binutils-gdb/gdb/osfsolib.c

/* Handle OSF/1 shared libraries for GDB, the GNU Debugger.
   Copyright 1993, 1994, 1995, 1996, 1998 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* FIXME: Most of this code could be merged with solib.c by using
   next_link_map_member and xfer_link_map_member in solib.c.  */

#include "defs.h"

#include <sys/types.h>
#include <signal.h>
#include "gdb_string.h"
#include <fcntl.h>

#include "symtab.h"
#include "bfd.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcore.h"
#include "command.h"
#include "target.h"
#include "frame.h"
#include "gnu-regex.h"
#include "inferior.h"
#include "language.h"
#include "gdbcmd.h"

#define MAX_PATH_SIZE 1024		/* FIXME: Should be dynamic */

/* When handling shared libraries, GDB has to find out the pathnames
   of all shared libraries that are currently loaded (to read in their
   symbols) and where the shared libraries are loaded in memory
   (to relocate them properly from their prelinked addresses to the
   current load address).

   Under OSF/1 there are two possibilities to get at this information:
   1) Peek around in the runtime loader structures.
      These are not documented, and they are not defined in the system
      header files. The definitions below were obtained by experimentation,
      but they seem stable enough.
   2) Use the undocumented libxproc.a library, which contains the
      equivalent ldr_* routines.
      This approach is somewhat cleaner, but it requires that the GDB
      executable is dynamically linked. In addition it requires a
      NAT_CLIBS= -lxproc -Wl,-expect_unresolved,ldr_process_context
      linker specification for GDB and all applications that are using
      libgdb.
   We will use the peeking approach until it becomes unwieldy.  */

#ifndef USE_LDR_ROUTINES

/* Definition of runtime loader structures, found by experimentation.  */
#define RLD_CONTEXT_ADDRESS	0x3ffc0000000

typedef struct
{
	CORE_ADDR next;
	CORE_ADDR previous;
	CORE_ADDR unknown1;
	char *module_name;
	CORE_ADDR modinfo_addr;
	long module_id;
	CORE_ADDR unknown2;
	CORE_ADDR unknown3;
	long region_count;
	CORE_ADDR regioninfo_addr;
} ldr_module_info_t;

typedef struct
{
	long unknown1;
	CORE_ADDR regionname_addr;
	long protection;
	CORE_ADDR vaddr;
	CORE_ADDR mapaddr;
	long size;
	long unknown2[5];
} ldr_region_info_t;

typedef struct
{
	CORE_ADDR unknown1;
	CORE_ADDR unknown2;
	CORE_ADDR head;
	CORE_ADDR tail;
} ldr_context_t;

static ldr_context_t ldr_context;

#else

#include <loader.h>
static ldr_process_t fake_ldr_process;

/* Called by ldr_* routines to read memory from the current target.  */

static int ldr_read_memory PARAMS ((CORE_ADDR, char *, int, int));

static int
ldr_read_memory (memaddr, myaddr, len, readstring)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
     int readstring;
{
  int result;
  char *buffer;

  if (readstring)
    {
      target_read_string (memaddr, &buffer, len, &result);
      if (result == 0)
        strcpy (myaddr, buffer);
      free (buffer);
    }
  else
    result = target_read_memory (memaddr, myaddr, len);

  if (result != 0)
    result = -result;
  return result;
}

#endif

/* Define our own link_map structure.
   This will help to share code with solib.c.  */

struct link_map {
  CORE_ADDR l_offset;			/* prelink to load address offset */
  char *l_name;				/* full name of loaded object */
  ldr_module_info_t module_info;	/* corresponding module info */
};

#define LM_OFFSET(so) ((so) -> lm.l_offset)
#define LM_NAME(so) ((so) -> lm.l_name)

struct so_list {
  struct so_list *next;			/* next structure in linked list */
  struct link_map lm;			/* copy of link map from inferior */
  struct link_map *lmaddr;		/* addr in inferior lm was read from */
  CORE_ADDR lmend;			/* upper addr bound of mapped object */
  char so_name[MAX_PATH_SIZE];		/* shared object lib name (FIXME) */
  char symbols_loaded;			/* flag: symbols read in yet? */
  char from_tty;			/* flag: print msgs? */
  struct objfile *objfile;		/* objfile for loaded lib */
  struct section_table *sections;
  struct section_table *sections_end;
  struct section_table *textsection;
  bfd *abfd;
};

static struct so_list *so_list_head;	/* List of known shared objects */

extern int
fdmatch PARAMS ((int, int));		/* In libiberty */

/* Local function prototypes */

static void
sharedlibrary_command PARAMS ((char *, int));

static void
info_sharedlibrary_command PARAMS ((char *, int));

static int
symbol_add_stub PARAMS ((char *));

static struct so_list *
find_solib PARAMS ((struct so_list *));

static struct link_map *
first_link_map_member PARAMS ((void));

static struct link_map *
next_link_map_member PARAMS ((struct so_list *));

static void
xfer_link_map_member PARAMS ((struct so_list *, struct link_map *));

static int
solib_map_sections PARAMS ((char *));

/*

LOCAL FUNCTION

	solib_map_sections -- open bfd and build sections for shared lib

SYNOPSIS

	static int solib_map_sections (struct so_list *so)

DESCRIPTION

	Given a pointer to one of the shared objects in our list
	of mapped objects, use the recorded name to open a bfd
	descriptor for the object, build a section table, and then
	relocate all the section addresses by the base address at
	which the shared object was mapped.

FIXMES

	In most (all?) cases the shared object file name recorded in the
	dynamic linkage tables will be a fully qualified pathname.  For
	cases where it isn't, do we really mimic the systems search
	mechanism correctly in the below code (particularly the tilde
	expansion stuff?).
 */

static int
solib_map_sections (arg)
     char *arg;
{
  struct so_list *so = (struct so_list *) arg;	/* catch_errors bogon */
  char *filename;
  char *scratch_pathname;
  int scratch_chan;
  struct section_table *p;
  struct cleanup *old_chain;
  bfd *abfd;
  
  filename = tilde_expand (so -> so_name);
  old_chain = make_cleanup (free, filename);
  
  scratch_chan = openp (getenv ("PATH"), 1, filename, O_RDONLY, 0,
			&scratch_pathname);
  if (scratch_chan < 0)
    {
      scratch_chan = openp (getenv ("LD_LIBRARY_PATH"), 1, filename,
			    O_RDONLY, 0, &scratch_pathname);
    }
  if (scratch_chan < 0)
    {
      perror_with_name (filename);
    }
  /* Leave scratch_pathname allocated.  bfd->name will point to it.  */

  abfd = bfd_fdopenr (scratch_pathname, gnutarget, scratch_chan);
  if (!abfd)
    {
      close (scratch_chan);
      error ("Could not open `%s' as an executable file: %s",
	     scratch_pathname, bfd_errmsg (bfd_get_error ()));
    }
  /* Leave bfd open, core_xfer_memory and "info files" need it.  */
  so -> abfd = abfd;
  abfd -> cacheable = true;

  if (!bfd_check_format (abfd, bfd_object))
    {
      error ("\"%s\": not in executable format: %s.",
	     scratch_pathname, bfd_errmsg (bfd_get_error ()));
    }
  if (build_section_table (abfd, &so -> sections, &so -> sections_end))
    {
      error ("Can't find the file sections in `%s': %s", 
	     bfd_get_filename (exec_bfd), bfd_errmsg (bfd_get_error ()));
    }

  for (p = so -> sections; p < so -> sections_end; p++)
    {
      /* Relocate the section binding addresses as recorded in the shared
	 object's file by the offset to get the address to which the
	 object was actually mapped.  */
      p -> addr += LM_OFFSET (so);
      p -> endaddr += LM_OFFSET (so);
      so -> lmend = (CORE_ADDR) max (p -> endaddr, so -> lmend);
      if (STREQ (p -> the_bfd_section -> name, ".text"))
	{
	  so -> textsection = p;
	}
    }

  /* Free the file names, close the file now.  */
  do_cleanups (old_chain);

  return (1);
}

/*

LOCAL FUNCTION

	first_link_map_member -- locate first member in dynamic linker's map

SYNOPSIS

	static struct link_map *first_link_map_member (void)

DESCRIPTION

	Read in a copy of the first member in the inferior's dynamic
	link map from the inferior's dynamic linker structures, and return
	a pointer to the copy in our address space.
*/

static struct link_map *
first_link_map_member ()
{
  struct link_map *lm = NULL;
  static struct link_map first_lm;

#ifdef USE_LDR_ROUTINES
  ldr_module_t mod_id = LDR_NULL_MODULE;
  size_t retsize;

  fake_ldr_process = ldr_core_process ();
  ldr_set_core_reader (ldr_read_memory);
  ldr_xdetach (fake_ldr_process);
  if (ldr_xattach (fake_ldr_process) != 0
      || ldr_next_module(fake_ldr_process, &mod_id) != 0
      || mod_id == LDR_NULL_MODULE
      || ldr_inq_module(fake_ldr_process, mod_id,
			&first_lm.module_info, sizeof(ldr_module_info_t),
			&retsize) != 0)
    return lm;
#else
  CORE_ADDR ldr_context_addr;

  if (target_read_memory ((CORE_ADDR) RLD_CONTEXT_ADDRESS,
			  (char *) &ldr_context_addr,
			  sizeof (CORE_ADDR)) != 0
      || target_read_memory (ldr_context_addr,
			     (char *) &ldr_context,
			     sizeof (ldr_context_t)) != 0
      || target_read_memory ((CORE_ADDR) ldr_context.head,
			     (char *) &first_lm.module_info,
			     sizeof (ldr_module_info_t)) != 0)
    return lm;
#endif

  lm = &first_lm;

  /* The first entry is for the main program and should be skipped.  */
  lm->l_name = NULL;

  return lm;
}

static struct link_map *
next_link_map_member (so_list_ptr)
     struct so_list *so_list_ptr;
{
  struct link_map *lm = NULL;
  static struct link_map next_lm;
#ifdef USE_LDR_ROUTINES
  ldr_module_t mod_id = so_list_ptr->lm.module_info.lmi_modid;
  size_t retsize;

  if (ldr_next_module(fake_ldr_process, &mod_id) != 0
      || mod_id == LDR_NULL_MODULE
      || ldr_inq_module(fake_ldr_process, mod_id,
			&next_lm.module_info, sizeof(ldr_module_info_t),
			&retsize) != 0)
    return lm;

  lm = &next_lm;
  lm->l_name = lm->module_info.lmi_name;
#else
  CORE_ADDR ldr_context_addr;

  /* Reread context in case ldr_context.tail was updated.  */

  if (target_read_memory ((CORE_ADDR) RLD_CONTEXT_ADDRESS,
			  (char *) &ldr_context_addr,
			  sizeof (CORE_ADDR)) != 0
      || target_read_memory (ldr_context_addr,
			     (char *) &ldr_context,
			     sizeof (ldr_context_t)) != 0
      || so_list_ptr->lm.module_info.modinfo_addr == ldr_context.tail
      || target_read_memory (so_list_ptr->lm.module_info.next,
			     (char *) &next_lm.module_info,
			     sizeof (ldr_module_info_t)) != 0)
    return lm;

  lm = &next_lm;
  lm->l_name = lm->module_info.module_name;
#endif
  return lm;
}

static void
xfer_link_map_member (so_list_ptr, lm)
     struct so_list *so_list_ptr;
     struct link_map *lm;
{
  int i;
  so_list_ptr->lm = *lm;

  /* OSF/1 shared libraries are pre-linked to particular addresses,
     but the runtime loader may have to relocate them if the
     address ranges of the libraries used by the target executable clash,
     or if the target executable is linked with the -taso option.
     The offset is the difference between the address where the shared
     library is mapped and the pre-linked address of the shared library.

     FIXME:  GDB is currently unable to relocate the shared library
     sections by different offsets. If sections are relocated by
     different offsets, put out a warning and use the offset of the
     first section for all remaining sections.  */
  LM_OFFSET (so_list_ptr) = 0;

  /* There is one entry that has no name (for the inferior executable)
     since it is not a shared object. */
  if (LM_NAME (so_list_ptr) != 0)
    {

#ifdef USE_LDR_ROUTINES
      int len = strlen (LM_NAME (so_list_ptr) + 1);

      if (len > MAX_PATH_SIZE)
	len = MAX_PATH_SIZE;
      strncpy (so_list_ptr->so_name, LM_NAME (so_list_ptr), MAX_PATH_SIZE);
      so_list_ptr->so_name[MAX_PATH_SIZE - 1] = '\0';

      for (i = 0; i < lm->module_info.lmi_nregion; i++)
	{
	  ldr_region_info_t region_info;
	  size_t retsize;
	  CORE_ADDR region_offset;

	  if (ldr_inq_region (fake_ldr_process, lm->module_info.lmi_modid,
			      i, &region_info, sizeof (region_info),
			      &retsize) != 0)
	    break;
	  region_offset = (CORE_ADDR) region_info.lri_mapaddr
			  - (CORE_ADDR) region_info.lri_vaddr;
	  if (i == 0)
	    LM_OFFSET (so_list_ptr) = region_offset;
	  else if (LM_OFFSET (so_list_ptr) != region_offset)
	    warning ("cannot handle shared library relocation for %s (%s)",
		     so_list_ptr->so_name, region_info.lri_name);
	}
#else
      int errcode;
      char *buffer;
      target_read_string ((CORE_ADDR) LM_NAME (so_list_ptr), &buffer,
			  MAX_PATH_SIZE - 1, &errcode);
      if (errcode != 0)
	error ("xfer_link_map_member: Can't read pathname for load map: %s\n",
	       safe_strerror (errcode));
      strncpy (so_list_ptr->so_name, buffer, MAX_PATH_SIZE - 1);
      free (buffer);
      so_list_ptr->so_name[MAX_PATH_SIZE - 1] = '\0';

      for (i = 0; i < lm->module_info.region_count; i++)
	{
	  ldr_region_info_t region_info;
	  CORE_ADDR region_offset;

	  if (target_read_memory (lm->module_info.regioninfo_addr
				   + i * sizeof (region_info),
				  (char *) &region_info,
				  sizeof (region_info)) != 0)
	    break;
	  region_offset = region_info.mapaddr - region_info.vaddr;
	  if (i == 0)
	    LM_OFFSET (so_list_ptr) = region_offset;
	  else if (LM_OFFSET (so_list_ptr) != region_offset)
	    {
	      char *region_name;
	      target_read_string (region_info.regionname_addr, &buffer,
				  MAX_PATH_SIZE - 1, &errcode);
	      if (errcode == 0)
		region_name = buffer;
	      else
		region_name = "??";
	      warning ("cannot handle shared library relocation for %s (%s)",
		        so_list_ptr->so_name, region_name);
	      free (buffer);
	    }
	}
#endif

      catch_errors (solib_map_sections, (char *) so_list_ptr,
		    "Error while mapping shared library sections:\n",
		    RETURN_MASK_ALL);
    }
}

/*

LOCAL FUNCTION

	find_solib -- step through list of shared objects

SYNOPSIS

	struct so_list *find_solib (struct so_list *so_list_ptr)

DESCRIPTION

	This module contains the routine which finds the names of any
	loaded "images" in the current process. The argument in must be
	NULL on the first call, and then the returned value must be passed
	in on subsequent calls. This provides the capability to "step" down
	the list of loaded objects. On the last object, a NULL value is
	returned.

	The arg and return value are "struct link_map" pointers, as defined
	in <link.h>.
 */

static struct so_list *
find_solib (so_list_ptr)
     struct so_list *so_list_ptr;	/* Last lm or NULL for first one */
{
  struct so_list *so_list_next = NULL;
  struct link_map *lm = NULL;
  struct so_list *new;
  
  if (so_list_ptr == NULL)
    {
      /* We are setting up for a new scan through the loaded images. */
      if ((so_list_next = so_list_head) == NULL)
	{
	  /* Find the first link map list member. */
	  lm = first_link_map_member ();
	}
    }
  else
    {
      /* We have been called before, and are in the process of walking
	 the shared library list.  Advance to the next shared object. */
      lm = next_link_map_member (so_list_ptr);
      so_list_next = so_list_ptr -> next;
    }
  if ((so_list_next == NULL) && (lm != NULL))
    {
      /* Get next link map structure from inferior image and build a local
	 abbreviated load_map structure */
      new = (struct so_list *) xmalloc (sizeof (struct so_list));
      memset ((char *) new, 0, sizeof (struct so_list));
      new -> lmaddr = lm;
      /* Add the new node as the next node in the list, or as the root
	 node if this is the first one. */
      if (so_list_ptr != NULL)
	{
	  so_list_ptr -> next = new;
	}
      else
	{
	  so_list_head = new;
	}      
      so_list_next = new;
      xfer_link_map_member (new, lm);
    }
  return (so_list_next);
}

/* A small stub to get us past the arg-passing pinhole of catch_errors.  */

static int
symbol_add_stub (arg)
     char *arg;
{
  register struct so_list *so = (struct so_list *) arg;	/* catch_errs bogon */
  CORE_ADDR text_addr = 0;

  if (so -> textsection)
    text_addr = so -> textsection -> addr;
  else if (so -> abfd != NULL)
    {
      asection *lowest_sect;

      /* If we didn't find a mapped non zero sized .text section, set up
	 text_addr so that the relocation in symbol_file_add does no harm.  */

      lowest_sect = bfd_get_section_by_name (so -> abfd, ".text");
      if (lowest_sect == NULL)
	bfd_map_over_sections (so -> abfd, find_lowest_section,
			       (PTR) &lowest_sect);
      if (lowest_sect)
	text_addr = bfd_section_vma (so -> abfd, lowest_sect) + LM_OFFSET (so);
    }
  
  so -> objfile = symbol_file_add (so -> so_name, so -> from_tty,
				   text_addr,
				   0, 0, 0, 0, 1);
  return (1);
}

/*

GLOBAL FUNCTION

	solib_add -- add a shared library file to the symtab and section list

SYNOPSIS

	void solib_add (char *arg_string, int from_tty,
			struct target_ops *target)

DESCRIPTION

*/

void
solib_add (arg_string, from_tty, target)
     char *arg_string;
     int from_tty;
     struct target_ops *target;
{	
  register struct so_list *so = NULL;   	/* link map state variable */

  /* Last shared library that we read.  */
  struct so_list *so_last = NULL;

  char *re_err;
  int count;
  int old;
  
  if ((re_err = re_comp (arg_string ? arg_string : ".")) != NULL)
    {
      error ("Invalid regexp: %s", re_err);
    }
  
  
  /* Add the shared library sections to the section table of the
     specified target, if any.  */
  if (target)
    {
      /* Count how many new section_table entries there are.  */
      so = NULL;
      count = 0;
      while ((so = find_solib (so)) != NULL)
	{
	  if (so -> so_name[0])
	    {
	      count += so -> sections_end - so -> sections;
	    }
	}
      
      if (count)
	{
	  int update_coreops;

	  /* We must update the to_sections field in the core_ops structure
	     here, otherwise we dereference a potential dangling pointer
	     for each call to target_read/write_memory within this routine.  */
	  update_coreops = core_ops.to_sections == target->to_sections;
	     
	  /* Reallocate the target's section table including the new size.  */
	  if (target -> to_sections)
	    {
	      old = target -> to_sections_end - target -> to_sections;
	      target -> to_sections = (struct section_table *)
		xrealloc ((char *)target -> to_sections,
			 (sizeof (struct section_table)) * (count + old));
	    }
	  else
	    {
	      old = 0;
	      target -> to_sections = (struct section_table *)
		xmalloc ((sizeof (struct section_table)) * count);
	    }
	  target -> to_sections_end = target -> to_sections + (count + old);
	  
	  /* Update the to_sections field in the core_ops structure
	     if needed.  */
	  if (update_coreops)
	    {
	      core_ops.to_sections = target->to_sections;
	      core_ops.to_sections_end = target->to_sections_end;
	    }

	  /* Add these section table entries to the target's table.  */
	  while ((so = find_solib (so)) != NULL)
	    {
	      if (so -> so_name[0])
		{
		  count = so -> sections_end - so -> sections;
		  memcpy ((char *) (target -> to_sections + old),
			  so -> sections, 
			  (sizeof (struct section_table)) * count);
		  old += count;
		}
	    }
	}
    }
  
  /* Now add the symbol files.  */
  so = NULL;
  while ((so = find_solib (so)) != NULL)
    {
      if (so -> so_name[0] && re_exec (so -> so_name))
	{
	  so -> from_tty = from_tty;
	  if (so -> symbols_loaded)
	    {
	      if (from_tty)
		{
		  printf_unfiltered ("Symbols already loaded for %s\n", so -> so_name);
		}
	    }
	  else if (catch_errors
		   (symbol_add_stub, (char *) so,
		    "Error while reading shared library symbols:\n",
		    RETURN_MASK_ALL))
	    {
	      so_last = so;
	      so -> symbols_loaded = 1;
	    }
	}
    }

  /* Getting new symbols may change our opinion about what is
     frameless.  */
  if (so_last)
    reinit_frame_cache ();
}

/*

LOCAL FUNCTION

	info_sharedlibrary_command -- code for "info sharedlibrary"

SYNOPSIS

	static void info_sharedlibrary_command ()

DESCRIPTION

	Walk through the shared library list and print information
	about each attached library.
*/

static void
info_sharedlibrary_command (ignore, from_tty)
     char *ignore;
     int from_tty;
{
  register struct so_list *so = NULL;  	/* link map state variable */
  int header_done = 0;
  
  if (exec_bfd == NULL)
    {
      printf_unfiltered ("No exec file.\n");
      return;
    }
  while ((so = find_solib (so)) != NULL)
    {
      if (so -> so_name[0])
	{
	  unsigned long txt_start = 0;
	  unsigned long txt_end = 0;

	  if (!header_done)
	    {
	      printf_unfiltered("%-20s%-20s%-12s%s\n", "From", "To", "Syms Read",
		     "Shared Object Library");
	      header_done++;
	    }
	  if (so -> textsection)
	    {
	      txt_start = (unsigned long) so -> textsection -> addr;
	      txt_end = (unsigned long) so -> textsection -> endaddr;
	    }
	  printf_unfiltered ("%-20s", local_hex_string_custom (txt_start, "08l"));
	  printf_unfiltered ("%-20s", local_hex_string_custom (txt_end, "08l"));
	  printf_unfiltered ("%-12s", so -> symbols_loaded ? "Yes" : "No");
	  printf_unfiltered ("%s\n",  so -> so_name);
	}
    }
  if (so_list_head == NULL)
    {
      printf_unfiltered ("No shared libraries loaded at this time.\n");	
    }
}

/*

GLOBAL FUNCTION

	solib_address -- check to see if an address is in a shared lib

SYNOPSIS

	char *solib_address (CORE_ADDR address)

DESCRIPTION

	Provides a hook for other gdb routines to discover whether or
	not a particular address is within the mapped address space of
	a shared library.  Any address between the base mapping address
	and the first address beyond the end of the last mapping, is
	considered to be within the shared library address space, for
	our purposes.

	For example, this routine is called at one point to disable
	breakpoints which are in shared libraries that are not currently
	mapped in.
 */

char *
solib_address (address)
     CORE_ADDR address;
{
  register struct so_list *so = 0;   	/* link map state variable */
  
  while ((so = find_solib (so)) != NULL)
    {
      if (so -> so_name[0] && so -> textsection)
	{
	  if ((address >= (CORE_ADDR) so -> textsection -> addr) &&
	      (address < (CORE_ADDR) so -> textsection -> endaddr))
	    return (so->so_name);
	}
    }
  return (0);
}

/* Called by free_all_symtabs */

void 
clear_solib()
{
  struct so_list *next;
  char *bfd_filename;
  
  while (so_list_head)
    {
      if (so_list_head -> sections)
	{
	  free ((PTR)so_list_head -> sections);
	}
      if (so_list_head -> abfd)
	{
	  bfd_filename = bfd_get_filename (so_list_head -> abfd);
	  if (!bfd_close (so_list_head -> abfd))
	    warning ("cannot close \"%s\": %s",
		     bfd_filename, bfd_errmsg (bfd_get_error ()));
	}
      else
	/* This happens for the executable on SVR4.  */
	bfd_filename = NULL;
      
      next = so_list_head -> next;
      if (bfd_filename)
	free ((PTR)bfd_filename);
      free ((PTR)so_list_head);
      so_list_head = next;
    }
}
  
/*
  
GLOBAL FUNCTION
  
	solib_create_inferior_hook -- shared library startup support
  
SYNOPSIS
  
	void solib_create_inferior_hook()
  
DESCRIPTION

	When gdb starts up the inferior, it nurses it along (through the
	shell) until it is ready to execute it's first instruction.  At this
	point, this function gets called via expansion of the macro
	SOLIB_CREATE_INFERIOR_HOOK.
	For a statically bound executable, this first instruction is the
	one at "_start", or a similar text label. No further processing is
	needed in that case.
	For a dynamically bound executable, this first instruction is somewhere
	in the rld, and the actual user executable is not yet mapped in.
	We continue the inferior again, rld then maps in the actual user
	executable and any needed shared libraries and then sends
	itself a SIGTRAP.
	At that point we discover the names of all shared libraries and
	read their symbols in.

FIXME

	This code does not properly handle hitting breakpoints which the
	user might have set in the rld itself.  Proper handling would have
	to check if the SIGTRAP happened due to a kill call.

	Also, what if child has exit()ed?  Must exit loop somehow.
  */

void
solib_create_inferior_hook()
{

  /* Nothing to do for statically bound executables.  */

  if (symfile_objfile == NULL
      || symfile_objfile->obfd == NULL
      || ((bfd_get_file_flags (symfile_objfile->obfd) & DYNAMIC) == 0))
    return;

  /* Now run the target.  It will eventually get a SIGTRAP, at
     which point all of the libraries will have been mapped in and we
     can go groveling around in the rld structures to find
     out what we need to know about them. */
 
  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);

  /*  solib_add will call reinit_frame_cache.
      But we are stopped in the runtime loader and we do not have symbols
      for the runtime loader. So heuristic_proc_start will be called
      and will put out an annoying warning.
      Delaying the resetting of stop_soon_quietly until after symbol loading
      suppresses the warning.  */
  if (auto_solib_add)
    solib_add ((char *) 0, 0, (struct target_ops *) 0);
  stop_soon_quietly = 0;
}


/*

LOCAL FUNCTION

	sharedlibrary_command -- handle command to explicitly add library

SYNOPSIS

	static void sharedlibrary_command (char *args, int from_tty)

DESCRIPTION

*/

static void
sharedlibrary_command (args, from_tty)
char *args;
int from_tty;
{
  dont_repeat ();
  solib_add (args, from_tty, (struct target_ops *) 0);
}

void
_initialize_solib()
{
  add_com ("sharedlibrary", class_files, sharedlibrary_command,
	   "Load shared object library symbols for files matching REGEXP.");
  add_info ("sharedlibrary", info_sharedlibrary_command, 
	    "Status of loaded shared object libraries.");

  add_show_from_set
    (add_set_cmd ("auto-solib-add", class_support, var_zinteger,
		  (char *) &auto_solib_add,
		  "Set autoloading of shared library symbols.\n\
If nonzero, symbols from all shared object libraries will be loaded\n\
automatically when the inferior begins execution or when the dynamic linker\n\
informs gdb that a new library has been loaded.  Otherwise, symbols\n\
must be loaded manually, using `sharedlibrary'.",
		  &setlist),
     &showlist);
}