Re: [patch] Implement qXfer:libraries for Linux/gdbserver

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi Paul,

with:
./gdbserver :1234 ~/t/pause64 
../gdb ~/t/pause64 -ex 'target remote localhost:1234' -ex 'b main' -ex c

it falls back back memory-transfers as DT_DEBUG is zero initially at _start.

just to get the patch integrated on some final patches assembly.


Thanks,
Jan


gdb/gdbserver/
2011-08-08  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix initial zero DT_DEBUG.
	* linux-low.c (linux_add_process): Remove r_debug initialization.
	(get_r_debug): Update function comment.  Return -1 when DT_DEBUG is not
	found.
	(linux_qxfer_libraries): Call get_r_debug on -1 (not 0).  Return on
	both -1 or 0.

--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -264,7 +264,6 @@ linux_add_process (int pid, int attached)
 
   proc = add_process (pid, attached);
   proc->private = xcalloc (1, sizeof (*proc->private));
-  proc->private->r_debug = (CORE_ADDR) -1;
 
   if (the_low_target.new_process != NULL)
     proc->private->arch_private = the_low_target.new_process ();
@@ -4863,7 +4862,8 @@ get_dynamic (const int pid, const int is_elf64)
   return 0;
 }
 
-/* Return &_r_debug in the inferior, or 0 if not present.  */
+/* Return &_r_debug in the inferior, or -1 if not present.  Return value
+   can be 0 if the inferior does not yet have the library list initialized.  */
 
 static CORE_ADDR
 get_r_debug (const int pid, const int is_elf64)
@@ -4874,7 +4874,7 @@ get_r_debug (const int pid, const int is_elf64)
 
   dynamic_memaddr = get_dynamic (pid, is_elf64);
   if (dynamic_memaddr == 0)
-    return 0;
+    return (CORE_ADDR) -1;
 
   while (linux_read_memory (dynamic_memaddr, buf, dyn_size) == 0)
     {
@@ -4981,12 +4981,10 @@ linux_qxfer_libraries (const char *annex, unsigned char *readbuf,
   is_elf64 = elf_64_file_p (filename);
   lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets;
 
-  if (priv->r_debug == (CORE_ADDR) -1)
+  if (priv->r_debug == 0)
     priv->r_debug = get_r_debug (pid, is_elf64);
 
-  gdb_assert (priv->r_debug != (CORE_ADDR) -1);
-
-  if (priv->r_debug == 0)
+  if (priv->r_debug == (CORE_ADDR) -1 || priv->r_debug == 0)
     {
       document = xstrdup ("<library-list/>\n");
     }