Record in `struct inferior' whether the target process id we have has been faked by GDB or not.

From: Pedro Alves <palves@redhat.com>


---
 gdb/inferior.c  |    1 +
 gdb/inferior.h  |    2 ++
 gdb/linux-nat.c |   18 ++++++++++++++----
 gdb/remote.c    |   42 ++++++++++++++++++++++++++++++++----------
 4 files changed, 49 insertions(+), 14 deletions(-)

diff --git a/gdb/inferior.c b/gdb/inferior.c
index 65948c4..4df8c77 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -276,6 +276,7 @@ exit_inferior_1 (struct inferior *inftoex, int silent)
   observer_notify_inferior_exit (inf);
 
   inf->pid = 0;
+  inf->fake_pid_p = 0;
   if (inf->vfork_parent != NULL)
     {
       inf->vfork_parent->vfork_child = NULL;
diff --git a/gdb/inferior.h b/gdb/inferior.h
index f05789f..7857cbf 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -421,6 +421,8 @@ struct inferior
   /* Actual target inferior id, usually, a process id.  This matches
      the ptid_t.pid member of threads of this inferior.  */
   int pid;
+  /* True if the PID was actually faked by GDB.  */
+  int fake_pid_p;
 
   /* State of GDB control of inferior process execution.
      See `struct inferior_control_state'.  */
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index d333c44..17236ec 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -5012,7 +5012,8 @@ linux_nat_info_proc_cmd_1 (char *args, enum info_proc_what what, int from_tty)
 {
   /* A long is used for pid instead of an int to avoid a loss of precision
      compiler warning from the output of strtoul.  */
-  long pid = PIDGET (inferior_ptid);
+  long pid = 0;
+  int explicit_pid = 0;
   int procfile;
   char buffer[MAXPATHLEN];
   char fname1[MAXPATHLEN], fname2[MAXPATHLEN];
@@ -5026,14 +5027,23 @@ linux_nat_info_proc_cmd_1 (char *args, enum info_proc_what what, int from_tty)
   int target_errno;
 
   if (args && isdigit (args[0]))
-    pid = strtoul (args, &args, 10);
+    {
+      pid = strtoul (args, &args, 10);
+      explicit_pid = 1;
+    }
 
   args = skip_spaces (args);
   if (args && args[0])
     error (_("Too many parameters: %s"), args);
 
-  if (pid == 0)
-    error (_("No current process: you must name one."));
+  if (!explicit_pid)
+    {
+      if (!target_has_execution)
+	error (_("No current process: you must name one."));
+      if (current_inferior ()->fake_pid_p)
+	error (_("Can't determine the current process's PID: you must name one."));
+      pid = ptid_get_pid (inferior_ptid);
+    }
 
   printf_filtered (_("process %ld\n"), pid);
   if (cmdline_f)
diff --git a/gdb/remote.c b/gdb/remote.c
index 7542882..c5c9481 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -3253,6 +3253,10 @@ remote_start_remote (int from_tty, struct target_ops *target, int extended_p)
 
   if (!non_stop)
     {
+      ptid_t ptid;
+      int fake_pid_p = 0;
+      struct inferior *inf;
+
       if (rs->buf[0] == 'W' || rs->buf[0] == 'X')
 	{
 	  if (!extended_p)
@@ -3272,19 +3276,37 @@ remote_start_remote (int from_tty, struct target_ops *target, int extended_p)
       /* Let the stub know that we want it to return the thread.  */
       set_continue_thread (minus_one_ptid);
 
-      /* Without this, some commands which require an active target
-	 (such as kill) won't work.  This variable serves (at least)
-	 double duty as both the pid of the target process (if it has
-	 such), and as a flag indicating that a target is active.
-	 These functions should be split out into seperate variables,
-	 especially since GDB will someday have a notion of debugging
-	 several processes.  */
-      inferior_ptid = magic_null_ptid;
+      inferior_ptid = minus_one_ptid;
 
       /* Now, if we have thread information, update inferior_ptid.  */
-      inferior_ptid = remote_current_thread (inferior_ptid);
+      ptid = remote_current_thread (inferior_ptid);
+      if (!ptid_equal (ptid, minus_one_ptid))
+	{
+	  if (ptid_get_pid (ptid) == -1)
+	    {
+	      ptid = ptid_build (ptid_get_pid (magic_null_ptid),
+				 ptid_get_lwp (ptid),
+				 ptid_get_tid (ptid));
+	      fake_pid_p = 1;
+	    }
+
+	  inferior_ptid = ptid;
+	}
+      else
+	{
+	  /* Without this, some commands which require an active
+	     target (such as kill) won't work.  This variable serves
+	     (at least) double duty as both the pid of the target
+	     process (if it has such), and as a flag indicating that a
+	     target is active.  These functions should be split out
+	     into seperate variables, especially since GDB will
+	     someday have a notion of debugging several processes.  */
+	  inferior_ptid = magic_null_ptid;
+	  fake_pid_p = 1;
+	}
 
-      remote_add_inferior (ptid_get_pid (inferior_ptid), -1);
+      inf = remote_add_inferior (ptid_get_pid (inferior_ptid), -1);
+      inf->fake_pid_p = fake_pid_p;
 
       /* Always add the main thread.  */
       add_thread_silent (inferior_ptid);