* core.c (core_open): Improve error message for bad file.

Pass .reg virtual memory address to fetch_core_registers to help
it find the registers in the core-file header.
* coredep.c (fetch_core_registers):  Take new argument, use it,
and pass it to register_addr to locate the block of registers.

2 files changed, 37 insertions, 11 deletions

diff --git a/gdb/core.c b/gdb/core.c
index ad2830c..2ec4244 100644
--- a/gdb/core.c
+++ b/gdb/core.c
@@ -131,8 +131,8 @@ core_open (filename, from_tty)
 
   if (!bfd_check_format (temp_bfd, bfd_core))
     {
-      bfd_close (temp_bfd);
-      error ("\"%s\" does not appear to be a core dump", filename);
+      make_cleanup (bfd_close, temp_bfd);	/* Do it after the err msg */
+      error ("\"%s\" is not a core dump: %s", filename, bfd_errmsg(bfd_error));
     }
 
   /* Looks semi-reasonable.  Toss the old core file and work on the new.  */
@@ -399,10 +399,10 @@ get_core_registers (regno)
   if (!reg_sec) goto cant;
   size = bfd_section_size (core_bfd, reg_sec);
   the_regs = alloca (size);
-  if (bfd_get_section_contents (core_bfd, reg_sec, the_regs,
-				(unsigned)0, size))
+  if (bfd_get_section_contents (core_bfd, reg_sec, the_regs, (file_ptr)0, size))
     {
-      fetch_core_registers (the_regs, size, 0);
+      fetch_core_registers (the_regs, size, 0,
+			    (unsigned) bfd_section_vma (abfd,reg_sec));
     }
   else
     {
@@ -416,10 +416,11 @@ cant:
   if (reg_sec) {
     size = bfd_section_size (core_bfd, reg_sec);
     the_regs = alloca (size);
-    if (bfd_get_section_contents (core_bfd, reg_sec, the_regs,
-				  (unsigned)0, size))
+    if (bfd_get_section_contents (core_bfd, reg_sec, the_regs, (file_ptr)0,
+				  size))
       {
-	fetch_core_registers (the_regs, size, 2);
+	fetch_core_registers (the_regs, size, 2,
+			      (unsigned) bfd_section_vma (abfd,reg_sec));
       }
     else
       {
diff --git a/gdb/coredep.c b/gdb/coredep.c
index 87011c4..81fb3a4 100644
--- a/gdb/coredep.c
+++ b/gdb/coredep.c
@@ -23,6 +23,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #include "defs.h"
 #include "param.h"
 #include "gdbcore.h"
+#include <stdio.h>
 
 /* Some of these are needed on various systems, perhaps, to expand
    REGISTER_U_ADDR appropriately?  */
@@ -38,20 +39,44 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 
 /* Extract the register values out of the core file and store
-   them where `read_register' will find them.  */
+   them where `read_register' will find them.
+
+   CORE_REG_SECT points to the register values themselves, read into memory.
+   CORE_REG_SIZE is the size of that area.
+   WHICH says which set of registers we are handling (0 = int, 2 = float
+         on machines where they are discontiguous).
+   REG_ADDR is the offset from u.u_ar0 to the register values relative to
+            core_reg_sect.  This is used with old-fashioned core files to
+	    locate the registers in a large upage-plus-stack ".reg" section.
+	    Original upage address X is at location core_reg_sect+x+reg_addr.
+ */
 
 void
-fetch_core_registers (core_reg_sect, core_reg_size)
+fetch_core_registers (core_reg_sect, core_reg_size, which, reg_addr)
      char *core_reg_sect;
      unsigned core_reg_size;
+     int which;
+     unsigned reg_addr;
 {
   register int regno;
   register unsigned int addr;
   int bad_reg = -1;
+  register reg_ptr = -reg_addr;		/* Original u.u_ar0 is -reg_addr. */
+
+  /* If u.u_ar0 was an absolute address in the core file, relativize it now,
+     so we can use it as an offset into core_reg_sect.  When we're done,
+     "register 0" will be at core_reg_sect+reg_ptr, and we can use
+     register_addr to offset to the other registers.  If this is a modern
+     core file without a upage, reg_ptr will be zero and this is all a big
+     NOP.  */
+  if (reg_ptr > core_reg_size)
+    reg_ptr -= KERNEL_U_ADDR;
+  if (reg_ptr > core_reg_size)
+    fprintf (stderr, "Can't find registers in core file\n");
 
   for (regno = 0; regno < NUM_REGS; regno++)
     {
-      addr = register_addr (regno, core_reg_size);
+      addr = register_addr (regno, reg_ptr);
       if (addr >= core_reg_size) {
 	if (bad_reg < 0)
 	  bad_reg = regno;