gdb) c
Continuing.
9004: C
9001: F
9004: C
9001: F

Program received signal SIGINT, Interrupt.
0xb7fe3410 in __kernel_vsyscall ()
(gdb) switch-inferior 3
(gdb) c
Continuing.
9001: F

Breakpoint 1, main (argc=<value optimized out>, argv=<value optimized out>,
    envp=<value optimized out>) at 1.c:18
18				printf ("%d: C\n", getpid ());


Thanks,
Hui

[-- Attachment #2: inferior-switch.txt --]
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--- gdb.orig/inferior.c
+++ gdb/inferior.c
@@ -26,6 +26,7 @@
 #include "gdbthread.h"
 #include "ui-out.h"
 #include "observer.h"
+#include "regcache.h"
 
 void _initialize_inferiors (void);
 
@@ -1124,6 +1125,29 @@
 }
 
 void
+switch_inferior_command (char *args, int from_tty)
+{
+  struct inferior *inf;
+  int pid;
+  ptid_t ptid;
+
+  /* Get ptid. */
+  get_inferior_or_pid (args, &inf, &pid);
+  if (pid <= 0)
+    {
+      printf_unfiltered (_("Can't switch to inferior %s\n"), args);
+    }
+  ptid = ptid_build (pid, pid, 0);
+  
+  if (ptid_equal (ptid, inferior_ptid))
+    return;
+
+  inferior_ptid = ptid;
+  reinit_frame_cache ();
+  registers_changed ();
+}
+
+void
 _initialize_inferiors (void)
 {
   add_com ("add-inferior", no_class, add_inferior_command, _("\
@@ -1132,6 +1156,9 @@
   add_com ("remove-inferior", no_class, remove_inferior_command, _("\
 Remove the inferiors in ITSET."));
 
+  add_com ("switch-inferior", no_class, switch_inferior_command, _("\
+Switch the inferiors in ITSET."));
+
   add_com ("name-inferior", no_class, name_inferior_command, _("\
 Change the name of inferior OLDNAME to NEWNAME."));
 
--- gdb.orig/linux-nat.c
+++ gdb/linux-nat.c
@@ -1127,11 +1127,11 @@
 {
   struct lwp_info *lp;
 
-  init_lwp_list ();
+  //init_lwp_list ();
   lp = add_lwp (new_ptid);
   lp->stopped = 1;
 
-  init_thread_list ();
+  //init_thread_list ();
   add_thread_silent (new_ptid);
 }