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/* Handle SVR4 shared libraries for GDB, the GNU Debugger.

   Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,

   2001

   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.  */

#include "defs.h"

#include "elf/external.h"

#include "elf/common.h"

#include "elf/mips.h"

#include "symtab.h"

#include "bfd.h"

#include "symfile.h"

#include "objfiles.h"

#include "gdbcore.h"

#include "target.h"

#include "inferior.h"

#include "solist.h"

#include "solib-svr4.h"

#ifndef SVR4_FETCH_LINK_MAP_OFFSETS

#define SVR4_FETCH_LINK_MAP_OFFSETS() svr4_fetch_link_map_offsets ()

#endif

static struct link_map_offsets *svr4_fetch_link_map_offsets (void);

static struct link_map_offsets *legacy_fetch_link_map_offsets (void);

/* fetch_link_map_offsets_gdbarch_data is a handle used to obtain the

   architecture specific link map offsets fetching function.  */

static struct gdbarch_data *fetch_link_map_offsets_gdbarch_data;

/* legacy_svr4_fetch_link_map_offsets_hook is a pointer to a function

   which is used to fetch link map offsets.  It will only be set

   by solib-legacy.c, if at all. */

struct link_map_offsets *(*legacy_svr4_fetch_link_map_offsets_hook)(void) = 0;

/* Link map info to include in an allocated so_list entry */

struct lm_info

  {

    /* Pointer to copy of link map from inferior.  The type is char *

       rather than void *, so that we may use byte offsets to find the

       various fields without the need for a cast.  */

    char *lm;

  };

/* On SVR4 systems, a list of symbols in the dynamic linker where

   GDB can try to place a breakpoint to monitor shared library

   events.

   If none of these symbols are found, or other errors occur, then

   SVR4 systems will fall back to using a symbol as the "startup

   mapping complete" breakpoint address.  */

static char *solib_break_names[] =

{

  "r_debug_state",

  "_r_debug_state",

  "_dl_debug_state",

  "rtld_db_dlactivity",

  "_rtld_debug_state",

  NULL

};

#define BKPT_AT_SYMBOL 1

#if defined (BKPT_AT_SYMBOL)

static char *bkpt_names[] =

{

#ifdef SOLIB_BKPT_NAME

  SOLIB_BKPT_NAME,              /* Prefer configured name if it exists. */

#endif

  "_start",

  "__start",

  "main",

  NULL

};

#endif

static char *main_name_list[] =

{

  "main_$main",

  NULL

};

/* Macro to extract an address from a solib structure.

   When GDB is configured for some 32-bit targets (e.g. Solaris 2.7

   sparc), BFD is configured to handle 64-bit targets, so CORE_ADDR is

   64 bits.  We have to extract only the significant bits of addresses

   to get the right address when accessing the core file BFD.  */

#define SOLIB_EXTRACT_ADDRESS(MEMBER) \

        extract_address (&(MEMBER), sizeof (MEMBER))

/* local data declarations */

/* link map access functions */

static CORE_ADDR

LM_ADDR (struct so_list *so)

{

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  return (CORE_ADDR) extract_signed_integer (so->lm_info->lm + lmo->l_addr_offset,

                                             lmo->l_addr_size);

}

static CORE_ADDR

LM_NEXT (struct so_list *so)

{

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  return extract_address (so->lm_info->lm + lmo->l_next_offset, lmo->l_next_size);

}

static CORE_ADDR

LM_NAME (struct so_list *so)

{

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  return extract_address (so->lm_info->lm + lmo->l_name_offset, lmo->l_name_size);

}

static int

IGNORE_FIRST_LINK_MAP_ENTRY (struct so_list *so)

{

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  return extract_address (so->lm_info->lm + lmo->l_prev_offset,

                          lmo->l_prev_size) == 0;

}

static CORE_ADDR debug_base;    /* Base of dynamic linker structures */

static CORE_ADDR breakpoint_addr;       /* Address where end bkpt is set */

/* Local function prototypes */

static int match_main (char *);

static CORE_ADDR bfd_lookup_symbol (bfd *, char *);

/*

   LOCAL FUNCTION

   bfd_lookup_symbol -- lookup the value for a specific symbol

   SYNOPSIS

   CORE_ADDR bfd_lookup_symbol (bfd *abfd, char *symname)

   DESCRIPTION

   An expensive way to lookup the value of a single symbol for

   bfd's that are only temporary anyway.  This is used by the

   shared library support to find the address of the debugger

   interface structures in the shared library.

   Note that 0 is specifically allowed as an error return (no

   such symbol).

 */

static CORE_ADDR

bfd_lookup_symbol (bfd *abfd, char *symname)

{

  long storage_needed;

  asymbol *sym;

  asymbol **symbol_table;

  unsigned int number_of_symbols;

  unsigned int i;

  struct cleanup *back_to;

  CORE_ADDR symaddr = 0;

  storage_needed = bfd_get_symtab_upper_bound (abfd);

  if (storage_needed > 0)

    {

      symbol_table = (asymbol **) xmalloc (storage_needed);

      back_to = make_cleanup (xfree, (PTR) symbol_table);

      number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);

      for (i = 0; i < number_of_symbols; i++)

        {

          sym = *symbol_table++;

          if (STREQ (sym->name, symname))

            {

              /* Bfd symbols are section relative. */

              symaddr = sym->value + sym->section->vma;

              break;

            }

        }

      do_cleanups (back_to);

    }

  if (symaddr)

    return symaddr;

  /* On FreeBSD, the dynamic linker is stripped by default.  So we'll

     have to check the dynamic string table too.  */

  storage_needed = bfd_get_dynamic_symtab_upper_bound (abfd);

  if (storage_needed > 0)

    {

      symbol_table = (asymbol **) xmalloc (storage_needed);

      back_to = make_cleanup (xfree, (PTR) symbol_table);

      number_of_symbols = bfd_canonicalize_dynamic_symtab (abfd, symbol_table);

      for (i = 0; i < number_of_symbols; i++)

        {

          sym = *symbol_table++;

          if (STREQ (sym->name, symname))

            {

              /* Bfd symbols are section relative. */

              symaddr = sym->value + sym->section->vma;

              break;

            }

        }

      do_cleanups (back_to);

    }

  return symaddr;

}

#ifdef HANDLE_SVR4_EXEC_EMULATORS

/*

   Solaris BCP (the part of Solaris which allows it to run SunOS4

   a.out files) throws in another wrinkle. Solaris does not fill

   in the usual a.out link map structures when running BCP programs,

   the only way to get at them is via groping around in the dynamic

   linker.

   The dynamic linker and it's structures are located in the shared

   C library, which gets run as the executable's "interpreter" by

   the kernel.

   Note that we can assume nothing about the process state at the time

   we need to find these structures.  We may be stopped on the first

   instruction of the interpreter (C shared library), the first

   instruction of the executable itself, or somewhere else entirely

   (if we attached to the process for example).

 */

static char *debug_base_symbols[] =

{

  "r_debug",                    /* Solaris 2.3 */

  "_r_debug",                   /* Solaris 2.1, 2.2 */

  NULL

};

static int look_for_base (int, CORE_ADDR);

/*

   LOCAL FUNCTION

   look_for_base -- examine file for each mapped address segment

   SYNOPSYS

   static int look_for_base (int fd, CORE_ADDR baseaddr)

   DESCRIPTION

   This function is passed to proc_iterate_over_mappings, which

   causes it to get called once for each mapped address space, with

   an open file descriptor for the file mapped to that space, and the

   base address of that mapped space.

   Our job is to find the debug base symbol in the file that this

   fd is open on, if it exists, and if so, initialize the dynamic

   linker structure base address debug_base.

   Note that this is a computationally expensive proposition, since

   we basically have to open a bfd on every call, so we specifically

   avoid opening the exec file.

 */

static int

look_for_base (int fd, CORE_ADDR baseaddr)

{

  bfd *interp_bfd;

  CORE_ADDR address = 0;

  char **symbolp;

  /* If the fd is -1, then there is no file that corresponds to this

     mapped memory segment, so skip it.  Also, if the fd corresponds

     to the exec file, skip it as well. */

  if (fd == -1

      || (exec_bfd != NULL

          && fdmatch (fileno ((FILE *) (exec_bfd->iostream)), fd)))

    {

      return (0);

    }

  /* Try to open whatever random file this fd corresponds to.  Note that

     we have no way currently to find the filename.  Don't gripe about

     any problems we might have, just fail. */

  if ((interp_bfd = bfd_fdopenr ("unnamed", gnutarget, fd)) == NULL)

    {

      return (0);

    }

  if (!bfd_check_format (interp_bfd, bfd_object))

    {

      /* FIXME-leak: on failure, might not free all memory associated with

         interp_bfd.  */

      bfd_close (interp_bfd);

      return (0);

    }

  /* Now try to find our debug base symbol in this file, which we at

     least know to be a valid ELF executable or shared library. */

  for (symbolp = debug_base_symbols; *symbolp != NULL; symbolp++)

    {

      address = bfd_lookup_symbol (interp_bfd, *symbolp);

      if (address != 0)

        {

          break;

        }

    }

  if (address == 0)

    {

      /* FIXME-leak: on failure, might not free all memory associated with

         interp_bfd.  */

      bfd_close (interp_bfd);

      return (0);

    }

  /* Eureka!  We found the symbol.  But now we may need to relocate it

     by the base address.  If the symbol's value is less than the base

     address of the shared library, then it hasn't yet been relocated

     by the dynamic linker, and we have to do it ourself.  FIXME: Note

     that we make the assumption that the first segment that corresponds

     to the shared library has the base address to which the library

     was relocated. */

  if (address < baseaddr)

    {

      address += baseaddr;

    }

  debug_base = address;

  /* FIXME-leak: on failure, might not free all memory associated with

     interp_bfd.  */

  bfd_close (interp_bfd);

  return (1);

}

#endif /* HANDLE_SVR4_EXEC_EMULATORS */

/*

   LOCAL FUNCTION

   elf_locate_base -- locate the base address of dynamic linker structs

   for SVR4 elf targets.

   SYNOPSIS

   CORE_ADDR elf_locate_base (void)

   DESCRIPTION

   For SVR4 elf targets the address of the dynamic linker's runtime

   structure is contained within the dynamic info section in the

   executable file.  The dynamic section is also mapped into the

   inferior address space.  Because the runtime loader fills in the

   real address before starting the inferior, we have to read in the

   dynamic info section from the inferior address space.

   If there are any errors while trying to find the address, we

   silently return 0, otherwise the found address is returned.

 */

static CORE_ADDR

elf_locate_base (void)

{

  sec_ptr dyninfo_sect;

  int dyninfo_sect_size;

  CORE_ADDR dyninfo_addr;

  char *buf;

  char *bufend;

  int arch_size;

  /* Find the start address of the .dynamic section.  */

  dyninfo_sect = bfd_get_section_by_name (exec_bfd, ".dynamic");

  if (dyninfo_sect == NULL)

    return 0;

  dyninfo_addr = bfd_section_vma (exec_bfd, dyninfo_sect);

  /* Read in .dynamic section, silently ignore errors.  */

  dyninfo_sect_size = bfd_section_size (exec_bfd, dyninfo_sect);

  buf = alloca (dyninfo_sect_size);

  if (target_read_memory (dyninfo_addr, buf, dyninfo_sect_size))

    return 0;

  /* Find the DT_DEBUG entry in the the .dynamic section.

     For mips elf we look for DT_MIPS_RLD_MAP, mips elf apparently has

     no DT_DEBUG entries.  */

  arch_size = bfd_get_arch_size (exec_bfd);

  if (arch_size == -1)  /* failure */

    return 0;

  if (arch_size == 32)

    { /* 32-bit elf */

      for (bufend = buf + dyninfo_sect_size;

           buf < bufend;

           buf += sizeof (Elf32_External_Dyn))

        {

          Elf32_External_Dyn *x_dynp = (Elf32_External_Dyn *) buf;

          long dyn_tag;

          CORE_ADDR dyn_ptr;

          dyn_tag = bfd_h_get_32 (exec_bfd, (bfd_byte *) x_dynp->d_tag);

          if (dyn_tag == DT_NULL)

            break;

          else if (dyn_tag == DT_DEBUG)

            {

              dyn_ptr = bfd_h_get_32 (exec_bfd,

                                      (bfd_byte *) x_dynp->d_un.d_ptr);

              return dyn_ptr;

            }

          else if (dyn_tag == DT_MIPS_RLD_MAP)

            {

              char *pbuf;

              pbuf = alloca (TARGET_PTR_BIT / HOST_CHAR_BIT);

              /* DT_MIPS_RLD_MAP contains a pointer to the address

                 of the dynamic link structure.  */

              dyn_ptr = bfd_h_get_32 (exec_bfd,

                                      (bfd_byte *) x_dynp->d_un.d_ptr);

              if (target_read_memory (dyn_ptr, pbuf, sizeof (pbuf)))

                return 0;

              return extract_unsigned_integer (pbuf, sizeof (pbuf));

            }

        }

    }

  else /* 64-bit elf */

    {

      for (bufend = buf + dyninfo_sect_size;

           buf < bufend;

           buf += sizeof (Elf64_External_Dyn))

        {

          Elf64_External_Dyn *x_dynp = (Elf64_External_Dyn *) buf;

          long dyn_tag;

          CORE_ADDR dyn_ptr;

          dyn_tag = bfd_h_get_64 (exec_bfd, (bfd_byte *) x_dynp->d_tag);

          if (dyn_tag == DT_NULL)

            break;

          else if (dyn_tag == DT_DEBUG)

            {

              dyn_ptr = bfd_h_get_64 (exec_bfd,

                                      (bfd_byte *) x_dynp->d_un.d_ptr);

              return dyn_ptr;

            }

        }

    }

  /* DT_DEBUG entry not found.  */

  return 0;

}

/*

   LOCAL FUNCTION

   locate_base -- locate the base address of dynamic linker structs

   SYNOPSIS

   CORE_ADDR locate_base (void)

   DESCRIPTION

   For both the SunOS and SVR4 shared library implementations, if the

   inferior executable has been linked dynamically, there is a single

   address somewhere in the inferior's data space which is the key to

   locating all of the dynamic linker's runtime structures.  This

   address is the value of the debug base symbol.  The job of this

   function is to find and return that address, or to return 0 if there

   is no such address (the executable is statically linked for example).

   For SunOS, the job is almost trivial, since the dynamic linker and

   all of it's structures are statically linked to the executable at

   link time.  Thus the symbol for the address we are looking for has

   already been added to the minimal symbol table for the executable's

   objfile at the time the symbol file's symbols were read, and all we

   have to do is look it up there.  Note that we explicitly do NOT want

   to find the copies in the shared library.

   The SVR4 version is a bit more complicated because the address

   is contained somewhere in the dynamic info section.  We have to go

   to a lot more work to discover the address of the debug base symbol.

   Because of this complexity, we cache the value we find and return that

   value on subsequent invocations.  Note there is no copy in the

   executable symbol tables.

 */

static CORE_ADDR

locate_base (void)

{

  /* Check to see if we have a currently valid address, and if so, avoid

     doing all this work again and just return the cached address.  If

     we have no cached address, try to locate it in the dynamic info

     section for ELF executables.  */

  if (debug_base == 0)

    {

      if (exec_bfd != NULL

          && bfd_get_flavour (exec_bfd) == bfd_target_elf_flavour)

        debug_base = elf_locate_base ();

#ifdef HANDLE_SVR4_EXEC_EMULATORS

      /* Try it the hard way for emulated executables.  */

      else if (!ptid_equal (inferior_ptid, null_ptid) && target_has_execution)

        proc_iterate_over_mappings (look_for_base);

#endif

    }

  return (debug_base);

}

/*

   LOCAL FUNCTION

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

   SYNOPSIS

   static CORE_ADDR first_link_map_member (void)

   DESCRIPTION

   Find the first element in the inferior's dynamic link map, and

   return its address in the inferior.  This function doesn't copy the

   link map entry itself into our address space; current_sos actually

   does the reading.  */

static CORE_ADDR

first_link_map_member (void)

{

  CORE_ADDR lm = 0;

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  char *r_map_buf = xmalloc (lmo->r_map_size);

  struct cleanup *cleanups = make_cleanup (xfree, r_map_buf);

  read_memory (debug_base + lmo->r_map_offset, r_map_buf, lmo->r_map_size);

  lm = extract_address (r_map_buf, lmo->r_map_size);

  /* FIXME:  Perhaps we should validate the info somehow, perhaps by

     checking r_version for a known version number, or r_state for

     RT_CONSISTENT. */

  do_cleanups (cleanups);

  return (lm);

}

/*

  LOCAL FUNCTION

  open_symbol_file_object

  SYNOPSIS

  void open_symbol_file_object (void *from_tty)

  DESCRIPTION

  If no open symbol file, attempt to locate and open the main symbol

  file.  On SVR4 systems, this is the first link map entry.  If its

  name is here, we can open it.  Useful when attaching to a process

  without first loading its symbol file.

  If FROM_TTYP dereferences to a non-zero integer, allow messages to

  be printed.  This parameter is a pointer rather than an int because

  open_symbol_file_object() is called via catch_errors() and

  catch_errors() requires a pointer argument. */

static int

open_symbol_file_object (void *from_ttyp)

{

  CORE_ADDR lm, l_name;

  char *filename;

  int errcode;

  int from_tty = *(int *)from_ttyp;

  struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

  char *l_name_buf = xmalloc (lmo->l_name_size);

  struct cleanup *cleanups = make_cleanup (xfree, l_name_buf);

  if (symfile_objfile)

    if (!query ("Attempt to reload symbols from process? "))

      return 0;

  if ((debug_base = locate_base ()) == 0)

    return 0;    /* failed somehow... */

  /* First link map member should be the executable.  */

  if ((lm = first_link_map_member ()) == 0)

    return 0;    /* failed somehow... */

  /* Read address of name from target memory to GDB.  */

  read_memory (lm + lmo->l_name_offset, l_name_buf, lmo->l_name_size);

  /* Convert the address to host format.  */

  l_name = extract_address (l_name_buf, lmo->l_name_size);

  /* Free l_name_buf.  */

  do_cleanups (cleanups);

  if (l_name == 0)

    return 0;            /* No filename.  */

  /* Now fetch the filename from target memory.  */

  target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode);

  if (errcode)

    {

      warning ("failed to read exec filename from attached file: %s",

               safe_strerror (errcode));

      return 0;

    }

  make_cleanup (xfree, filename);

  /* Have a pathname: read the symbol file.  */

  symbol_file_add_main (filename, from_tty);

  return 1;

}

/* LOCAL FUNCTION

   current_sos -- build a list of currently loaded shared objects

   SYNOPSIS

   struct so_list *current_sos ()

   DESCRIPTION

   Build a list of `struct so_list' objects describing the shared

   objects currently loaded in the inferior.  This list does not

   include an entry for the main executable file.

   Note that we only gather information directly available from the

   inferior --- we don't examine any of the shared library files

   themselves.  The declaration of `struct so_list' says which fields

   we provide values for.  */

static struct so_list *

svr4_current_sos (void)

{

  CORE_ADDR lm;

  struct so_list *head = 0;

  struct so_list **link_ptr = &head;

  /* Make sure we've looked up the inferior's dynamic linker's base

     structure.  */

  if (! debug_base)

    {

      debug_base = locate_base ();

      /* If we can't find the dynamic linker's base structure, this

         must not be a dynamically linked executable.  Hmm.  */

      if (! debug_base)

        return 0;

    }

  /* Walk the inferior's link map list, and build our list of

     `struct so_list' nodes.  */

  lm = first_link_map_member ();

  while (lm)

    {

      struct link_map_offsets *lmo = SVR4_FETCH_LINK_MAP_OFFSETS ();

      struct so_list *new

        = (struct so_list *) xmalloc (sizeof (struct so_list));

      struct cleanup *old_chain = make_cleanup (xfree, new);

      memset (new, 0, sizeof (*new));

      new->lm_info = xmalloc (sizeof (struct lm_info));

      make_cleanup (xfree, new->lm_info);

      new->lm_info->lm = xmalloc (lmo->link_map_size);

      make_cleanup (xfree, new->lm_info->lm);

      memset (new->lm_info->lm, 0, lmo->link_map_size);

      read_memory (lm, new->lm_info->lm, lmo->link_map_size);

      lm = LM_NEXT (new);

      /* For SVR4 versions, the first entry in the link map is for the

         inferior executable, so we must ignore it.  For some versions of

         SVR4, it has no name.  For others (Solaris 2.3 for example), it

         does have a name, so we can no longer use a missing name to

         decide when to ignore it. */

      if (IGNORE_FIRST_LINK_MAP_ENTRY (new))

        free_so (new);

      else

        {

          int errcode;

          char *buffer;

          /* Extract this shared object's name.  */

          target_read_string (LM_NAME (new), &buffer,

                              SO_NAME_MAX_PATH_SIZE - 1, &errcode);

          if (errcode != 0)

            {

              warning ("current_sos: Can't read pathname for load map: %s\n",

                       safe_strerror (errcode));

            }

          else

            {

              strncpy (new->so_name, buffer, SO_NAME_MAX_PATH_SIZE - 1);

              new->so_name[SO_NAME_MAX_PATH_SIZE - 1] = '\0';

              xfree (buffer);

              strcpy (new->so_original_name, new->so_name);

            }

          /* If this entry has no name, or its name matches the name

             for the main executable, don't include it in the list.  */

          if (! new->so_name[0]

              || match_main (new->so_name))

            free_so (new);

          else

            {