* Beginnings of SOM shared library support. Breakpoints and

	single frame backtracing within the library only.  Only works when
	using the HPUX 9 dynamic linker.  More functionality to be added
	soon.

	* somsolib.c, somsolib.h: New files.
	* Makefile.in (HFILES_NO_SRCDIR): Add somsolib.h
	(ALLDEPFILES): Add somsolib.c.
	(somsolib.o): Add some dependencies.
	* mpw-make.in (HFILES_NO_SRCDIR): Add somsolib.h
	(ALLDEPFILES): Add somsolib.c.
	(somsolib.o): Add some dependencies.
	* somread.c (som_symtab_read): Accept multiple section offsets.
	All callers changed.  Adjust all text symbols with the first
	section offset.
	* symfile.c (find_lowest_section): Enable this function.  Add some
	tie-breaking logic when sections have the same vma.
	(syms_from_objfile): Use find_lowest_section rather than looking
	for ".text" by name.  Relax warning to only warn if the lowest
	section is not a code section.
	* config/pa/{hppabsd.mh, hppahpux.mh} (NATDEPFILES): Add somsolib.o
	* config/pa/{nm-hppab.h, nm-hppah.h}: Include somsolib.h.

1 files changed, 319 insertions, 0 deletions

diff --git a/gdb/somsolib.c b/gdb/somsolib.c
new file mode 100644
index 0000000..67d12ab
--- /dev/null
+++ b/gdb/somsolib.c
@@ -0,0 +1,319 @@
+/* Handle HP SOM shared libraries for GDB, the GNU Debugger.
+   Copyright 1993 Free Software Foundation, Inc.
+   
+This file is part of GDB.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+Written by the Center for Software Science at the Univerity of Utah
+and by Cygnus Support.  */
+
+
+#include "defs.h"
+
+#include "frame.h"
+#include "bfd.h"
+#include "som.h"
+#include "libhppa.h"
+#include "gdbcore.h"
+#include "symtab.h"
+#include "breakpoint.h"
+#include "symfile.h"
+#include "objfiles.h"
+#include "inferior.h"
+
+/* We don't currently use this structure, but it isn't documented anywhere,
+   and we'll likely need it in som_solib_add as more shared library support
+   is added.  */
+
+struct som_solib_mapped_entry
+{
+  /* The name of the library.  */
+  char *name;
+
+  /* Version of this structure (it is expected to change again in hpux10.  */
+  unsigned char struct_version;
+
+  /* Binding mode for this library.  */
+  unsigned char bind_mode;
+
+  /* Version of this library.  */
+  short library_version;
+
+  /* Start of text address, link-time text location, end of text address.  */
+  CORE_ADDR text_addr;
+  CORE_ADDR text_link_addr;
+  CORE_ADDR text_end;
+
+  /* Start of data, start of bss and end of data.  */
+  CORE_ADDR data_start;
+  CORE_ADDR bss_start;
+  CORE_ADDR data_end;
+
+  /* Value of linkage pointer (%r19).  */
+  CORE_ADDR got_value;
+
+  /* Next entry.  */
+  struct som_solib_mapped_entry *next;
+
+  /* There are other fields, but I don't have information as to what is
+     contained in them.  */
+};
+
+/* Add symbols from shared libraries into the symtab list.  */
+
+void
+som_solib_add (arg_string, from_tty, target)
+     char *arg_string;
+     int from_tty;
+     struct target_ops *target;
+{	
+  struct minimal_symbol *msymbol;
+  CORE_ADDR addr;
+  int status;
+  char buf[4];
+
+  msymbol = lookup_minimal_symbol ("__dld_list", (struct objfile *) NULL);
+  if (!msymbol)
+    {
+      /* Older crt0.o files (hpux8) don't have __dld_list as a symbol,
+	 but the data is still available if you know where to look.  */
+      msymbol = lookup_minimal_symbol ("__dld_flags", (struct objfile *)NULL);
+      if (!msymbol)
+	{
+	  error ("Unable to find dynamic library list.\n");
+	  return;
+	}
+      addr = SYMBOL_VALUE_ADDRESS (msymbol) - 8;
+    }
+  else
+    addr = SYMBOL_VALUE_ADDRESS (msymbol);
+
+  status = target_read_memory (addr, buf, 4);
+  if (status != 0)
+    {
+      error ("Unable to find dynamic library list.\n");
+      return;
+    }
+
+  addr = extract_unsigned_integer (buf, 4);
+
+  /* If addr is zero, then we're using an old dynamic loader which
+     doesn't maintain __dld_list.  We'll have to use a completely
+     different approach to get shared library information.  */
+  if (addr == 0)
+    goto old_dld;
+
+  /* Using the information in __dld_list is the preferred method
+     to get at shared library information.  It doesn't depend on
+     any functions in /usr/lib/end.o and has a chance of working
+     with hpux10 when it is released.  */
+  status = target_read_memory (addr, buf, 4);
+  if (status != 0)
+    {
+      error ("Unable to find dynamic library list.\n");
+      return;
+    }
+
+  /* addr now holds the address of the first entry in the dynamic
+     library list.  */
+  addr = extract_unsigned_integer (buf, 4);
+
+  /* Now that we have a pointer to the dynamic library list, walk
+     through it and add the symbols for each library.
+
+     Skip the first entry since it's our executable.  */
+  status = target_read_memory (addr + 36, buf, 4);
+  if (status != 0)
+    {
+      error ("Error while reading dynamic library list.\n");
+      return;
+    }
+  addr = extract_unsigned_integer (buf, 4);
+
+  while (1)
+    {
+      CORE_ADDR name_addr, text_addr;
+      unsigned int name_len;
+      char *name;
+      if (addr == 0)
+	break;
+
+      /* Get a pointer to the name of this library.  */
+      status = target_read_memory (addr, buf, 4);
+      if (status != 0)
+	{
+	  error ("Error while reading dynamic library list.\n");
+	  return;
+	}
+      name_addr = extract_unsigned_integer (buf, 4);
+      name_len = 0;
+      while (1)
+	{
+	  target_read_memory (name_addr + name_len, buf, 1);
+	  if (status != 0)
+	    {
+	      error ("Error while reading dynamic library list.\n");
+	      return;
+	    }
+	  name_len++;
+	  if (*buf == '\0')
+	    break;
+	}
+      name = alloca (name_len);
+      status = target_read_memory (name_addr, name, name_len);
+      if (status != 0)
+	{
+	  error ("Error while reading dynamic library list.\n");
+	  return;
+	}
+      name = obsavestring (name, name_len - 1,
+			   &symfile_objfile->symbol_obstack);
+
+      status = target_read_memory (addr + 8, buf, 4);
+      if (status != 0)
+	{
+	  error ("Error while reading dynamic library list.\n");
+	  return;
+	}
+      text_addr = extract_unsigned_integer (buf, 4);
+
+      /* OK, we've got everything we need.  Tell GDB about it.  */
+      symbol_file_add (name, from_tty, text_addr, 0, 0, 0);
+
+      /* Get address of the next record.  */
+      status = target_read_memory (addr + 36, buf, 4);
+      if (status != 0)
+	{
+	  error ("Error while reading dynamic library list.\n");
+	  return;
+	}
+      addr = extract_unsigned_integer (buf, 4);
+    }
+
+  /* Getting new symbols may change our opinion about what is
+     frameless.  */
+  reinit_frame_cache ();
+  return;
+
+old_dld:
+  error ("Debugging dynamic executables loaded via the hpux8 dld.sl is not supported.\n");
+  return;
+}
+
+/* This hook gets called just before the first instruction in the
+   inferior process is executed.
+
+   This is our opportunity to set magic flags in the inferior so
+   that GDB can be notified when a shared library is mapped in and
+   to tell the dynamic linker that a private copy of the library is
+   needed (so GDB can set breakpoints in the library).
+
+   __dld_flags is the location of the magic flags; as of this implementation
+   there are 3 flags of interest:
+
+   bit 0 when set indicates that private copies of the libraries are needed
+   bit 1 when set indicates that the callback hook routine is valid
+   bit 2 when set indicates that the dynamic linker should maintain the
+         __dld_list structure when loading/unloading libraries.
+
+   Note that shared libraries are not mapped in at this time, so we have
+   run the inferior until the libraries are mapped in.  Typically this
+   means running until the "_start" is called.  */
+   
+void 
+som_solib_create_inferior_hook()
+{
+  struct minimal_symbol *msymbol;
+  asection *shlib_info;
+  unsigned int dld_flags, status;
+  char shadow_contents[BREAKPOINT_MAX], buf[4];
+  CORE_ADDR anaddr;
+
+  /* First see if the objfile was dynamically linked.  */
+  shlib_info = bfd_get_section_by_name (symfile_objfile->obfd, "$SHLIB_INFO$");
+  if (!shlib_info)
+    return;
+
+  /* It's got a $SHLIB_INFO$ section, make sure it's not empty.  */
+  if (bfd_section_size (symfile_objfile->obfd, shlib_info) == 0)
+    return;
+
+  /* Get the address of __dld_flags, if no such symbol exists, then we can
+     not debug the shared code.  */
+  msymbol = lookup_minimal_symbol ("__dld_flags", (struct objfile *) NULL);
+  if (msymbol == NULL)
+    {
+      error ("Unable to find __dld_flags symbol in object file.\n");
+      return;
+    }
+
+  anaddr = SYMBOL_VALUE_ADDRESS (msymbol);
+  /* Read the current contents.  */
+  status = target_read_memory (anaddr, buf, 4);
+  if (status != 0)
+    {
+      error ("Unable to read __dld_flags\n");
+      return;
+    }
+  dld_flags = extract_unsigned_integer (buf, 4);
+
+  /* Turn on the flags we care about.  */
+  dld_flags |= 0x5;
+  store_unsigned_integer (buf, 4, dld_flags);
+  status = target_write_memory (anaddr, buf, 4);
+  if (status != 0)
+    {
+      error ("Unable to write __dld_flags\n");
+      return;
+    }
+
+  /* Now find the address of _start and set a breakpoint there.  */
+  msymbol = lookup_minimal_symbol ("_start", symfile_objfile);
+  if (msymbol == NULL)
+    {
+      error ("Unable to find _start symbol in object file.\n");
+      return;
+    }
+
+  anaddr = SYMBOL_VALUE_ADDRESS (msymbol);
+  if (target_insert_breakpoint (anaddr, shadow_contents))
+    {
+      error ("Unable to set breakpoint at _start.\n");
+      return;
+    }
+
+  /* Start the process again and wait for it to hit our breakpoint.  */
+  clear_proceed_status ();
+  stop_soon_quietly = 1;
+  stop_signal = TARGET_SIGNAL_0;
+  do
+    {
+      target_resume (-1, 0, stop_signal);
+      wait_for_inferior ();
+    }
+  while (stop_signal != TARGET_SIGNAL_TRAP);
+  stop_soon_quietly = 0;
+
+  /* All the libraries should be mapped in now.  Remove our breakpoint and
+     read in the symbol tables from the shared libraries.  */
+  if (target_remove_breakpoint (anaddr, shadow_contents))
+    {
+      error ("Unable to remove breakpoint at _start.\n");
+      return;
+    }
+
+  som_solib_add ((char *) 0, 0, (struct target_ops *) 0);
+}