A detach patch for gdb

[H.J. Lu]

Hi,

Detaching a process in gdb 4.17 will go into an infinite loop if the
process is killed. You cannot even get out of gdb. Here is a patch to
fix it.

Thanks.


-- 
H.J. Lu (hjl@gnu.org)
--
Thu Nov 19 08:17:43 1998  H.J. Lu  <hjl@gnu.org>

	* infptrace.c (detach): Handle errno == ESRCH gracefully.

	* target.c (print_waitstatus): New function.
	(debug_to_wait): Use it.
	* target.h (print_waitstatus): Add prototype.

Index: infptrace.c
===================================================================
RCS file: /home/work/cvs/gnu/gdb/gdb/infptrace.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 infptrace.c
--- infptrace.c	1998/05/29 13:57:35	1.1.1.1
+++ infptrace.c	1998/11/19 18:12:27
@@ -221,7 +221,26 @@ detach (signal)
   errno = 0;
   ptrace (PT_DETACH, inferior_pid, (PTRACE_ARG3_TYPE) 1, signal);
   if (errno)
-    perror_with_name ("ptrace");
+    {
+      if (errno == ESRCH)
+	{
+	  /* When we detach from a process, it may be killed and no
+	     longer exists. We should not go into an infinite loop. */
+	  print_sys_errmsg ("ptrace", errno);
+
+	  if (current_target.to_wait)
+	    {
+	      /* Let the process go. */
+	      int retval;
+	      struct target_waitstatus status;
+
+	      retval = current_target.to_wait (inferior_pid, &status);
+	      print_waitstatus (inferior_pid, &status, retval);
+	    }
+	}
+      else
+	perror_with_name ("ptrace");
+    }
   attach_flag = 0;
 }
 #endif /* ATTACH_DETACH */
Index: target.c
===================================================================
RCS file: /home/work/cvs/gnu/gdb/gdb/target.c,v
retrieving revision 1.2
diff -u -p -r1.2 target.c
--- target.c	1998/05/29 14:03:38	1.2
+++ target.c	1998/11/19 18:10:33
@@ -1696,6 +1696,17 @@ debug_to_wait (pid, status)
 
   retval = debug_target.to_wait (pid, status);
 
+  print_waitstatus (pid, status, retval);
+
+  return retval;
+}
+
+void
+print_waitstatus (pid, status, retval)
+     int pid;
+     struct target_waitstatus *status;
+     int retval;
+{
   fprintf_unfiltered (stderr, "target_wait (%d, status) = %d,   ", pid, retval);
   fprintf_unfiltered (stderr, "status->kind = ");
   switch (status->kind)
@@ -1721,8 +1732,6 @@ debug_to_wait (pid, status)
       fprintf_unfiltered (stderr, "unknown???\n");
       break;
     }
-
-  return retval;
 }
 
 static void
Index: target.h
===================================================================
RCS file: /home/work/cvs/gnu/gdb/gdb/target.h,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 target.h
--- target.h	1998/05/29 13:57:38	1.1.1.1
+++ target.h	1998/11/19 18:10:51
@@ -770,8 +770,10 @@ extern asection *target_memory_bfd_secti
 
 /* Functions for helping to write a native target.  */
 
-/* This is for native targets which use a unix/POSIX-style waitstatus.  */
+/* These are for native targets which use a unix/POSIX-style waitstatus.  */
 extern void store_waitstatus PARAMS ((struct target_waitstatus *, int));
+extern void print_waitstatus PARAMS ((int, struct target_waitstatus *,
+				      int));
 
 /* Convert between host signal numbers and enum target_signal's.  */
 extern enum target_signal target_signal_from_host PARAMS ((int));