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/* GDB routines for manipulating the minimal symbol tables.

   Copyright 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001

   Free Software Foundation, Inc.

   Contributed by Cygnus Support, using pieces from other GDB modules.

   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.  */

/* This file contains support routines for creating, manipulating, and

   destroying minimal symbol tables.

   Minimal symbol tables are used to hold some very basic information about

   all defined global symbols (text, data, bss, abs, etc).  The only two

   required pieces of information are the symbol's name and the address

   associated with that symbol.

   In many cases, even if a file was compiled with no special options for

   debugging at all, as long as was not stripped it will contain sufficient

   information to build useful minimal symbol tables using this structure.

   Even when a file contains enough debugging information to build a full

   symbol table, these minimal symbols are still useful for quickly mapping

   between names and addresses, and vice versa.  They are also sometimes used

   to figure out what full symbol table entries need to be read in. */

#include "defs.h"

#include <ctype.h>

#include "gdb_string.h"

#include "symtab.h"

#include "bfd.h"

#include "symfile.h"

#include "objfiles.h"

#include "demangle.h"

#include "value.h"

#include "cp-abi.h"

/* Accumulate the minimal symbols for each objfile in bunches of BUNCH_SIZE.

   At the end, copy them all into one newly allocated location on an objfile's

   symbol obstack.  */

#define BUNCH_SIZE 127

struct msym_bunch

  {

    struct msym_bunch *next;

    struct minimal_symbol contents[BUNCH_SIZE];

  };

/* Bunch currently being filled up.

   The next field points to chain of filled bunches.  */

static struct msym_bunch *msym_bunch;

/* Number of slots filled in current bunch.  */

static int msym_bunch_index;

/* Total number of minimal symbols recorded so far for the objfile.  */

static int msym_count;

/* Compute a hash code based using the same criteria as `strcmp_iw'.  */

unsigned int

msymbol_hash_iw (const char *string)

{

  unsigned int hash = 0;

  while (*string && *string != '(')

    {

      while (isspace (*string))

        ++string;

      if (*string && *string != '(')

        {

          hash = hash * 67 + *string - 113;

          ++string;

        }

    }

  return hash;

}

/* Compute a hash code for a string.  */

unsigned int

msymbol_hash (const char *string)

{

  unsigned int hash = 0;

  for (; *string; ++string)

    hash = hash * 67 + *string - 113;

  return hash;

}

/* Add the minimal symbol SYM to an objfile's minsym hash table, TABLE.  */

void

add_minsym_to_hash_table (struct minimal_symbol *sym,

                          struct minimal_symbol **table)

{

  if (sym->hash_next == NULL)

    {

      unsigned int hash = msymbol_hash (SYMBOL_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

      sym->hash_next = table[hash];

      table[hash] = sym;

    }

}

/* Add the minimal symbol SYM to an objfile's minsym demangled hash table,

   TABLE.  */

static void

add_minsym_to_demangled_hash_table (struct minimal_symbol *sym,

                                  struct minimal_symbol **table)

{

  if (sym->demangled_hash_next == NULL)

    {

      unsigned int hash = msymbol_hash_iw (SYMBOL_DEMANGLED_NAME (sym)) % MINIMAL_SYMBOL_HASH_SIZE;

      sym->demangled_hash_next = table[hash];

      table[hash] = sym;

    }

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME.  If OBJF is non-NULL, limit

   the search to that objfile.  If SFILE is non-NULL, limit the search

   to that source file.  Returns a pointer to the minimal symbol that

   matches, or NULL if no match is found.

   Note:  One instance where there may be duplicate minimal symbols with

   the same name is when the symbol tables for a shared library and the

   symbol tables for an executable contain global symbols with the same

   names (the dynamic linker deals with the duplication). */

struct minimal_symbol *

lookup_minimal_symbol (register const char *name, const char *sfile,

                       struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

  struct minimal_symbol *found_file_symbol = NULL;

  struct minimal_symbol *trampoline_symbol = NULL;

  unsigned int hash = msymbol_hash (name) % MINIMAL_SYMBOL_HASH_SIZE;

  unsigned int dem_hash = msymbol_hash_iw (name) % MINIMAL_SYMBOL_HASH_SIZE;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

  if (sfile != NULL)

    {

      char *p = strrchr (sfile, '/');

      if (p != NULL)

        sfile = p + 1;

    }

#endif

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile)

        {

          /* Do two passes: the first over the ordinary hash table,

             and the second over the demangled hash table.  */

        int pass;

        for (pass = 1; pass <= 2 && found_symbol == NULL; pass++)

            {

            /* Select hash list according to pass.  */

            if (pass == 1)

              msymbol = objfile->msymbol_hash[hash];

            else

              msymbol = objfile->msymbol_demangled_hash[dem_hash];

            while (msymbol != NULL && found_symbol == NULL)

                {

                if (SYMBOL_MATCHES_NAME (msymbol, name))

                    {

                    switch (MSYMBOL_TYPE (msymbol))

                      {

                      case mst_file_text:

                      case mst_file_data:

                      case mst_file_bss:

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

                        if (sfile == NULL || STREQ (msymbol->filename, sfile))

                          found_file_symbol = msymbol;

#else

                        /* We have neither the ability nor the need to

                           deal with the SFILE parameter.  If we find

                           more than one symbol, just return the latest

                           one (the user can't expect useful behavior in

                           that case).  */

                        found_file_symbol = msymbol;

#endif

                        break;

                      case mst_solib_trampoline:

                        /* If a trampoline symbol is found, we prefer to

                           keep looking for the *real* symbol. If the

                           actual symbol is not found, then we'll use the

                           trampoline entry. */

                        if (trampoline_symbol == NULL)

                          trampoline_symbol = msymbol;

                        break;

                      case mst_unknown:

                      default:

                        found_symbol = msymbol;

                        break;

                      }

                    }

                /* Find the next symbol on the hash chain.  */

                if (pass == 1)

                  msymbol = msymbol->hash_next;

                else

                  msymbol = msymbol->demangled_hash_next;

                }

            }

        }

    }

  /* External symbols are best.  */

  if (found_symbol)

    return found_symbol;

  /* File-local symbols are next best.  */

  if (found_file_symbol)

    return found_file_symbol;

  /* Symbols for shared library trampolines are next best.  */

  if (trampoline_symbol)

    return trampoline_symbol;

  return NULL;

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME and of text type.

   If OBJF is non-NULL, limit

   the search to that objfile.  If SFILE is non-NULL, limit the search

   to that source file.  Returns a pointer to the minimal symbol that

   matches, or NULL if no match is found.

 */

struct minimal_symbol *

lookup_minimal_symbol_text (register const char *name, const char *sfile,

                            struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

  struct minimal_symbol *found_file_symbol = NULL;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

  if (sfile != NULL)

    {

      char *p = strrchr (sfile, '/');

      if (p != NULL)

        sfile = p + 1;

    }

#endif

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile)

        {

          for (msymbol = objfile->msymbols;

               msymbol != NULL && SYMBOL_NAME (msymbol) != NULL &&

               found_symbol == NULL;

               msymbol++)

            {

              if (SYMBOL_MATCHES_NAME (msymbol, name) &&

                  (MSYMBOL_TYPE (msymbol) == mst_text ||

                   MSYMBOL_TYPE (msymbol) == mst_file_text))

                {

                  switch (MSYMBOL_TYPE (msymbol))

                    {

                    case mst_file_text:

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

                      if (sfile == NULL || STREQ (msymbol->filename, sfile))

                        found_file_symbol = msymbol;

#else

                      /* We have neither the ability nor the need to

                         deal with the SFILE parameter.  If we find

                         more than one symbol, just return the latest

                         one (the user can't expect useful behavior in

                         that case).  */

                      found_file_symbol = msymbol;

#endif

                      break;

                    default:

                      found_symbol = msymbol;

                      break;

                    }

                }

            }

        }

    }

  /* External symbols are best.  */

  if (found_symbol)

    return found_symbol;

  /* File-local symbols are next best.  */

  if (found_file_symbol)

    return found_file_symbol;

  return NULL;

}

/* Look through all the current minimal symbol tables and find the

   first minimal symbol that matches NAME and of solib trampoline type.

   If OBJF is non-NULL, limit

   the search to that objfile.  If SFILE is non-NULL, limit the search

   to that source file.  Returns a pointer to the minimal symbol that

   matches, or NULL if no match is found.

 */

struct minimal_symbol *

lookup_minimal_symbol_solib_trampoline (register const char *name,

                                        const char *sfile, struct objfile *objf)

{

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *found_symbol = NULL;

#ifdef SOFUN_ADDRESS_MAYBE_MISSING

  if (sfile != NULL)

    {

      char *p = strrchr (sfile, '/');

      if (p != NULL)

        sfile = p + 1;

    }

#endif

  for (objfile = object_files;

       objfile != NULL && found_symbol == NULL;

       objfile = objfile->next)

    {

      if (objf == NULL || objf == objfile)

        {

          for (msymbol = objfile->msymbols;

               msymbol != NULL && SYMBOL_NAME (msymbol) != NULL &&

               found_symbol == NULL;

               msymbol++)

            {

              if (SYMBOL_MATCHES_NAME (msymbol, name) &&

                  MSYMBOL_TYPE (msymbol) == mst_solib_trampoline)

                return msymbol;

            }

        }

    }

  return NULL;

}

/* Search through the minimal symbol table for each objfile and find

   the symbol whose address is the largest address that is still less

   than or equal to PC, and matches SECTION (if non-null).  Returns a

   pointer to the minimal symbol if such a symbol is found, or NULL if

   PC is not in a suitable range.  Note that we need to look through

   ALL the minimal symbol tables before deciding on the symbol that

   comes closest to the specified PC.  This is because objfiles can

   overlap, for example objfile A has .text at 0x100 and .data at

   0x40000 and objfile B has .text at 0x234 and .data at 0x40048.  */

struct minimal_symbol *

lookup_minimal_symbol_by_pc_section (CORE_ADDR pc, asection *section)

{

  int lo;

  int hi;

  int new;

  struct objfile *objfile;

  struct minimal_symbol *msymbol;

  struct minimal_symbol *best_symbol = NULL;

  /* pc has to be in a known section. This ensures that anything beyond

     the end of the last segment doesn't appear to be part of the last

     function in the last segment.  */

  if (find_pc_section (pc) == NULL)

    return NULL;

  for (objfile = object_files;

       objfile != NULL;

       objfile = objfile->next)

    {

      /* If this objfile has a minimal symbol table, go search it using

         a binary search.  Note that a minimal symbol table always consists

         of at least two symbols, a "real" symbol and the terminating

         "null symbol".  If there are no real symbols, then there is no

         minimal symbol table at all. */

      if ((msymbol = objfile->msymbols) != NULL)

        {

          lo = 0;

          hi = objfile->minimal_symbol_count - 1;

          /* This code assumes that the minimal symbols are sorted by

             ascending address values.  If the pc value is greater than or

             equal to the first symbol's address, then some symbol in this

             minimal symbol table is a suitable candidate for being the

             "best" symbol.  This includes the last real symbol, for cases

             where the pc value is larger than any address in this vector.

             By iterating until the address associated with the current

             hi index (the endpoint of the test interval) is less than

             or equal to the desired pc value, we accomplish two things:

             (1) the case where the pc value is larger than any minimal

             symbol address is trivially solved, (2) the address associated

             with the hi index is always the one we want when the interation

             terminates.  In essence, we are iterating the test interval

             down until the pc value is pushed out of it from the high end.

             Warning: this code is trickier than it would appear at first. */

          /* Should also require that pc is <= end of objfile.  FIXME! */

          if (pc >= SYMBOL_VALUE_ADDRESS (&msymbol[lo]))

            {

              while (SYMBOL_VALUE_ADDRESS (&msymbol[hi]) > pc)

                {

                  /* pc is still strictly less than highest address */

                  /* Note "new" will always be >= lo */

                  new = (lo + hi) / 2;

                  if ((SYMBOL_VALUE_ADDRESS (&msymbol[new]) >= pc) ||

                      (lo == new))

                    {

                      hi = new;

                    }

                  else

                    {

                      lo = new;

                    }

                }

              /* If we have multiple symbols at the same address, we want

                 hi to point to the last one.  That way we can find the

                 right symbol if it has an index greater than hi.  */

              while (hi < objfile->minimal_symbol_count - 1

                     && (SYMBOL_VALUE_ADDRESS (&msymbol[hi])

                         == SYMBOL_VALUE_ADDRESS (&msymbol[hi + 1])))

                hi++;

              /* The minimal symbol indexed by hi now is the best one in this

                 objfile's minimal symbol table.  See if it is the best one

                 overall. */

              /* Skip any absolute symbols.  This is apparently what adb

                 and dbx do, and is needed for the CM-5.  There are two

                 known possible problems: (1) on ELF, apparently end, edata,

                 etc. are absolute.  Not sure ignoring them here is a big

                 deal, but if we want to use them, the fix would go in

                 elfread.c.  (2) I think shared library entry points on the

                 NeXT are absolute.  If we want special handling for this

                 it probably should be triggered by a special

                 mst_abs_or_lib or some such.  */

              while (hi >= 0

                     && msymbol[hi].type == mst_abs)

                --hi;

              /* If "section" specified, skip any symbol from wrong section */

              /* This is the new code that distinguishes it from the old function */

              if (section)

                while (hi >= 0

                       /* Some types of debug info, such as COFF,

                          don't fill the bfd_section member, so don't

                          throw away symbols on those platforms.  */

                       && SYMBOL_BFD_SECTION (&msymbol[hi]) != NULL

                       && SYMBOL_BFD_SECTION (&msymbol[hi]) != section)

                  --hi;

              if (hi >= 0

                  && ((best_symbol == NULL) ||

                      (SYMBOL_VALUE_ADDRESS (best_symbol) <

                       SYMBOL_VALUE_ADDRESS (&msymbol[hi]))))

                {

                  best_symbol = &msymbol[hi];

                }

            }

        }

    }

  return (best_symbol);

}

/* Backward compatibility: search through the minimal symbol table

   for a matching PC (no section given) */

struct minimal_symbol *

lookup_minimal_symbol_by_pc (CORE_ADDR pc)

{

  return lookup_minimal_symbol_by_pc_section (pc, find_pc_mapped_section (pc));

}

/* Return leading symbol character for a BFD. If BFD is NULL,

   return the leading symbol character from the main objfile.  */

static int get_symbol_leading_char (bfd *);

static int

get_symbol_leading_char (bfd *abfd)

{

  if (abfd != NULL)

    return bfd_get_symbol_leading_char (abfd);

  if (symfile_objfile != NULL && symfile_objfile->obfd != NULL)

    return bfd_get_symbol_leading_char (symfile_objfile->obfd);

  return 0;

}

/* Prepare to start collecting minimal symbols.  Note that presetting

   msym_bunch_index to BUNCH_SIZE causes the first call to save a minimal

   symbol to allocate the memory for the first bunch. */

void

init_minimal_symbol_collection (void)

{

  msym_count = 0;

  msym_bunch = NULL;

  msym_bunch_index = BUNCH_SIZE;

}

void

prim_record_minimal_symbol (const char *name, CORE_ADDR address,

                            enum minimal_symbol_type ms_type,

                            struct objfile *objfile)

{

  int section;

  switch (ms_type)

    {

    case mst_text:

    case mst_file_text:

    case mst_solib_trampoline:

      section = SECT_OFF_TEXT (objfile);

      break;

    case mst_data:

    case mst_file_data:

      section = SECT_OFF_DATA (objfile);

      break;

    case mst_bss:

    case mst_file_bss:

      section = SECT_OFF_BSS (objfile);

      break;

    default:

      section = -1;

    }

  prim_record_minimal_symbol_and_info (name, address, ms_type,

                                       NULL, section, NULL, objfile);

}

/* Record a minimal symbol in the msym bunches.  Returns the symbol

   newly created.  */

struct minimal_symbol *

prim_record_minimal_symbol_and_info (const char *name, CORE_ADDR address,

                                     enum minimal_symbol_type ms_type,

                                     char *info, int section,

                                     asection *bfd_section,

                                     struct objfile *objfile)

{

  register struct msym_bunch *new;

  register struct minimal_symbol *msymbol;

  if (ms_type == mst_file_text)

    {

      /* Don't put gcc_compiled, __gnu_compiled_cplus, and friends into

         the minimal symbols, because if there is also another symbol

         at the same address (e.g. the first function of the file),

         lookup_minimal_symbol_by_pc would have no way of getting the

         right one.  */

      if (name[0] == 'g'

          && (strcmp (name, GCC_COMPILED_FLAG_SYMBOL) == 0

              || strcmp (name, GCC2_COMPILED_FLAG_SYMBOL) == 0))

        return (NULL);

      {

        const char *tempstring = name;

        if (tempstring[0] == get_symbol_leading_char (objfile->obfd))

          ++tempstring;

        if (STREQN (tempstring, "__gnu_compiled", 14))

          return (NULL);

      }

    }

  if (msym_bunch_index == BUNCH_SIZE)

    {

      new = (struct msym_bunch *) xmalloc (sizeof (struct msym_bunch));

      msym_bunch_index = 0;

      new->next = msym_bunch;

      msym_bunch = new;

    }

  msymbol = &msym_bunch->contents[msym_bunch_index];

  SYMBOL_NAME (msymbol) = obsavestring ((char *) name, strlen (name),

                                        &objfile->symbol_obstack);

  SYMBOL_INIT_LANGUAGE_SPECIFIC (msymbol, language_unknown);

  SYMBOL_VALUE_ADDRESS (msymbol) = address;

  SYMBOL_SECTION (msymbol) = section;

  SYMBOL_BFD_SECTION (msymbol) = bfd_section;

  MSYMBOL_TYPE (msymbol) = ms_type;

  /* FIXME:  This info, if it remains, needs its own field.  */

  MSYMBOL_INFO (msymbol) = info;        /* FIXME! */

  /* The hash pointers must be cleared! If they're not,

     add_minsym_to_hash_table will NOT add this msymbol to the hash table. */

  msymbol->hash_next = NULL;

  msymbol->demangled_hash_next = NULL;

  msym_bunch_index++;

  msym_count++;

  OBJSTAT (objfile, n_minsyms++);

  return msymbol;

}

/* Compare two minimal symbols by address and return a signed result based

   on unsigned comparisons, so that we sort into unsigned numeric order.

   Within groups with the same address, sort by name.  */

static int

compare_minimal_symbols (const void *fn1p, const void *fn2p)

{

  register const struct minimal_symbol *fn1;

  register const struct minimal_symbol *fn2;

  fn1 = (const struct minimal_symbol *) fn1p;

  fn2 = (const struct minimal_symbol *) fn2p;

  if (SYMBOL_VALUE_ADDRESS (fn1) < SYMBOL_VALUE_ADDRESS (fn2))

    {

      return (-1);              /* addr 1 is less than addr 2 */

    }

  else if (SYMBOL_VALUE_ADDRESS (fn1) > SYMBOL_VALUE_ADDRESS (fn2))

    {

      return (1);               /* addr 1 is greater than addr 2 */

    }

  else

    /* addrs are equal: sort by name */

    {

      char *name1 = SYMBOL_NAME (fn1);

      char *name2 = SYMBOL_NAME (fn2);

      if (name1 && name2)       /* both have names */

        return strcmp (name1, name2);

      else if (name2)

        return 1;               /* fn1 has no name, so it is "less" */

      else if (name1)           /* fn2 has no name, so it is "less" */

        return -1;

      else

        return (0);              /* neither has a name, so they're equal. */

    }

}

/* Discard the currently collected minimal symbols, if any.  If we wish

   to save them for later use, we must have already copied them somewhere

   else before calling this function.

   FIXME:  We could allocate the minimal symbol bunches on their own

   obstack and then simply blow the obstack away when we are done with

   it.  Is it worth the extra trouble though? */

static void

do_discard_minimal_symbols_cleanup (void *arg)

{

  register struct msym_bunch *next;

  while (msym_bunch != NULL)

    {

      next = msym_bunch->next;

      xfree (msym_bunch);

      msym_bunch = next;

    }

}

struct cleanup *

make_cleanup_discard_minimal_symbols (void)

{

  return make_cleanup (do_discard_minimal_symbols_cleanup, 0);

}

/* Compact duplicate entries out of a minimal symbol table by walking

   through the table and compacting out entries with duplicate addresses

   and matching names.  Return the number of entries remaining.

   On entry, the table resides between msymbol[0] and msymbol[mcount].

   On exit, it resides between msymbol[0] and msymbol[result_count].

   When files contain multiple sources of symbol information, it is

   possible for the minimal symbol table to contain many duplicate entries.

   As an example, SVR4 systems use ELF formatted object files, which

   usually contain at least two different types of symbol tables (a

   standard ELF one and a smaller dynamic linking table), as well as

   DWARF debugging information for files compiled with -g.

   Without compacting, the minimal symbol table for gdb itself contains

   over a 1000 duplicates, about a third of the total table size.  Aside

   from the potential trap of not noticing that two successive entries

   identify the same location, this duplication impacts the time required

   to linearly scan the table, which is done in a number of places.  So we

   just do one linear scan here and toss out the duplicates.

   Note that we are not concerned here about recovering the space that

   is potentially freed up, because the strings themselves are allocated

   on the symbol_obstack, and will get automatically freed when the symbol

   table is freed.  The caller can free up the unused minimal symbols at

   the end of the compacted region if their allocation strategy allows it.

   Also note we only go up to the next to last entry within the loop

   and then copy the last entry explicitly after the loop terminates.

   Since the different sources of information for each symbol may

   have different levels of "completeness", we may have duplicates

   that have one entry with type "mst_unknown" and the other with a

   known type.  So if the one we are leaving alone has type mst_unknown,

   overwrite its type with the type from the one we are compacting out.  */